DÄ internationalArchive46/2016Unnecessary Investigations in Environmental Medicine

Original article

Unnecessary Investigations in Environmental Medicine

A Retrospective Cohort Study

Dtsch Arztebl Int 2016; 113: 773-80. DOI: 10.3238/arztebl.2016.0773

Greiner, A; Drexler, H

Background: Patients in environmental medicine often want a thorough diagnostic evaluation of nonspecific symptoms. Unconventional testing, as well as conventional testing for indications other than the established ones, can lead to false diagnoses and, in turn, to substantial emotional, social, and financial harm. The goal of this single-center study was to assess inappropriate diagnostic testing among the patients of a specialized university outpatient clinic for environmental medicine.

Methods: The charts of 653 consecutive outpatients seen in the institute and outpatient clinic of occupational, social, and environmental medicine in Erlangen from 2010 to 2015 were evaluated, and inappropriate diagnostic tests were assessed.

Results: 9% of the patients had received at least one inappropriate diagnostic test. The most common one was an inappropriate heavy-metal test (26%), followed by an inappropriately ordered hair analysis (15%) and biomonitoring in the blood or urine with an erroneous choice of the testing matrix or an erroneous interpretation of the findings (15%). Biomonitoring performed by us did not confirm the suspected environmental diagnosis in any case. Laboratory values exceeding the normal limits were rarer among these patients than in the patients for whom we considered biomonitoring to be indicated without any pretesting.

Conclusion: An appreciable number of patients in environmental medicine were subjected to inappropriate diagnostic testing. When this happens, proper testing often needs to be done thereafter in order to confirm or refute the findings. This phenomenon should be more thoroughly assessed and quantified.

LNSLNS

One of the tasks of the physician is to explain the role and importance of the wide variety of medical tests that may be recommended to any given patient. Particularly in the field of environmental medicine, patients often demand investigations to determine the cause of unspecific symptoms (1) or bring previous findings with them to the first consultation. In accordance with the obligation to “first, do no harm,” patients must be protected from a detrimental excess of medical procedures; this is termed “quaternary prevention” (2, 3). Together with painstaking documentation of the patient's history, the correct choice and conduct of diagnostic tests is crucial (1, 4, 5). Use of unvalidated methods or faulty interpretation of findings may lead to incorrect diagnoses and superfluous treatments, and in our experience can have damaging mental, social, and financial consequences for patients (4, 68). We therefore decided to find out which of the diagnostic investigations previously carried out in patients who consulted us had been inappropriate (i.e., scientifically unjustified) and how often such unnecessary procedures had been performed.

Methods

We evaluated the records of all 653 patients who attended the outpatient clinic of the Institute of Occupational, Social, and Environmental Medicine of the Friedrich Alexander University of Erlangen between September 2010 and December 2015. All of these patients had been referred by physicians in private practice. In many cases the patients' problems could not be classified as purely occupational, social, or environmental, and two or all three fields were involved. For this reason, no attempt was made to divide the sample into environmental, occupational, and social subgroups. No occupational medicine screening and no assessments of occupational fitness were carried out in our outpatient clinic in these patients.

We inspected the patients' records for previous inappropriate investigations. Diagnostic procedures were classified as inappropriate if they were unconventional, i.e., not scientifically established, or conventional but used outside the established indications. Classification of the methods was based on publications of the Robert Koch Institute, statements issued by medical societies or commissions, and other scientific publications.

Every patient's age, sex, insurance status, and employment status were ascertained. Employment status was classified as employed, unemployed, unfit for work, retired, or other/unknown. The employed group contained those engaged in paid work. Those with jobs but currently unfit for work were assigned to a separate group because their work incapacity was often a long-term situation. Furthermore, we documented how often we had ordered biomonitoring during the course of outpatient consultations, i.e., quantitative investigation of xenobiotics or their metabolites in samples (usually of blood or urine) from patients, and whether any reference levels or thresholds were found to have been exceeded. The criterion for a given substance was, if available, the reference value for background exposure of the general population from the environmental survey of the German Federal Environment Agency. The reference value is the 95th percentile of all concentrations of a xenobiotic or metabolite of a xenobiotic from a representative sample of the general population or a population group (9). If no reference value was available for a given substance, we took the reference values for biological substances of the German Research Foundation's Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area. These reference values for biological substances describe the “background exposure to [a] substance at a particular time in a reference population comprising persons of working age with no occupational exposure to the substance” (10) and are defined, in analogy to the reference values laid down by the Human Biomonitoring Commission of the German Federal Environment Agency, by the 95th percentile of the concentration of the substance or metabolite. Neither the reference values of the Human Biomonitoring Commission nor the reference values for biological substances take any account of possible effects on health. Exceeding these values by no means implies a health hazard (9).

Moreover, we looked for cases where threshold values were exceeded. Threshold values, in contrast to reference values, have toxicological significance. Primarily the HBM-I and HBM-II threshold values published by the Human Biomonitoring Commission were used (9) (Table 1).

Interpretation of the HBM categories of the German Federal Environment Agency (adapted from [9])
Table 1
Interpretation of the HBM categories of the German Federal Environment Agency (adapted from [9])

The patients in whom inappropriate diagnostic investigations had been performed were compared with the remaining patients in the cohort, referred to hereinafter as the comparison group. Statistical analyses were carried out using SPSS Statistics 23 with Fisher's exact test to determine differences. We did not set an α level (significance level) with Bonferroni correction; the p values presented are descriptive.

Furthermore, we carried out a systematic survey of the available literature using the PubMed database and the search engine Google (google.de for German, google.com for English). We searched for a total of 23 terms. Only publications in German or English were included. If any of these referred to further relevant texts, those too were inspected.

