Comparative contributions of visceral adiposity and muscle-related parameters to postoperative complications after...

Body composition is increasingly recognised as an important determinant of surgical outcomes, yet the relative contributions of its distinct physiological domains, particularly metabolic burden and structural or functional reserve, remain unclear. We aimed to comparatively evaluate the independent associations of visceral adiposity and muscle-related parameters with postoperative complications after gastrectomy within a unified analytical framework.

In this retrospective cohort study, we analysed 362 patients undergoing curative gastrectomy for gastric cancer. Preoperative body composition was assessed using CT-derived skeletal muscle index, muscle density, and visceral fat area, together with functional measures including grip strength and walking speed. Associations with short-term and 30-day postoperative complications were examined using hierarchical multivariable logistic regression models. Dose-response relationships were evaluated using restricted cubic splines, and supplementary sensitivity and internal validation analyses were performed.

Across all adjusted models, visceral adiposity showed a consistent and independent association with postoperative complications. Each one-standard deviation increase in visceral fat area was associated with higher odds of short-term complications (OR 1.55, 95% CI 1.14-2.10) and 30-day complications (OR 1.70, 95% CI 1.23-2.36). In contrast, skeletal muscle index, muscle density, grip strength, and walking speed were not independently associated with postoperative outcomes after adjustment. Dose-response analyses demonstrated a graded increase in risk across increasing levels of visceral fat area, supporting a continuous association with postoperative risk. The addition of visceral fat area to conventional clinical models provided modest incremental predictive information, particularly for 30-day postoperative complications.

In this comparative analysis, visceral adiposity emerged as a more consistent correlate of postoperative complications than muscle-related parameters. These findings support a domain-based interpretation of body composition and suggest that metabolic and inflammatory burden may play a more prominent role than structural or functional reserve in determining perioperative risk after gastrectomy. Visceral adiposity may also provide modest incremental risk stratification information beyond conventional clinical factors.