General distress and symptoms of anxiety and depression: A factor analysis in two cohorts of dialysis patients

Objective: Depression and anxiety often coexist in patients with end-stage-kidney disease. Recently, studies showed that a composite ‘general distress score’ which combines depression and anxiety symptoms provides a good fit in dialysis and oncology patients. We aim to investigate if the three most frequently used self-report questionnaires to measure depression and anxiety in dialysis patients are sufficiently unidimensional to warrant the use of such a general distress score in two cohorts of dialysis patients. Methods: This study includes two prospective observational cohorts of dialysis patients (total n = 749) which measured depression and anxiety using Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI) and Hospital Anxiety and Depression Scale (HADS). Confirmatory factor analyses was used to investigate both a strictly unidimensional model and a multidimensional bifactor model that includes a general distress, depression and anxiety factor. The comparative fit index (CFI) and The Root Mean Square Error of Approximation (RMSEA) were used as model fit indices. Results: Factor analysis did not show a good fit for a strictly unidimensional general distress factor for both the BDI/BAI and HADS (CFI 0.690 and 0.699, RMSEA 0.079 and 0.125 respectively). The multidimensional model performed better with a moderate fit for the BDI/BAI and HADS (CFI 0.873 and 0.839, RMSEA 0.052 and 0.102). Conclusions: This data shows that the BDI/BAI and HADS are insufficiently unidimensional to warrant the use of a general distress score in dialysis patients without also investigating anxiety and depression separately. Future research is needed whether the use of a general distress score might be beneficial to identify patients in need of additional (psychological) support.