Self-reported depression symptoms in haemodialysis patients: Bi-factor structures of two common measures and their association with clinical factors

• Published in: General hospital psychiatry 2018-09, Vol.54, p.31-36
• Main Authors: Chilcot, Joseph, Almond, Michael K., Guirguis, Ayman, Friedli, Karin, Day, Clara, Davenport, Andrew, Wellsted, David, Farrington, Ken
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; BDI-II; Depression; Depression - diagnosis; Depressive Disorder, Major - diagnosis; Dialysis; End Stage Liver Disease - psychology; End Stage Liver Disease - therapy; End-stage kidney failure; Factor analysis; Factor Analysis, Statistical; Female; Humans; Male; Middle Aged; PHQ-9; Psychiatric Status Rating Scales - standards; Psychometrics; Renal Dialysis - psychology; Screening; Self Report
• ISSN: 0163-8343; 1873-7714
• DOI: 10.1016/j.genhosppsych.2018.08.007

To validate the factor structure of two common self-report depression tools in a large sample of haemodialysis (HD) patients and to examine their demographic and clinical correlates, including urine output, history of depression and transplantation. Factor structures of the Beck Depression Inventory (BDI-II) and Patient Health Questionnaire (PHQ-9) were evaluated using confirmatory factor analysis (CFA). Data was utilised from the screening phase (n = 709) of a placebo-controlled feasibility randomised control trial (RCT) of sertraline in HD patients with mild to moderate Major Depressive Disorder. Alternative factor models including bi-factor models for the BDI-II and PHQ-9 were evaluated. Coefficient omega and omega-hierarchical were calculated. For both measures, bi-factor measurement models had the overall best fit to the data, with dominant general depression factors. Omega-hierarchical for the general BDI-II and PHQ-9 factors was 0.94 and 0.88 respectively. Both general factors had high reliability (coefficient omega = 0.97 and 0.94 respectively) and explained over 85% of the explained common variance within their respective models. BDI-II and PHQ-9 general depression factors were negatively associated with age and urine output and positively with a history of depression, antidepressant use within the last 3 months and a history of failed transplantation. In adjusted regression models, age, urine output and a history of depression remained significant. These data suggest that both the BDI-II and PHQ-9 are sufficiently unidimensional to warrant the use of a total score. Younger age, lower urine output and a history of depression appear consistent correlates of depression severity among HD patients.