Objective: To evaluate the association of patient-reported baseline expectation with efficacy outcomes in a randomized placebo-controlled trial (RCT) in PD.

Background: Expectation of benefit can contribute to therapeutic efficacy in PD in the form of placebo and lessebo effects. Although SURE-PD3 was a disease modifying trial, at baseline, 53% study participants expected improvement in their symptoms over two years of treatment with inosine and 90% preferred being allocated to inosine.

Method: We administrated a patient-reported expectancy questionnaire (EQ) in the RCT SURE-PD3 (NCT02642393, n=297) and tested the association between each of two sentiments (EQ) assessed at baseline, an expectation of benefit from inosine treatment and a preference for inosine treatment, and short-term (baseline to 6 weeks) and long-term (baseline to end of treatment at 12 to 24 months) change in motor and non-motor symptoms (MDS-UPDRS Part I-III total score and each part separately). Sentiments were tested as baseline covariates in a random-slopes linear mixed models that censored follow-up at the start of antiparkinsonian medication and adjusted for sex, baseline Schwab and England ADL score, and baseline use of an MAO-B inhibitor. A step-down Bonferroni-adjusted P <0.05 was deemed statistically significant.

Results: We found no association between greater patient-reported baseline expectation of benefit for inosine or treatment preference for inosine and rate of change in MDS-UPDRS Part I-III (or parts I, II and III separately) between baseline, and week 6 or end of treatment.

Conclusion: Our results do not support an association between patient-reported baseline expected benefit from a potentially disease-modifying experimental therapy or treatment preference and clinical trial efficacy outcomes. In the context of disease-modification trials in PD, it is possible that the participant experiences during the clinical trial, including ongoing interactions with study staff, modifies pre-treatment attitudes and changes the magnitude of placebo and lessebo effects.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/does-baseline-expectation-of-benefit-predict-outcome-in-sure-pd3-a-randomized-double-blind-placebo-controlled-phase-iii-trial-of-inosine-in-parkinsons-disease/