CT-derived body-composition markers and short-term recovery after cholecystectomy in older adults with acute cholecystitis: an exploratory single-center cohort study

Background Routine preoperative CT may provide body-composition information relevant to physiological reserve in older adults. We examined associations between CT-derived psoas area, intermuscular fat area (IMA), and short-term recovery after cholecystectomy, and explored whether these markers added information beyond routine clinical variables. Methods This retrospective single-center cohort included 154 consecutive patients aged 65 years or older who underwent index-admission cholecystectomy for acute cholecystitis. The primary endpoint was a composite of major postoperative complication, 30-day readmission, or postoperative length of stay longer than 8 days. The main association model included ASA class, psoas area per standard-deviation (SD) decrease, and IMA per SD increase. A routine clinical model (ASA class, age, albumin, and log-transformed CRP) was compared with the same model plus both CT markers. Major complication or 30-day readmission was examined as a key sensitivity endpoint. Results The primary composite occurred in 31 of 154 patients (20.1%). In the association model, the ORs were 2.38 (95% CI: 1.29–4.39) per SD decrease in psoas area, 2.85 (95% CI: 1.60–5.06) per SD increase in IMA, and 2.97 (95% CI: 1.39–6.37) per ASA grade increase. Adding the CT markers to the routine clinical model changed the apparent AUC from 0.846 to 0.859 (difference: 0.013, 95% CI: −0.033 to 0.055); bootstrap-corrected AUCs were 0.826 and 0.824, respectively. For the sensitivity endpoint of major complication or 30-day readmission (23 events), apparent AUCs were 0.795 and 0.799, and psoas area was not associated with outcome in the three-variable association model ( P = 0.163). Conclusions Smaller psoas area and greater IMA were associated with the short-term recovery composite. After both CT markers were added to the routine clinical model, the apparent AUC changed from 0.846 to 0.859; the corresponding bootstrap-corrected AUCs were 0.826 and 0.824. For major complication or 30-day readmission, IMA remained associated with outcome, whereas psoas area did not.