The 15‐item Geriatric Depression Scale as a Predictor of Mortality in Older Adults Undergoing Hemodialysis

To the Editor: Symptoms of depression are commonly associated with poor prognosis. Patients with end-stage renal disease (ESRD) are at high risk for depression, with a prevalence estimated at approximately 20% to 30%.1,2 A diagnosis of depression in people with ESRD has been linked to greater numbers of hospitalizations,2 impaired cellular immunity,3 and high morbidity4 and mortality.2 The 15-item Geriatric Depression Scale (GDS-15) was recently investigated and validated as an effective screening tool for depression in older adults undergoing hemodialysis.5 The objective of the current study was to evaluate whether GDS-15 scores correlate with greater mortality in older adults undergoing hemodialysis (whether the GDS-15 can predict mortality risk). All patients undergoing chronic hemodialysis treatment for ESRD at four dialysis units were identified. Inclusion criteria were aged 65 and older, fluent in English, and able to provide informed consent. Individuals with an acute illness requiring hospitalization, known malignancy, dementia, or active alcohol or recreational drug abuse were excluded. Baseline clinical data were obtained from patient interviews and review of the medical records. The GDS-15 was administered to qualifying participants between March 11, 2005, and November 9, 2006. Participants were followed until death, transfer out of the unit (with no further data availability), or censor date of October 21, 2010. All statistical analysis was performed using SAS Statistical Software for Windows, version 9.2 (SAS Institute, Inc., Cary, NC). Means and standard deviations (SDs) were used to describe continuous data and frequencies and percentages to describe categorical data. The Kaplan-Meier survival method was used to estimate survival probability for participants with and without depression, respectively, and the survival difference between the two groups was evaluated using log-rank test. The Cox proportional hazards model was used to estimate the relative risk of death for participants with and without depression, adjusting for patient characteristics including age, sex, race, and marital status (Figure 1). Kaplan-Meier survival estimates in participants with and without depression: solid line “___” for participants with depression and dashed line “- - - - - - - -” for those without (log-rank test, P=.04). There were no significant differences in age, sex, racial ethnicity, or marital status between participants with and without depression. Seventy-seven participants completed the study; 46 died during the study period. Twenty-six patients had a GDS-15 score of 5 or greater. The mean follow-up period was 35.2 months (0.8–66 months), during which 19 patients in the group with depression (73%) and 27 in the group without (53%) died. One-, 2-, and 3-year survival was 72.2%, 47.1%, and 38.5%, respectively, for those with depression and 79.9%, 63.5%, and 52.9% for those without. In the Cox regression, sex, race, and marital status were not significantly associated with mortality. Adjusting for age, there was a 91% higher risk of death in participants with depression than in those without (hazard ratio=1.91, 95% confidence interval (CI)=1.05–3.46). Median survival time in participants who were not depressed (45.2 months, 95% CI=23.4–66.3) was nearly twice that of those who were depressed (23.15 months, 95% CI=13.0–46.6). These results provide evidence that the GDS-15 screening tool predicts mortality in older depressed adults undergoing hemodialysis. Although a few studies have failed to show a significant association between depression and mortality in patients with ESRD,6,7 the vast majority have confirmed that association.2,4,8 Possible reasons for that discrepancy among studies are the wide variety of tools used to assess depression, variable approaches to interpreting the results of different depression screening tools, and variable consideration of an array of demographic and clinical covariates. In a recent prospective, blinded cohort study,5 the GDS-15 was validated for use as an effective screening tool for depression in older adults with ESRD, a population previously identified as being at a particularly high risk for depression.9 The GDS-15 is a simple, self-report questionnaire that is less costly and less time-consuming than the criterion standard psychiatric interview and, unlike other depression screening tools such as the Beck Depression Inventory, was designed specifically for the elderly population.10 A modest sample size (n=77) narrows the focus and analysis of this study to exclude consideration of any possible effects of extrarenal comorbidities, although it is likely that inclusion of patients with extrarenal comorbidities would have resulted in even higher rates of depression and mortality and would not have altered the conclusions about the usefulness of the GDS-15. The current study is the first to investigate and confirm that scores from this validated, convenient depression screening tool correlate well with mortality in older adults undergoing hemodialysis. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. National Kidney Foundation serving Virginia (formerly National Kidney Foundation of the Virginias Inc.) grant-in-aid to RAB, SAB, and EMA. Author Contributions: RAB and EMR: study concept, design, acquisition of subjects and preparation of manuscript. SAB, ALK, FT, and CPK: preparation of manuscript. JZM: analysis and interpretation of data. Sponsor's Role: No sponsor.