“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” (2026) Frontier in Medical and Health Research, 4(3), pp. 748–759. Available at: https://fmhr.net/index.php/fmhr/article/view/2503 (Accessed: 8 November 2026).