Intensity of Imaging for Low Back Pain in Elderly Patients

1. Intensity of Imaging for Low Back Pain in Elderly Patients HH Pham, MD, MPH, D Schrag, MD, MPH C Corey, MS, J Reschovsky, PhD HR Rubin, MD, PhD, BE Landon, MD, MBA AcademyHealth Annual Meeting June 2007

2. Background • Medicare spending on imaging services has increased dramatically since 2000 with unclear clinical benefits for beneficiaries • Guidelines allow discretion for imaging of elderly patients with acute low back pain • Little representative data on non-clinical factors associated with intensity of imaging

3. Research questions What physician, practice, market, and non-clinical patient factors are associated with more intensive imaging for acute low back pain?  Does the economic environment in which physicians practice influence discretionary use of imaging?

4. Data sources (1) 2000-2001 Community Tracking Study Physician Survey • Nationally representative, clustered in 60 communities • Non-federal, completed training, 20+ hrs of clinical care/week • 12,406 respondents, ~50% PCPs • 59% response rate Questions • Specialty, board certification, FMG status • Practice type, revenue sources (Medicaid, Medicare), capitation • Ability to obtain specialist and imaging referrals • Overall effect of financial incentives (increase/decrease services) • Compensation based on quality, profiling, patient satisfaction • Practice ownership

5. Data sources (2) Complete 2000-2002 Medicare claims for 1.09 million beneficiaries seen by CTS physicians in year 2000 Geographic data from Area Resources File on number of patient care radiologists per capita, household income, and education levels

6. Design and Analysis • Back pain diagnosis identified for year 2001 • Followed for 6 months after back pain diagnosis • Modeled “intensity” of imaging • never imaged  imaged 29 -180 days  imaged within 28 days • “Intensity” measured for: • (a) any imaging modality; and (b) only CT/MRI • Excluded patients diagnosed by a radiologist • Adjusted for comorbidities during year 2000, physician, practice, and area factors (site fixed effects) • Repeated analyses, excluding patients with visits to other physicians between diagnosis and imaging dates

7. Study population 63,075 (15%) patients of 318,148 linked to a CTS PCP and had a diagnosis of acute low back pain in 2001 24,515 (39%) meeting clinical inclusion criteria (no potential indications for imaging 6 months prior to LBP diagnosis or between diagnosis and imaging dates 21,992 (89%) meeting inclusion criteria and not diagnosed by a radiologist • 5,964 (28%) imaged within 28 days • 5,330 (90%) by XR • 725 (12%) by CT/MRI • 1,017 (4%) imaged between 29-180 days • 734 (73%) by XR • 314 (31%) by CT/MRI 15,011 (67%) never imaged

8. Clinical exclusions Modified NCQA’s measure of inappropriate imaging for acute LBP • Cancers* • Neurologic deficits* • Trauma,* falls, injury • Infections – endocarditis, osteomyelitis, TB, etc. • IV drug use* • Anemia – not hereditary, Fe deficiency, or blood loss • Constitutional symptoms – weight loss, fever, night sweats, fatigue/malaise, loss of appetite

9. Care relationships between acute LBP patients and their plurality PCP

10. Site of imaging studies performed within 28 days of diagnosis

11. Timing of imaging after LBP diagnosis

12. Predictors of intensity of imagingPatient factors and radiologist supply No effect for median household income in the patient zip code; % adults with 12+ yrs of education in the county; or Klabunde or Charlson scores

13. Predictors of intensity of imagingPhysician factors No effect for years in practice; board certification; IMG status; compensation based on productivity, quality, profiling or patient satisfaction measures, or practice ownership

14. Predictors of intensity of imagingPractice factors No consistent effect for revenue from managed care, Medicare, or Medicaid

15. Limitations No certainty regarding appropriateness of imaging • Not benchmarking – only comparing relative performance • Unlikely systematic under-coding of exclusions by physician or practice characteristics, or by white patient race and higher SES • Uncertainty is comparable to claims-based measures of underuse Lack data on presence of imaging equipment in practices Cannot identify physician(s) responsible for referrals • For imaging or to specialists • But consistent relationships between characteristics of the CTS PCP and intensity of imaging

16. Conclusions • Substantial minority of elderly patients with uncomplicated LBP are imaged early, often in their physician’s practice • Most cases of rapid imaging use XR’s, not CT/MRI • Overall financial incentives matter, but no association with specific types of performance-based compensation • Subgroups of patients who tend to receive fewer services may sometimes benefit  Incentives to increase or decrease services may have mixed effects on quality that may go undetected if the majority of performance metrics reflect underuse

17. Geographic variation in percent of patients imaged within 28 days