Knee replacement surgery: Are rural patients accessing treatment equitably?

Introduction: Knee rheumatoid and osteo-arthritis are debilitating conditions that cause significant pain and disability. Untreated knee arthritis worsens over time, resulting in development of other joint symptoms and decline in general health. Knee arthroplasty can significantly improve pain and functional status for those who receive it. We examined whether rural residence affected the likelihood of receiving knee arthroplasty for patients with knee arthritis.

Methods: Using the 2006 Nationwide Inpatient Sample (NIS) Hospital Discharge and National Ambulatory Medical Care Survey (NAMCS) datasets, we estimated the prevalence of knee arthritis, and examined rates of surgery for rural and urban residents. We used ANOVA and Chi-Square testing to compare underlying knee arthritis rates using the 2006 NAMCS, and rates and characteristics of patients who received arthroplasty from the 2006 NIS. We performed univariate survey logistic regression to determine the likelihood, expressed in odds ratios, of knee replacement associated with unique characteristics.

Results: Of the 300 million visits represented in NAMCS in 2006, 10,995,723 had a documented diagnosis of arthritis and were treated for knee pain. The incidence of knee arthritis was 6.3% among rural patients compared to 3.0% among urban patients. Among 110,391 rural inpatients represented in the 2006 NIS, 2.9% received knee replacement surgery, compared to 5.3% of the 385,088 urban patients (Chi-square p<.001). Other factors predicting for higher rates of knee replacement were white race: 3.2% versus 2.3% for non-whites, median ZIP Code area income >$60,000 (5.9% versus 4.3% at lower income levels), and Medicare coverage (5.9% versus 3.7% private insurance and 1.2% or less for Medicaid or self-pay.)

Discussion: While the prevalence of knee arthritis among rural outpatients was more than double that for urban outpatients, the likelihood of rural patients receiving arthroplasty was jabout half that for urban patients. We found that other characteristics strongly associated with lower likelihood of obtaining arthroplasty included non-white race, lower community income level, younger age, and lack of either Medicare or private insurance. Our findings do not consider the role of patient expectations, choice, and timing in accessing knee arthroplasty though others have shown that rural patients are less likely to access specialty care for their arthritis than urban patients with comparable functional impairment. Assuming that lower rates of knee arthroplasty among rural patients is related to limited access rather than choice, efforts to improve rural patient access to procedures like knee replacement that improve functioning and quality of life should be encouraged.