There’s a new preprint with what seem to be good controls, although based on self-report and the participation rate was low, about 1/3:
Post-acute symptoms, new onset diagnoses and health problems 6 to 12 months after SARS-CoV-2 infection: a nationwide questionnaire study in the adult Danish population
Anna Irene Vedel Sørensen, Lampros Spiliopoulos, Peter Bager, Nete Munk Nielsen, Jørgen Vinsløv Hansen, Anders Koch, Inger Kristine Meder, Steen Ethelberg, Anders Hviid
Methods We conducted a nationwide cross-sectional study including 152 880 individuals aged 15-years or older, consisting of RT-PCR confirmed SARS-CoV-2 cases between September 2020-April 2021 (N=61 002) and a corresponding test-negative control group (N=91 878). Data were collected 6, 9 or 12 months after the test using web-based questionnaires. The questionnaire covered acute and post-acute symptoms, selected diagnoses, sick leave and general health, together with demographics and life style at baseline. Risk differences (RDs) between test-positives and -negatives were reported, adjusted for age, sex, single comorbidities, Charlson comorbidity score, obesity and healthcare-occupation.
I recommend checking out the figures for risk differences for new self-reported health problems and new self-reported diagnoses. From figure 2, the risk difference for a new self-reported diagnosis of chronic fatigue syndrome (pooled across groups) was 2.5%=4%-1.5%, the largest of the diagnoses and statistically significant. 1.15% for anxiety, 1% for depression, 0.16% for PTSD and a non-statistically significant difference for fibromyalgia. From figure 3, the risk differences for new health problems they tested were pretty big, 17.27% (sleep problems) to 40.45% (physical exhaustion).
Figure 4 has risk differences for various health conditions by age group and gender, but not necessarily for new onset since COVID.
They highlight self-report and participation rates as the main limitations:
The main limitations of the study are the self-reporting of symptoms and the participation rate. With little over 1⁄3 of the invitees choosing to participate, we cannot rule out participation bias. The motivation for participation could be higher among those experiencing post-acute symptoms, but on the other hand, those with very severe symptoms might not have had the energy to participate. Still, response rates among test-positives and –negatives were similar. However, because of the size of the study and the marked risk differences between the case- and control groups, we believe that our results are valid.
And caution about CFS diagnoses:
The overrepresentation of CFS among test-positives must be interpreted with care due to variability in how this diagnosis is made and the risk of confusing CFS with other conditions when filling in the questionnaire.
They also looked at sick leave rates, but unfortunately no durations:
Among the test-positives 12.0% reported taking any sick leave 4 weeks after test and until filling in the questionnaire 6-12 months later, compared to 7.7% of test-negatives (RD=4.32%, 95% CI 4.00-4.64%). Full-time sick leave was reported by 9.4% of test-positives and 6.5% of test-negatives (RD=3.20, 95% CI 2.88-3.47%), whereas part-time sick-leave was reported by 4.2% of test-positives compared to 1.7% of test-negatives (RD=2.43%, 95% CI 2.25-2.62%).
There’s a new preprint with what seem to be good controls, although based on self-report and the participation rate was low, about 1/3:
Post-acute symptoms, new onset diagnoses and health problems 6 to 12 months after SARS-CoV-2 infection: a nationwide questionnaire study in the adult Danish population
Anna Irene Vedel Sørensen, Lampros Spiliopoulos, Peter Bager, Nete Munk Nielsen, Jørgen Vinsløv Hansen, Anders Koch, Inger Kristine Meder, Steen Ethelberg, Anders Hviid
medRxiv 2022.02.27.22271328; doi: https://doi.org/10.1101/2022.02.27.22271328
I recommend checking out the figures for risk differences for new self-reported health problems and new self-reported diagnoses. From figure 2, the risk difference for a new self-reported diagnosis of chronic fatigue syndrome (pooled across groups) was 2.5%=4%-1.5%, the largest of the diagnoses and statistically significant. 1.15% for anxiety, 1% for depression, 0.16% for PTSD and a non-statistically significant difference for fibromyalgia. From figure 3, the risk differences for new health problems they tested were pretty big, 17.27% (sleep problems) to 40.45% (physical exhaustion).
Figure 4 has risk differences for various health conditions by age group and gender, but not necessarily for new onset since COVID.
They highlight self-report and participation rates as the main limitations:
And caution about CFS diagnoses:
They also looked at sick leave rates, but unfortunately no durations: