Financial incentives for completion of fecal occult blood tests among veterans: a 2-stage, pragmatic, cluster, randomized, controlled trial.
Across the Veterans Health Administration (VHA), the most commonly used colorectal cancer (CRC) screening method is the fecal occult blood test (FOBT) (1). This test reduces mortality from CRC (2, 3) and is cheaper and perhaps more convenient for patients than other CRC screening methods. However, rates of completion of prescribed FOBTs are often low (4, 5) because of poor patient adherence (69), which can delay diagnosis of CRC (10, 11). A promising tool for improving rates of FOBT completion is financial incentives (12, 13), which capitalize on insights from behavioral economics that suggest patients overweight near-term costs and benefits (14). When prescribed FOBTs, patients may forgo completion because the tests confer a certain and immediate disutility in return for the uncertain and distant benefit of early detection of CRC for a few patients who screen positive and no tangible benefit for most patients who screen negative. This overweighting of tangible, short-term costs and benefits might be leveraged to promote FOBT completion by providing an immediate financial reward for this behavior, yet this approach remains untested. The goal of this pilot study was to identify the dose and design of modest financial incentives that could increase rates of initial completion of prescribed FOBTs among VHA primary care patients. We used cluster randomization for practical reasons and to minimize contamination across patients, and we used a pragmatic design (15) to test incentives in a real-world clinical setting. Methods Design Overview We conducted a 2-stage parallel-design, pragmatic cluster randomized, controlled trial in the primary care clinic of the Philadelphia Veterans Affairs Medical Center (PVAMC) between 14 February 2012 and 9 October 2012. The clusters were clinic calendar days. In stage 1, 40 clusters of all 713 patients who were prescribed an FOBT (Figure 1) were assigned to usual care or to receipt of $5, $10, or $20 incentives for completing their FOBT within 30 days. In stage 2, 48 clusters of all 836 patients who were prescribed an FOBT (Figure 2) were assigned to usual care or receipt of incentives of $5, a 1 in 10 chance of $50, or entry into a $500 raffle for completing their FOBT within 30 days. Both stages included a usual care control group to account for temporal variation in FOBT completion. All incentives were disbursed as mailed paper vouchers that could be exchanged for cash at the PVAMC. The institutional review boards of the PVAMC and VA Ann Arbor Healthcare System approved the study. Need for patient consent was waived because the research involved no more than minimal risk and could not have been practicably carried out without the waiver. Figure 1. Study flow diagram: stage 1. FOBT = fecal occult blood test. Figure 2. Study flow diagram: stage 2. FOBT = fecal occult blood test. Setting and Participants The clinic calendar day clusters were eligible for randomization if they occurred during each study period. Because of the waiver of consent, all patients in each cluster who had a new FOBT order were included in the study. After each clinic day we recorded how many FOBT kits were distributed and stopped each stage once we reached our target sample size for each group. Randomization and Interventions The unit of randomization was the clinic calendar day. All patients in a given day were assigned to the same condition to minimize contamination. In each stage the allocation sequence was based on a permuted blocked randomization schedule with a fixed block size of 8 that was generated by a study investigator who had no contact with patients or access to patient data. Before each clinic day, the research coordinator inserted a brightly colored index card with the group assignment into all clinic FOBT kits. For patients randomly assigned to an incentive group, the card described the incentive they would receive if they completed and returned their FOBT within 30 days. For patients randomly assigned to the usual care control group, the card asked patients to complete and return their FOBT within 30 days. All investigators and analysts were blinded to group assignment until all data were collected. The research coordinator could not be blinded to group assignment because she stocked the clinic with study FOBTs before each clinic day and distributed financial incentives after FOBT completion. However, she had no contact with study participants before FOBT completion. Clinic staff and patients could not be blinded because the interventions were integrated into usual care, which entailed clinic staff briefly counseling patients about how to complete their FOBT. In stage 1, clusters of patients were randomly assigned to usual care or to receipt of $5, $10, or $20 for FOBT completion within 30 days. We chose these modest financial incentive amounts because, if found to be effective, they might be more likely to be adopted