A meta-analysis of the association between patients’ early perception of treatment credibility and their posttreatment outcomes
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A meta-analysis of the association between patients’ early perception of treatment credibility and their posttreatment outcomes.

Constantino M.J., Coyne A.E., Vîsla A. et al.
Psychotherapy: 2018, 55(4), p. 486–495.
Unable to obtain a copy by clicking title? Try asking the author for a reprint by adapting this prepared e-mail or by writing to Dr Constantino at mconstantino@psych.umass.edu.

Review commissioned by the American Psychological Association suggests therapists should incorporate strategies to enhance the credibility of treatment when explaining its rationale and throughout therapy. The more a treatment ‘makes sense’ to a patient, the better outcomes tend to be.

Summary [Though not specific to clients with drug and alcohol problems, the principles derived from this review of psychotherapy are likely to be applicable, partly because severe substance use problems generally form part of a complex of broader psychosocial problems. Addictions work may not necessarily best be conceptualised as psychotherapy, but there is a therapeutic element to it which makes these findings relevant to keyworkers and counsellors.]

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Key points
From summary and commentary

Commissioned by a task force of the American Psychological Association, this review evaluated the influence of the client’s perception of the credibility of the treatment on the outcomes of that treatment.

Across all 24 samples of patients among whom studies have investigated this link, it was small but statistically significant.

Though this association is not necessarily a causal one, it is recommended that to improve outcomes therapists should incorporate strategies to enhance their credibility and that of the treatment.

The featured review is one of several in a special issue of the journal Psychotherapy devoted to features of the therapist–client relationship related to effectiveness, based on the work of a task force established by the American Psychological Association. This particular review’s aim was to evaluate the influence of how credible the therapy seems to the client on how well they respond to it.

Patients’ beliefs in the credibility of a treatments and practitioners are often conceptualised as a ‘common factor’ (1 2) underlying effective psychotherapy, regardless of its theoretical orientation. Drawing on social psychological research which established that credibility partly determines degree of influence, therapy can be likened to a social influence process whereby therapists establish themselves as professionally credible by embodying ‘expert’ status, trustworthiness, and attractiveness, and then leverage their credibility to promote desired changes in their patients.

It is important to recognise that credibility and progress in treatment may have a reciprocal relationship: credibility may promote treatment progress, but making progress may also boost the credibility of the treatment. Similarly, the successes or failures of previous treatments can be expected to affect the credibility of another attempt adopting the same approach.

Measuring the credibility of treatment

The Credibility/Expectancy Questionnaire is the most widely used measure of the credibility of treatment. Its three relevant questions are reproduced below, using the example of depression, but it can be adapted for different problems by replacing the term referring to the condition being treated:
• “At this point, how logical does the therapy offered seem to you?”
• “At this point, how successful do you think this treatment will be in reducing your depressive symptoms?”
• “How confident would you be in recommending this treatment to a friend who experiences similar problems?”

Patients’ perceptions of treatment credibility have usually been seen as ‘nuisance’ variables to be eliminated from the analysis in clinical trials. Few early studies aimed to test their therapeutic impact. Only recently have studies actually focused on credibility as a possible determinant of improvement across therapies with different theoretical foundations. This trend has been aided by the development of a sound measure that distinguishes treatment credibility from outcome expectations panel right.

Credibility can attach either to the therapist or the treatment. However, for this review no studies were found linking therapist credibility to outcomes. Consequently the review focused on the credibility of the treatment – the degree to which the patient finds its conceptualisation of the problem and its remedies logical and personally applicable. The review incorporated a meta-analysis amalgamating results from relevant studies to estimate the overall strength of the link between the credibility of the treatment and patients’ improvements, and to probe for influences on the strength of that link. The assumption was made that there is no single, true strength of the link between expectations and outcomes which appears to vary only because of methodological differences, but that instead strength really did vary across the studies included in the analysis.

Studies were included in the analysis if their results had been published in English, included post-treatment mental health outcomes, involved samples of patients in treatment receiving psychotherapy intended to last at least three sessions, and related outcomes to the patients’ perceptions of the credibility of the treatment assessed before treatment or at the first or second session. Searches found 19 articles reporting usable data on 24 samples of patients cumulating to 1,504 participants. No studies were found which deliberately sought to change perceptions of credibility to test the impact on outcomes. Most of the samples had been offered cognitive-behavioural therapy.

The strength of the link between credibility and outcomes was calculated as a correlation coefficient, an expression of the degree to which outcomes co-varied with credibility. The chosen metric ranges from -1 (perfect negative co-variation meaning that as one side of the link gets larger the other diminishes) to +1 (perfect positive co-variation meaning that as one side of the link gets larger so does the other). These coefficients were also converted to effect sizes. Effectively these metrics indicate how influential perceptions of treatment credibility had been if causally linked to outcomes.

Main findings

The overall correlation was a statistically significant 0.12 corresponding to an effect size of 0.24, indicating a weak but appreciable link between perceptions of treatment credibility and post-treatment outcomes. In other words, as credibility became more positive, outcomes tended to do the same, but the relationship was a loose one. Excluding an ‘outlier’ study which found the link unusually strong slightly reduced the correlation to 0.10, but it remained statistically significant.