Results

We identified nine categories of inappropriate investigations that according to the present state of knowledge (1136) had no or only little relevance to the patient's symptoms. These procedures had been used in 57 (9%) of the 653 patients in the cohort. In some cases two or more such investigations had been carried out in the same patient, yielding a total of 65 procedures in 57 patients. Repeated use of the same procedure in the same patient was not documented owing to the frequent lack of precision in the medical records. Table 2 shows the types of investigations and how often they were used.

The inappropriate investigations used in patients of the cohort
Table 2
The inappropriate investigations used in patients of the cohort

Some of the investigations have scientifically established uses but are often applied inappropriately. Box 1 gives an overview of the indications and limitations of these techniques. New findings and technical advances may modify the indications. Our statements regarding indications and inappropriate use (Box 1) are based on the current state of knowledge.

Supplementary information
Box 2
Supplementary information
Inappropriate use of scientifically established procedures in the patients of the cohort
Box 1
Inappropriate use of scientifically established procedures in the patients of the cohort

There are no scientifically recognized indications for bioresonance, applied kinesiology, or pendulum divination (22, 2836).

Bioresonance techniques are based on the premise that human beings and also potential allergens radiate an ultra-fine spectrum of oscillations that cannot be detected using conventional physical means of measurement. The “resonance pattern” is assessed with the aid of a sensor (28). In accordance with the guidelines of the Joint Federal Committee on Investigation and Treatment Techniques in Private Practice (Gemeinsamer Bundesausschuss zu Untersuchungs- und Behandlungsmethoden der vertragsärztlichen Versorgung), bioresonance is not covered by health insurance (29).

Applied kinesiology assesses the reaction of a muscle to manual pressure exerted by the investigator while the patient is touching, for example, a suspected allergen (32).

There are various techniques of pendulum divination. For example, the investigator may concentrate on the question concerned while suspending an unrestrained pendulum. The meanings of the various possible movements of the pendulum are determined in advance (22, 36).

In the course of consultation in the outpatient clinic, validated biomonitoring to confirm a suspected diagnosis was found to be indicated in 70% (40/57) of the patients with previous inappropriate investigations and in 26% (157/596) of those in the comparison group. Reference values were exceeded in only 13% (5/40) of patients in the inappropriate investigations group, and in no case were health-related threshold values exceeded. In the comparison group reference values were exceeded around twice as often, i.e., in 26% of patients (p = 0.093) (Table 3), and in two cases, both associated with occupational exposure, threshold values were exceeded.

Comparison of the patients with and without inappropriate investigations: biomonitoring, employment status, age, sex, and type of health insurance
Table 3
Comparison of the patients with and without inappropriate investigations: biomonitoring, employment status, age, sex, and type of health insurance

The two groups had comparable age structures (median: 48 years in the inappropriate investigations group versus 46 years in the comparison group; upper quartile: 56 versus 54 years; lower quartile: 37 versus 35 years). The proportion of women was higher in the inappropriate investigations group (60% versus 43%, p = 0.025). Among patients with previous inappropriate diagnostic procedures the proportion with private health insurance was 25%, against only 13% in the comparison group (p = 0.025).

With regard to employment status, the most obvious features were the lower proportion of patients in employment (47.4% versus 72.1%, p = 0.0002) and the higher rates of work incapacity (10.5% versus 3.0%, p = 0.013) and unemployment (15.8% versus 4.2%, p = 0.001) in the inappropriate investigations group. The proportion of patients who had retired from work was slightly higher (10.5% versus 6.0%; p = 0.250), and there was hardly any difference between the groups in the proportion of patients whose employment status was other/unknown (15.8% versus 14.6%; p = 0.844).

The systematic literature search for information on the application of unconventional diagnostic techniques identified 2456 publications, of which seven contained data on the frequency of such methods. The essential contents of these studies are shown in Table 4.

Data on the frequency with which unconventional or unconventionally applied investigations have been used in other environmental medicine facilities
Table 4
Data on the frequency with which unconventional or unconventionally applied investigations have been used in other environmental medicine facilities

Furthermore, statements on unconventional diagnostic procedures issued by leading institutions in Germany and other countries also yield information regarding the use of these methods (Table 5).

Statements/recommendations from leading institutions in Germany and other countries that refer to unconventional diagnostic procedures
Table 5
Statements/recommendations from leading institutions in Germany and other countries that refer to unconventional diagnostic procedures

The report of the Committee on Education, Research, and Technology Assessment of to the Parliament of the Federal Republic of Germany notes that some patients turn to unconventional procedures because of a frequent lack of reliable findings in the field of environmental medicine (e17). In Germany a dedicated committee of the Robert Koch Institute, the Committee on Methods and Quality Assurance in Environmental Medicine, has been set up to prepare statements and expert opinions on this topic (13).

Numerous publications mention that the use of unconventional methods is widespread without providing numerical data (e.g., 12, 13, e6, e18–e23). For example, the Italian researcher de Luca notes that ever-growing numbers of patients in many countries are being subjected to the uncontrolled application of diagnostic and therapeutic procedures that have neither been adequately validated nor shown to be safe and clinically efficacious (e24).

Discussion

Before any diagnostic method is used in patients, its validity, reproducibility, analytic accuracy, sensitivity, and specificity, among other characteristics, should be tested and evaluated (5).

The inappropriate investigations described above were retrospectively identified in the cohort of patients seen in our outpatient clinic. It is highly likely that not all patients report all the diagnostic procedures they have resorted to in the past. Techniques far beyond the bounds of scientific medical practice may have been mentioned less often than unconventional application of verified scientific methods. Overall, the number of patients who used inappropriate investigations is probably higher than presented here. Given that not all of the patients cared for by alternative medical therapists also consult qualified university-based physicians, it can be assumed that such methods are actually applied far more often in patients with suspected environment-related illnesses.

