Continued increases in blood pressure over two decades in Samoa (1991-2013); around one-third of the increase explained by rising obesity levels

Background: To analyse trends over the period 1991-2013 in systolic blood pressure (SBP), diastolic blood pressure (DBP) and the prevalence of hypertension in adults aged 25-64 years in Samoa; and to assess the contribution of rising obesity levels to period trends. Methods: Unit record data from seven population-based surveys (n = 10,881) conducted between 1991 and 2013 were included for analysis. Surveys were adjusted to the nearest previous census to improve national representativeness. Hypertension was defined as SBP >= 140 mmHg and/or DBP >= 90 mmHg and/or on medication for hypertension. Obesity was measured by body mass index (BMI). Poisson, linear and meta-regression were used to assess period trends. Results: Over 1991-2013 mean SBP and DBP (mmHg), and the prevalence of hypertension (%) increased in both sexes. Increases in hypertension were: from 18.3 to 33.9% (p < 0.001) in men (mean BP from 122/74 to 132/78); and from 14.3 to 26.4% (p < 0.001) in women (mean BP from 118/73 to 126/78). The estimate of the age-adjusted mean SBP and DBP over 1991-2013, and the relative risk for hypertension in 2013 compared to 1991, were attenuated after adjusting for BMI: by 22% (men) and 32% (women) for mean SBP; 37% (men) and 32% (women) for mean DBP; and 19% in both sexes for hypertension. Conclusions: Significant increases have occurred in SBP/DBP and hypertension prevalence in both sexes in Samoa during 1991-2013, which would contribute significantly to premature mortality from cardiovascular disease. Obesity accounts for around one-third of the rising trend in blood pressure in the Samoan population. Strengthening of population control of hypertension through reduction in obesity and salt intake, and case detection and treatment through primary care, is required to reduce premature mortality from cardiovascular disease in Samoa.