Use and overuse of diagnostic neck ultrasound in Ontario: Retrospective population-based cohort study.

OBJECTIVE: To provide an overview of the use and possible overuse of diagnostic neck ultrasound (DNUS) by describing and comparing both the ordering rates and the downstream results of DNUS by regions across Ontario.
DESIGN: Retrospective population-based cohort study based on electronic health care data.
SETTING: Ontario. PARTICIPANTS: Ontario residents (adults aged > 18 years) who had a diagnosis of thyroid cancer between October 1, 1999, and June 30, 2014, and residents who had a DNUS in 2012. MAIN OUTCOME MEASURES: Proportion of Ontario residents in each sub-Local Health Integration Network (LHIN) group who had their first DNUS in 2012 and went on to other relevant tests, diagnoses, and surgery. The sub-LHIN groups were based on increasing age- and sex-adjusted rates of first DNUS.
RESULTS: There were 77 238 DNUS tests in 2012 and there was a 7.4-fold variation in the rate of test ordering across the sub-LHIN populations leading to variable rates of actual disease, suggesting screening or uncertain indications for tests.
CONCLUSION: Across Ontario, the indications for ordering DNUS are variable, and screening or testing without indication might be a common practice. Establishing effective guidelines for the ordering of DNUS would potentially reduce costs and ultimately reduce the rates of thyroid cancer. Copyright© the College of Family Physicians of Canada.