Frequency of High Diagnostic Testing and its Association With the Specialist Interval in Ontario Symptomatic Breast Cancer Patients

Abstract

Purpose: The breast cancer diagnostic process is complex. Patients can receive various tests including mammograms, ultrasounds, MRI scans and biopsies. A protracted time to diagnosis can affect a patient’s prognosis and mental well-being. This thesis examined the association between high diagnostic testing and diagnostic delay and described high testing differences across Ontario Local Health Integration Networks (LHINs). Methods: This was a cross-sectional study of symptom-detected patients diagnosed in Ontario from 2007 to 2015 (N=38,590) using data from linked administrative datasets. Patients diagnosed from 2012 to 2015 were included in the LHIN-specific analyses. High testing was defined as patients having received > 2 days of mammogram appointments, > 2 days of ultrasound appointments, > 1 day of MRI appointments, or > 2 days of biopsy appointments. The outcome studied was whether patients had a specialist interval (time from first specialist test or consultation to diagnosis) longer than 30 or 90 days. Hierarchical logistic regression controlled for potential confounders and clustering by diagnosing institution. Results: High diagnostic testing occurred in 13.4% of patients. Patients with high testing had higher odds of having a specialist interval longer than 30 days (adjusted OR=9.9; 95% CI: 9.2-10.7) and 90 days (adjusted OR=8.0; 95% CI: 7.4-8.7) compared to patients who received standard testing. High diagnostic testing varied by LHIN, ranging from 4.0% to 31.6%. Studying the LHINs indicated variation in high testing after controlling for potential confounders and that repeat breast ultrasound appeared to be driving the high testing rate. Conclusions: This thesis provides evidence that there is a strong association between receiving a high amount of diagnostic testing and the time to a breast cancer diagnosis in symptomatic patients. Additionally, ultrasound is the diagnostic test repeated most often and the test that explains high test variation across LHINs. This information could help Ontario and other health care jurisdictions develop models of high-quality breast cancer care that also aim to reduce repeat diagnostic testing with the goal of shortening the time to diagnosis.