Primary care variability in patients at higher risk for colorectal cancer: evaluation of screening and preventive care practices

Establishing Clinical Utility for Diagnostic Tests Using a Randomized Controlled, Virtual Patient Trial Design

Demonstrating clinical utility for diagnostic tests and securing coverage and reimbursement requires high quality and, ideally, randomized controlled trial (RCT) data. Traditional RCTs are often too costly, slow, and cumbersome for diagnostic firms. Alternative data options are needed. We evaluated four RCTs using virtual patients to demonstrate clinical utility. Each study used a similar pre-post intervention, two round design to facilitate comparison. Representative samples of physicians were recruited and randomized into control and intervention arms. All physicians were asked to care for their virtual patients during two assessment rounds, separated by a multi-week time interval. Between rounds, intervention physicians reviewed educational materials on the diagnostic test. All physician responses were scored against evidence-based care criteria. RCTs using virtual patients can demonstrate clinical utility for a variety of diagnostic test types, including: (1) an advanced multi-biomarker blood test, (2) a chromosomal microarray, (3) a proteomic assay analysis, and (4) a multiplex immunofluorescence imaging platform. In two studies, utility was demonstrated for all targeted patient populations, while in the other two studies, utility was only demonstrated for a select sub-segment of the intended patient population. Of these four tests, two received positive coverage decisions from Palmetto, one utilized the study results to support commercial payer adjudications, and the fourth company went out of business. RCTs using virtual patients are a cost-effective approach to demonstrate the presence or absence of clinical utility.

Clinical utility of a blood-based protein assay to increase screening of elevated-risk patients for colorectal cancer in the primary care setting

PURPOSE

Colorectal cancer (CRC) screening is effective in finding early stage CRC and dramatically improves survival rates. Despite this, the number of eligible patients who do not obtain CRC screening is unacceptably high.

METHODS

We conducted a longitudinal, randomized controlled trial investigating the utility of a blood-based protein assay on the quality of care delivered by practicing PCPs in the United States. We used standardized simulated patients (CPVs), presenting with symptoms suggestive of a higher likelihood of CRC, to measure how frequently these PCPs ordered diagnostic colonoscopy. 190 PCPs cared for three patients at baseline and three patients post-intervention. The PCPs were randomized into one of two study arms: control and intervention. The intervention arm consisted of educational materials about the blood-based protein assay and positive test results. Each simulated patient in the intervention arm had a positive test result that was given to the doctor. The controls were given neither intervention materials nor blood-based protein assay results. Physician responses in both groups were scored against evidence-based criteria. Data were collected at baseline and post-intervention.

RESULTS

At baseline, we found that 71% of physicians ordered diagnostic colonoscopy. In round 2, 23% of physicians in the intervention arm adopted the new blood-based protein assay. Ordering physicians were 3.88 (95% CI 1.67-9.03) times more likely to order a diagnostic colonoscopy. In percentage terms, those who ordered the assay were more likely to order colonoscopy (92%) than either intervention physicians who did not order the assay (77%) or control physicians (66%) (p < 0.001). A marginal effects estimation showed that use of the assay would increase ordering colonoscopy to nearly 95%.

CONCLUSION

Over one-third of adults in the United States do not follow the recommended screening guidelines for CRC. The introduction of a blood-based protein assay significantly increased the likelihood that physicians would order diagnostic colonoscopies in elevated-risk patients compared to those without access to the assay results. The overall change in clinical utility observed here has the potential to significantly improve clinical care.