The association of neighborhood disadvantage, preoperative serum albumin, and health resource utilization after minimally invasive lumbar spine surgery

OBJECTIVE: Preoperative albumin has been explored as a potential predictor of outcomes following spine surgery. However, given the lower levels of invasiveness and faster recoveries in minimally invasive (MIS) spine surgeries, the value of albumin as a predictor of outcomes is unknown. The authors sought to uncover the association of preoperative albumin on outcomes following MIS lumbar spine surgery. METHODS: The authors identified all patients undergoing MIS lumbar decompressions or decompression with fusions at our institution using Current Procedural Terminology codes. Preoperative serum hypoalbuminemia was categorized as < 3.5 g/dL. Area Deprivation Indices (ADIs) were retrieved based on patient addresses, with higher national rankings indicating greater levels of relative socioeconomic deprivation. To assess the relationship between serum albumin and length of stay (LOS) and ADI, the authors used multivariate linear regressions. Multivariate logistic regression models with robust standard errors to adjust for clustering were used to assess the effect of serum albumin on readmissions and complications. RESULTS: A total of 465 patients with preoperative serum albumin levels were included for analysis (median age 65 [IQR 57-72] years), of whom 8.2% had hypoalbuminemia preoperatively. On multiple linear regression, for every 1-g/dL decrease in preoperative albumin, the LOS increased by an mean of 0.9 (95% CI 0.51-1.3) days. Lower serum albumin was associated with greater levels of socioeconomic disadvantage as well (β -8.9, 95% CI -14 to -3.7). Patients with any degree of hypoalbuminemia preoperatively had increased odds of requiring reoperation within 90 days (OR 5.39, 95% CI 1.95-14.9) and postoperative complications (OR 3.68, 95% CI 1.56-8.72) after adjustment for potential confounders. A multivariate model with preoperative serum albumin predicting prolonged LOS displayed high discriminative ability (area under the receiver operating characteristic curve 0.87, 95% CI 0.80-0.94). CONCLUSIONS: Low serum albumin is associated with longer LOS, readmissions, and complications in MIS lumbar spine surgery despite the decreased invasiveness. Notably, low preoperative serum albumin was also associated with socioeconomic disadvantage. Preoperative optimization of both albumin and socioeconomic factors may improve outcomes in patients undergoing MIS lumbar spine surgery and represents an important area of future research.