Tirzepatide reduces body weight across body mass index (BMI) categories: A SURMOUNT-1 prespecified analysis

Question Is tirzepatide (TZP 5, 10, 15mg) efficacious in reducing body weight across different classes of obesity? Methodology Adult participants, with obesity, or overweight (OW) with weight‐related comorbidities (excluding diabetes), were randomised (1:1:1:1) to once‐weekly TZP, or placebo (PBO). Percent change from baseline in body weight (BW) and proportion of participants achieving ≥ 5 %BW reduction at week72 were assessed in participants with BMI ≥ 27 ‐ < 30 (OW), ≥ 30 ‐ < 35 (Class 1 obesity), ≥ 35 ‐ < 40 (Class 2 obesity), and ≥ 40kg/m2 (Class 3 obesity). On‐treatment data prior to discontinuation of study drug were used for analysis. Results 2539 adults were randomised (female = 68 %, mean age = 45 years, BW = 104.8kg, BMI = 38.0kg/m2). All TZP doses lowered BW vs PBO regardless of baseline BMI category (p < 0.001). Estimated treatment difference (95 %CI) of TZP 5, 10, and 15mg, respectively, vs PBO for the %BW change from baseline was: ‐13.6 % (‐18.0,‐9.3), ‐15.2 % (‐19.6,‐10.8), and ‐15.2 % (‐19.6,‐10.7) in OW; ‐13.9 % (‐15.7,‐12.2), ‐19.3 % (‐21.1,‐17.5), and ‐18.6 % (‐20.4,‐16.7) in Class 1 obesity; ‐13.3 % (‐15.3,‐11.2), ‐20.0 % (‐22.0,‐17.9), and ‐22.5 % (‐24.5,‐20.4) in Class 2 obesity; and ‐13.4 % (‐15.5,‐11.3), ‐18.2 % (‐20.2,‐16.2), and ‐20.3 % (‐22.3,‐18.3) in Class 3 obesity. The proportion of participants achieving ≥ 5 %BW reduction in each BMI category, respectively, was significantly greater with TZP (92‐100 %, 90‐98 %, 90‐98 %, and 87‐97 %) vs PBO (30 %, 28 %, 25 %, and 30 %). Conclusions In adults with obesity, each TZP dose led to significant BW reductions vs PBO irrespective of baseline BMI. TZP doses 10, 15mg led to greater BW reductions.