Comparison of depressive symptoms in type 2 diabetes using a two-stage survey design.
OBJECTIVE
To test the validity of the Patient Health Questionnaire-9 (PHQ-9) in adults with newly diagnosed Type 2 diabetes mellitus (T2DM) and compare the distribution of PHQ-9 items in those with and without Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) depression.


METHODS
A two-stage survey design was used in primary care centers (n = 96). In Stage 1, participants were administered the PHQ-9 and biopsychosocial measures. In Stage 2, PHQ-9 positives (score ≥ 10) and randomly selected PHQ-9 negatives (score <10) had a diagnostic interview, Schedule for Clinical Assessment in Neuropsychiatry 2.1. The sensitivity, specificity and receiver operating characteristics of the PHQ-9 were calculated. The means of PHQ-9 items were compared.


RESULTS
Stage 1: Prevalence of PHQ-9 positives (completing Stage 2) was 12.1% (n = 182). PHQ-9 positives were younger (mean [standard deviation] age = 52.8 [9.47] versus 56.2 [11.50] years, p < .001) and had higher body mass index (32.7 [7.08] versus 31.6 [6.25] kg/m(2), p = .028) than PHQ-9 negatives (n = 1278). Stage 2: Prevalence of DSM-IV depression was 5.6% (n = 84). The optimal cutoff was ≥ 12 (sensitivity = 86.9%, specificity = 80.3%). PHQ-9 true positives scored significantly higher than PHQ-9 false positives on all items, excluding sleep (mean [standard deviation] score = 2.4 [0.98] versus 2.2 [1.06]), fatigue (2.5 [0.80] versus 2.3 [0.86]), and appetite (1.6 [1.23] versus 1.5 [1.26]).


CONCLUSIONS
Over-identification of depression by PHQ-9 in T2DM may be driven by presence of symptoms in keeping with an organic origin.
Division of Psychological Medicine, King's College London, Western Education Centre, 10 Cutcombe Road, SE5 9RJ, London, UK. Katherine.twist@kcl.ac.uk.
Katherine
K
Twist
Daniel
D
Stahl
Stephanie A
SA
Amiel
Stephen
S
Thomas
Kirsty
K
Winkley
Khalida
K
Ismail
D000293:Adolescent; D000328:Adult; D000368:Aged; D003866:Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology* / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005189:False Positive Reactions; D005260:Female; D006306:Health Surveys / Q000379:methods; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011320:Primary Health Care; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires / Q000592:standards*; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
depression and affective disorders; diabetes mellitus; epidemiology; primary care; psychological measurement; self-report screening tools