Association of Low Muscle Mass and Low Muscle Radiodensity With Morbidity and Mortality for Colon Cancer Surgery

Importance Given the risks of postoperative morbidity and its consequent economic burden and impairment to patients undergoing colon resection, evaluating risk factors associated with complications will allow risk stratification and the targeting of supportive interventions. Evaluation of muscle characteristics is an emerging area for improving preoperative risk stratification. Objective To examine the associations of muscle characteristics with postoperative complications, length of hospital stay (LOS), readmission, and mortality in patients with colon cancer. Design, Setting, and Participants This population-based retrospective cohort study was conducted among 1630 patients who received a diagnosis of stage I to III colon cancer from January 2006 to December 2011 at Kaiser Permanente Northern California, an integrated health care system. Preliminary data analysis started in 2017. Because major complication data were collected between 2018 and 2019, the final analysis using the current cohort was conducted between 2019 and 2020. Exposures Low skeletal muscle index (SMI) and/or low skeletal muscle radiodensity (SMD) levels were assessed using preoperative computerized tomography images. Main Outcomes and Measures Length of stay, any complication (>= 1 predefined complications) or major complications (Clavien-Dindo classification score >= 3), 30-day mortality and readmission up to 30 days postdischarge, and overall mortality. Results The mean (SD) age at diagnosis was 64.0 (11.3) years and 906 (55.6%) were women. Patients with low SMI or low SMD were more likely to remain hospitalized 7 days or longer after surgery (odds ratio [OR], 1.33; 95% CI, 1.05-1.68; OR, 1.39; 95% CI, 1.05-1.84, respectively) and had higher risks of overall mortality (hazard ratio, 1.40; 95% CI, 1.13-1.74; hazard ratio, 1.44; 95% CI, 1.12-1.85, respectively). Additionally, patients with low SMI were more likely to have 1 or more postsurgical complications (OR, 1.31; 95% CI, 1.04-1.65) and had higher risk of 30-day mortality (OR, 4.85; 95% CI, 1.23-19.15). Low SMD was associated with higher odds of having major complications (OR, 2.41; 95% CI, 1.44-4.04). Conclusions and Relevance Low SMI and low SMD were associated with longer LOS, higher risk of postsurgical complications, and short-term and long-term mortality. Research should evaluate whether targeting potentially modifiable factors preoperatively, such as preserving muscle mass, could reverse the observed negative associations with postoperative outcomes. This cohort study examines the association of low skeletal muscle index and low skeletal muscle radiodensity levels with the risk of postoperative complications, mortality, hospitalization, and long-term mortality for patients undergoing colon resection. Question What are the associations of low skeletal muscle index and low skeletal muscle radiodensity levels with outcomes after colon resection? Findings In this population-based cohort study of 1630 patients undergoing colon resection, radiographically assessed low skeletal muscle index and low skeletal muscle radiodensity levels were associated with greater risks of postoperative complications, mortality, hospitalization, and long-term mortality for patients at the time of diagnosis. Meaning Muscle mass and radiodensity assessed radiographically demonstrated good discrimination in identifying patients at higher risk of worse prognosis after colon resection and may be used to improve clinical and operational decision-making.