Background: Major depressive disorder (MDD) is highly prevalent in the Spanish primary care (PC) setting and the leading cause of disability in Spain. The aim of this study was to evaluate several key psychometric properties of the Sheehan Disability Scale (SDS) in patients with or without MDD and varying degrees of symptom severity using the Patient Health Questionnaire-9 (PHQ-9).
Method: A total of 1,704 PC patients participating in the PsicAP clinical trial completed the SDS and PHQ-9. We evaluated the factor structure, measurement invariance across gender, internal consistency, and the discriminative and predictive validity.
Results: Confirmatory factor analyses revealed a unifactorial model of the SDS containing 4 items (SDS-4) with the best model fit (CFI: .99; GFI: .99; TLI: 96; RMSEA: .10). This model contained the three life domain items (work, family, and social life) plus perceived stress (PS) with significant loadings. The internal consistency of the SDS-4 was acceptable in patients with or without MDD, regardless of symptom severity. The SDS-4 also showed good discriminative capacity and acceptable predictive validity in all subsamples.
Conclusions: These findings support the use of the SDS-4 to assess depression-related disability in patients at Spanish primary care centres.