The Impact of the COVID-19 Pandemic on Self-Reported Health
Eearly evidence from the German National Cohort
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Background: The pandemic caused by the coronavirus SARS-CoV-2 and the countermeasures taken to protect the public are having a substantial effect on the health of the population. In Germany, nationwide protective measures to halt the spread of the virus were implemented in mid-March for 6 weeks.
Methods: In May, the impact of the pandemic was assessed in the German National Cohort (NAKO). A total of 113 928 men and women aged 20 to 74 years at the time of the baseline examination conducted 1 to 5 years earlier (53%) answered, within a 30-day period, a follow-up questionnaire on SARS-CoV-2 test status, COVID-19-associated symptoms, and self-perceived health status.
Results: The self-reported SARS-CoV-2 test frequency among the probands was 4.6%, and 344 participants (0.3%) reported a positive test result. Depressive and anxiety-related symptoms increased relative to baseline only in participants under 60 years of age, particularly in young women. The rate of moderate to severe depressive symptoms increased from 6.4% to 8.8%. Perceived stress increased in all age groups and both sexes, especially in the young. The scores for mental state and self-rated health worsened in participants tested for SARS-CoV-2 compared with those who were not tested. In 32% of the participants, however, self-rated health improved.
Conclusion: The COVID-19 pandemic and the protective measures during the first wave had effects on mental health and on self-rated general health.
The very first case of COVID-19 in Germany was detected on 27 January 2020 (1). The German health authorities isolated the first cases and traced and tested their contacts, but by mid-March 2020 community spread had become apparent in many regions. Testing capacities and dedicated medical care structures were set up to limit the spread and safeguard care of the general population. Within 2 weeks, nationwide countermeasures were introduced for a 6-week period. The goal was to contain the short- and long-term health impact of infection. However, concerns were raised regarding potential health consequences due to social isolation, increased stress and negative socioeconomic effects.
Large population-based cohort studies offer the opportunity to study emerging new diseases and their effects on health. Thus, they are ideal for measuring the spread of COVID-19 in the general population (2) and to evaluate the health impacts of protective measures (3). In the study presented here we analyzed data on more than 100 000 individuals from the German National Cohort (NAKO) (4). The following parameters were considered:
- Regional differences in COVID-19 occurrence among NAKO participants in comparison with the official statistics in spring 2020
- The frequency of COVID-19-associated symptoms
- Changes in mental health and self-rated general health status compared with a baseline assessment 1 to 5 years earlier.
Between 2014 and 2019, the NAKO recruited 205 219 randomly selected persons aged 20 to 74 years for the baseline examination at 18 study centers (4). Approval had been given by all study centers’ local ethics committees, and all participants had provided written consent for study participation and repeat contact. The first follow-up examination started in 2019, but had to be halted in mid-March 2020 because of the COVID-19 pandemic and the Germany-wide protective countermeasures. Within a short time a new COVID-NAKO questionnaire was developed to collect information on SARS-CoV-2 tests and COVID-19-related symptoms and psychosocial factors. Further details can be found in eBox 1. The findings reported here rest on data collected from questionnaires completed during in the first 30 days (30 April to 29 May) by 113 928 COVID-NAKO participants (Table). Questionnaire participants had the same age as non-participants (mean 50 years) and a slim majority were women (52%, against 49% in non-participants). Participation varied among the study regions, from 34% in the northeast to 67% in the southwest (eTable 1 and eTable 2).
Numbers of expected COVID-19 cases were calculated on the basis of official records from the Robert Koch Institute and the Federal Statistical Office, as described in eBox 2. The frequencies of COVID-19-related symptoms and their co-occurrence were graphically evaluated by means of bar plots and Euler diagrams.
The NAKO baseline examination included (4):
- Physical examinations
- A standardized personal interview
- Self-administered questionnaires and tests
- Acquisition of biological samples.
Several modules from the German version of the Patient Health Questionnaire (PHQ) (5, 6) for the assessment of mental health were included in the questionnaires to assess the severity of depressive symptoms (PHQ-9), anxiety symptoms (GAD-7), and perceived psychosocial strains (PHQ-stress).
