Depression in veterans with Parkinson's disease: frequency, co-morbidity, and healthcare utilization.

OBJECTIVE To determine the frequency of depression in Parkinson's disease (PD) in routine clinical care, and to examine its association with co-morbid psychiatric and medical conditions and healthcare utilization. METHODS Depression diagnoses and healthcare utilization data for all male veterans with PD age 55 or older seen in fiscal year 2002 (n = 41,162) were analyzed using Department of Veterans Affairs (VA) national databases. Frequencies of co-morbid disorders and healthcare utilization were determined for depressed and non-depressed patients; associations with depression were examined using multivariate logistic regression models. RESULTS A depression diagnosis was recorded for 18.5% of PD patients, including major depression in 3.9%. Depression decreased in frequency and severity with increasing age. In multivariate logistic regression models, depressed patients had significantly greater psychiatric and medical co-morbidity, including dementia, psychosis, stroke, congestive heart failure, diabetes, and chronic obstructive pulmonary disease than non-depressed patients (all p < 0.01). Depressed PD patients were also significantly more likely to have medical (OR = 1.34, 95% CI = 1.25-1.44) and psychiatric hospitalizations (OR = 2.14, 95% CI = 1.83-2.51), and had more outpatient visits (p < 0.01), than non-depressed PD patients in adjusted models. CONCLUSION Depression in PD in non-tertiary care settings may not be as common or as severe as that seen in specialty care, though these findings also may reflect under-recognition or diagnostic imprecision. The occurrence of depression in PD is associated with greater psychiatric and medical co-morbidity, and greater healthcare utilization. These findings suggest that screening for depression in PD is important and should be embedded in a comprehensive psychiatric, neuropsychological, and medical evaluation.