Background: Cost-containment strategies may discourage hospitals from performing surgery for patients with preexisting risk factors such as those with high body mass index (BMI), those with high hemoglobin A1c (HbA1c), or those who smoke cigarettes. Because these risk factors may not appear in equal proportions across the population, using these risk factors as inflexible eligibility criteria for lower extremity joint arthroplasty may exacerbate existing racial-ethnic, gender, and socioeconomic disparities pertaining to access to an operation that can improve health and quality of life. However, any effects on such disparities have not yet been quantified nor have the groups been identified that may be most affected by inflexible eligibility criteria.

Questions/purposes: Does the use of inflexible eligibility criteria related to (1) BMI; (2) HbA1c level; and (3) smoking status potentially decrease the odds of lower extremity joint arthroplasty eligibility for members of racial-ethnic minority groups, women, and those of lower socioeconomic status more than it does for non-Hispanic whites, men, and those of higher socioeconomic status?

Methods: We pooled data from 21,294 adults aged ≥ 50 years from the 1999-2014 National Health and Nutrition Examination Survey (NHANES). NHANES is a nationally administered series of surveys that assess the health and nutritional status of the US population and collect information on many risk factors for diseases. NHANES is uniquely suited to examine our study questions because it includes data from physical examinations and laboratory assessments as well as comprehensive questionnaires, and it is nationally representative. We determined the odds of lower extremity arthroplasty eligibility by running separate multivariable logistic regressions for each criterion (that is, for each dependent variable): (1) BMI < 35 kg/m; (2) BMI < 40 kg/m; (3) HbA1c < 8%; and (4) current nonsmoker status. Independent variables of interest were race-ethnicity, gender, educational level, and annual household income. Each model included all independent variables of interest, age, and survey year.

Results: The BMI < 35-kg/m criterion resulted in lower arthroplasty eligibility for non-Hispanic blacks compared with non-Hispanic whites (odds ratio [OR], 0.62; 95% confidence interval [CI], 0.55-0.70; p < 0.001), women versus men (OR, 0.61; 95% CI, 0.55-0.69; p < 0.001), individuals of lower socioeconomic status versus those of higher socioeconomic status (annual household income < USD 45,000 versus ≥ USD 45,000 [OR, 0.81; 95% CI, 0.71-0.93; p = 0.002], and those with a high school degree or less versus those with a degree beyond a high school degree (OR, 0.66; 95% CI, 0.57-0.77; p < 0.001). The HbA1c < 8% criterion resulted in lower arthroplasty eligibility for non-Hispanic blacks (OR, 0.44; 95% CI, 0.37-0.53; p < 0.001) and Hispanics (OR, 0.41; 95% CI, 0.33-0.51; p < 0.001) versus non-Hispanic whites, for individuals of lower socioeconomic status versus those of higher socioeconomic status (OR, 0.73; 95% CI, 0.56-0.94; p = 0.015), and for those with a high school degree or less versus those with a degree beyond a high school degree (OR, 0.58; 95% CI, 0.44-0.77; p < 0.001). Excluding smokers resulted in lower arthroplasty eligibility for non-Hispanic blacks versus non-Hispanic whites (OR, 0.84; 95% CI, 0.73-0.97; p = 0.019), for individuals of lower socioeconomic status versus those of higher socioeconomic status (OR, 0.53; 95% CI, 0.47-0.61; p < 0.001), and for those with a high school degree or less versus those with a degree beyond a high school degree (OR, 0.29; 95% CI, 0.24-0.35; p < 0.001).

Conclusions: Payment structures and clinical decision-making algorithms that set inflexible cutoffs with respect to BMI, HbA1c, and smoking status disproportionately discourage performing lower extremity arthroplasty for non-Hispanic blacks and individuals of lower socioeconomic status. We do not advocate performing elective surgery for patients with multiple, uncontrolled medical comorbidities. However, ample evidence suggests that many patients whose BMI values are > 35 kg/m (or even > 40 kg/m) may be reasonable candidates for arthroplasty surgery, and BMI is not an easily modifiable risk factor for many patients. We discourage across-the-board cutoff parameters in these domains because such cutoffs will worsen current racial-ethnic, gender-based, and socioeconomic disparities and limit access to an operation that can improve quality of life.

Level of evidence: Level III, economic and decision analysis.