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Association between use of a specialized diagnostic assessment unit and the diagnostic interval in Ontario breast cancer patients

Kingston, ON, Canada: Queen’s University (masters thesis).

Queen’s University, Kingston, ON, Canada

BACKGROUND: The amount of time that it takes to get a breast cancer diagnosis is very important to patients. The Ontario diagnostic assessment unit (DAU) is designed to improve the quality and timeliness of care during a breast cancer diagnosis. This study described and examined the association between the length of the diagnostic interval and DAU use in Ontario, Canada.

METHODS: This was a retrospective cohort study among all breast cancer patients diagnosed between Jan 1st, 2011 and Dec 31st, 2011 in Ontario, Canada. DAU use and diagnostic intervals were described. The association between DAU use and the diagnostic interval was examined separately in a cohort of 2499 screen-detected patients and a cohort of 4381 symptomatic patients. Study data sources included administrative databases available at the Institute for Clinical Evaluative Sciences (ICES) and Cancer Care Ontario (CCO). The diagnostic interval was defined as the time from the index contact to the cancer diagnosis. DAU use was determined based on the payment record within the organized screening program as well as the hospital where patients were diagnosed. Multivariate median regressions were used to control for possible confounders.

RESULTS: On average, Ontario breast cancer patients waited 4.6 weeks to be diagnosed. Forty-eight percent were diagnosed in a DAU and 52% were diagnosed in the usual care route. In screen-detected patients, DAUs had a higher rate in meeting national timeliness targets compared to usual care (79.1% vs. 70.2%, p0.001). DAU use was significantly associated with an 8.3-day decrease in the time to diagnosis (95% CI: 6.5-10.2) after controlling for potential confounders. In symptomatic patients, DAUs also had a higher rate in achieving the Canadian timeliness targets compare to usual care (71.7% vs. 58.1%, p<0.01). DAUs significantly reduced the time to diagnosis by 10 days (95% CI: 7.8-11.9) after controlling for possible confounders.

CONCLUSIONS: We observed considerable variation in breast cancer diagnostic intervals and DAU use in Ontario. Use of Ontario DAUs was associated with improved diagnostic timeliness for breast cancer patients.