Examining the impact of low magnitude incentives in contingency management protocols: Non-engagement in Petry et al. 2004.

Introduction/method: Current federal regulations limit the use of incentives in contingency management (CM) interventions to a nominal total value (i.e., up to $75/patient/year in aggregate of federal funds). This limit represents a striking divergence from the magnitudes used in evidence-based CM protocols. In the present report, we re-analyze data from the Petry et al. (2004) study, which was designed to test the efficacy of two different magnitude CM protocols ($80 and $240 in 2004 dollars) relative to usual intensive outpatient services for treatment-seeking patients with cocaine use. Petry et al. (2004) found that the $240 condition [~$405 in 2024 dollars], but not the $80 condition [~$135 in 2024 dollars], improved abstinence outcomes relative to usual care. The lower-cost $80 condition is the closest condition to the current federal $75 limit that permits a head-to-head comparison of magnitudes. A re-analysis offers an opportunity to examine the impact of low magnitude protocols in more detail, specifically in terms of non-engagement with treatment (defined as absence of negative samples and thus not encountering incentives for abstinence).

Results: We found moderate to large effects favoring the $240 condition over both usual care (ds ranging 0.33 to 0.97) and the $80 condition (ds ranging 0.39 to 0.83) across various thresholds of non-engagement with the incentives/reinforcers for abstinence. Importantly, the $80 condition evidenced higher (worse) rates of non-engagement compared to the usual care condition (i.e., small and negative effect sizes ranging -0.30 to 0.14), though not reaching statistical significance.

Conclusions: These results suggest that CM protocols designed to stay within the federal limitation of $75 should be discouraged, and evidence-based protocols should be recommended along with the regulatory reforms necessary to support their implementation.