Temporal trend analysis of stroke and salt intake: a 15-year population-based study

Abstract

Objectives: The aim of this study was to evaluate temporal trends of salt intake with stroke incidence, stroke subtypes, and blood pressure in an adult population. Methods: Data were extracted from Isfahan Salt Study. The stroke incidence rate, average salt intake, systolic and diastolic blood pressure in adults, aged over 18 years were considered from 2000 to 2014. The Average Annual Percent Changes (AAPC), parallelism, and the coincidence of trends were estimated, using a permutation test. Results: The trend of salt intake was increased from 2010 to 2014 (AAPC = +1.59, P-value = 0.004). The trend of the stroke incidence rate was nonlinear with two change points in 2003 and 2009. The overall stroke incidence rate increased by 6.65 per year (95 CI: 1.66, 11.8, P-value = 0.015). The temporal trend changes of stroke incidence rate were steeper in patients who aged 40-45 and over 50 years (+6 to +11.5) than in patients who aged 19-40 and 45-50 (range: -3.3 to 0). The parallelism hypothesis of longitudinal changes between salt intake and ischemic stroke was accepted in patients, aged <50 years (P-value = 0.871). Conclusions: The average salt intake and its cone-shaped variance over 15 years of the study, indicated that salt intake reduction programs and policies were effective to stop associating intake increase until 2007, however, associated intake was increased since that time, which necessitates performing preventive programs. More importantly, the trend of salt intake and ischemic stroke was similar in patients who aged <50 years, regardless of considering their blood pressure.