Shifts in waist-to-height ratio categories within tirzepatide groups: a post-hoc analysis of SURMOUNT-1

OBJECTIVE: To evaluate shifts in waist-to-height ratio (WHtR) categories among adults with obesity or overweight, with or without prediabetes, treated with tirzepatide in the SURMOUNT-1 study. METHODS: This post hoc analysis included 2,538 participants from the SURMOUNT-1 Phase 3, double-blind, randomized, placebo-controlled trial. Adults with BMI ≥ 30 or ≥ 27 kg/m² and at least one obesity-related complication (ORC), excluding diabetes, were randomized to receive once-weekly tirzepatide (5, 10, or 15 mg) or placebo, alongside a reduced-calorie diet and increased physical activity. Participants were grouped by baseline WHtR (≤ 0.49, > 0.49 to ≤ 0.59, > 0.59) according to the National Institute for Health and Care Excellence (NICE) framework. Participants with prediabetes at baseline had additional follow-up data beyond week 72, and shifts in their WHtR categories at week 176 were also included. Change from baseline in WHtR was analyzed using a mixed model for repeated measures (MMRM). Shift tables were used to summarize changes from baseline to post-baseline WHtR category levels. RESULTS: At baseline, 89.8% of participants had a WHtR > 0.59, 10.1% had > 0.49 to ≤ 0.59, and 0.1% had ≤ 0.49. After 72 weeks of tirzepatide (10/15 mg), 16.7% of participants achieved a WHtR ≤ 0.49, and 54.7% improved their baseline WHtR category compared to 9.6% with placebo. At 176 weeks, among participants with prediabetes, 12.2% achieved WHtR ≤ 0.49, and 46.4% improved their category with tirzepatide versus 9.3% with placebo. CONCLUSIONS: Tirzepatide treatment was associated with sustained improvements in WHtR categories, with a greater proportion of participants shifting to a better WHtR category compared to participants treated with placebo. Improved WHtR may be suggestive of lower future cardiometabolic risk. Further analyses of this nature will enhance the understanding and application of WHtR in obesity management across diverse populations.