Mutual influence in therapist competence and adherence to motivational enhancement therapy

Abstract

Although psychotherapy involves the interaction of client and therapist, mutual influence is not typically considered as a source of variability in therapist adherence and competence in providing treatments assessed in clinical trials. We examined variability in therapist adherence and competence in Motivational Enhancement Therapy (MET) both within and between caseloads in a large multi-site clinical trial. Three-level multilevel models (repeated measures, nested within clients, nested with therapists) indicated significant variability both within and between therapists. There was as much and sometimes more variability in MET adherence and competence within therapist caseloads than between therapists. Variability in MET adherence and competence within caseloads was not consistently associated with client severity of addiction at baseline. However, client motivation at the beginning of the session and days of use during treatment were consistent predictors of therapist adherence and competence. Results raise questions about the nature of therapist adherence and competence in treatment protocols. Accordingly, future analysis of clinical trials should consider the role of mutual influence in measures of therapist performance.

Introduction

There is a strong evidence base for the efficacy of Motivational interviewing (MI; Miller and Rollnick, 2002) and its implementation incorporating feedback, Motivational Enhancement Therapy (MET; Miller and Rollnick, 2009; Hettema et al., 2005, Lundahl et al., 2010). Dozens of clinical trials (see Lundahl et al., 2010) have given way to studies of the process of effective MI. The majority of research examining the mechanisms of MI and MET has involved evaluations of therapist adherence to MI principles and the competence with which these interventions are delivered (Carroll et al., 2000). There is a growing body of research indicating that the therapist impacts client behaviors in MET (see Miller and Rose, 2009 for a review). However, levels of therapist adherence and competence tend to be variable. More generally, across a variety of treatments and disorders, the relationships between therapist adherence, competence, and clinical outcomes tend to be small (see recent meta-analysis by Webb et al., 2010). As a result, the components of treatment responsible for change remain unclear (Carroll et al., 2006a).

One potential explanation for the lack of predicted relationships between therapist adherence, competence with treatment outcomes is that research on the practice of MET is often uni-directional – focusing on how therapist behaviors influence clients. However, MI and MET are based on a theory of interpersonal behavior involving the mutual influence of clients and therapists on each other. Specifically, therapist confrontation and client resistance to change are considered complementary behaviors that reinforce each other (Miller and Rollnick, 2002, Miller, 2006). Accordingly, a fundamental tenet of motivational interviewing is that client resistance is not merely a client factor, but a dyadic process that occurs “within the context of a relationship or a system” (Miller and Rollnick, 2002, p.46). MI and MET are designed to promote client motivation by training therapists to resist the tendency to respond to client resistance with confrontation by maintaining an empathic stance and strategically eliciting client statements in favor of change (Hartzler et al., 2009, Miller and Rose, 2009). The purpose of the current paper is to provide an initial test of the hypothesis that therapist adherence and competence in providing MET is partially determined by the mutual influence of therapists and clients on each other.

If therapists are influenced by client behaviors, there are two opposite models for conceptualizing the direction of the effect. One hypothesis suggests that therapist adherence and competence may be negatively impacted by more difficult clients. For example, clients with high psychiatric severity may negatively impact ratings of therapist adherence by decreasing the extent to which therapists can engage in motivational strategies such as making plans for change and pro/con lists. Similarly, the complexity of working with patients with more psychiatric problems may result in decreased ratings of therapist competence. It is also possible that clients who present as more resistant elicit MI-inconsistent behaviors from therapists such as confrontation (Francis et al., 2005). Alternatively, the second and rival hypothesis, consistent with the goals of training therapists in MI, posits that difficult or resistant behaviors on the part of clients should elicit greater use of MI strategies among therapists. A core goal of training in MI is to teach therapists to not reciprocate client resistance with confrontation (Miller and Rollnick, 2002). Analyses that examine how and to what extent therapists trained in MET might respond with behaviors consistent or inconsistent with MET by different clients may further clarify the mechanisms of action responsible for client change, as well as lead to improved training procedures related to working with challenging clients. The influence of clients on therapist adherence and competence may be particularly important for client outcomes, as certain client behaviors could encourage the very therapist behaviors that MET views as working against a goal of reduced substance use.

