Extremes in body mass index: probability of healthcare expenditures

This study was conducted as a first initiative to investigate the relationship between body mass index [BMI, weight(kg)/height(m)2] and healthcare expenditures by third party providers for lifestyle-related diseases and disorders.

Data were analyzed for 383 individuals who were continuously employed and covered by the same comprehensive health insurance plan during a 2-year baseline period followed by a 5-year observation period. A multiple logistic regression analysis that adjusted for covariates was used to ascertain whether BMI and baseline expenditure status separately or in combination influenced the probability of healthcare expenditures during the observation period.

After controlling for age, gender, and smoking status, probability of healthcare expenditures for lifestyle-related medical problems was significantly (P < 0.04) greater during the observation period for adults with high as well as low BMIs plus baseline expenditures and lowest for subjects whose BMIs were in the midrange regardless of their baseline expenditures. Odds of expenditures increased significantly (P = 0.0079) with age of nonsmokers, but was approximately constant and high for smokers at all ages. The absence of any significant interaction of either smoking status or age with BMI indicated that the relationship between BMI and the log odds of expenditures was consistent across age and smoking categories.

The analyses support the conclusion that the highest probability of expenditures occurs with the combination of baseline insurance expenditures and BMI extremes and the lowest probability occurs when BMIs are near 26 or 27 (approximately 19% above the ideal of 22). The findings also provide further justification for focusing on extremes in body weight as health priorities.