Validity of the PHQ-2 for the screening of major depression in Parkinson's disease: two questions and one important answer.

INTRODUCTION

Depression is the most common psychiatric comorbidity in Parkinson's disease (PD), but is often under-diagnosed and under-recognized.

OBJECTIVES

To evaluate and compare the psychometric qualities of the Patient Health Questionnaire (PHQ-2) and the depression item of the Unified Parkinson's Disease Rating Scale (UPDRS).

METHOD

Cross-sectional study conducted at a movement disorders outpatient clinic. One hundred ten patients with a diagnosis of PD without dementia were evaluated. A neurologist administered the PHQ-2 and the UPDRS, and the diagnosis of major depression was performed using the structured clinical interview for DSM disorders - clinical version. Two self-rating scales (Zung Self-rating Depression Scale and 15-item Geriatric Depression Scale) were also used.

RESULTS

The prevalence of current depression in the sample was 25.5% (n = 28). The scores of the PHQ-2 discriminated between subjects with and without depression, with an area under the receiver operating characteristic curve of 0.90. The sensitivity and specificity for a cut-off score of three were 75% and 89%, respectively. The values for the depression item of the UPDRS were slightly lower.

CONCLUSION

The PHQ-2 is a valid tool for screening depression in PD.