1. Menachem M Meller,MD, PhD
The Feasibility and Impact of Using Large Administrative Databases to Evaluate The Significance of Obesity as a Risk Factor in THR
Norman A Johanson, MD
Menachem M Meller,MD, PhD
Mark H Gonzales, MD, PhD
Nader Toossi, MD
Min-sun Son,PhD
Edmund Lau, MS

2. We have nothing to disclose.

3. BMI Classification by WHO
Underweight
< 18.5 kg/m2
Normal range
kg/m2
Overweight
≥ 25 kg/m2
Pre-obese
kg/m2
Obese
≥ 30 kg/m2
Obese class I
kg/m2
Obese class II
kg/m2
Obese class III (morbidly obese)
≥ 40.0 kg/m2

4. Obesity Epidemics More than % 30 of US adult population are obese
Morbid and super obesity prevalence grow 2 & 3 times faster, respectively, than moderate obesity
Currently, higher proportions of patients undergoing THR are obese

5. The current literature on the effect of obesity on the outcome of THA:
Inconclusive
Controversial
Small sample sizes
Higher strata of obesity (super obesity) not investigated
Not all confounding factors considered

6. Bundled payment program for hip and knee replacement proposed by CMS, based on CCJR model
Need to identify high-risk groups in total joint replacement patients, and high-cost complications and readmissions

7. The Purpose
The purpose of this study is to determine the risk and cost of 90-day postoperative complications following primary THA in elderly morbidly obese (BMI ≥ 40 kg/m2) during and in elderly super-obese patients (BMI ≥ 50 kg/m2) during 2010(Q4)-2013

8. Methods
Retrospective cohort study of Medicare inpatient claims data accessed through a limited dataset (LDS) format
Inclusion Criteria:
Age ≥ 65 y/o
Enrollment in Medicare at least one year before admission
Residing in 50 US states
Exclusion Criteria:
Knee arthroplasty procedure during the study period

9. Methods
Tracking of patients for 90 days after the index surgery (January 1, 2008 through December 31, 2013) Since October 2010, further stratification of patients with BMI ≥ 40 kg/m2 has been possible through ICD-9 diagnosis codes. Thus, the opportunity to identify super-obese patients Hazard ratio calculated for each complication using multivariate Cox models

10. ICD-9-CM Codes Used to Identify Postoperative Complications
Identification
Death
Medicare Enrollment Data
DVT
453.40, , , 453.8x, 453.2x, 451.1x,
PJI
996.66
Revision
81.53, 00.70, 00.71, 00.72, 00.73
Pulmonary Embolism
415.1x
Implant Failure
996.4x,
Wound Dehiscence
998.30, , MI
410.0x – 410.9x
Pneumonia
480.x – 486.x
Dislocation
996.42
Readmission
Subsequent Claim Records in 90 Days
Acute Renal Failure
584.x

11. Results 2008–2013 2010(Q4) – 2013 Age (average) 75.0 ± 6.7 70.6 ± 4.8
Normal Weight
(BMI<25 kg/m2)
Morbidly Obese
(BMI≥40 kg/m2)
Super Obese
(BMI≥50 kg/m2)
Age (average)
75.0 ± 6.7
70.6 ± 4.8
69.8 ± 4.3
Female
62%
68%
76%
Caucasian
African American
Others
94%
89%
87% 4% 9%
12% 2% 1%
Number of patients
514,422
9,932
570

12. Morbid Obesity Super Obesity
Complications Hazard Ratio P-value
Hazard Ratio P-value
Wound Dehiscence 4
<0.001
9.4
Periprosthetic Joint Infection
3.8
<0.00
6.3
Revision
2.1
1.6
Non-significant
Renal Failure
1.7
Readmission
1.5
DVT
1.4
0.002
Pulmonary Embolism
1.2
Implant Failure
0.9
90-day post-THA significant complications and corresponding hazard ratios comparing super and morbidly obese patients with the normal-weight,
adjusted for age, sex, race, economic status, Charlson Comorbidity Index, institutional factors and the experience of surgeon
Periprosthetic Joint Infection
6.27
<0.001
Readmission
2.11
Renal Failure
1.72
Wound Dehiscence
9.35

13. Dose-response relationship between obesity and
Wound Dehiscence
9.4 HR
BMI Level ( kg/m2)

14. Dose-response relationship between obesity and
Periprosthetic Joint Infection
6.3 HR
BMI Level ( kg/m2)

15. Dose-response relationship between obesity and
Readmission
2.1 HR
BMI Level ( kg/m2)

16. from the initial THA through the postoperative 90 days
Total hospital charges of patient with normal BMI, BMI 40-49, and BMI≥50
from the initial THA through the postoperative 90 days $

17. Conclusion
Morbid obesity, in general, and super obesity, in particular, are associated with increased risk and cost of specific 90-day postoperative complications following primary THA in elderly patients.
Knowledge of the excess hospital costs during the 90-day post-THA period in super-obese patients may have implications in negotiating CMS bundled payments and charge carve outs.

18. Thank you
Thank you
Hahnemann
University Hospital