Global prevalence and trends in hypertension and type 2 diabetes mellitus among slum residents: a systematic review and meta-analysis

Objective First, to obtain regional estimates of prevalence of hypertension and type 2 diabetes in urban slums; and second, to compare these with those in urban and rural areas. Design Systematic review and meta-analysis. Eligibility criteria Studies that reported hypertension prevalence using the definition of blood pressure >= 140/90 mm Hg and/or prevalence of type 2 diabetes. Information sources Ovid MEDLINE, Cochrane CENTRAL and EMBASE from inception to December 2020. Risk of bias Two authors extracted relevant data and assessed risk of bias independently using the Strengthening the Reporting of Observational Studies in Epidemiology guideline. Synthesis of results We used random-effects meta-analyses to pool prevalence estimates. We examined time trends in the prevalence estimates using meta-regression regression models with the prevalence estimates as the outcome variable and the calendar year of the publication as the predictor. Results A total of 62 studies involving 108 110 participants met the inclusion criteria. Prevalence of hypertension and type 2 diabetes in slum populations ranged from 4.2% to 52.5% and 0.9% to 25.0%, respectively. In six studies presenting comparator data, all from the Indian subcontinent, slum residents were 35% more likely to be hypertensive than those living in comparator rural areas and 30% less likely to be hypertensive than those from comparator non-slum urban areas. Limitations of evidence Of the included studies, only few studies from India compared the slum prevalence estimates with those living in non-slum urban and rural areas; this limits the generalisability of the finding. Interpretation The burden of hypertension and type 2 diabetes varied widely between countries and regions and, to some degree, also within countries. PROSPERO registration number CRD42017077381.