The assessment of mental health in the COVID-NAKO questionnaire comprised the same scales (PHQ-9, GAD-7 and PHQ-stress). Summary scores for all three mental health scales were calculated according to the PHQ manual. The respective minimum and maximum scores are 0 to 27 points for PHQ-9, 0 to 21 points for GAD-7 and 0 to 20 points for PHQ-stress. The test-retest reliability of PHQ-9 and GAD-7 is high (7, 8). Differences between the COVID-NAKO questionnaire and the baseline examination were analyzed for all participants with data available at both time points. Student´s t-test was used to assess differences in mental health scores according to study center, age group, and sex. Multivariable linear regression models were applied with the difference in score between the COVID-NAKO questionnaire and baseline for each scale as dependent variable and age at baseline, sex, and baseline score as independent variables.
Self-rated health was assessed using the first question from the Short Form Health Questionnaire (SF-12). Changes in subjective state of health between the baseline examination and the time of the COVID-NAKO questionnaire were evaluated graphically and by means of adjusted logistic regression models. The binary outcome was worsening of self-rated health compared with baseline.
Cumulative incidence of SARS-CoV-2-positive test results
Overall, 4.6% of NAKO participants reported having been tested for SARS-CoV-2 since 1 February 2020. Of the 5245 tested participants, 344 (6.6%) were positive for SARS-CoV-2, yielding an overall cumulative incidence of 0.3%. The mean age of participants who were tested for SARS CoV-2 was higher than for than those who were not tested (50 years vs 47 years) and the proportion of women among the tested participants was slightly higher (57%). The number of cases tested positive in our study was 34% (p < 0.001) higher than was predicted on the basis of the official statistics. More than 80% of the cases that tested positive had been detected by mid-April (eFigure 1a). A higher cumulative incidence was observed in the more strongly affected southern study centers (Freiburg, Saarbrücken, Regensburg) than in the north and east (Neubrandenburg, Leipzig, Kiel) (eFigure 1b, eTable 2).
Frequency and distribution of symptoms
Across all regions, upper and lower respiratory tract symptoms were reported by 31% and 8% of the participants, respectively (eTable 3). Of the 36 609 participants with either upper or lower respiratory tract symptoms in the preceding 4 months, 8.3% had been tested for SARS-CoV-2 infection. Among those tested, the rate of respiratory tract symptoms was much higher (59%). Specifically, 39% reported upper respiratory tract symptoms only, 3% lower respiratory tract symptoms only, and 17% reported symptoms in both segments (eFigure 2). Persons who tested positive constituted only a minor fraction (0.93%) of all participants with respiratory tract symptoms (eFigure 2). However, those with a positive test result reported on average more symptoms—such as fatigue, non-specific pain, loss of taste and smell—than those with a negative result (eFigure 3). Thirty-six percent of participants with a positive test result reported no symptoms at all.
Changes in mental health
Figure 1 and eTable 5 illustrate the changes in mental health scores between the NAKO baseline examination and the time of the COVID-NAKO questionnaire. Figure 1 shows the mean increase in summary scores for self-perceived stress (1.14 ± 0.02) and for the severity of depressive (0.38 ± 0.02) and anxiety symptoms (0.36 ± 0.02), stratified by age and sex.
Increases in perceived stress were observed across all age groups, while increases in depressive symptoms and anxiety symptoms were limited to those below the age of 60 years. The most pronounced increases on all three scales were seen in the younger age groups. Women showed much higher increases than men, e.g., a rise of 1.94 points on the stress scale (minimum 0, maximum 20) in the age group 30–39 years.
On all three scales for mental health, the differences from baseline were somewhat less pronounced in the NAKO regions with a low cumulative incidence than in the regions with intermediate or high incidence (eFigure 4). This pattern was apparent for all scales regardless of the absolute increase in score.
