Do doctors who order more routine medical tests diagnose more cancers? A population‐based study from Ontario Canada

The overuse of medical tests leads to higher costs, wasting of resources and the potential for OverDiagnosis of disease. Using electronic health care data we determined the rates of 23 routine medical tests and the rates of 12 new cancer diagnoses for the 4 900 000 patients of 6849 family doctors in Ontario Canada. We found that the patients of the doctors who ordered more tests than their peers had increased rates of thyroid and prostate cancers consistent with the literature on OverDiagnosis.

Abstract

Background

The overuse of medical tests leads to higher costs, wasting of resources, and the potential for overdiagnosis of disease. This study was designed to determine whether the patients of family doctors who order more routine medical tests are diagnosed with more cancers.

Method

A retrospective population‐based cross‐sectional study using administrative health care data in Ontario Canada. We investigated the ordering of 23 routine laboratories and imaging tests 2008‐20012 by 6849 Ontario family physicians on their 4.9 million rostered adult patients. We compared physicians' test utilization and calculated case‐mix adjusted observed to expected (O:E) utilization ratios to categorize physicians as Typical, Higher or Lower testers. Age‐sex standardized rates (cases/10 000 patient years) and Rate Ratios were determined for cancers of the thyroid, prostate, breast, lymphoma, kidney, melanoma, uterus, ovary, lung, esophagus, and pancreas for each tester group.

Results

There was wide variation in the use of the 23 tests by Ontario physicians. 26% and 24% of physicians were deemed Higher Testers for laboratory and imaging tests, while 41% and 38% were Typical Testers. The patients of higher test users were diagnosed with more cancers of thyroid (laboratory [RR 1.61, 95% CI 1.39‐1.87] and imaging [RR 2.08, 95% CI 0.88‐2.30]) and prostate (laboratory [RR 1.10, 95% CI 1.03‐1.18] and imaging [RR 1.05, 95% CI 1.00‐1.10]).

Conclusion

There is a wide variation in the ordering of routine and common medical tests among Ontario family doctors. The patients of higher testers were diagnosed with more thyroid and prostate cancers.

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