Purpose: Evidence regarding the onset of depressive symptoms in primary care is rarely available but can help inform policy development, service planning, and clinical decision making. The objective of this study was to estimate the 12-month cumulative incidence and predictors of a positive screen for depressive symptoms on the 9-item Patient Health Questionnare-9 (PHQ-9) among primary care patients with no history of physician-diagnosed depression.
Methods: We monitored a cohort of 2,929 adult primary care patients with no past history of physician-diagnosed depression and with baseline PHQ-9 scores of 9 or lower by telephone interview at 3, 6, and 12 months. A generalized linear mixed effects Poisson Model was used to explore factors associated with the incidence of PHQ-positive symptoms.
Results: The cumulative incidence of positive screening on the PHQ-9 over 12 months was 5.23% (95% CI, 3.83%-6.64%). Positive predictors included being female, coming from a lower-income household, being a smoker, having at least 2 comorbidities, having a family history of depression, and having consulted a physician at least twice in the past 4 weeks. Consulting a physician with qualifications in both family medicine and psychological medicine was a negative predictor.
Conclusions: The cumulative incidence of PHQ-9-screened depressive symptoms in this study population was higher than those reported for depressive disorders in earlier systematic reviews. Groups who may warrant greater treatment attention include women, patients with multimorbidity, smokers, patients with recent high rates of medical consultations, and those who are from lower-income households or who have a family history of depression. Greater physician training may have a protective effect.
Keywords: Chinese; depression; mental health; practice-based research; primary care; screening.
© 2016 Annals of Family Medicine, Inc.