Factorial structure of the patient health questionnaire-9 in long-term survivors of severe COVID-19

Introduction Depression is prevalent among survivors of severe COVID-19, yet psychometric evidence for screening instruments in this population remains limited, particularly in Latin America. The factor structure of the Patient Health Questionnaire-9 (PHQ-9) remains unclear in long-term survivors of severe COVID-19. This study aimed to evaluate the psychometric properties and factor structure of the PHQ-9 in a Colombian cohort of long-term survivors of severe COVID-19. Materials and methods The PHQ-9 was administered to 177 individuals previously hospitalized with severe COVID-19, with follow-up extending up to 20 months post-discharge. Both exploratory (EFA) and confirmatory factor analyses (CFA) were conducted to evaluate competing structural models. Results The unifactorial solution demonstrated superior internal consistency ( α = 0.81, ω = 0.86) compared with the two-factor solution (Factor 1: α = 0.74; Factor 2: α = 0.61). The two-factor item distribution did not correspond to established depression frameworks. CFA showed both models had acceptable fit, but chi-square difference testing revealed no significant improvement for the two-factor model (Δχ 2 = 0.27, p = 0.602). The fatigue item exhibited the lowest factor loading. Conclusion The PHQ-9 demonstrated a predominantly unidimensional structure in this population. The weak performance of the fatigue item suggests potential overlap between long COVID–related fatigue and depressive symptomatology, warranting future criterion validation against structured psychiatric assessment.