Body mass index and outcomes following gastrointestinal cancer surgery in Japan

• Published in: British journal of surgery Vol. 100; no. 10; pp. 1335 - 1343
• Main Authors: Yasunaga, H., Horiguchi, H., Matsuda, S., Fushimi, K., Hashimoto, H., Ayanian, J. Z.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.09.2013; Oxford University Press
• Subjects: Aged; Body Mass Index; Cohort Studies; Colorectal Neoplasms - complications; Colorectal Neoplasms - mortality; Colorectal Neoplasms - surgery; Female; Gastrectomy - mortality; Gastrectomy - statistics & numerical data; Hospital Mortality; Humans; Japan - epidemiology; Male; Overweight - complications; Overweight - mortality; Postoperative Complications - etiology; Postoperative Complications - mortality; Stomach Neoplasms - complications; Stomach Neoplasms - mortality; Stomach Neoplasms - surgery; Thinness - complications; Thinness - mortality; Treatment Outcome; Japan
• ISSN: 0007-1323; 1365-2168
• DOI: 10.1002/bjs.9221

Background Recent studies in the USA have shown a lower postoperative mortality rate in mildly obese patients, described as the ‘obesity paradox’. The results from the relatively obese population in Western countries may not be generalizable to Asian countries, prompting the present study to investigate the relationship between body mass index (BMI) and outcomes after gastrointestinal surgery. Methods Patients who underwent gastrectomy or colorectal resection for stage I–III cancer between July and December 2010 were identified from a nationwide inpatient database in Japan. Multivariable logistic regression models for in‐hospital mortality and postoperative complications, and a linear regression model for total costs were established, with adjustment for age, sex, co‐morbidities, cancer stage and BMI. Restricted cubic spline functions were used to consider potential non‐linear associations between BMI and the outcomes. Results Among 30 765 eligible patients, associations between BMI and the outcomes were U‐shaped, with the lowest mortality, morbidity and total costs in patients with a BMI of around 23·0 kg/m2. A BMI of 18·5 kg/m2 was associated with significantly greater mortality (odds ratio (OR) 2·04, 95 per cent confidence interval 1·64 to 2·55), postoperative complications (OR 1·10, 1·03 to 1·18) and total costs (difference €1389, 1139 to 1640) compared with a BMI of 23·0 kg/m2. Patients with a BMI exceeding 30·0 kg/m2 had significantly higher rates of postoperative complications and total costs than those with a BMI of 23·0 kg/m2, but no significant association was evident between a BMI of more than 23·0 kg/m2 and in‐hospital death. Conclusion Unlike previous studies in the USA, in the present national Japanese cohort of patients undergoing surgery for gastrointestinal cancer, those who were either underweight or overweight had more postoperative complications and greater perioperative costs than those of normal weight. Japanese patients really are different