Bariatric surgery has mostly positive impact in knee arthroplasty

Bariatric surgery prior to arthroplasty reduces the likelihood of multiple complications but some risks increase, a large study has found.

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The study, led by Yicun Wang, PhD, of Nanjing (China) University was published in the Journal of Arthroplasty. “Generally speaking, bariatric surgery decreases some postoperative complications, decreases length of stay, and lowers mortality,” the study investigators wrote, [but] anemia and blood transfusion seem to be more common in patients with prior bariatric surgery.

They analyzed the effect of bariatric surgery on subsequent arthroplasty in morbidly obese patients in the United States using Nationwide Inpatient Sample 2006-2014 data on total hip arthroplasty (THA) and total knee arthroplasty (TKA). The researchers defined morbid obese patients as those with a body mass index higher than 40 kg/m².

Among patients who underwent TKA, the researchers compared a group of 9,803 morbidly obese patients with the same number of patients who had undergone bariatric surgery. The two groups were matched by age, sex, income, primary insurance payer, and race.

There were large differences between the bariatric surgery group vs. morbidly obese group: Pulmonary embolism was much more common in the morbid obesity group (odds ratio, 0.22; 95% confidence interval, 0.05-1.03; P = .0346) while blood transfusion was more common in the bariatric surgery group (OR, 1.76; 95% CI, 1.52-2.03; P less than .0001).

For TKA, the researchers used the same approach to analyze 2,540 matched pairs of patients. In the bariatric surgery vs. morbidly obese comparison, pulmonary embolism was more common in the morbidly obese group (OR, 0.34; 95% CI, 0.20-0.57; P less than .0001), as were respiratory complications (OR, 0.45; 95% CI, 0.26-0.78; P = .0032) and death (OR, 0.07; 95% CI, 0.01-0.50; P = .0005). But the bariatric surgery group had higher levels of blood transfusion (OR, 1.87; 95% CI, 1.71-2.04; P less than .0001) and anemia (OR, 1.16; 95% CI, 1.09-1.24; P less than .0001).

Going forward, the researchers write, “future studies on these patients should attempt to evaluate the impact of bariatric surgery on the long-term outcomes of arthroplasty.”

The study was supported by various funders including the National Natural Science Foundation of China, the Natural Science Foundation of Guangdong Province, the Project of Administration of Traditional Chinese Medicine of Guangdong Province and others. No author disclosures are reported.

SOURCE: Wang Y et al. J Arthroplasty. 2019;S0883-5403(19)30667-9.