Estimating the Prevalence of Mental and Substance Use Disorders: A Systematic Approach to Triangulating Available Data to Inform Health Systems Planning:: Estimer la prévalence des troubles mentaux et des troubles liés à une substance: une approche systématique de la triangulation des données disponibles pour éclairer la planification du système de santé.

OBJECTIVE To estimate the prevalence of specific mental and substance use disorders (MSUDs), by age and sex, as a first step toward informing needs-based health systems planning by decision-makers. METHODS We developed a conceptual framework and a systematic methodology for combining available data sources to yield prevalence estimates for specific MSUDs. Data sources used included published, peer-reviewed literature from Canada and comparable countries, Canadian population survey data, and health administrative data from British Columbia. Several well-established methodologies including systematic review and meta-analyses of published prevalence estimates, modelling of age- and sex-specific distributions, and the Global Burden of Disease severity distribution model were incorporated in a novel mode of triangulation. RESULTS Using this novel approach, we obtained prevalence estimates for 10 MSUDs for British Columbia, Canada, as well as prevalence distributions across age groups, by sex. CONCLUSION Obtaining reliable assessments of disorder prevalence and severity is a useful first step toward rationally estimating service need and plan health services. We propose a methodology to leverage existing information to obtain robust estimates in a timely manner and with sufficient granularity to, after adjusting for comorbidity and matching with severity-specific service bundles, inform need-based planning efforts for adult (15 years and older) mental health and substance use services.