The effect of age and gender on acute postoperative pain and function following lumbar spine surgeries.

Background And Purpose: Understanding the factors contributing to the variability in postoperative pain and function following lumbar spine surgeries (LSS) is necessary to plan inpatient rehabilitation and optimize surgical outcomes. In particular, variability due to age and gender has not been studied. This study's aim was to evaluate the variability in postoperative pain and function, during hospital stay, due to age and gender following LSS.

Methods: We conducted a retrospective analysis of 585 patients who underwent LSS during their hospital stay. Univariate ANCOVA was performed to study the differences in postoperative pain, and multivariate ANCOVA was performed to study the differences in postoperative function (gait distance, independency combined score, and balance combined score) between age groups (older adults [≥65 years of age] vs. younger adults) and gender.

Results: Younger patients reported statistically, but not clinically, significant higher postoperative pain than older patients (β = 0.652 [95% CI (0.382-0.986)], p < 0.001), and males reported statistically, but not clinically, significant lower postoperative pain than female patients (β = -0.583 [95% CI (-0.825 to -0.252)], p < 0.001) with adjustment of covariates. Male patients walked significantly longer distance than female patients (β = 0.272 [95% CI (0.112-0.432)], p = 0.001) with adjustment of covariates. However, these were clinically insignificant. With adjustment of preoperative diagnosis, type of surgery, severity of illness, and prior level of function, there was no statistically significant difference between age groups in walking distance, and between age and gender groups in independency combined score and balance combined scores.

Discussion: Following LSS, the difference in postoperative pain between age groups and gender are statistically but not clinically significant, suggesting patients require similar effective postoperative pain management regardless of age and gender. The apparent difference in age and gender in postoperative functional outcomes could be due to other factors.