Baseline body mass index modifies the effects of digital health interventions compared with usual care on cardiovascular disease risk in people with type 2 diabetes: a secondary analysis of the SMARTDiabetes trial.

BACKGROUND

Body weight is a critical determinant of cardiovascular disease (CVD) risk among people with type 2 diabetes mellitus (T2DM), substantially contributing to the incidence of and outcomes from CVD. However, the impact of body weight on the effectiveness of digital health interventions, an increasingly used innovation to improve care outcomes, remains uncertain.

OBJECTIVES

This study aimed to examine the effectiveness of digital health interventions in improving CVD risks and whether baseline body mass index (BMI) modified these effects in people with T2DM.

METHODS

SMARTDiabetes was an open-label, parallel, cluster randomized controlled trial examining the effects of digital health interventions compared with usual care on T2DM management over 24 mo. In this secondary analysis, we compared 10-y CVD risk scores between intervention and usual care groups and examined the heterogeneity of intervention effects across different BMI subgroups.

RESULTS

The study included 2072 patients with T2DM, of whom 714 were in the normal BMI range (<25 kg/m2), 996 were overweight (25 to <30 kg/m2), and 362 were obese (≥30 kg/m2) at baseline. There was no difference in mean 10-y CVD risk between intervention and usual care groups from baseline to 24 mo [between-group difference: -0.201%; 95% confidence interval (CI): -0.788, 1.190; P = 0.691]. However, there was significant heterogeneity by BMI subgroup (P-interaction = 0.009). Among individuals with normal BMI, the intervention was associated with a significant reduction in mean 10-y CVD risk [-1.108%; (95% CI -1.831, -0.386; P = 0.003)], whereas no significant benefit was observed in individuals with overweight or obesity. A similar heterogeneity of intervention effects was observed for change in body weight and systolic blood pressure (P-interaction < 0.1 for all comparisons).

CONCLUSIONS

Digital health interventions had heterogeneous effects on reducing CVD risk and were only effective among people with a normal baseline BMI. Digital health interventions should be tailored to better suit the needs of people with T2DM and elevated BMI. The SMARTDiabetes trial is registered at clinicaltrials.gov as NCT02726100.