Participants who reported having been tested for SARS-CoV-2, regardless of whether the test result was positive or negative, had higher scores on all scales for mental health than those who had not been tested (eFigure 5). The increase in mean severity of both depressive symptoms and anxiety symptoms raised the proportion of those who were above the cut-off points on these two scales (≥10 points): from 6.4% to 8.8% (depression) and from 4.3% to 5.7% (anxiety). The cut-off value shows symptoms of depression or anxiety with clinical relevance (9).
Changes in self-rated health status
Thirty-two percent of the participants stated an improvement in self-rated state of health since baseline (Figure 2), while 12% reported deterioration. Worsening was reported predominantly by persons who had been tested (odds ratio for those tested negative: 1.68, 95% confidence interval [1.54; 1.82], odds ratio for those tested positive: 2.38 [1.83; 3.10]), after adjustment for age, sex, study center, and self-rated health at baseline (eTable 6). Furthermore, there was a relationship between deterioration in self-rated health and worsening of mental health (eFigure 6).
Consistently with official figures from local health offices, the results of this large, population-based cohort study indicate that up to the end of May 2020, a low proportion of infections with SARS-CoV-2 were self-reported (0.3%). Nevertheless, the NAKO data revealed 34% more positive test results than predicted on the basis of official reporting statistics. Selection bias may be at work here, as persons who tested positive may have been more likely to participate in the survey. The data cover the time from the start of the pandemic until it reached its peak in Europe (10). Early on, the epidemic was driven mainly by people coming back from abroad. This group tended to be of higher socio-economic status, a stratum which is also overrepresented in the NAKO. Furthermore, the higher cumulative incidence could also be due to increased health consciousness on the part of the NAKO participants. The implementation of a test-based case identification strategy along with countermeasures such as social distancing could have contributed to the decline in new SARS-CoV-2 infections in the NAKO study regions observed in our sample (11, 12, 13).
Most of the persons with positive test results described their symptoms as mild, with 36% reporting no symptoms and 12% requiring hospitalization. Our data confirm that loss of smell and taste is associated with a higher likelihood of a positive SARS-CoV-2 test (14,15).
Participants reported more perceived stress and more symptoms of depression and anxiety during the pandemic than at the time of the baseline examination, conducted 1 to 5 years earlier. While various factors may have contributed to this change over time, the fact that NAKO participants living in regions of low SARS-CoV-2 incidence reported fewer mental problems than those from regions of higher incidence supports a relation with the pandemic. Greater severity of depressive and anxiety symptoms was restricted to those younger than 60, with a focus on young adults between the ages of 20 and 39 years. Similar findings have recently been reported in the UK (16) and in a small follow-up survey conducted in April 2020 at Johns Hopkins University. The latter found a clear increase in severe psychological distress compared with a prior assessment in 2018, particularly in young adults aged 18 to 29 years (17).
A study with Dutch students showed that the lockdown in March 2020 negatively affected the students’ ability to stabilize their mood through familiar activities (18). Young and middle-aged adults were under particular pressure, having to manage various tasks in a situation of limited services and multiple challenges associated with the advice to stay at home. This included, for example, the coordination of working from home or other changes in working conditions with home schooling, childcare, or care for the elderly.
Very recent commentaries and recommendations (3, 19) emphasize the urgent necessity to collect high-quality data on the mental health effects of the COVID-19 pandemic across the whole population and in vulnerable groups (3) and point to the fact that the pandemic may have considerable implications for individual and collective health as well as for emotional and social functioning (19). They also address the need to provide mental health services that target patients’ health needs and reduce (social) disparities (20).
Self-rated health deteriorated in participants who underwent testing, especially in those with a positive test result. However, self-rated health also improved in a considerable number of participants. Given that this is self-perceived health, subjective changes in health consciousness rather than objective improvements may be responsible for this observation. While contact restrictions were in place, beginning in mid-March, essential shopping, access to the workplace (in the absence of reduced hours or working from home), and outdoor exercising were allowed at all times in the NAKO study regions. The national government and the individual federal states implemented a wide range of support programs to lessen the socioeconomic burden.