The systematic literature survey showed that the data on the frequency of inappropriate diagnostic procedures and their consequences for patients and for healthcare and social services are sparse. Unconventional means of diagnosis were documented more often in the environmental medicine clinic of the Hesse Center for Clinical Environmental Medicine at Giessen University Hospital than in our cohort. In view of the small case numbers, percentages may vary widely; nevertheless, both here and in the Giessen publications, results are reported in percentages for the sake of comprehensibility. Furthermore, the patient populations were not identical in composition, in that our outpatient clinic covers occupational and social medicine as well as environmental medicine. Presumably the collectives in the four surveys carried out in the Giessen environmental medicine clinic overlapped.

Although biomonitoring had to be carried out more frequently in patients with a history of inappropriate investigations, to exclude exposure or just to reassure the patient, reference values were exceeded much less often than among patients in whom physicians from our hospital ordered biomonitoring without regard to previous findings. In the latter group, biomonitoring was indicated on the basis of a history of exposure or symptoms. It cannot be completely excluded that exposure decreased between the time of the previous diagnostic procedures and our investigation and that this explains the lower number of cases where reference values were exceeded and the lack of findings exceeding threshold values in patients who underwent biomonitoring in our outpatient clinic. However, the patients still had symptoms. If exposure had decreased, one would expect the symptoms to be less severe.

Overall, our cohort contained more men than women. In contrast, the study by Hornberg et al. (e25) showed a predominance of women among the patients visiting environmental medicine clinics or using information services. Inspection of the records from our own hospital for the period 1979 to 1992 revealed that 55% of the patients with complaints suspected to be of environmental origin were women. The lower proportion of women in the present collective may be due to the fact that our clinic also covers occupational and social medicine. Our group of patients with previous inappropriate investigations contained more women than men. Women form 51% of the population in Germany (e26). There are no data that might show whether the sex ratio at comparable clinics or information services has changed in the intervening years.

The proportion of privately insured patients was almost twice as high in the group of patients with previous inappropriate investigations. This may be explained by socioeconomic factors. A number of the above-mentioned diagnostic techniques and the treatments associated with them are not covered by statutory health insurers (e27), whereas with private insurance reimbursement depends on the terms of the contract. However, the follow-up costs (further diagnostic procedures, unnecessary treatment) of inappropriate investigations are generally borne by the insurers.

A striking finding was the much higher rates of work incapacity (10.5%) and unemployment (15.8%) in the group of patients with a history of inappropriate investigations. In comparison, the unemployment rate in Germany in January 2016 was 6.7% (e28). Studies are required to determine whether the work incapacity and unemployment are causes or effects of resorting to inappropriate diagnostic procedures.

Limitations

Our study was restricted to a single center. The extent to which the results are valid for environmental medicine outpatient clinics in general is unknown. Patients cannot attend our clinic without being referred by a physician. There may therefore be a selection effect, particularly with regard to the kind of patients who place themselves in the hands of alternative medical therapists and tend to take a skeptical view of scientific, university-based medicine. Our clinic is not devoted purely to environmental medicine but also covers occupational and social medicine; as a rule, consultations involve all three aspects. Some patients with previous inappropriate investigations suspected that their symptoms arose from workplace exposure. Differences between our patients and those attending clinics dedicated to environmental medicine alone cannot be excluded.

Conclusion

Inappropriate diagnostic procedures are used in a significant proportion of environmental medicine patients. They lead to insecurity on the part of the patients and to false diagnoses. One can only speculate what the socioeconomic consequences might be.

To improve quaternary prevention, both patients and therapists must receive better information. Adequate biomonitoring requires, among other things, knowledge of the following: the validity of the analytical method involved, the appropriate investigation materials, the half-life of the xenobiotic concerned, and the relevant reference values and toxicologically derived assessment values (9).

Much more research is needed into the diagnostic procedures used in environmental medicine and the consequences of inappropriate investigations for the healthcare and social insurance systems. It is important that medical students continue to receive well-grounded basic instruction in this field. The methods used in medicine can change rapidly, so the future physician must acquire the scientific acumen required to evaluate the validity of new techniques.

University environmental medicine facilities give advice to patients who have been subjected to inappropriate procedures or are seeking diagnostic investigation of symptoms that may be of environmental origin. These clinics counter the negative effects of inappropriate investigations. Effective cooperation with the primary care physician and potentially with colleagues from other specialties is vital. University-based environmental medicine clinics generally run at a loss, but probably reduce overall expenditure on health.

Conflict of interest statement

The authors declare that no conflict of interest exists.

Manuscript submitted on 15 June 2016, revised version accepted on
30 August 2016

Translated from the original German by Caroline Shimakawa-Devitt, M.A.

Corresponding author

Dr. med. Annette Greiner
Institut und Poliklinik für Arbeits-, Sozial- und Umweltmedizin

Universität Erlangen-Nürnberg

Schillerstr. 29,
91054 Erlangen, Germany

annette.greiner@fau.de

@Supplementary material
For eReferences please refer to:
www.aerzteblatt-international.de/ref4616

