Hypertension and diabetes in Zanzibar – prevalence and access to care

Background
Cardiovascular diseases are among the most common causes of hospital admissions and deaths in Zanzibar. This study assessed prevalence of, and antecedent factors and care access for the two common cardiovascular risk factors, hypertension and diabetes, to support health system improvements. 

Methods
Data was from a population based nationally representative survey. Prevalence of hypertension was defined as systolic blood pressure ≥ 140 mmHg, diastolic blood pressure ≥ 90 mmHg or a self-reported diagnosis of hypertension; diabetes was defined as a fasting blood glucose ≥ 6.1 mmol/L or a self-reported diagnosis of diabetes. Care-cascades for hypertension and diabetes were created with four stages: being tested, diagnosed, treated, and achieving control. Multivariable logistic regression models were constructed to evaluate individual-level factors – including symptoms of mental illness - associated with having hypertension or diabetes, and with progressing through the hypertension care cascade. Whether people at overt increased risk of hypertension or diabetes (defined as >50 years old, BMI>30 kg/m2, or currently smoking) were more likely to be tested was assessed using chi squared. 

Results
Prevalence of hypertension was 33.5% (CI 30.6-36.5). Older age (OR 7.7, CI 4.93-12.02), some education (OR 0.6, CI 0.44-0.89), obesity (OR 3.1, CI 2.12-4.44), and raised fasting blood glucose (OR 2.4, CI 2.38) were significantly independently associated with hypertension.Only 10.9% (CI 8.6-13.8) of the entire hypertensive population achieved blood pressure control, associated factors were being female (OR 4.8, CI 2.33-9.88), formally employed (OR 3.0, CI 1.26-7.17), and over-weight (OR 2.5, CI 1.29-4.76). The prevalence of diabetes was 4.4% (CI 3.4-5.5), and associated with old age (OR 14.1, CI 6.05-32.65) and almost significantly with obesity (OR 2.1, CI 1.00-4.37). Only 11.9% (CI 6.6-20.6) of the diabetic population had achieved control. Individuals at overt increased risk were more likely to have been tested for hypertension (chi2 19.4) or diabetes (chi2 33.2) compared to the rest of the population. Symptoms of mental illness were not associated with prevalence of disease or progress through the cascade.

Conclusion
High prevalence of hypertension and suboptimal management along the care cascades indicates a large unmet need for hypertension and diabetes care in Zanzibar.