Estimating the potential impact fraction of hypertension as the main risk factor of stroke: Application of the distribution shift method.

Few published studies have assessed the impact of quantitative risk factors such as high blood pressure on stroke. The aim of this study was to quantify the potential impact fraction (PIF) of hypertension on stroke in Hamadan Province, western Iran. Avoidable burden of stroke associated with high blood pressure was calculated using distribution shift at different scenarios. Data on the prevalence of high blood pressure among residents of Hamadan province older than 19 years were extracted from non-communicable diseases risk factors surveillance system in 2009. Five mmHg hypothetical reduction in systolic blood pressure above 140 mmHg, leads to 3.5% (PIF=0.035) reduction in the total burden to stroke. This value may reach 7%, if systolic blood pressure decreases 10 mmHg. In addition, 5 mmHg hypothetical reduction in diastolic blood pressure above 82 mmHg, leads to 4.87% reduction in the total burden to stroke. PIF more than 10 mmHg modification on distribution of diastolic blood pressure was estimated as 9.38%. According to these findings, policy makers are advised to implement interventions on hypertension based on the distribution shift method rather than the proportion shift one.