1.
Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Untersuchungsgang in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2001; 44: 1209–16 CrossRef
2.
Jamoulle M: Quaternary prevention, an answer of family doctors to overmedicalization. Int J Health Policy Manag 2015; 4: 61–4 CrossRef MEDLINE PubMed Central
3.
Kühnlein T: Prävention in der Allgemeinmedizin. Bayer Arztebl 2014; 6: 304–9.
4.
Herr C, Otterbach I, Nowak D, Hornberg C, Eikmann T, Wiesmüller GA: Clinical environmental medicine. Dtsch Arztebl Int 2008; 105: 523–31 VOLLTEXT
5.
Kleine-Tebbe J, Herold DA: Ungeeignete Testverfahren in der Allergologie. Hautarzt 2010; 61: 961–6 CrossRef MEDLINE
6.
Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Leitlinien diagnostische Validität. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2008; 51: 1353–6 CrossRef MEDLINE
7.
Drexler H, Göen T: Interpretation von toxikologischen Daten in der klinischen Umweltmedizin. Dtsch Med Wochenschr 1998; 123: 807–13 CrossRef MEDLINE
8.
Wrbitzky R, Drexler H, Letzel S, Gräf W, Lehnert G: Umweltmedizin – Eine Standortbestimmung. Dtsch Arztebl 1996; 93: 2456 VOLLTEXT
9.
AWMF online: Umweltmedizinische Leitlinie Human-Biomonitoring. Leitlinie der Deutschen Gesellschaft für Arbeitsmedizin und Umweltmedizin e. V. (DGAUM). Stand 9/2011. www.awmf.org/uploads/tx_szleitlinien/002–024l_S1_Human_Biomonitoring_2011–10.pdf (last accessed on 19 May 2016).
10.
Deutsche Forschungsgemeinschaft (DFG). Ständige Senatskommission zur Prüfung gesundheitsschädlicher Arbeitsstoffe: MAK- und BAT-Werte-Liste 2016. Weinheim: Wiley-VCH 2016.
11.
American College of Medical Toxicology position statement on post-chelator challenge urinary metal testing. J Med Toxicol 2010; 6: 74–5 CrossRef MEDLINE PubMed Central
12.
Ruha AM: Recommendations for provoked challenge urine testing.
J Med Toxicol 2013; 9: 318–25 CrossRef MEDLINE PubMed Central
13.
Eis D: Methoden und Qualitätssicherung in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2000; 43: 336–42 CrossRef
14.
Kommission „Human-Biomonitoring“ des Umweltbundesamtes: Einsatz von Chelatbildnern in der Umweltmedizin? Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 1999; 42: 823–4 CrossRef
15.
Heyl GmbH: Fachinformation „Dimaval (DMPS) 100 mg Hartkapseln“. Stand Dezember 2014.
16.
Kommission „Human-Biomonitoring“ des Umweltbundesamtes: Haaranalyse in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2005; 48: 246–50 CrossRef
17.
Triebig G, Drexler H, Letzel S, Nowak D: Biomonitoring in Arbeitsmedizin und Umweltmedizin. München: Ecomed-Verlag 2012 MEDLINE
18.
Schaller KH: Quecksilberverbindungen, organische, Addendum [BAT value documentation in German language, 2003]. The MAK Collection for Occupational Health and Safety 2012: 11–3.
19.
Drexler H, Schaller KH: Haaranalysen in der klinischen Umweltmedizin: Eine kritische Betrachtung. Dtsch Arztebl 2002; 99: 3026 VOLLTEXT
20.
Kruse-Jarres JD: Interpretation von Haaranalysen: Rückschlüsse auf den Stoffwechsel unmöglich. Dtsch Arztebl 1997; 94: 2180 VOLLTEXT
21.
Seidel S, Kreutzer R, Smith D, McNeel S, Gilliss D: Assessment of commercial laboratories performing hair mineral analysis. JAMA 2001; 285: 67–72 CrossRef
22.
Ernst E: Komplementärmedizinische Diagnoseverfahren.
Dtsch Arztebl 2005; 102: 3034–7 VOLLTEXT
23.
Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Diagnostische Relevanz des Lymphozytentransformationstestes in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2002; 45: 745–9 CrossRef
24.
Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Qualitätssicherung beim Lymphozytentransformationstest – Addendum zum LTT-Papier. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2008; 51: 1070–76 CrossRef MEDLINE
25.
Renz H: Kurzfassung des Positionspapiers der DGAI: In-vitro-Diagnostik allergischer Erkrankungen. Klinikarzt 2003; 32: 119–23 CrossRef
26.
Michalke B, Rossbach B, Goen T, Schaferhenrich A, Scherer G: Saliva as a matrix for human biomonitoring in occupational and environmental medicine. Int Arch Occup Environ Health 2015; 88: 1–44 CrossRef MEDLINE
27.
Kommission „Human-Biomonitoring“ des Umweltbundesamtes: „Speicheltest“ – Quecksilberbelastung durch Amalgamfüllungen. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 1997; 40: 76.
28.
Wüthrich B, Frei PC, Bircher A, et al.: Stellungnahme der Fach-
kommission der Schweizierischen Gesellschaft für Allergologie und Immunologie (SGAI) zu den Bioresonanz- und Elektroakupunktur-
geräten zur Diagnostik und Therapie von (vermeintlichen) Allergien: Bioresonanz – diagnostischer und therapeutischer Unsinn. Schweiz Arzteztg 2006; 87: 50–4.
29.
Gemeinsamer Bundesausschuss der Ärzte und Krankenkassen: Richtlinie des Gemeinsamen Bundesausschusses zu Untersuchungs- und Behandlungsmethoden der vertragsärztlichen Versorgung, Anlage II, Stand 1. April 2016 www.g-ba.de/downloads/62–492–1151/MVV-RL_2015–11–27_iK-2016–04–01.pdf (last accessed on 16 May 2016).
30.
Schoni MH, Nikolaizik WH, Schoni-Affolter F: Efficacy trial of biores-onance in children with atopic dermatitis. Int Arch Allergy Immunol 1997; 112: 238–46 CrossRef
31.
Lichtnecker H, Lindemann J: Wie wirksam sind Bioresonanzverfahren? Rheinisches Arztebl 2003; 8: 16.
32.
Ludtke R, Kunz B, Seeber N, Ring J: Test-retest-reliability and validity of the kinesiology muscle test. Complement Ther Med 2001; 9: 141–5 CrossRef MEDLINE
