The epidemiology and naturalistic outcomes of depressive disorders in Hong Kong's primary care

Abstract

Primary care is the entry point for most people into the health system and primary care physicians (PCPs) are ideally placed to serve as the central service provider for patients with depressive disorders. Identifying and managing depressive disorders is challenging in primary care and the long-term outcomes and factors affecting prognosis remain unclear particularly in non-Western settings where few studies have been conducted. This study aimed to examine the prevalence, incidence and 12-month outcomes of depressive disorders in Hong Kong’s primary care.

A practice-based research network was formed consisting of 59 PCPs who assisted in recruitment of subjects and data collection. These doctors worked in public and private sector clinics territory-wide representative of the settings where primary care is delivered in Hong Kong.

A cross-sectional followed by a 12-month cohort study was conducted on adult patients recruited from the doctors’ waiting rooms. Key study instruments included the Patient Health Questionnaire-9 Item (PHQ-9), the Centre for Epidemiologic Studies Depression Scale (CES-D) and the Short-Form Health Survey Version 2.0 (SF-12v2).

10,179 subjects completed the cross-sectional survey and index doctor visit (response rate 81.0%). 4358 subjects joined the cohort study (response rate 42.8%) and were followed-up by telephone interview at 12, 26 and 52 weeks.

The cross-sectional prevalence of PHQ-positive depressive disorders was 10.7%; 12-month cumulative incidence was 5.3%; and 12-month cumulative remission was 60.3%. PCPs identified 23.1% of the PHQ-positive subjects as having depression. At highest risk for prevalence were patients with a past history of depression, with multiple co-morbidities or who were unemployed. PCP identification did not affect 12-month remission but was associated with a faster improvement in health-related quality of life (HRQOL). Patients with milder depressive symptoms, better physical health and better HRQOL at baseline were more likely to report symptom remission over 12 months. Patients with moderate to severe depressive symptoms at baseline had a more heterogeneous set of symptom trajectories. Patients at greatest risk of chronicity were those with multiple co-morbidities or with pain. Patients reporting low levels of health service use were at greatest risk of deterioration over 12 months.

Uptake of mental health services was low in patients who were screened PHQ-positive. Over 12-months, 21.7% reported receiving mental health treatments from a psychiatrist, 11.6% from a PCP, and 3.6% from a psychologist. Identification of depression by the PCP was associated with a higher uptake of mental health services, however baseline depressive symptom severity was not.

Identification of depression is challenging, nonetheless, PCP non-detection does not appear to contribute to persistence of depressive symptoms as most patients in this setting improve naturalistically over time.

In clinical practice, doctors need to be more vigilant in patients who are at high-risk for prevalence and incidence to prevent delays in detection and treatment. Greater treatment attention is required for patients with multiple co-morbidities or who suffer from pain, to enable them to cope better with their complex bio-psycho-social health problems and enhance HRQOL. Regular follow-up should be scheduled for those who are at risk for poor prognosis.