Assessing symptoms of long/post COVID and chronic fatigue syndrome using the DePaul symptom questionnaire-2: a validation in a German-speaking population

Abstract

ABSTRACT Objective A subset of Covid-19 survivors will develop persisting health sequelae (i.e. Long Covid/LC or Post Covid/PC) similar to Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). In the absence of a reliable biomarker to diagnose LC/PC and ME/CFS, their classification based on symptoms becomes indispensable. Hence, we translated and validated the DePaul Symptom Questionnaire−2 (DSQ-2), to offer a screening tool for the German-speaking population. Methods A sample of healthy adults, and adults with ME/CFS and LC/PC (N = 502) completed a reduced-item version of the DSQ-2 and SF-36 questionnaire online. We performed an exploratory factor analysis, assessed construct validity, diagnostic accuracy and compared the symptom profiles of individuals with ME/CFS versus LC/PC versus healthy adults. Results Exploratory factor analysis revealed a 10-factor solution with excellent internal consistencies. The sensitivity of the DSQ-2 was excellent. The specificity was moderate with moderate inter-rater reliability. Construct validity of the DSQ-2 was supported by strong negative correlations with physical health subscales of the SF-36. A visual comparison of the symptom profiles of individuals with ME/CFS versus LC/PC revealed a comparable pattern. Conclusion Despite lower symptom severity, individuals with LC/PC reported significantly stronger limitations in general health and physical functioning and were more likely to meet ME/CFS diagnostic criteria with ongoing sickness duration, suggesting that ME/CFS can be considered a long-term sequela of LC/PC. This study offers a translated and validated version of the reduced-item DSQ-2 that can guide medical evaluation and aid physicians in identifying a ME/CFS-like subtype of LC/PC.