Gender Disparities in Postoperative Outcomes Following Elective Spine Surgery: a Systematic Review and Meta-Analysis

OBJECTIVE Several studies have described disparities between male and female patients following spine surgery, but no pooled analyses have performed a robust review characterizing differences in postoperative outcomes based on gender. The purpose of this study was to broadly assess the effects of gender on postoperative outcomes following elective spine surgery. METHODS Between November 2022 and March 2023, PubMed, MEDLINE, ERIC, and Embase were queried using artificial intelligence-assisted software for relevant cohort studies. Cohort studies with a minimum sample of 100 patients conducted in the United States since 2010 were eligible. Studies related to trauma, tumors, infections, and spinal cord pathology were excluded. Independent extraction by multiple reviewers was performed using Nested Knowledge software. A fixed- or random-effects model was used if heterogeneity among included studies in a meta-analysis was < 50% or >= 50%, respectively. Risk of bias was assessed independently by multiple reviewers using the Newcastle-Ottawa Scale. Pooled effect sizes were calculated for readmission, nonroutine discharge (NRD), length of stay (LOS), extended LOS, reoperation, mortality, all medical complications (individual analyses for cardiovascular, deep venous thrombosis/ pulmonary embolism, genitourinary, neurological, respiratory, and systemic infection complications), and wound-related complications. For each outcome, two subanalyses were performed with studies that used either center-based (singleor multi-institution) or high-volume (national or state-wide) databases. RESULTS Across 124 included studies, male patients had an increased incidence of mortality (OR 0.54, p < 0.0001) and all medical complications (OR 0.80, p = 0.0114), specifically cardiovascular (OR 0.68, p < 0.0001) and respiratory (OR 0.76, p = 0.0008) complications. Female patients were more likely to experience a wound-related surgical complication (OR 1.16, p = 0.0183). These findings persisted in the high-volume database subanalyses. Only center-based subanalyses showed that female patients were at greater odds of experiencing an NRD (OR 1.18, p = 0.0476), longer LOS (SMD 0.23, p = 0.0036), and extended LOS (OR 1.28, p < 0.0001). CONCLUSIONS Males are more likely to experience death and medical complications, whereas females were more likely to face wound-related surgical complications. At the institution level, females more often experience NRD and longer hospital stays. These findings may better inform preoperative expectation management and provide more detailed postoperative risk assessments based on the patient's gender.