33.
Haas M, Cooperstein R, Peterson D: Disentangling manual muscle testing and applied kinesiology: critique and reinterpretation of a
literature review. Chiropr Osteopat 2007; 15: 11 CrossRef MEDLINE PubMed Central
34.
Schwartz SA, Utts J, Spottiswoode SJ, et al.: A double-blind, ran-domized study to assess the validity of applied kinesiology (AK) as
a diagnostic tool and as a nonlocal proximity effect. Explore (NY) 2014; 10: 99–108 CrossRef MEDLINE
35.
Hall S, Lewith G, Brien S, Little P: A review of the literature in applied and specialised kinesiology. Forsch Komplementmed 2008; 15: 40–6 CrossRef MEDLINE
36.
McCarney R, Fisher P, Spink F, Flint G, van Haselen R: Can homeopaths detect homeopathic medicines by dowsing? A randomized, double-blind, placebo-controlled trial. J R Soc Med 2002; 95: 189–91 CrossRef
37.
Drobitch RK, Svensson CK: Therapeutic drug monitoring in saliva. An update. Clin Pharmacokinet 1992; 23: 365–79 CrossRef MEDLINE
38.
Liu H, Delgado MR: Therapeutic drug concentration monitoring using saliva samples. Focus on anticonvulsants. Clin Pharmacokinet 1999; 36: 453–70 MEDLINE MEDLINE
39.
Patsalos PN, Berry DJ: Therapeutic drug monitoring of antiepileptic drugs by use of saliva. Ther Drug Monit 2013; 35: 4–29 CrossRef MEDLINE
40.
Herr C, Kopka I, Mach J, Eikmann T: Beurteilung des Einsatzes von Human- und Ambientemonitoring. In: Nowak D, Praml G (eds.): Perspektiven der klinischen Arbeits- und Umweltmedizin: Stäube-Feinstäube-Ultrafeinstäube. Fulda, Rindt-Druck 2002: 288–91.
e1.
Körner EM: Beschreibung eines Patientenkollektives des „Hessischen Zentrums für klinische Umweltmedizin“ anhand Anamnese und Diagnostik unter Einsatz verschiedener psychometrischer Verfahren. Inauguraldissertation. Fachbereich Humanmedizin der Justus-Liebig-Universität Gießen 2003.
e2.
Herr CE, Kopka I, Mach J, et al.: Interdisciplinary diagnostics in environmental medicine—findings and follow-up in patients with chronic medically unexplained health complaints. Int J Hyg Environ Health 2004; 207: 31–44 CrossRef
e3.
Eis D, Helm D, Laußmann D, et al.: Robert Koch-Institut im Auftrag des Bundesgesundheitsministeriums: Berliner Studie zu umweltbezogenen Erkrankungen 2005.
e4.
Kales SN, Goldman RH: Mercury exposure: current concepts, controversies, and a clinic’s experience. J Occup Environ Med 2002; 44: 143–54.
e5.
ASCIA Australasian Society of Clinical Immunology and Allergy: ASCIA Position Statement—unorthodox techniques for the diagnosis and treatment of allergy, asthma and immune disorders. 2007.
e6.
Oepen I: Unkonventionelle diagnostische und therapeutische Methoden in der Umweltmedizin. Gesundheitswesen 1998; 60: 420–30 MEDLINE
e7.
Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Amalgam: Stellungnahme aus umweltmedizinischer Sicht. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2007; 50: 1304–7 CrossRef MEDLINE
e8.
Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Bedeutung der Bestimmung von Lymphozyten-Subpopulationen in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2006; 49: 468–84 CrossRef
e9.
Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Genetische Polymorphismen (Sequenzvariationen) von Fremdstoff-metabolisierenden Enzymen und ihre Bedeutung in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2004; 47: 1115–23 CrossRef MEDLINE
e10.
Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Melatonin in der umweltmedizinischen Diagnostik im Zusammenhang mit elektromagnetischen Feldern. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2005; 48: 1406–8 CrossRef
e11.
Muraro A, Werfel T, Hoffmann-Sommergruber K, et al.: EAACI food allergy and anaphylaxis guidelines: diagnosis and management of food allergy. Allergy 2014; 69: 1008–25 CrossRef CrossRef CrossRef CrossRef
e12.
U.S. Food and Drug Administration: FDA press release: FDA issues warnings to marketers of unapproved ’chelation’ products. Veröffentlicht am 14.10.2010. www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/2010/ucm229320.htm (last accessed on 11 February 2016).
e13.
Reisman RE: American Academy of Allergy: Position statements—controversial techniques. J Allergy Clin Immunol 1981; 67: 333–8 CrossRef
e14.
Loh R, Said M, Allen K, et al.: National allergy strategy: Improving the health and quality of life of Australians with allergic disease. Stand August 2015. www.nationalallergystrategy.org.au (last
accessed on 19 July 2016).
e15.
Hawarden D: ALLSA consensus document: Guideline for diagnostic testing in allergy—update 2014. Current allergy & clinical immunology 2014; 27: 216–22.
e16.
Allergy Society of South Africa: Position statement: ALCAT and IgG allergy & intolerance tests. www.allergysa.org/Professionals/Statements (last accessed on 19 July 2016).
e17.
Möllemann JW, Burchardt U, Fischer AE, Fell HJ, Marquardt A: Bericht des Ausschusses für Bildung, Forschung und Technikfolgenabschätzung (19. Ausschuss) gemäß § 56a der Geschäftsordnung – Drucksache 14/2848 – Technikfolgenabschätzung; hier: „Umwelt und Gesundheit“ vom 02.03.2000. https://www.dip21.bundestag.de/dip21/btd/14/028/1402848.pdf (last accessed on 18 July 2016).
e18.
Felton DJ, Kales SN, Goldman RH: An update and review of unconventional metals testing and treatment. Toxics 2014; 2: 403–16 CrossRef
e19.
Bernstein IL, Li JT, Bernstein DI, et al.: Allergy diagnostic testing: an updated practice parameter. Ann Allergy Asthma Immunol 2008; 100: 1–148 CrossRef CrossRef
