Can a supervised algorithmic assessment of men for prostate cancer improve the quality of care? A retrospective evaluation of a prostate assessment pathway in Saskatchewan

Abstract

Introduction: The Saskatoon Prostate Assessment Pathway (SPAP) was developed in 2013 in part to decrease the wait times between physician referral and biopsy for patients with suspected prostate cancer. Using an algorithm carefully designed to optimize appropriate prostate biopsy rates, physicians can directly refer patients for biopsy through the SPAP without seeing a urologist. All other patients are referred to the Saskatoon Urology Associates (SUA). The present study evaluates the performance of the algorithm.

Methods: 971 patients seen at the SUA and 302 patients seen through the SPAP were identified. Information on age, biopsy status and outcome, risk stratification, and time between referral and biopsy was collected. Biopsy wait time data was analyzed using gamma distribution. Association between referral method and biopsy rate, and between referral method and risk stratification, was analyzed using Z-test.

Results: The expected wait time from referral to biopsy for patients seen through SUA was 2.63 times longer than those seen through SPAP (34 vs. 91 days). The biopsy rate of patients seen in the SPAP was significantly higher than those by SUA (88% vs. 69%, 95% confidence interval [CI] 0.14-0.26; p<0.00001). There was no significant difference in positive biopsy rates for patients seen through the SPAP vs. SUA (81% vs. 74%, 95% CI -0.011,0.14; p=0.095), for detection of low-risk cancer, (12% vs. 10%, 95% CI -0.034,0.080; p=0.44), or for clinically relevant cancer, i.e., intermediate- and high-risk cancer, for SPAP vs. SUA (56.54% vs. 56.68%, 95% CI -0.091,0.089; p=0.49).

Conclusions: The algorithm used in the SPAP is effective in decreasing wait time to prostate biopsy and has the same cancer/pre-cancer detection rate, but at the cost of a higher biopsy rate. Both referral mechanisms result in few low-risk cancer detection biopsies, finding primarily cases of high- or intermediate-risk cancer.

Fig. 1

Flowchart outlining patient referral mechanism for followup. Only patients who were included in the study are shown. Patients referred to Saskatoon Prostate Assessment Pathway (SPAP) who were pathway-ineligible or eligible but did not get a biopsy for whatever reason were automatically referred to Saskatoon Urology Associates (SUA) and seen by a urologist for further assessment. DRE: digital rectal exam; PSA: prostate-specific antigen.

Fig. 2

Wait time between physician referral and biopsy. Patients seen through Saskatoon Urology Associates (SUA) had an expected time between referral and biopsy of 91 days, whereas patients seen through Saskatoon Prostate Assessment Pathway (SPAP) had an expected wait time of 34 days. The expected time was calculated based on gamma distribution, as the data is non-normal and has a right skew.

Fig. 3

Biopsy rates for patients seen either by the Saskatoon Urology Associates (SUA) or the Saskatoon Prostate Assessment Pathway (SPAP). The right side of the graph shows biopsy rates after patients who declined biopsy were removed, as it is assumed that regardless of which referral mechanism the patient went through, he would refuse biopsy. Patients who were lost to followup were also removed from the sample for the right side of the graph, as it is unclear what their outcome would have been had they been followed up on. *p<0.05.

Fig. 4A

Biopsy results showing positive findings. Positive findings include pathology results of cancer (low-, intermediate- or high-risk stratification), or atypical small acinar proliferation (ASAP), as these cells are more likely to eventually progress to prostate cancer. SPAP: Saskatoon Prostate Assessment Pathway; SUA: Saskatoon Urology Associates.

Fig. 4B

Risk stratification for patients who underwent a biopsy. *p<0.05. SPAP: Saskatoon Prostate Assessment Pathway; SUA: Saskatoon Urology Associates.