Differential effect by chronic disease risk: A secondary analysis of the ChooseWell 365 randomized controlled trial

Whether employees' health status is associated with the effectiveness of workplace health promotion programs is unknown. The objective of this study was to determine if the effect of a workplace healthy eating intervention differed by baseline chronic disease status.

This was a secondary analysis of a randomized controlled trial conducted September 2016 to February 2018 among US hospital employees to test the effect of a 12-month behavioral intervention (personalized feedback, peer comparisons, and financial incentives) on diet and weight. Participants were classified as having chronic disease (yes/no) based on self-reported hypertension, hyperlipidemia, heart disease, stroke, pre-diabetes, diabetes, cancer or another serious illness. BMI was measured at study visits and calories purchased were measured from cafeteria sales data over 24 months. Mixed models with random effects assessed heterogeneity of treatment effects by chronic disease.

Participants (N = 548) were mostly female (79.7 %) and white (81.2 %); 224 (40.9 %) had chronic disease. Among those with chronic disease, intervention participants reduced caloric intake by 74.4 [22.3] kcal more than control, with a smaller difference between intervention and control (-1.9 [18.7] kcal) (three-way p-interaction = 0.02). The effect on BMI for those with chronic disease (0.47 [0.21] kg/m²) indicated weight stability among intervention participants and weight gain among controls while the effect (-0.56 [0.18] kg/m²) for those without chronic disease was the opposite (three-way p-interaction < 0.01).

Those with chronic diseases had greater reductions in calories purchased and gained less weight. Employers with limited resources for health promotion might consider tailoring programs to employees at highest risk.