Utilization of Hip or Knee MRI in Patients 50 Years and Older With Atraumatic Pain: An Analysis of the National Ambulatory Medical Care Survey.

Purpose: The aim of this study was to use the National Ambulatory Medical Care Survey database to assess MRI utilization in patients 50 years and older with atraumatic hip or knee pain.

Methods: National Ambulatory Medical Care Survey weighted survey data (2007-2019) were obtained for ambulatory visits in patients 50 years and older with atraumatic hip or knee pain. The outcome variable was MRI ordering status, and analyzed characteristics included patient age, race/ethnicity, payer, physician specialty, metropolitan statistical area, and a coexistent radiography order. Multivariable logistic regressions were conducted to assess the association between MRI ordering status and the analyzed patient characteristics. All tests were two sided, and P values ≤.05 were considered to indicate statistical significance.

Results: In total, 88,978,804 knee pain and 28,675,725 hip pain patient visits (survey weighted) were analyzed, with 4,690,943 (5.3%) and 2,023,226 (7.1%) having knee or hip MRI orders, respectively. Overall, 2,454,433 knee pain visits (2.8%) and 575,155 hip pain visits (2.0%) had orders for both MRI and radiographs. Black patients (P = .03) and patients 80 years and older (P = .04) were less likely to have knee MRI ordered, whereas uninsured patients were less likely to have hip MRI ordered (P = .01). Patients with hip pain were more likely to have hip MRI ordered if seen by a surgical subspecialist (P = .01).

Conclusions: A low proportion of MRI examinations were ordered for visits in patients 50 years and older with atraumatic hip or knee pain. Groups with lower health care access were less likely to have an MRI order, highlighting known disparities in health care equity.