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.