We are not aware of any research addressing the potential impact of clients on therapist MET competence. However, there is some evidence supporting the first hypothesis that client difficulty decreases therapist adherence in providing MET. Francis and colleagues (2005) found that therapists who provided treatment to highly resistant confederate clients were independently rated as more confrontational than those working with less resistant clients. However, these therapists had not yet been trained in MI or MET. Similarly, a sequential analysis of therapist and client utterances indicated that client change talk is more likely to be followed by MI-consistent responses from therapists (Moyers and Martin, 2006). Continued client substance use during treatment may also influence therapist use of MI. Thyrian et al. (2007) found that clients who had stopped smoking were 3 times more likely to receive a higher quality MI session as compared to those who were daily smokers. In contrast and consistent with the second hypothesis that therapists will not be drawn into MET inconsistent behaviors by client resistance, an analysis of process data from Project MATCH (Carroll et al., 1998) and the multisite Marijuana Treatment Project (Gibbons et al., 2010) indicated that continued substance use during treatment was associated with greater use of MET techniques.

In sum, theory and preliminary research suggests clients may influence therapist adherence and competence in providing MET. However, there are few studies in this area and the direction of effects remains unclear.

The social relations model (SRM; Kenny et al., 2006) provides a framework for partitioning sources of variability in interpersonal interactions such as therapist adherence and competence. The SRM posits that interpersonal behavior can differ as a result of three main components: 1) the actor, 2) the partner, and 3) the relationship. In psychotherapy, this translates to 1) client, 2) therapist, and 3) relationship or dyad components. Psychotherapy clinical trials are typically nested in structure wherein one therapist treats several different clients, but clients receive treatment from only one therapist. Nested designs allow the researcher to disentangle sources of variability in a target behavior (e.g., therapist adherence) into therapist components (i.e., between therapist differences) as well as patient and relationship components (i.e., differences between clients within therapist caseloads). The between therapist component is a measure of consensus – the similarity of ratings of adherence and competence for a given therapist. High levels of consensus indicate that some therapists were more adherent and competent than others across clients in their respective caseloads. The patient and relationship component is a measure of uniqueness–do clients experience different amounts of adherence and competence with their therapists? Differences between clients within a therapist's caseload may be the result of characteristics unique to the client or the relationship of a given client with a therapist. Round robin designs, in which clients are treated by multiple therapists, are necessary to separate relationship effects from client effects, but are typically unfeasible in applied clinical studies. The structure of current data in which clients are nested or clustered within therapists allows for the partitioning of adherence and competence into between and within therapist components and provides an indication of the extent to which adherence and competence are determined by therapists as well as factors unique to either clients or their relationship with clients (see Marcus et al., 2009, Raudenbush and Bryk, 2002).

If therapist adherence and competence are the product mutual influence, then we would expect relatively high levels of variability in adherence and competence within a therapist's caseload. However, if a therapist's adherence and competence in providing MET are primarily driven by the therapist, variability in these measures within caseloads should be negligible.

In the current paper, we analyzed data from a large multi-site study of substance use treatment to examine if therapist adherence and competence in providing MET is variable within therapist caseloads and impacted by client behaviors. We hypothesized that adherence and competence in providing MET will vary within therapist caseloads (Hypothesis 1). Given mixed findings in prior literature, we further evaluated two rival Hypotheses (2a and 2b) with respect to the relationships between client difficulty (e.g., substance use, motivation, other severity indicators), both at baseline and during treatment and ratings of therapist adherence to MET. Based on ideas of interpersonal complementarity discussed in the MI literature (Miller, 2006, Miller and Rollnick, 2002), 2a predicts that client difficulty will be associated with less adherence. However, consistent with the goals of MET training, 2b predicts that client resistance will be associated with greater adherence to MET protocols. Given the absence of prior research regarding the effects of clients on therapist competence, we regarded analyses of client indicators of resistance on therapist competence as exploratory.