STOP CRC Trial: Analytic Challenges and Pragmatic Solutions


Investigators from the STOP CRC pragmatic trial, an NIH Collaboratory Demonstration Project, have recently published an article in the journal eGEMs describing solutions to issues that arose in the trial’s implementation phase. STOP CRC tests a program to improve colorectal cancer screening rates in a collaborative network of Federally Qualified Health Centers by mailing fecal immunochemical testing (FIT) kits to screen-eligible patients at clinics in the intervention arm. Clinics in the control arm provided opportunistic colorectal-cancer screening to patients at clinic visits in Year 1 and implemented the intervention in Year 2. In this cluster-randomized trial, clinics are the unit of analysis, rather than individual patients, with the primary outcome being the proportion of screen-eligible patients at each clinic who complete a FIT.

The team dealt with various challenges that threatened the validity of their primary analysis, one of which related to potential contamination of the primary outcome due to the timing of the intervention rollout: for control participants, the Year 2 intervention actively overlapped with the Year 1 control measurements. The other challenge was due to a lack of synchronization between the measurement and accrual windows. To deal with these issues, the team had to slightly modify the study design in addition to developing a few sensitivity analyses to better estimate the true impact of the intervention.

“While the nature of the challenges we encountered are not unique to pragmatic trials, we believe they are likely to be more common in such trials due to both the types of designs commonly used in such studies and the challenges of implementing system-based interventions within freestanding health clinics.” (Vollmer et al. eGEMs 2015)

The Publish EDM Forum Community publishes eGEMs (generating evidence & methods to improve patient outcomes) and provides free and open access to this methods case study. Readers can access the article here.