Association between systolic blood pressure and cardiovascular inpatient cost moderated by peer-support intervention among adult patients with type 2 diabetes : a 2-cohort study

Objectives: People with type 2 diabetes and increased systolic blood pressure (SBP) are at high risk of cardiovascular disease (CVD). In this study, we aimed to investigate the association between CVD-related hospital payments and SBP and tested whether this association is influenced by diabetes peer support. Methods: Two cohorts comprising people with type 2 diabetes were included in the study. The first cohort comprised 4,704 patients with type 2 diabetes assessed between 2008 and 2009 from 18 general practices in Cambridgeshire and followed up to 2009-2011. The second cohort comprised 1,121 patients with type 2 diabetes from post-trial follow-up data, recruited between 2011 and 2012 and followed up to 2015. SBP was measured at baseline. Inpatient payments for CVD hospitalization within 2 years since baseline was the main outcome. The impact of 1:1, group or combined diabetes peer support and usual care were investigated in the second cohort. Adjusted mean CVD inpatient payments per person were estimated using a 2-part model after adjusting for baseline characteristics. Results: A "hockey-stick" relationship between baseline SBP and estimated CVD inpatient payment was identified in both cohorts, with a threshold at 133 to 141 mmHg, suggesting increased payments for patients with SBP below and above the threshold. The combined peer-support intervention altered the aforementioned association, with no increased payment with SBP above the threshold, and payment slightly decreased with SBP beyond the threshold. Conclusions: SBP maintained between 133 and 141 mmHg is associated with the lowest CVD disease management costs for patients with type 2 diabetes. Combined peer-support intervention could significantly decrease CVD-related hospital payments.