Depression and all-cause and cardiovascular mortality in patients on haemodialysis: a multinational cohort study

Background: Depression and early death are both common in adults with Stage 5 chronic kidney disease. Studies have shown an association between depression and total mortality, but the association between depression and cardiovascular death is less certain. Methods: We conducted a prospective multinational cohort study involving adults who were treated with long-term haemodialysis within a single dialysis network between April and November 2010. Depression was considered present when patients reported a Beck Depression Inventory (BDI) II score >= 14 at baseline. Sensitivity analyses considered a BDI II score >= 20 to identify moderate depression. Multivariable Cox proportional hazards regression was used to assess adjusted hazards for all-cause and cardiovascular mortality at 12 months. Results: Three thousand and eighty-six participants in the network received the BDI II questionnaire, and 2278 (73%) provided complete responses to the survey questions. Among these, 1047 (46%) reported depression. During a mean follow-up of 11 (standard deviation: 2.5) months (2096 person-years), we recorded 175 deaths, of which 66 were attributable to cardiovascular causes. Depression (BDI score >= 14) was not associated with all-cause mortality [adjusted hazard ratio: 1.26 (95% confidence interval: 0.93-1.71)] or cardiovascular mortality [0.82 (0.50-1.34)]. When a higher BDI score (BDI score >= 20) was used to identify moderate depression, depression was associated with total mortality [1.40 (1.02-1.93)] but not cardiovascular mortality [1.05 (0.63-1.77)]. Conclusions: The association between depression and cardiovascular mortality in adults with kidney failure treated with haemodialysis is uncertain. Depression is a heterogeneous disorder and may only be a risk factor for premature death when at least of moderate severity.