This study examined the effects of patient preferences on a range of outcomes in an RCT of the treatment of major depression. Results suggest several negative implications of being randomly assigned to a non-preferred mode of treatment. Mismatch had an effect on whether patients started treatment, such that none of those who refused randomization received a preferred treatment. Similarly, those randomized to a non-preferred treatment were more likely to drop out of the study and attend fewer expected visits.3
Patients assigned to a non-preferred treatment also reported a less positive early therapeutic alliance than those assigned to a preferred treatment. These findings converge with efforts in collaborative care highlighting the importance of patient preferences in staying in treatment for depression (Byrne et al., 2006
). These results are thus consistent with the suggestion that preference matching influences indirect outcomes (TenHave et al., 2003
We did not find significant direct effects of preference mismatch on improvement in depression over the course of treatment. This is consistent with the findings of Leykin and colleagues (2007)
, who also found small, nonsignificant effects of preference matching on depression outcomes, using a similar study design. MacKinnon et al (2002)
have noted that a lack of such direct effects of distal factors on primary outcomes is not uncommon when effect sizes and sample sizes are small and that it is possible to observe significant indirect effects via more proximal mediators. Given the significant effects of preference match on both attendance and early alliance, we used a path analysis to examine whether these variables mediated the effect of preference match on improvement in depression. This hypothesis was supported by our data, with 16% of the variance in depressive severity improvement explained (a medium effect size), primarily by a direct effect of attendance.
Thus, preferences appear to have an indirect effect on depression outcomes via commitment to and engagement in therapy. When patients do not receive a preferred treatment, they may be less likely to start treatment, stay in treatment, and attend an adequate number of treatment sessions. Even for the most efficacious treatments, patients needs to remain in treatment long enough to provide an opportunity to benefit from the treatment procedures. In fact, we may have underestimated the indirect effect of preference match on depression outcomes if symptom severity persisted or worsened for those who failed to start treatment (strongly predicted by preference match) or dropped out prior to 8 weeks (in which case their data were not available to be included in the analysis of change in depression). Furthermore, there are potentially other mediators of the preference-depression relationship not tested here (e.g., treatment adherence). It is also possible that some participants were generally unwilling to express a preference for fear of being excluded from the study.
These findings highlight the need to discuss a patient’s preferences at the outset of treatment or even prior to treatment assignment. A skilled therapist may help a patient who prefers one treatment see the value of alternative interventions, such as a more empirically-supported treatment. Persuasive strategies could be individually tailored to consider patients’ specific knowledge, beliefs and opinions about various treatment options (Hawkins, Kreuter, Resnicow, Fishbein, & Dijkstra, 2008
). Preferences may be based on beliefs about the etiology of depression, beliefs about the purpose of emotion, and cultural or religious beliefs (Givens et al., 2006
). Ignoring preferences could discount patients’ own valid perspectives on disease and alienate them in the process of seeking treatment. Inquiring about patient preferences may be especially important among specific patient populations who are highly vulnerable to non-engagement with recommended clinical interventions. For instance, a lack of attention to treatment preferences and beliefs is a barrier to the depression referral process for perinatal women, a group that experiences marked problems with depression treatment engagement (Flynn, O’Mahen, Massey, & Marcus, 2006
A potential implication of these findings is that preferences may need to be addressed even before a patient has contact with a mental health professional. Although a mental health clinician may have the skills and time to address effectively a patient’s reluctance to try a treatment about which the patient is skeptical, providers in primary care settings who are most likely to have first contact with depressed patients may have fewer resources for addressing such preference related barriers to care. Thus, as preferences seem to matter especially for starting treatment, effectively managing treatment preferences could be an important skill for those involved in referral processes.
These data also suggest that many people may prefer not to use medication as treatment for depression. It is possible that the greater preference for psychotherapy was reflective of selection factors, with individuals preferring psychotherapy being more likely to enroll in the trial given the greater availability of pharmacotherapy versus psychotherapy in routine clinical service delivery systems. However, it is also possible that greater preference for psychotherapy reflects the treatment preferences of many depressed adults, highlighting the importance of focusing on training, policy and service delivery to support empirically-supported psychotherapy for the treatment of depression and other mental disorders, allowing those who do prefer this option to have their preferences met.
It is important to emphasize potential limitations regarding generalizabilty of these findings. Preferences may impact outcomes differently (and may need to be addressed differently) outside the context of a randomized trial. Other research designs may be better suited to studying the effects of preferences on direct and indirect outcomes (e.g., patient preference trials). The results also do not speak to the question of for whom preferences are more important. Indeed, some studies suggest that not all patients want to participate in shared decision making. Schneider and colleagues (2006)
found that those with high external health locus of control expressed lower preference for involvement in decision making. Thus, individuals with more external health locus of control may be more content with any assigned or prescribed treatment, whereas those with more internal health locus of control may respond poorly to receiving a non-preferred mode of treatment.
Other methodological limitations are of note. The preference measure was administered to only a sub-sample of participants in this study. Although we found no significant differences in demographic or clinical characteristics between these groups, the limited administration did reduce statistical power. Also, although the use of the ETI was an improvement over other studies in that it explicitly assessed treatment preference, the ETI asks patients to make a forced choice response indicating discretely (rather than continuously) whether they preferred drug therapy, talking therapy, or had no preference. This measure does not allow for ambivalence or indication of to what degree a patient finds either mode of treatment acceptable. Also, it is not clear what “no preference” indicates for each individual. For example, it could mean that either treatment was acceptable, the patient had no opinion, or that the patient was unwilling to express an opinion.
In summary, patient preferences were important predictors of engagement in treatment, including starting treatment, staying in treatment, attending expected visits, and forming positive early therapeutic alliances, which ultimately predicted depression outcomes. Such findings underscore the importance of patient preferences in the design of RCTs, the provision of treatment recommendations, and the development of clinical services. It will be important for future research to address innovative ways of assessing, accommodating and modifying patient preferences, among general clinical populations and among specific groups vulnerable to non-engagement in treatment.