e20.
Frisch M, Schwartz BS: The pitfalls of hair analysis for toxicants in clinical practice: three case reports. Environ Health Perspect 2002; 110: 433–6 CrossRef
e21.
Stapel SO, Asero R, Ballmer-Weber BK, et al.: Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI task force report. Allergy 2008; 63: 793–6 CrossRef MEDLINE
e22.
Niggemann B, Grüber C: Unkonventionelle Verfahren in der Allergologie – Kontroverse oder Alternative? Allergologie 2002; 25: 34–46 MEDLINE
e23.
Burkhard B: Unkonventionelle Konzepte in der Umweltmedizin. VersMed 1996; 48: 179–84.
e24.
De Luca C, Raskovic D, Pacifico V, Thai JC, Korkina L: The search for reliable biomarkers of disease in multiple chemical sensitivity and other environmental intolerances. Int J Environ Res Public Health 2011; 8: 2770–97 CrossRef MEDLINE PubMed Central
e25.
Hornberg C, Malsch AKF, Weißbach W, Wiesmüller GA: Umweltbezogene Gesundheitsstörungen – Erfahrungen und Perspektiven umweltmedizinischer Patientenversorgung. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2004; 47: 780–94 MEDLINE
e26.
Statistisches Bundesamt: Ergebnisse der Bevölkerungsfortschreibung auf Grundlage des Zensus 2011, Daten vom 31.03.2015. www.destatis.de/DE/ZahlenFakten/GesellschaftStaat/Bevoelkerung/Bevoelkerungsstand/Tabellen/Zensus_Geschlecht_Staats
angehoerigkeit.html (last accessed on 31 March 2015).
e27.
Kassensuche GmbH, Frankfurt am Main: Leistungstabelle zum Bereich Naturheilverfahren. www.gesetzlichekrankenkassen.de/leistungsvergleich/leistungstabelle.html?data=naturheilverfahren (last accessed on 19 May 2016).
e28.
Statistisches Bundesamt: Arbeitslosenquote Deutschland.
www.destatis.de/DE/ZahlenFakten/Indikatoren/Konjunkturindikatoren/ Arbeitsmarkt/arb210.html (last accessed on 19 May 2016).
Institute and Outpatient Clinic of Occupational, Social, and Environmental Medicine, University of Erlangen-Nuremberg: Dr. Greiner, Prof. Drexler
Inappropriate use of scientifically established procedures in the patients of the cohort
Box 1
Inappropriate use of scientifically established procedures in the patients of the cohort
Supplementary information
Box 2
Supplementary information
Key messages
Interpretation of the HBM categories of the German Federal Environment Agency (adapted from [9])
Table 1
Interpretation of the HBM categories of the German Federal Environment Agency (adapted from [9])
The inappropriate investigations used in patients of the cohort
Table 2
The inappropriate investigations used in patients of the cohort
Comparison of the patients with and without inappropriate investigations: biomonitoring, employment status, age, sex, and type of health insurance
Table 3
Comparison of the patients with and without inappropriate investigations: biomonitoring, employment status, age, sex, and type of health insurance
Data on the frequency with which unconventional or unconventionally applied investigations have been used in other environmental medicine facilities
Table 4
Data on the frequency with which unconventional or unconventionally applied investigations have been used in other environmental medicine facilities
Statements/recommendations from leading institutions in Germany and other countries that refer to unconventional diagnostic procedures
Table 5
Statements/recommendations from leading institutions in Germany and other countries that refer to unconventional diagnostic procedures
1. Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Untersuchungsgang in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2001; 44: 1209–16 CrossRef
2. Jamoulle M: Quaternary prevention, an answer of family doctors to overmedicalization. Int J Health Policy Manag 2015; 4: 61–4 CrossRef MEDLINE PubMed Central
3. Kühnlein T: Prävention in der Allgemeinmedizin. Bayer Arztebl 2014; 6: 304–9.
4. Herr C, Otterbach I, Nowak D, Hornberg C, Eikmann T, Wiesmüller GA: Clinical environmental medicine. Dtsch Arztebl Int 2008; 105: 523–31 VOLLTEXT
5. Kleine-Tebbe J, Herold DA: Ungeeignete Testverfahren in der Allergologie. Hautarzt 2010; 61: 961–6 CrossRef MEDLINE
6.Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Leitlinien diagnostische Validität. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2008; 51: 1353–6 CrossRef MEDLINE
7. Drexler H, Göen T: Interpretation von toxikologischen Daten in der klinischen Umweltmedizin. Dtsch Med Wochenschr 1998; 123: 807–13 CrossRef MEDLINE
8. Wrbitzky R, Drexler H, Letzel S, Gräf W, Lehnert G: Umweltmedizin – Eine Standortbestimmung. Dtsch Arztebl 1996; 93: 2456 VOLLTEXT
9. AWMF online: Umweltmedizinische Leitlinie Human-Biomonitoring. Leitlinie der Deutschen Gesellschaft für Arbeitsmedizin und Umweltmedizin e. V. (DGAUM). Stand 9/2011. www.awmf.org/uploads/tx_szleitlinien/002–024l_S1_Human_Biomonitoring_2011–10.pdf (last accessed on 19 May 2016).
10.Deutsche Forschungsgemeinschaft (DFG). Ständige Senatskommission zur Prüfung gesundheitsschädlicher Arbeitsstoffe: MAK- und BAT-Werte-Liste 2016. Weinheim: Wiley-VCH 2016.
11. American College of Medical Toxicology position statement on post-chelator challenge urinary metal testing. J Med Toxicol 2010; 6: 74–5 CrossRef MEDLINE PubMed Central
12. Ruha AM: Recommendations for provoked challenge urine testing.
J Med Toxicol 2013; 9: 318–25 CrossRef MEDLINE PubMed Central
