Methodological limitations prevent definitive conclusions on the effects of patients’ preferences in randomized clinical trials evaluating musculoskeletal conditions

The impact of treatment preferences: A narrative review

Attending to treatment preferences is an element of person-centred care, reported as beneficial in improving treatment adherence, satisfaction, and outcome, in practice. The results of preference trials were inconsistent in supporting these benefits in intervention evaluation research. Informed by the conceptualisation of treatment preferences positing their indirect impact on outcomes, this narrative review aimed to summarise the evidence on the effects of preferences on enrolment; withdrawal or attrition; engagement, enactment, and satisfaction with treatment; and outcomes. The search yielded 72 studies (57 primary trials and 15 reviews). The results of vote counting indicated that (1) offering participants the opportunity to choose treatment enhances enrolment (reported in 87.5% of studies), and (2) providing treatments that match participants' preferences reduces attrition (48%); enhances engagement (67%), enactment (50%) and satisfaction with (43%) treatment; and improves outcomes (35%). The results are attributed to conceptual and methodological issues including less-than-optimal assessment of treatment preferences, which contributes to ill-identified preferences, accounting for withdrawal, low enactment, and limited satisfaction with treatment. These treatment processes, in turn, mediate the impact of treatment preferences on outcomes. It is important to refine and standardise the methods for assessing preferences and to examine their indirect impact (mediated by treatment processes) on outcomes in future preference trials to validly identify their benefits.

Factors and situations influencing the value of patient preference studies along the medical product lifecycle: a literature review

Industry, regulators, health technology assessment (HTA) bodies, and payers are exploring the use of patient preferences in their decision-making processes. In general, experience in conducting and assessing patient preference studies is limited. Here, we performed a systematic literature search and review to identify factors and situations influencing the value of patient preference studies, as well as applications throughout the medical product lifecyle. Factors and situations identified in 113 publications related to the organization, design, and conduct of studies, and to communication and use of results. Although current use of patient preferences is limited, we identified possible applications in discovery, clinical development, marketing authorization, HTA, and postmarketing phases.

The influence of clinical equipoise and patient preferences on outcomes of conservative manual interventions for spinal pain: an experimental study

Background

Expected pain relief from treatment is associated with positive clinical outcomes in patients with musculoskeletal pain. Less studied is the influence on outcomes related to the preference of patients and providers for a specific treatment.

Objectives

We sought to determine how provider and patient preferences for a manual therapy intervention influenced outcomes in individuals with acutely induced low back pain (LBP).

Participants and methods

Pain-free participants were randomly assigned to one of two manual therapies (joint biased [JB] or constant touch [CT]) 48 hours after completing an exercise protocol to induce LBP. Expectations for pain relief and preferences for treatment were collected at baseline, prior to randomization. Pain relief was assessed using a 100 mm visual analog scale. All study procedures were conducted in a private testing laboratory at the University of Florida campus.

Results

Sixty participants were included in this study. After controlling for preintervention pain intensity, the multivariate model included only preintervention pain (B=0.12, p=0.07) and provider preference (B=3.05, p<0.0001) and explained 35.8% of the variance in postintervention pain. When determining whether a participant met his or her expected pain relief, receiving an intervention from a provider with a strong preference for that intervention increased the odds of meeting a participant’s expected pain relief 68.3 times (p=0.013) compared to receiving any intervention from a provider with no preference. Receiving JB intervention from any provider increased the odds of meeting expected relief 29.7 times (p=0.023). The effect of a participant receiving an intervention they preferred was retained in the model but did not meet the criteria for a significant contribution.

Conclusion

Our primary findings were that participant and provider preferences for treatment positively influence pain outcomes in individuals with acutely induced LBP, and joint-biased interventions resulted in a greater chance of meeting participants’ expected outcomes. This is contrary to our hypothesis that the interaction of receiving an intervention for which a participant had a preference would result in the best outcome.

A theoretical analysis showed that blinding cannot eliminate potential for bias associated with beliefs about allocation in randomized clinical trials

OBJECTIVES

To explore the theoretical justification for blinding in randomized trials and make recommendations concerning the implementation and interpretation of blinded randomized trials.

STUDY DESIGN AND SETTING

A theoretical analysis was conducted of the potential for bias in randomized trials with successful blinding (ie, trials in which beliefs about allocation to treatment or control groups are independent of actual allocation). The analysis identified conditions that must be satisfied to ensure that blinding eliminates the potential for bias associated with beliefs about allocation.

RESULTS

Even when beliefs about allocation are independent of actual allocation, they can still cause bias. The potential for bias is eliminated when the belief is uniformly one of complete ambivalence about allocation.

CONCLUSION

Even when blinding succeeds in making beliefs about allocation independent of actual allocation, beliefs about allocation may still cause bias. It is difficult to determine the extent of bias in any particular trial. Bias could be eliminated by establishing a state of complete ambivalence about the allocation of every trial participant, but universal ambivalence may be difficult to achieve and may reduce the generalizability of the trial's findings.