Optimal Body Mass Index Cut-off Point for Predicting Colorectal Cancer Survival in an Asian Population: A National Health Information Database Analysis

The optimal body mass index (BMI) range for predicting survival in Asian colorectal cancer patients is unknown. We established the most appropriate cut-off point of BMI to predict better survival in Asian colorectal cancer patients using a two-stage approach. Two cohorts of colorectal cancer patients were included in this study: 5815 hospital-based development cohort and 54,043 nationwide validation cohort. To determine the optimal BMI cut-off point at diagnosis, the method of Contal and O’Quigley was used. We evaluated the association between BMI and overall survival (OS) using the Cox proportional hazard model. During a median follow-up of 5.7 and 5.1 years for the development and the validation cohort, 1180 (20.3%) and 10,244 (19.0%) deaths occurred, respectively. The optimal cut-off of BMI identified as 20.2 kg/m(2) (p(log-rank) < 8.0 × 10(−16)) for differentiating between poorer and better OS in the development cohort. When compared to the patients with a BMI < 20.2 kg/m(2), the patients with a BMI ≥ 20.2 kg/m(2) had a significantly better OS (HR = 0.62, 95% CI = 0.54–0.72, p = 1.1 × 10(−10)). The association was validated in the nationwide cohort, showing better OS in patients with a BMI ≥ 20.2 kg/m(2) (HR = 0.64, 95% CI = 0.60–0.67, p < 0.01). We suggest the use of a BMI value of 20.2 kg/m(2) to predict survival in Asian colorectal cancer patients.