Can Computed Tomography Findings for Kidney, Ureter and Bladder Correlate with Medical Comorbidity in Renal Colic Patients?

Background/Objectives: Sarcopenia is a progressive skeletal muscle disorder linked to adverse outcomes. Computed Tomography (CT) can quantify skeletal muscle, while the Charlson Comorbidity Index (CCI) predicts mortality by categorising comorbidities. This study examined whether Computed Tomography of the Kidneys, Ureters, and Bladder (CT-KUB)-derived skeletal muscle measurements correlate with CCI scores in hospitalised patients. Methods: This retrospective study included all patients admitted with renal colic to the Urology Department, Blacktown Hospital and underwent cystoscopy between June 2022 and June 2025. Data were obtained from electronic medical records. CCI scores, incorporating age and comorbidities, generated 10-year survival estimates. CT-KUB scans were reviewed for psoas muscle perimeter, area, height, width and Hounsfield unit at the aortic bifurcation. Skeletal Muscle Index (SMI) was calculated as skeletal muscle area (SMA)/height2. Associations between CCI, psoas muscle metrics and outcomes (length of stay, Intensive Care Unit (ICU) admission, Emergency Department (ED) re-presentation) were assessed using Pearson’s correlations and between-group comparisons. Results: A total of 397 patients were analysed. Median Length of Stay (LOS) was 1 day (mean = 1.92, SD = 1.88). ICU admission occurred in 2.3% of patients, and 18.6% re-presented to ED within 30 days. Both CCI survival percentage and psoas muscle metrics (including SMI) were significantly associated with LOS. Lower SMA, Hounsfield unit (HU), length and perimeter were linked to higher ICU admission risk. Neither CCI nor muscle measures predicted ED re-presentation. Conclusions: CCI and CT-derived muscle metrics were independently associated with outcomes such as LOS and ICU admission. Combining these measures may improve risk stratification, warranting further prospective evaluation.