than a larger incentive. Further, many VHA patients have lower socioeconomic status (16), and thus even a small incentive could be highly valued and lead to FOBT completion (12, 17). In stage 2 we tested a fixed payment, a lottery-based incentive, and a raffle incentiveall with an approximately equal per-patient dollar allocationagainst a usual care control group. The per-patient dollar allocation was left undefined until stage 1 was completed. If 1 or more stage 1 incentives increased FOBT completion, in stage 2 we would allocate the smallest effective dollar amount as a fixed payment, lottery incentive, or raffle. If no stage 1 intervention was effective, we would use the smallest per-patient dollar amount ($5) in stage 2. On the basis of these rules, we chose a $5 per-patient allocation for stage 2 and delivered this as a $5 fixed payment, lottery with a 1 in 10 chance of $50, or raffle in which 1 randomly chosen patient received $500. For the raffle, the FOBT kit card stated If you complete and return this kit as instructed within 30 days, you and about 100 other patients will be entered into a raffle in which 1 randomly chosen patient will be mailed a voucher that can be exchanged for $500 at PVAMC. Outcomes and Follow-up In both stages, the primary outcome was FOBT completion within 30 days (18). We limited data collection to the 30 days following an FOBT order because our main focus was measuring the initial effects of incentives. However, this precluded examination of the longer-term effects of incentives (19) and comparisons with alternative strategies tested in trials with longer follow-up (7, 2024). We considered patients to have completed their FOBT within 30 days if they had an FOBT result in the Veterans Integrated Service Network 4 Data Warehouse within 45 days of an FOBT order. This definition reflected 2 logistic challenges inherent to this pragmatic trial. First, we could not determine the date of FOBT specimen collection and thus had to rely on the FOBT processing date in the Veterans Integrated Service Network 4 Data Warehouse. Second, there could be a lag of up to approximately 15 days between patient completion of an FOBT and processing (personal communication with PVAMC laboratory staff), so we added 15 days to the 30-day outcome window. In each stage we hypothesized that each incentive would increase the rate of 30-day FOBT completion relative to the control group. In each stage, our protocol included a preplanned subgroup analysis in which we examined 30-day FOBT completion by nonadherence to (that is, failure to complete) a prescribed FOBT in the year before the study. We hypothesized that each incentive would be more effective among previously nonadherent patients relative to patients who had been adherent to (that is, completed) a prescribed FOBT in the previous year. We also conducted exploratory analyses of 30-day FOBT completion among patients who had no FOBT order in the previous year. Statistical Analysis We conducted separate analyses for each stage. All participants who were prescribed an FOBT were included in the analyses testing for differences between groups. SAS software, version 9.3 (SAS Institute), was used to analyze the data. In all analyses we used PROC GENMOD to fit marginal models based on generalized estimating equations with a logit link and exchangeable correlation structure to produce parameter estimates and robust SEs. The clustering unit was the clinic calendar day. In the primary outcome models we adjusted for patient age, race and ethnicity, marital status, median household income in ZIP code of residence, percentage of residents with a high school education in ZIP code of residence, VA service connection, and FOBT nonadherence in the previous year. Data on patient characteristics were obtained from the Veterans Integrated Service Network 4 Data Warehouse except for median household income and percentage of residents with a high school education in ZIP code of residence, which were obtained from the U.S. Census Bureau. For subgroup analyses, we fit separate models to data from 3 subgroups: 1) FOBT nonadherence (an FOBT order not followed by a result) in the previous year, 2) FOBT adherence (an FOBT order followed by a result) in the previous year, and 3) no FOBT order in the previous year. In these models we adjusted for the aforementioned patient characteristics except FOBT nonadherence in the previous year. Among patients with an FOBT order in the previous year, we fit models in which FOBT nonadherence interacted with each incentive group (25, 26). Data were missing for a few baseline covariates. In stage 1, data on race and ethnicity were missing for 1.3% of patients; data on both median household income and percentage of residents with a high school education in ZIP code of residence were missing for 2.2% of patients. In stage 2, there were missing data on race and ethnicity for 0.7% of patients and on both median household income and percentage of residents with a high school education in ZIP code of residence for 1.