Outcomes and revision rates in normal, overweight, and obese patients 5 years after lumbar fusion.

BACKGROUND CONTEXT

Obesity is a growing problem in health care. Studies have demonstrated similar functional outcomes but higher complication rates after spine surgery in obese patients.

PURPOSE

This study aimed to compare patient-reported outcomes and revision rates 5 years after instrumented posterior lumbar fusion between normal, overweight, and obese patients.

STUDY DESIGN

Propensity matched case control.

PATIENT SAMPLE

Patients who had posterior instrumented lumbar spinal fusion from 2001 to 2008 from a single spine specialty center with complete preoperative and 5-year postoperative outcome measures were identified.

OUTCOME MEASURES

Oswestry Disability Index (ODI), Back Pain (0-10) and Leg Pain (0-10) Numeric Rating Scales, and Short Form-36 Physical Composite Summary Scores (SF-36 PCS).

METHODS

Three comparison groups, one with body mass index (BMI) ≥20-25 kg/m (normal), another with ≥25-<30 kg/m (overweight), and another with ≥30-40 kg/m (obese) were created using propensity matching techniques based on demographics, baseline clinical outcome measures, and surgical characteristics. Five-year postoperative outcome measures and revision rates in the three groups were compared. One-way analysis of variance was used to compare continuous variables, and Fisher exact test was used to compare categorical variables between the groups. Significance was set at p<.01.

RESULTS

There were 82 cases matched in each cohort. Estimated blood loss (440 cc vs. 702 cc vs. 798 cc, p=.000) and operative time (234 minutes vs. 263 minutes vs. 275 minutes, p=.003) were significantly greater in the overweight and obese patients. Improvements in ODI (14.2 vs. 9.6 vs. 10.4, p=.226), SF-36 PCS (5.9 vs. 2.9 vs. 3.5, p=.361), back pain (3.0 vs. 2.0 vs. 2.1, p=.028), and leg pain (3.0 vs. 2.3 vs. 2.3, p=.311) scores were similar among the groups. Revision rates (14 vs. 15 vs. 13, p=.917), and time between index and revision surgery (p=.990) were similar among the three groups as well.

CONCLUSION

When considering a subset of patient-reported outcomes and revision surgery after 5 years, patients with an elevated BMI >25 at baseline did not appear to have worse outcomes than those with a normal BMI of 20-25 when undergoing posterior lumbar fusion surgery. Obesity should not be considered a contraindication to surgery in patients with appropriate surgical indications.