13. Eis D: Methoden und Qualitätssicherung in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2000; 43: 336–42 CrossRef
14. Kommission „Human-Biomonitoring“ des Umweltbundesamtes: Einsatz von Chelatbildnern in der Umweltmedizin? Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 1999; 42: 823–4 CrossRef
15. Heyl GmbH: Fachinformation „Dimaval (DMPS) 100 mg Hartkapseln“. Stand Dezember 2014.
16. Kommission „Human-Biomonitoring“ des Umweltbundesamtes: Haaranalyse in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2005; 48: 246–50 CrossRef
17. Triebig G, Drexler H, Letzel S, Nowak D: Biomonitoring in Arbeitsmedizin und Umweltmedizin. München: Ecomed-Verlag 2012 MEDLINE
18. Schaller KH: Quecksilberverbindungen, organische, Addendum [BAT value documentation in German language, 2003]. The MAK Collection for Occupational Health and Safety 2012: 11–3.
19. Drexler H, Schaller KH: Haaranalysen in der klinischen Umweltmedizin: Eine kritische Betrachtung. Dtsch Arztebl 2002; 99: 3026 VOLLTEXT
20. Kruse-Jarres JD: Interpretation von Haaranalysen: Rückschlüsse auf den Stoffwechsel unmöglich. Dtsch Arztebl 1997; 94: 2180 VOLLTEXT
21. Seidel S, Kreutzer R, Smith D, McNeel S, Gilliss D: Assessment of commercial laboratories performing hair mineral analysis. JAMA 2001; 285: 67–72 CrossRef
22. Ernst E: Komplementärmedizinische Diagnoseverfahren.
Dtsch Arztebl 2005; 102: 3034–7 VOLLTEXT
23. Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Diagnostische Relevanz des Lymphozytentransformationstestes in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2002; 45: 745–9 CrossRef
24. Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Qualitätssicherung beim Lymphozytentransformationstest – Addendum zum LTT-Papier. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2008; 51: 1070–76 CrossRef MEDLINE
25. Renz H: Kurzfassung des Positionspapiers der DGAI: In-vitro-Diagnostik allergischer Erkrankungen. Klinikarzt 2003; 32: 119–23 CrossRef
26. Michalke B, Rossbach B, Goen T, Schaferhenrich A, Scherer G: Saliva as a matrix for human biomonitoring in occupational and environmental medicine. Int Arch Occup Environ Health 2015; 88: 1–44 CrossRef MEDLINE
27. Kommission „Human-Biomonitoring“ des Umweltbundesamtes: „Speicheltest“ – Quecksilberbelastung durch Amalgamfüllungen. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 1997; 40: 76.
28. Wüthrich B, Frei PC, Bircher A, et al.: Stellungnahme der Fach-
kommission der Schweizierischen Gesellschaft für Allergologie und Immunologie (SGAI) zu den Bioresonanz- und Elektroakupunktur-
geräten zur Diagnostik und Therapie von (vermeintlichen) Allergien: Bioresonanz – diagnostischer und therapeutischer Unsinn. Schweiz Arzteztg 2006; 87: 50–4.
29. Gemeinsamer Bundesausschuss der Ärzte und Krankenkassen: Richtlinie des Gemeinsamen Bundesausschusses zu Untersuchungs- und Behandlungsmethoden der vertragsärztlichen Versorgung, Anlage II, Stand 1. April 2016 www.g-ba.de/downloads/62–492–1151/MVV-RL_2015–11–27_iK-2016–04–01.pdf (last accessed on 16 May 2016).
30.Schoni MH, Nikolaizik WH, Schoni-Affolter F: Efficacy trial of biores-onance in children with atopic dermatitis. Int Arch Allergy Immunol 1997; 112: 238–46 CrossRef
31. Lichtnecker H, Lindemann J: Wie wirksam sind Bioresonanzverfahren? Rheinisches Arztebl 2003; 8: 16.
32. Ludtke R, Kunz B, Seeber N, Ring J: Test-retest-reliability and validity of the kinesiology muscle test. Complement Ther Med 2001; 9: 141–5 CrossRef MEDLINE
33. Haas M, Cooperstein R, Peterson D: Disentangling manual muscle testing and applied kinesiology: critique and reinterpretation of a
literature review. Chiropr Osteopat 2007; 15: 11 CrossRef MEDLINE PubMed Central
34. Schwartz SA, Utts J, Spottiswoode SJ, et al.: A double-blind, ran-domized study to assess the validity of applied kinesiology (AK) as
a diagnostic tool and as a nonlocal proximity effect. Explore (NY) 2014; 10: 99–108 CrossRef MEDLINE
35. Hall S, Lewith G, Brien S, Little P: A review of the literature in applied and specialised kinesiology. Forsch Komplementmed 2008; 15: 40–6 CrossRef MEDLINE
36. McCarney R, Fisher P, Spink F, Flint G, van Haselen R: Can homeopaths detect homeopathic medicines by dowsing? A randomized, double-blind, placebo-controlled trial. J R Soc Med 2002; 95: 189–91 CrossRef
37. Drobitch RK, Svensson CK: Therapeutic drug monitoring in saliva. An update. Clin Pharmacokinet 1992; 23: 365–79 CrossRef MEDLINE
38. Liu H, Delgado MR: Therapeutic drug concentration monitoring using saliva samples. Focus on anticonvulsants. Clin Pharmacokinet 1999; 36: 453–70 MEDLINE MEDLINE
39. Patsalos PN, Berry DJ: Therapeutic drug monitoring of antiepileptic drugs by use of saliva. Ther Drug Monit 2013; 35: 4–29 CrossRef MEDLINE
40. Herr C, Kopka I, Mach J, Eikmann T: Beurteilung des Einsatzes von Human- und Ambientemonitoring. In: Nowak D, Praml G (eds.): Perspektiven der klinischen Arbeits- und Umweltmedizin: Stäube-Feinstäube-Ultrafeinstäube. Fulda, Rindt-Druck 2002: 288–91.
e1. Körner EM: Beschreibung eines Patientenkollektives des „Hessischen Zentrums für klinische Umweltmedizin“ anhand Anamnese und Diagnostik unter Einsatz verschiedener psychometrischer Verfahren. Inauguraldissertation. Fachbereich Humanmedizin der Justus-Liebig-Universität Gießen 2003.
