Path Analysis of the Impact of Obesity on Postoperative Outcomes in Colorectal Cancer Patients: A Population-Based Study

Background: Obesity is adversely affecting perioperative outcomes; however, long-term outcomes do not appear to be affected by excess body weight (the obesity paradox). The purpose of this study is to examine the association between obesity and surgical outcomes in patients with colorectal cancer (CRC) using data from the United States National Inpatient Sample (NIS). Methods: Patients ≥20 years old diagnosed with CRC who received surgery were identified in the 2004–2014 NIS database. Patients who were obese (ICD-9-CM code: 278.0) were matched with controls (non-obese) in a 1:4 ratio for age, sex, and severity of CRC (metastasis vs. no metastasis). Linear regression and path analysis were used to compare outcomes between obese and non-obese patients. A total of 107,067 patients (53,376 males, 53,691 females) were included in the analysis, and 7.86% were obese. Results: The rates of postoperative infection, shock, bleeding, wound disruption, and digestive system complications were significantly different between the obese and non-obese groups. The obesity group had increased incidence of postoperative infection by 1.9% (∂P/∂X = 0.019), shock by 0.25% (∂P/∂X = 0.0025), postoperative bleeding by 0.5% (∂P/∂X = 0.005), wound disruption by 0.6% (∂P/∂X = 0.006), and digestive system complications by 1.35% (∂P/∂X = 0.0135). Path analysis showed that obesity group had higher in-hospital mortality through mentioned above five complications by 66.65 × 10(−5)%, length of hospital stay by 0.32 days, and total hospital charges by 2384 US dollars. Conclusions: Obesity increases the risk of postoperative complications in patients with CRC undergoing surgery. It also increased in-hospital mortality, length of hospital stay, and total hospital charges. Therefore, patients with obesity might require a higher level of preoperative interventions and complications monitoring to improve outcomes.