@article{ref1,
title="Survival bias may explain the appearance of the obesity paradox in hip fracture patients",
journal="Osteoporosis international",
year="2021",
author="Amin, R. M. and Raad, M. and Rao, S. S. and Musharbash, F. and Best, M. J. and Amanatullah, D. F.",
volume="ePub",
number="ePub",
pages="ePub-ePub",
abstract="Patients with low-energy hip fractures do not follow the obesity paradox as previously reported. In datasets where injury mechanism is not available, the use of age >50 years (as opposed to commonly used >65 years) as a surrogate for a low-energy hip fracture patients may be a more robust inclusion criterion.  PURPOSE: In elderly patients with a hip fracture, limited data suggests that obese patients counterintuitively have improved survival compared to normal-weight patients. This &quot;obesity paradox&quot; may be the byproduct of selection bias. We hypothesized that the obesity paradox would not apply to elderly hip fracture patients. <br><br>METHODS: The National Surgical Quality Improvement Project dataset identified 71,685 hip fracture patients ≥50 years-of-age with complete body mass index (BMI) data that underwent surgery. Patients were stratified into under and over 75-year-old cohorts (n=18,956 and 52,729, respectively). Within each age group, patients were stratified by BMI class and compared with respect to preoperative characteristics and 30-day mortality. Significant univariate characteristics (p<0.1) were included in multivariate analysis to determine the independent effect of obesity class on 30-day mortality (p<0.05). <br><br>RESULTS: Multivariate analysis of <75-year-old patients with class-III obesity were more likely to die within 30-days than similarly aged normal-weight patients (OR 1.91, CI 1.06-3.42, p=0.030). Multivariate analysis of ≥75-year-old overweight (OR 0.69, CI 0.62-0.77, p<0.001), class-I obese (OR 0.62, CI 0.51-0.74, p<0.001), or class-II obese (OR=0.69, CI 0.50-0.95, p=0.022) patients were less likely to die within 30-days when compared to similarly aged normal-weight patients. <br><br>CONCLUSIONS: Our data suggest that obesity is a risk factor for mortality in low-energy hip fracture patients, but the appearance of the &quot;obesity paradox&quot; in elderly hip fracture patients results from statistical bias that is only evident upon subgroup analysis.<p /> <p>Language: en</p>",
language="en",
issn="0937-941X",
doi="10.1007/s00198-021-06046-7",
url="http://dx.doi.org/10.1007/s00198-021-06046-7"
}