While working conditions became much worse for some employees, such as those in the health care sector, other population groups gained additional leisure time and experienced a slower pace of life, increased health consciousness, and neighborhood support. The results were not adjusted for individual socioeconomic factors; future analyses should specifically examine their potential role as modifiers.
A major strength of the results presented here is that they are derived from a large, population-based cohort with a defined sampling frame from 16 geographic regions of Germany. The baseline data supply a detailed characterization of the health status of the participants before the outbreak of the COVID-19 pandemic. The COVID-NAKO questionnaire offered a timely longitudinal follow-up and included several questions and scales previously employed in the baseline assessment. This provided the opportunity to analyze changes in health scores over time. Limitations arise from the fact that all responses are based on self-reports. Changes in the scores for mental health could be attributable to the pandemic, to the countermeasures, or to other unrelated factors. The mental health scores were analyzed on the dimensional scale only; in other words, no (subtype) diagnoses, e.g., major depressive disorder, were applied. The reported SARS-CoV-2 test results are only a snapshot, reflecting the situation at the time of filling in the questionnaire.
The worsening of results regarding mental health was stronger in regions with a higher background cumulative incidence. Moreover, it was slightly more pronounced among participants who had undergone the baseline examination only 1 or 2 years previously. This speaks for an association between worsening of mental health and the pandemic. Because the population was confronted with constantly changing regulations concerning health and general behavior, the results need to be discussed within the context of the dynamics of the pandemic. Repeated assessments are required to determine whether the consequences of the countermeasures will persist for a longer period.
Although the cumulative incidence of detected SARS-CoV-2 infections was low on the population level in Germany in spring 2020, we observed a deterioration in mental health scores during the nationwide 6-week period of protective measures in the entire NAKO cohort, irrespective of test or infection status. Our results indicate health consequences at population level that go substantially beyond the direct health impact of COVID-19.
Funding and support
The German National Cohort (NAKO) (www.nako.de) is funded by the Federal Ministry of Education and Research (project numbers: 01ER1301A/B/C and 01ER1511D), the federal states, and the Helmholtz Association, with additional financial support from the participating universities and the participating institutes of the Leibniz Association and the Helmholtz Association.
We thank all staff at the study centers, the NAKO data management center, and the NAKO head office who made this study possible. Furthermore, we thank Maren Albrecht and Dr. Barbara Bohn for their committed work and their valuable contributions to the implementation of the questionnaire, as well as Dr. Susanne Göttlicher for her assistance in finalizing the manuscript.
Conflict of interest statement
Prof. Lieb owns shares in Biontech.
The remaining authors declare that no conflict of interest exists.
Manuscript received on 6 October 2020, revised version accepted on 18 November 2020.
Prof. Dr. rer. biol. hum. Annette Peters
Institut für Epidemiologie, Helmholtz Zentrum München
Deutsches Zentrum für Gesundheit und Umwelt GmbH
Ingolstädter Landstr. 1
85764 Neuherberg, Germany
Cite this as:
Peters A et al.: The impact of the COVID-19 pandemic on self-reported health—early evidence from the German National Cohort.
Dtsch Arztebl Int 2020; 117: 861–7. DOI: 10.3238/arztebl.2020.0861
eFigures, eTables, eBoxes:
Institute for Epidemiology, Helmholtz Center Munich: Prof. Dr. rer. biol. hum. Annette Peters, Dr. rer. biol. hum. Susanne Rospleszcz, Dr. rer. nat. Marco Dallavalle
Chair of Epidemiology, Institute for Medical Information Processing, Biometry and Epidemiology, Medical Faculty, Ludwig-Maximilians-Universität München, Munich: Prof. Dr. rer. biol. hum. Annette Peters, Dr. rer. biol. hum. Susanne Rospleszcz
Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA, USA: Prof. Dr. rer. biol. hum. Annette Peters
Department of Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg: Dr. med. Karin H. Greiser
Institute of Epidemiology and Social Medicine, University of Münster: Prof. Dr. med. Klaus Berger
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