e2.Herr CE, Kopka I, Mach J, et al.: Interdisciplinary diagnostics in environmental medicine—findings and follow-up in patients with chronic medically unexplained health complaints. Int J Hyg Environ Health 2004; 207: 31–44 CrossRef
e3. Eis D, Helm D, Laußmann D, et al.: Robert Koch-Institut im Auftrag des Bundesgesundheitsministeriums: Berliner Studie zu umweltbezogenen Erkrankungen 2005.
e4. Kales SN, Goldman RH: Mercury exposure: current concepts, controversies, and a clinic’s experience. J Occup Environ Med 2002; 44: 143–54.
e5. ASCIA Australasian Society of Clinical Immunology and Allergy: ASCIA Position Statement—unorthodox techniques for the diagnosis and treatment of allergy, asthma and immune disorders. 2007.
e6. Oepen I: Unkonventionelle diagnostische und therapeutische Methoden in der Umweltmedizin. Gesundheitswesen 1998; 60: 420–30 MEDLINE
e7. Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Amalgam: Stellungnahme aus umweltmedizinischer Sicht. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2007; 50: 1304–7 CrossRef MEDLINE
e8. Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Bedeutung der Bestimmung von Lymphozyten-Subpopulationen in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2006; 49: 468–84 CrossRef
e9. Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Genetische Polymorphismen (Sequenzvariationen) von Fremdstoff-metabolisierenden Enzymen und ihre Bedeutung in der Umweltmedizin. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2004; 47: 1115–23 CrossRef MEDLINE
e10. Kommission „Methoden und Qualitätssicherung in der Umweltmedizin“ am Robert Koch-Institut: Melatonin in der umweltmedizinischen Diagnostik im Zusammenhang mit elektromagnetischen Feldern. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2005; 48: 1406–8 CrossRef
e11. Muraro A, Werfel T, Hoffmann-Sommergruber K, et al.: EAACI food allergy and anaphylaxis guidelines: diagnosis and management of food allergy. Allergy 2014; 69: 1008–25 CrossRef CrossRef CrossRef CrossRef
e12. U.S. Food and Drug Administration: FDA press release: FDA issues warnings to marketers of unapproved ’chelation’ products. Veröffentlicht am 14.10.2010. www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/2010/ucm229320.htm (last accessed on 11 February 2016).
e13. Reisman RE: American Academy of Allergy: Position statements—controversial techniques. J Allergy Clin Immunol 1981; 67: 333–8 CrossRef
e14. Loh R, Said M, Allen K, et al.: National allergy strategy: Improving the health and quality of life of Australians with allergic disease. Stand August 2015. www.nationalallergystrategy.org.au (last
accessed on 19 July 2016).
e15. Hawarden D: ALLSA consensus document: Guideline for diagnostic testing in allergy—update 2014. Current allergy & clinical immunology 2014; 27: 216–22.
e16. Allergy Society of South Africa: Position statement: ALCAT and IgG allergy & intolerance tests. www.allergysa.org/Professionals/Statements (last accessed on 19 July 2016).
e17. Möllemann JW, Burchardt U, Fischer AE, Fell HJ, Marquardt A: Bericht des Ausschusses für Bildung, Forschung und Technikfolgenabschätzung (19. Ausschuss) gemäß § 56a der Geschäftsordnung – Drucksache 14/2848 – Technikfolgenabschätzung; hier: „Umwelt und Gesundheit“ vom 02.03.2000. https://www.dip21.bundestag.de/dip21/btd/14/028/1402848.pdf (last accessed on 18 July 2016).
e18. Felton DJ, Kales SN, Goldman RH: An update and review of unconventional metals testing and treatment. Toxics 2014; 2: 403–16 CrossRef
e19. Bernstein IL, Li JT, Bernstein DI, et al.: Allergy diagnostic testing: an updated practice parameter. Ann Allergy Asthma Immunol 2008; 100: 1–148 CrossRef CrossRef
e20. Frisch M, Schwartz BS: The pitfalls of hair analysis for toxicants in clinical practice: three case reports. Environ Health Perspect 2002; 110: 433–6 CrossRef
e21. Stapel SO, Asero R, Ballmer-Weber BK, et al.: Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI task force report. Allergy 2008; 63: 793–6 CrossRef MEDLINE
e22. Niggemann B, Grüber C: Unkonventionelle Verfahren in der Allergologie – Kontroverse oder Alternative? Allergologie 2002; 25: 34–46 MEDLINE
e23. Burkhard B: Unkonventionelle Konzepte in der Umweltmedizin. VersMed 1996; 48: 179–84.
e24. De Luca C, Raskovic D, Pacifico V, Thai JC, Korkina L: The search for reliable biomarkers of disease in multiple chemical sensitivity and other environmental intolerances. Int J Environ Res Public Health 2011; 8: 2770–97 CrossRef MEDLINE PubMed Central
e25. Hornberg C, Malsch AKF, Weißbach W, Wiesmüller GA: Umweltbezogene Gesundheitsstörungen – Erfahrungen und Perspektiven umweltmedizinischer Patientenversorgung. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2004; 47: 780–94 MEDLINE
e26. Statistisches Bundesamt: Ergebnisse der Bevölkerungsfortschreibung auf Grundlage des Zensus 2011, Daten vom 31.03.2015. www.destatis.de/DE/ZahlenFakten/GesellschaftStaat/Bevoelkerung/Bevoelkerungsstand/Tabellen/Zensus_Geschlecht_Staats
angehoerigkeit.html (last accessed on 31 March 2015).
e27. Kassensuche GmbH, Frankfurt am Main: Leistungstabelle zum Bereich Naturheilverfahren. www.gesetzlichekrankenkassen.de/leistungsvergleich/leistungstabelle.html?data=naturheilverfahren (last accessed on 19 May 2016).
e28. Statistisches Bundesamt: Arbeitslosenquote Deutschland.
www.destatis.de/DE/ZahlenFakten/Indikatoren/Konjunkturindikatoren/ Arbeitsmarkt/arb210.html (last accessed on 19 May 2016).