Summed score of the Patient Health Questionnaire-9 was a reliable and valid method for depression screening in chronically ill elderly patients.
OBJECTIVE
To assess the psychometric properties of the Patient Health Questionnaire-9 (PHQ-9) as a screening instrument for depression in elderly patients with diabetes mellitus (DM) and chronic obstructive pulmonary disease (COPD) without known depression.


METHODS
DM and COPD patients aged >59 years were selected from general practices. A test-retest was conducted in 105 patients. Criterion validity, using the Mini International Neuropsychiatric Interview psychiatric interview to diagnose major depressive disorder (MDD) and any depressive disorder (ADD) as diagnostic standard, was evaluated for both summed and algorithm-based PHQ-9 score in 713 patients. Correlations with quality of life and severity of illness were calculated to assess construct validity.


RESULTS
Cohen's kappa for the algorithm-based score was 0.71 for MDD and 0.69 for ADD. Correlation for test-retest assessment of the summed score was 0.91. The algorithm-based score had low sensitivity and high specificity, but both sensitivity and specificity were high for the optimal cut-off point of 6 on the summed score for ADD (Se 95.6%, Sp 81.0%). Correlations between summed score and quality of life and severity of illness were acceptable.


CONCLUSIONS
The summed PHQ-9 score seems a valid and reliable screening instrument for depression in elderly primary care patients with DM and COPD.
Care and Public Health Research Institute (CAPHRI), Department of Social Medicine, Faculty of Health, Medicine and Life Sciences, Maastricht University, P.O. Box 616, 6200 MD Maastricht, the Netherlands. f.lamers@zw.unimaas.nl
Femke
F
Lamers
Catharina C M
CC
Jonkers
Hans
H
Bosma
Brenda W J H
BW
Penninx
J André
JA
Knottnerus
Jacques Th M
JT
van Eijk
D000368:Aged; D002908:Chronic Disease / Q000523:psychology; D003863:Depression / Q000175:diagnosis*; D003924:Diabetes Mellitus, Type 2 / Q000523:psychology; D006801:Humans; D007406:Interview, Psychological; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics; D029424:Pulmonary Disease, Chronic Obstructive / Q000523:psychology; D012647:Self-Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires