Uncovering Survivorship Bias in Longitudinal Mental Health Surveys During the COVID-19 Pandemic

Czeisler, Mark É.; Wiley, Joshua F.; Czeisler, Charles A.; Rajaratnam, Shantha M.W.; Howard, Mark E.

BACKGROUND: Markedly elevated adverse mental health symptoms were widely observed early in the coronavirus disease 2019 (COVID-19) pandemic. Unlike the U.S., where cross-sectional data indicate anxiety and depression symptoms have remained elevated, such symptoms reportedly declined in the U.K., according to analysis of repeated measures from a largescale longitudinal study. However, nearly 40% of U.K. respondents (those who did not complete multiple follow-up surveys) were excluded from analysis, suggesting that survivorship bias might partially explain this discrepancy. METHODS: We therefore assessed survivorship bias among U.S. respondents invited to complete multiple mental health surveys during the pandemic. Survivorship bias was assessed for (1) demographic differences in follow-up survey participation, (2) differences in adjusted initial adverse mental health symptom prevalences, and (3) differences in follow-up survey participation based on mental health experiences. RESULTS: Adjusting for demographics, individuals who completed only one or two out of four surveys had higher prevalences of anxiety and depression symptoms in April 2020 (e.g., one-survey versus four-survey, anxiety symptoms, adjusted prevalence ratio [aPR]: 1.30, 95% confidence interval [CI]: 1.08–1.55, P=0.0045; depression symptoms, aPR: 1.43, 95% CI: 1.17–1.75, P=0.00052). Moreover, individuals who experienced incident anxiety or depression symptoms had higher odds of not completing follow-up surveys (adjusted odds ratio [aOR]: 1.68, 95% CI: 1.49–2.48, P=0.0015, aOR: 1.56, 95% CI: 1.15–2.12, P=0.0046, respectively). CONCLUSIONS: Survivorship bias among longitudinal mental health survey respondents may lead to overly optimistic interpretations of mental health trends. Cross-sectional surveys may therefore provide more accurate estimates of population-level adverse mental health symptom prevalences.