Impact of restricting diagnostic imaging reimbursement for uncomplicated low back pain in Ontario: a population-based interrupted time series analysis

Background — In 2012 the Ontario government withdrew coverage of imaging tests for uncomplicated low back pain. We studied the impact of this on test-ordering by physicians.

Methods — We compared the numbers of x-ray, spine CT and single segment MRI studies ordered by family practitioners and specialists in the 3 years before and after the policy change in April 2012. We linked claims reimbursed by the Ontario Health Insurance Program with physician characteristics to calculate rates per test-ordering physician. Segmented regression analysis of interrupted time series data compared changes in rates of monthly test ordering by specialists and family physicians before and after the policy change.

Results — Overall, the numbers of lumbar spine X-ray and spine CT examinations ordered by family practitioners fell by 98 597 and 17 499 respectively in the year after the policy change, with little change in ordering by specialists. Lumbar spine X-rays dropped by 0.81 tests/month/family practitioner (P<.0.0001) after the restriction, then remained stable. Ordering of spine CT by family practitioners fell 0.1 test/month/FP (P<0.0001). Ordering of limited spine MRI by family physicians rose prior to the restriction, fell by 0.18/month/FP (P<0.0001) after the restriction and started to rise again. Ordering of limited spine MRI by specialists, which had been stable, fell by 0.1/month/SP (P=0.0009) after the restriction and then climbed back to the pre-intervention levels.

Interpretation — Overall, the restriction in coverage caused a larger decrease in the ordering practices of family practitioners than specialists and a larger and more sustained reduction in the use of lumbar spine X-rays and spine CT than MRI.