Impact of body mass index on surgical outcomes, narcotics consumption, and hospital costs following anterior cervical discectomy and fusion

Abstract

OBJECTIVE: Given the increasing prevalence of obesity, more patients with a high body mass index (BMI) will require surgical treatment for degenerative spinal disease. In previous investigations of lumbar spine pathology, obesity has been associated with worsened postoperative outcomes and increased costs. However, few studies have examined the association between BMI and postoperative outcomes following anterior cervical discectomy and fusion (ACDF) procedures. Thus, the purpose of this study was to compare surgical outcomes, postoperative narcotics consumption, complications, and hospital costs among BMI stratifications for patients who have undergone primary 1-to 2-level ACDF procedures. METHODS: The authors retrospectively reviewed a prospectively maintained surgical database of patients who had undergone primary 1-to 2-level ACDF for degenerative spinal pathology between 2008 and 2015. Patients were stratified by BMI as follows: normal weight (< 25.0 kg/m2), overweight (25.0-29.9 kg/m2), obese I (30.0-34.9 kg/m2), or obese II-III (≥ 35.0 kg/m2). Differences in patient demographics and preoperative characteristics were compared across the BMI cohorts using 1-way ANOVA or chi-square analysis. Multivariate linear or Poisson regression with robust error variance was used to determine the presence of an association between BMI category and narcotics utilization, improvement in visual analog scale (VAS) scores, incidence of complications, arthrodesis rates, reoperation rates, and hospital costs. Regression analyses were controlled for preoperative demographic and procedural characteristics. RESULTS: Two hundred seventy-seven patients were included in the analysis, of whom 20.9% (n = 58) were normal weight, 37.5% (n = 104) were overweight, 24.9% (n = 69) were obese I, and 16.6% (n = 46) were obese ll-lll. A higher BMI was associated with an older age (p = 0.049) and increased comorbidity burden (p = 0.001). No differences in sex, smoking status, insurance type, diagnosis, presence of neuropathy, or preoperative VAS pain scores were found among the BMI cohorts (p > 0.05). No significant differences were found among these cohorts as regards operative time, intraoperative blood loss, length of hospital stay, and number of operative levels (p > 0.05). Additionally, no significant differences in postoperative narcotics consumption, VAS score improvement, complication rates, arthrodesis rates, reoperation rates, or total direct costs existed across BMI stratifications (p > 0.05). CONCLUSIONS: Patients with a higher BMI demonstrated surgical outcomes, narcotics consumption, and hospital costs comparable to those of patients with a lower BMI. Thus, ACDF procedures are both safe and effective for all patients across the entire BMI spectrum. Patients should be counseled to expect similar rates of postoperative complications and eventual clinical improvement regardless of their BMI.