Association Between Body Mass Index and Severity of Postoperative Pain Among Patients Undergoing Abdominal Surgeries: A Cross-Sectional Study

Background: The association between body mass index (BMI) and postoperative pain remains unclear, with conflicting evidence. This study evaluated the relationship between BMI and postoperative pain severity following abdominal surgeries.
Methods: A cross-sectional study included 180 patients (90 obese, 90 non-obese) undergoing elective abdominal surgeries at a tertiary care hospital. Postoperative pain was assessed using the Numerical Rating Scale (NRS) at 12, 24, and 48 hours. Demographics, ASA status, educational level, comorbidities, surgical duration, and hospital stay were recorded. Associations between BMI and other variables with pain severity were analyzed.
Results: Obese patients reported significantly higher pain scores at all time points: 12 hours (6.9±0.96 vs 5.4±0.72, p<0.001), 24 hours (6.05±0.91 vs 4.1±1.0, p<0.001), and 48 hours (4.5±0.99 vs 3.1±0.68, p<0.001). Age, gender, ASA status, and educational level showed no significant correlation with pain severity. Duration of surgery did not correlate with pain scores except for a marginal association at 48 hours in non-obese patients (r=0.20, p=0.05). Hospital stay was paradoxically shorter in obese patients (13.2±4.8 vs 15.4±3.4 days, p=0.01). Among patients with comorbidities, obese individuals had higher pain scores at 24 hours compared to non-obese counterparts (5.6±0.9 vs 4.9±0.9, p=0.02).
Conclusion: Obesity is significantly associated with increased postoperative pain severity after abdominal surgery, independent of demographic and clinical factors.