Hypertension and diabetes prevalence, associated factors, care cascade, and quality of life in older adults: cross-sectional population-based study in The Gambia, South Africa, and Zimbabwe

Background

Hypertension and diabetes prevalence are increasing across Africa. We investigated the prevalence, associated factors, achievement of stages within the care cascade (diagnosis, treatment, control), and health-related quality of life (HRQoL).

Methods and findings

This cross-sectional study recruited adults aged ≥40 years in five settings: rural (n=1052) and urban (n=1218) Gambia, rural (n=948) and urban (n=968) South Africa (SA), and urban (n=1110) Zimbabwe between 2022 and 2024. Data were collected using researcher-administered questionnaires and assessments. Hypertension and diabetes were defined using self-reported diagnosis, medication use, and blood pressure and glucose measurements. HRQoL was assessed using EuroQol-5 Dimension 5 Level questionnaire, with a minimally important difference (MID) defined as half a standard deviation (SD). Diabetes complications included neuropathy, cardiovascular disease, and kidney disease. Associations between hypertension and diabetes and risk factors were assessed using study site, age, sex, educational attainment, and wealth index-adjusted Generalised Linear Mixed Effects Models. Associations between care cascade stages and HRQoL were assessed using linear models.
Analysis included 5296 adults, 53% female and 52% age ≥60 years. Overall hypertension prevalence was 55.6% (95% confidence intervals [CI] 54.2-56.9%); ranging from 39.6% (95% CI: 36.7-42.7) in rural Gambia, to 66.9% (64.1-69.7) in urban Zimbabwe. Overall, diabetes prevalence was 14.0% (13.1-15.0%), ranging from 9.2% (7.6-11.0) in urban Zimbabwe to 19.4% (16.9-22.1) in rural SA. Both overweight and obesity, compared to normal weight, were associated with higher odds of hypertension (adjusted odds ratios: 1.73 (95% CI [1.47,2.03]; p<0.001) and 2.08 (95% CI [1.74,2.49]; p<0.001), respectively and diabetes (1.53 (95% CI [1.22,1.91];p<0.001) and 2.12 (95% CI [1.67,2.69); p<0.001), respectively. The proportion with treated and controlled hypertension was 31.0% (913/2944), with 27.2% (800/2944) undiagnosed, and 26.0% (766/2944) treated but uncontrolled. Overall, 21.9% (161/735) had treated and controlled diabetes, whilst 49.7% (365/735) were undiagnosed, and 15.4% (113/735) were diagnosed and untreated. Underdiagnosis and inadequate treatment and control of both diseases were more common in men and in The Gambia. Overall, hypertension targets of 80-80-80% in diagnosis, treatment and control were 72.8%(2144/2944), 78.3% (1679/2144) and 54.4% (913/1679), respectively. Diabetes targets of 80-80-80-60% in diagnosis, glucose control, hypertension control, and statin use were 50.8%(377/742), 65.7% (243/370), 60.4% (224/371), and 17.8% (67/377), respectively. For both disease targets, South Africa performed better than The Gambia and Zimbabwe. The overall mean±SD HRQoL utility score was 0.829±0.107 (MID=0.054). Compared to being non-hypertensive, having diagnosed and untreated hypertension was associated with a -0.07 (95%CI [-0.05, -0.08]; p<0.001) lower HRQoL utility score. Compared to being non-diabetic, having treated and controlled diabetes was associated with lower HRQoL: -0.07 (95% CI [-0.01, -0.13]; p=0.028) in The Gambia and -0.08 (95% CI [-0.03, -0.12]; p<0.001) in Zimbabwe. Having ≥1 complication was associated with lower HRQoL: -0.04 (95% CI [-0.03,- 0.05];p<0.001). Study limitations are the cross-sectional design and reliance on single measurements of blood pressure and glucose concentrations.

Conclusions

The high prevalence of hypertension and diabetes in mid-age and older adults in rural and urban Africa necessitates urgent diagnostic, preventive and control interventions. This can include interventions targeted at obesity, screening of all adults age ≥40 years, prompt and optimal treatment for those diagnosed, and ongoing monitoring to limit complications.