Representation of solutions within and across studies
The remainder of the results section relates the configurations we identified back to the specific studies included in the review to provide examples of how these configurations were represented within the studies. Any individual study covered by a particular configuration may or may not contain other BCTs not explicitly identified by an uppercase or lowercase notation in the solution term. Because the minimization process removes logically redundant terms, the final solutions do not contain a term for all nine BCTs. For example, the set of studies covered by the configuration of “KS” all contain an intervention component to increase knowledge AND a component to enhance self-efficacy, but any one individual study covered by “KS” may or may not also contain components targeting awareness, attitude, intention formation, action control, maintenance, facilitation, and motivation, all of which “fell out” during the minimization process because their presence or their absence was inconsistently associated with the outcome of improved adherence.
The most empirically relevant configuration we identified was “KS”; studies covered by this configuration included intervention components to increase knowledge AND to enhance self-efficacy. The 17 studies covered by the “KS” configuration spanned six different clinical conditions (hypertension, depression, diabetes, asthma, congestive heart failure, and hyperlipidemia); all but one targeted only a single chronic condition. “KS” interventions were delivered in-person or by telephone, and also included interventions that were automated, such as the use of computer-generated feedback or mailed educational information. This configuration included several clusters of studies by the same author or research team, though using different study populations. The knowledge component of the “KS” configuration was similar across these 17 studies and was exemplified through a variety of intervention components designed to increase patient knowledge on disease facts (prevalence, symptoms, triggers, pathophysiology), medications available for treatment and side effects of medications, and short- or long-term adverse consequences of poor adherence or no treatment at all.
In the 17 “KS” studies,
knowledge components were coupled with techniques to raise
self-efficacy, specifically information and skills needed to overcome barriers to adherence, although the specific self-efficacy techniques used by study interventions varied. These techniques included skills training [
17‐
21], problem solving skills and coping skills [
21,
22], and counseling or aids to enhance self-management behaviors and increase self-efficacy to self-manage [
22‐
26]. Some of the studies used theory-based interventions; for example, a highly structured depression treatment program used brief psychotherapy based on Bandura’s social cognitive theory and several social learning theories [
21]. Several interventions were based on the transtheoretical model [
27]; two of these studies by the same author included stage-matched, computer-generated information reports based on participant responses to a baseline assessment [
28,
29]. Similarly, one study used telephone care managers combined with a workbook designed for behavioral activation to support long-term self-management and self-care for patients with depression; the self-efficacy component is exemplified by a focus on identifying and challenging negative thoughts [
30]. One study, based on the theory of planned behavior, used a cardiovascular nurse to provide education and counseling for patients with congestive heart failure; the self-efficacy component included skills needed to overcome barriers to adherence [
31]. Another study used tailored interactive voice response technology to deliver a behavioral intervention based on the health belief model, social cognitive theory, and self-regulation theory to increase adherence to statin medication [
32]. In this intervention, baseline patient measures of knowledge and self-efficacy, in addition to other baseline measures, were used to provide highly tailored feedback to study participants to enhance both knowledge and self-efficacy. One study, based on protection motivation theory, was designed to influence both asthma knowledge and asthma self-efficacy, as both have been associated with adherence behavior [
33].
Four studies were covered by the configuration “fG”; these interventions did NOT have a
facilitation component but did include a
motivational interviewing component. The “fG” configuration uniquely covered two studies. One of these studies evaluated the use of an automated telephone patient monitoring and counseling approach on adherence to antihypertensive medication and blood pressure control [
34]. The
motivational interviewing component of this study was exemplified by use of motivational counseling messages to improve adherence. The other study uniquely covered by this configuration included a software-based counseling intervention provided by telephone by call center (nonclinical) staff for improving adherence to a specific biological therapy (interferon beta-1a) among patients with multiple sclerosis [
35]. The software-based counseling was based on principles of motivational interviewing, as developed by Miller and Rollnick [
36]. The absence of a
facilitation component is exemplified by the automated or semiautomated nature of both interventions, with the absence of continuous professional support, individualizing of regimens, and reducing environmental barriers to adherence.
Two studies were uniquely covered by the “KRFICm” configuration; these studies included components to increase
knowledge and
awareness, provide
facilitation, and increase
intention formation and use of
action control but lacked a
maintenance component. One study involved nurse-led telephone encounters in the Department of Veterans Affairs healthcare system using computer-tailored feedback and home blood pressure monitoring to improve adherence to both antihypertensive regimens and lifestyle behaviors associated with better blood pressure control [
37]. The other study was an intervention to prevent readmissions in elderly patients with congestive heart failure [
38]. This intervention was mostly delivered face-to-face while patients were still in the hospital, with some follow-up after discharge, using a teaching guide focused on diet and medication adherence.
Three studies, all by the same author, were covered by the “KrFT” configuration, which includes components to increase
knowledge, provide
facilitation, and improve
attitude, but does NOT include an
awareness component. These studies were similar in intervention design—two were conducted in different populations of patients with depression and diabetes [
39,
40] and one study was in patients with depression and hypertension [
41]. These studies used an integrated care manager to work with patients and their physicians to individually address factors involved in adherence, based on a conceptual model adapted from Cooper et al. [
42].
Only one study was covered by the “kfCm” configuration, which includes an
action control component, but does not include components to increase
knowledge, provide
facilitation, or support maintenance. This study consisted exclusively of daily, 3- to 5-min telephone or video medication reminder calls by a research assistant to community-dwelling patients over age 65 with congestive heart failure [
43]. This study exemplifies an effective intervention strategy, despite the absence of components directed at increasing patient knowledge, providing facilitation, or maintenance strategies.