Kathryn M Berzins, Trish A Gray, Heather Waterman, Jill J Francis

In response to recent calls for clearer specification of behavior change interventions, the purpose of this study was to apply a system of taxonomy for behavior change techniques (BCTs) to two educational interventions to improve adherence to glaucoma eye drops. Clarification of constituent BCTs will promote easy and reliable application of the interventions in clinical settings and research. A published taxonomy of BCTs was used to code two interventions (group and individual) to increase adherence to eye drops. Intervention materials were coded by assigning a BCT label to each text unit. We noted the frequency with which each BCT occurred, compared the interventions in terms of the BCTs that were delivered, and identified whether the taxonomy was sufficient to describe the intervention components. The individual intervention consisted of 94 text units. Fifty-seven were identified as targeting behavior change and coded using 18 BCTs, many coded more than once. In the group intervention, 165 units of text were identified, and 125 were coded using 22 BCTs. The most frequently coded BCT was "provide information about behavior-health link" in the group intervention and "prompt barrier identification" in the individual intervention. The interventions included similar BCTs. All text units targeting behavior change were codable into BCTs. The similarity of the two interventions may have implications for the cost-effectiveness of the interventions. The taxonomy was found sufficient to describe both interventions. This level of specification can be used to ensure that precisely the same intervention that has been pilot tested is reproducible in the clinical setting and in any further research.