IMPACT OF PREOPERATIVE COMORBIDITIES ON POSTOPERATIVE MORBIDITY AND MORTALITY IN ADULTS UNDERGOING MAJOR ABDOMINAL SURGERY: A SYSTEMATIC REVIEW AND META-ANALYSIS OF DIABETES MELLITUS, HYPERTENSION, CHRONIC KIDNEY DISEASE, AND OBESITY. FMHR. 2026;4(3):748-759. Accessed November 8, 2026. https://fmhr.net/index.php/fmhr/article/view/2503