The strength of the credibility–outcomes link varied significantly across studies. In 11 of the 24 samples of patients it was either zero or (in four cases) negative – the latter meaning outcomes tended to get worse the more credible the patient found the treatment. None of the differences between the studies tested in the analysis accounted for this variation. Among these differences were the patients’ diagnosis, age or sex, treatment orientation and modality, research design, publication date, and whether a treatment manual was used. Across all these distinctions the link between credibility and outcomes was fairly consistent and robust.

These findings from the analysis which aggregated results from relevant studies were complimented by a review of how credibility might affect outcomes, one informed by just a single study which tested one of these theories on a sample of patients. It has been argued that perceived treatment credibility may influence patients’ expectations of the outcomes of their treatment, which could in turn promote greater improvement. Non-clinical studies have indeed found that the provision of a logical and compelling treatment rationale can augment outcome expectations, but no study has tested the final link in the chain leading to outcomes. Similarly, studies have supported the theory that treatments seen as more credible facilitate the formation of a stronger therapeutic alliance with the therapist, but only one (of depressed patients) went on test whether in turn outcomes were improved. It found no evidence that they were.

Also reviewed were studies indicating what types of patients perceive their psychotherapy treatment as more or less credible. The patchy evidence includes indications that credibility is weaker among older, more highly educated or more severely affected patients (though even they may come to feel treatment is more credible if they improve), and stronger among women than men.

The authors’ conclusions

The limitations of the research mean that, for now, treatment credibility can only be seen as a correlate of post-treatment outcomes, that therapists might do well to assess and respond to sensitively when indicated. Establishing a causal connection would require clinical studies which deliberately sought to change perceptions of credibility to test the impact on outcomes. Moving the treatment credibility construct from a static belief ‘possessed’ by the patient to a dynamic variable that can be modified over time by the treatment, by the therapist, or by patient and therapist, would require repeated measures, especially among clinical samples of patients in treatment. It also seems likely that the credibility of the therapist would be more influential than that of the treatment, but no clinical studies have tested therapist credibility as an outcome determinant. Finally, research examining what therapists can do specifically to foster credibility is virtually nonexistent.

Practice implications

Drawing on the best available research evidence, the reviewers offered practice suggestions (selection below) to help therapists cultivate and respond to their patients’ beliefs about the therapist’s credibility and that of their treatment:
• Enter regularly into a dialogue about what patients do and do not find compelling about a treatment rationale/plan.
• Assess as well the patient’s perceptions of the therapist’s credibility as a distinct construct, eg: “I know that the treatment itself seems to suit you, but I wonder if you have any feeling about me being the one to deliver it?”
• Be aware of any patient characteristics that might affect treatment credibility. This will help clinicians forecast negative beliefs as a well as directly assessing them in the here and now.
• Deliver a logical and compelling account of the rationale for the treatment taking into account the individual and the context, trying various ways to make a treatment sound personally logical, suitable, and efficacious. If necessary, respond to the patient’s reactions by changing or adapting the programme. The aim is to influence the patient’s belief system, not simply deliver a ‘scripted’ theoretical rationale.
• Enhance credibility by identifying explicit elements which patients find credible, and assimilating them into psychotherapy.
• Try to promote, early, palpable symptom improvement; research suggests such improvement promotes treatment credibility.
• Mind your posture, as there is preliminary evidence that greater therapist eye contact and leaning forward in one’s seat are associated with greater treatment credibility, as well as with other processes such as the quality of the therapeutic alliance between patient and therapist and perceptions of the empathy shown by the therapist.

Findings logo commentary The practice recommendations advanced by the reviewers are based on the possibility of a causal link – that the degree to which patients believe in the treatment or the therapist influences effectiveness. However, they are clear that such a link has not been established, and even if it were real, it would it seems be a very loose relationship. Links between outcomes and therapist credibility may be stronger if the studies had been done to test this, but from the reviewed studies the average impact (if there is one) of beliefs about the credibility of treatment accounts for just 1% of the variation in outcomes. Among nearly half the patient samples the credibility-outcomes link was either zero or negative, and it seems none of the studies were about treating substance use problems.

How much substance use therapists should invest in boosting credibility on the basis of this evidence must be open to question, especially given the potential risks of ‘over-egging’ a treatment’s credentials. Instilling optimism in the form of credibility is almost certainly on balance usually positive, but with relapse the norm in substance use treatment, perhaps not if it leads to greater disillusion and distrust of treatment when it fails.

Listed below are analyses of the other reviews commissioned by the American Psychological Association task force.
Overall conclusions based on the other 16 reviews
The ‘real’, person-to-person relationship
Therapist–client alliance
Alliance in couple and family therapy
Alliance in child and adolescent therapy
Cohesion in group therapy
Therapist empathy
Goal consensus and collaboration
Positive regard
Therapist congruence/genuineness
Therapist self-disclosure and ‘immediacy’
Therapist and client emotional expression
Repairing ruptured alliances between therapists and clients
Managing ‘countertransference’
Treatment outcome expectations
Feeding back client progress data therapists

Last revised 28 March 2019. First uploaded 16 November 2018

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