Health Policy & Economics
Body Mass Index More Than 45 kg/m2 as a Cutoff Point Is Associated With Dramatically Increased Postoperative Complications in Total Knee Arthroplasty and Total Hip Arthroplasty

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Abstract

Background

Higher body mass index (BMI) has been associated with postoperative complications in total knee arthroplasty (TKA) and total hip arthroplasty (THA). However, the association of incremental increases of BMI and its effects on postoperative complications has not been well studied. We hypothesize that there is a BMI cutoff at which there is a significant increase of the risk of postoperative complications.

Methods

We studied the American College of Surgeons National Surgical Quality Improvement Program from 2006 to 2013. The final cohort included 77,785 primary TKA and 49,475 primary THA subjects, respectively. Patients were separated into 7 groups based on BMI (18.5-24.9 kg/m2, 25.0-29.9 kg/m2, 30.0-34.9 kg/m2, 35.0-39.9 kg/m2, 40.0-44.9 kg/m2, 45.0-49.9 kg/m2, and >50.0 kg/m2). We analyzed data on five 30-day composite complication variables, including any complication, major complication, wound infection, systemic infection, and cardiac and/or pulmonary complication.

Results

The odds ratio for 4 (any complication, major complication, wound infection, and systemic infection) of 5 composite complications started to increase exponentially once BMI reached 45.0 kg/m2 or higher in TKA. Similarly, the odds ratio in 3 (any complication, systemic infection, and wound infection) of 5 composite complications showed similar trends in THA patients. These findings were further confirmed with propensity score matching and entropy balancing.

Conclusions

Our study suggested that there was a positive correlation between BMI and incidences of 30-day postoperative complications in both TKA and THA. The odds of complications increased dramatically once BMI reached 45.0 kg/m2.

Section snippets

Material and Methods

This study was exempted by the institutional review board.

Results

Using BMI 18.5-24.9 kg/m2 as the baseline, Figure 3A-E presented the ORs and corresponding 95% CI for 5 composite complications after the primary TKA across 7 BMI groups. ORs were gradually increasing along with increase of BMI, but they were insignificantly different from baseline for BMI ≤45.0 kg/m2. For patients with BMI >45.0 kg/m2, the ORs were statistically significantly greater than the baseline for most composite complications (any complication, major complication, wound infection, and

Discussion

Our study of the American College of Surgeons NSQIP database from 2006 to 2013 showed that there was a positive association between increased BMI and 30-day postoperative complications in both TKA and THA. The odds of complications increased dramatically once BMI surpassed 45.0 kg/m2. Further consideration of the risks and benefits for surgical treatment with TKA or THA among super obese patients is warranted.

Obesity is a pandemic phenomenon that is drawing increasing attention throughout

Conclusion

We studied primary TKA and primary THA patients in NSQIP with a specific question of whether there is a cutoff point of BMI that is associated with marked increased risks of postoperative complications. Our study suggested that there was a positive correlation between BMI and incidences of 30-day postoperative complications in both TKA and THA. The odds of complications increased dramatically once BMI reached 45.0 kg/m2. Further consideration of risk and benefit for surgical treatment with TKA

Acknowledgments

The authors would like to thank Lee A. Fleisher, MD for his valuable insight in the study.

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    One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2015.10.042.

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