COVID-19 Pandemic
Comparison of survey questions to define Long COVID: implications for prevalence and disparities Jana L. Hirschtick* Jana Hirschtick Nancy L. Fleischer
Background: Survey-based Long COVID estimates vary widely. Although survey mode, sampling approach, setting, and pandemic phase contribute to this variation, how and when the survey questions are asked may also impact Long COVID estimates.
Methods: Using a population-based cohort of adults with confirmed SARS-CoV-2, we compared Long COVID estimates from baseline and follow-up surveys (median of 4 and 18 months after COVID-19 onset, respectively) overall and by race, ethnicity, and sex. We defined Long COVID as: 1) 90-day symptoms at baseline; 2) ever Long COVID at follow-up; 3) current Long COVID at follow-up; and 4) diagnosed Long COVID at follow-up.
Results: In our sample (n=3,826), 17.0% reported 90-day symptoms at baseline. At follow-up, 24.5% reported ever Long COVID, 16.9% reported current Long COVID, and 10.8% reported diagnosed Long COVID. Among adults without 90-day symptoms at baseline, 17.3% reported ever Long COVID at follow-up. Relatedly, among adults with 90-day symptoms at baseline, 31.1% reported they never had Long COVID at follow-up. Further, the use of different survey questions had implications for Long COVID disparities. Although American Indian/Alaskan Native adults had the highest prevalence of 90-day symptoms at baseline (24.5%, 95% CI 16.7-34.4%), Black adults had the highest prevalence of ever Long COVID at follow-up (33.6%, 28.8-38.9%). Also, while Black females and males did not have a statistically different prevalence of 90-day symptoms at baseline (23.9% vs. 21.4%, p=0.607), Black females (vs. males) had a statistically higher prevalence of current Long COVID at follow-up (33.4% vs. 14.7%, p<0.001).
Conclusion: Surveys should employ several questions to define Long COVID and interpret findings within the context of factors that may impact responses, including Long COVID symptom fluctuation, reinfection, awareness, and potential stigma.