Depressive Symptoms in Dialysis: Prevalence and Relationship with Uremia-Related Biochemical Parameters

Background: Depression is the most common psychiatric disorder in long-term dialysis patients and a risk factor for morbidity and mortality. Although there is a relevance of the issue in the dialysis setting, we still know little about possible relationships between depression and uraemia-related biochemical abnormalities. Our aims were to evaluate (1) the prevalence of depression in our haemodialysis (HD) and peritoneal dialysis (PD) population using a validated and easy-to-implement screening tool and (2) the association between depression and the main uraemia-related clinical and biochemical parameter changes. Methods: In this monocentric cross-sectional study, all patients of our centre with at least 3 months of dialysis were screened by Patient Health Questionnaire-9 (PHQ-9), a self-administered depression-screening questionnaire validated in dialysis setting. The impact of depressive symptoms on daily life was also assessed. We then analysed relationships between the PHQ-9-derived depressive score, functional impairment score, demographic, clinical and laboratory variables. Results: In our cohort of 145 patients, depressive symptoms were found in 69 patients (46%). Stratifying for severity, mild, moderate and severe grade accounted for 31, 13 and 2% respectively. Depressive symptoms affected 36% of patients on PD versus 52% of patients on HD. Moreover, the PD patients had significantly less functional impairment derived from depressive symptoms than the HD patients. Simple and multiple regression analysis identified serum phosphorus as the only uraemia-related laboratory parameter that was high statistically associated with depressive score. Conclusions: Using a reliable, simple and fast tool, we found that depressive symptoms affect almost half of dialysis patients, particularly so the HD cohort. Severity of depressive symptoms seems related to serum levels of phosphorus possibly because depression affects compliance to therapy.