Do cardiovascular disease prevention programs in northern Sweden impact on population health? An interrupted time series analysis

BACKGROUND: Cardiovascular disease (CVD) is the main cause of morbidity and mortality in Sweden. This study aims to assess the impact of a CVD intervention implemented in 1993 in northern Sweden on the reduction of premature ischemic heart disease (IHD) morbidity and mortality in women and men during the period 1987-2013. METHODS: An ecological controlled interrupted time series design, with pre-intervention period defined as 1987-1993 and post-intervention period 1994-2013 was carried out. For each year, IHD events, stratified by sex, were retrieved from national registers. RESULTS: Impressive reductions on IHD premature morbidity and mortality were observed to a similar degree in both the intervention county and the other comparison counties across the last 27 years. Significant differences in the pre-post intervention trends indicating the intervention group had smaller reductions than expected from its pre-intervention trend and the trend of control counties were found among men for both IHD morbidity and mortality. A similar pattern was observed among women but without significant differences. CONCLUSIONS: Taken together, the data do not support that the intervention has contributed to an additional reduction on IHD morbidity and mortality, above and beyond that which is already seen in neighbouring counties without similar programs.