Original Article

Patient Body Mass Index is an Independent Predictor of 30-Day Hospital Readmission After Elective Spine Surgery

Background

Hospital readmission within 30 days of index surgery is receiving increased scrutiny as an indicator of poor quality of care. Reducing readmissions achieves the dual benefit of improving quality and reducing costs. With the growing prevalence of obesity, understanding its impact on 30-day unplanned readmissions and patients' perception of health status is important for appropriate risk stratification of patients. The aim of this study was to determine if obesity is an independent risk factor for unplanned 30-day readmissions after elective spine surgery.

Methods

The medical records of 500 patients (nonobese, n = 281; obese, n  = 219) undergoing elective spine surgery at a major academic medical center were reviewed. Preoperative body mass index (BMI) was measured on all patients. BMI that was ≥30 kg/m 2 was classified as obese. Patient demographics, comorbidities, and postoperative complication rates were collected. The primary outcome investigated was unplanned all-cause 30-day hospital readmission. The association between preoperative obesity and 30-day readmission rate was assessed via multivariate logistic regression analysis.

Results

Baseline characteristics and operative variables and complication profiles were similar between both cohorts. Overall, 8.6% of patients were readmitted within 30 days of discharge; obese patients experienced a 2-fold increase in 30-day readmission rates (obese 12.33% vs. nonobese 5.69%, P = 0.01). In a multivariate logistic regression analysis, preoperative obesity (BMI ≥30 kg/m2) was found to be an independent predictor of 30-day readmission after elective spine surgery (P = 0.001).

Conclusions

Preoperative obesity is an independent risk factor for readmission within 30 days of discharge after elective spine surgery. In a cost-conscious health care climate, preoperative BMI can identify patients at risk for early unplanned hospital readmission.

Introduction

Unplanned hospital readmissions within 30 days of surgery can lead to negative consequences for patients and providers and are costly for public and private payers. According to the Centers for Medicare and Medicaid Services, inpatient readmissions within 30 days of discharge accounted for approximately $17 billion in Medicare spending.1, 2 The U.S. government, through the Affordable Care Act of 2010, introduced several initiatives aimed at decreasing inpatient hospital readmissions. Understanding the patient-level factors contributing to higher readmission rates is integral for appropriate preoperative risk stratification.

Obesity is a modifiable risk factor that is associated with increased surgical morbidity and health care resource utilization. Despite the link between obesity and increasing postoperative complications after spine surgery, not much is known about the link between obesity and readmission rates.3, 4 The aim of this study was to determine if obesity is an independent risk factor for unplanned 30-day readmissions after elective spine surgery.

Section snippets

Materials and Methods

This ambispective study comprised 500 patients undergoing elective spine surgery at a major academic medical center during the period 2008–2010. Institutional review board approval was obtained before study initiation. Included patients were 18–70 years old 1) with low back pain and/or radiculopathy, 2) with magnetic resonance imaging evidence of grade I–II spondylolisthesis with central or foraminal stenosis, 3) who failed at least 6 weeks of nonsurgical treatment, and 4) who underwent lumbar

Results

The study comprised 500 adult patients (nonobese cohort, n = 281; obese cohort, n = 219). There was no significant difference in age between the groups (nonobese 56.74 years ± 15.13 vs. obese 56.23 years ± 13.34, P = 0.68) (Table 1). An approximately equal proportion of men and women was included in both groups (nonobese cohort, 48.04% men; obese, 42.47% men) (Table 1). Smoking status was similar between cohorts (nonobese 23.49% vs. obese 17.35%, P = 0.09) (Table 1). There were no significant

Discussion

In this ambispective cohort study of patients undergoing elective spine surgery, we observed that obese patients (BMI ≥30 kg/m2) have higher rates of unplanned 30-day readmission compared with nonobese patients. Moreover, BMI ≥30 kg/m2 was shown to be an independent risk factor for unplanned readmission within 30 days of hospital discharge.

Previous studies examining the effects of BMI on spine surgery outcomes are controversial. A few studies have shown that increased BMI is correlated with a

Conclusions

BMI ≥30 kg/m2 is a potentially modifiable risk factor for elective spine surgery. Our study demonstrated that obesity is an independent risk factor for all-cause readmission within 30 days of discharge after elective spine surgery. Obesity can be used to identify patients at risk for unplanned readmissions in a cost-conscious health care environment.

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