Medication non-adherence and blood pressure control among hypertensive migrant and non-migrant populations of sub-Saharan African origin: the RODAM study

Large differences in blood pressure (BP) control rates have been observed between sub-Saharan African migrant populations in Europe compared to their counterparts living in Africa. Our main objective was to investigate whether inter-geographical differences in BP control rates can be explained by differences in medication non-adherence. Additionally, we studied the prevalence of medication non-adherence and associations between medication non-adherence, socio-demographic-related, clinical/treatment-related, lifestyle factors, and experienced stress on the one hand and BP control on the other hand. We used data from the multi-center RODAM (Research on Obesity and Diabetes Among African Migrants) study, from Ghanaians receiving antihypertensive therapy and residing in three European countries versus non-migrants residing in rural and urban Ghana (n = 1303). Bivariate and multivariate logistic regression analyses stratified by sex were applied. We found inter-geographical differences in BP control rates among Ghanaian males but not among females. Ghanaian males residing in Amsterdam and Berlin had not only the lowest BP control rates but also the lowest rates of medication non-adherence. Inter-geographical differences in BP control rates among males became therefore more pronounced after adjustment for medication adherence. Medication non-adherence was significantly and independently associated with suboptimal BP control in males and females. Other factors associated with suboptimal BP control in females were a higher number of prescribed antihypertensives, higher fasting glucose levels, and pregnancy-induced diabetes. When adjusted for medication non-adherence and socio-demographic-, clinical/treatment-, lifestyle-, and stress-related factors, inter-geographical differences in BP control in males disappeared, except for Berlin. In conclusion, the observed inter-geographical differences in BP control rates in Ghanaian males cannot be explained by differences in medication non-adherence.