Measuring depression levels in HIV-infected patients as part of routine clinical care using the nine-item Patient Health Questionnaire (PHQ-9).
Little is known about the psychometric properties of depression instruments among persons infected with HIV. We analyzed data from a large sample of patients in usual care in two US cities (n=1467) using the nine-item Patient Health Questionnaire (PHQ-9) from the PRIME-MD. The PHQ-9 had curvilinear scaling properties and varying levels of measurement precision along the continuum of depression measured by the instrument. In our cohort, the scale showed a prominent floor effect and a distribution of scores across depression severity levels. Three items had differential item functioning (DIF) with respect to race (African-American vs. white); two had DIF with respect to sex; and one had DIF with respect to age. There was minimal individual-level DIF impact. Twenty percent of the difference in mean depression levels between African-Americans and whites was due to DIF. While standard scores for the PHQ-9 may be appropriate for use with individual HIV-infected patients in cross-sectional settings, these results suggest that investigations of depression across groups and within patients across time may require a more sophisticated analytic framework.
Crane
P K
PK
Department of Medicine, Harborview Medical Center, University of Washington, Seattle, WA, USA. pcrane@u.washington.edu
Gibbons
L E
LE
Willig
J H
JH
Mugavero
M J
MJ
Lawrence
S T
ST
Schumacher
J E
JE
Saag
M S
MS
Kitahata
M M
MM
Crane
H M
HM
D000328:Adult; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000175:diagnosis*; D005260:Female; D015658:HIV Infections / Q000523:psychology*; D006801:Humans; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D011594:Psychometrics; D011795:Surveys and Questionnaires; D055815:Young Adult