Impact of Propranolol and Psychologically Informed Intervention on Pain Sensitivity: Secondary Analysis from the Biopsychosocial Influence on Shoulder Pain Preclinical Randomized Trial.

Purpose: Measures of pain sensitivity have potential relevance for patient care. We previously identified a subgroup of people at risk for ongoing pain characterized by genetic AND psychological factors. Here, we report planned secondary analyses examining the effect of personalized interventions on pain sensitivity outcomes.

Patients And Methods: Two hundred and sixty-one healthy individuals with the COMT SNP rs6269 AA genotype and Pain Catastrophizing Scale scores of 5 or higher received exercise-induced muscle injury, followed by a randomly assigned treatment: (1) general education and placebo; (2) personalized psychological intervention and placebo; (3) general education and propranolol; or (4) personalized psychological intervention and propranolol. Pain sensitivity outcomes (pressure pain thresholds (PPT), suprathreshold heat rating, temporal summation, and conditioned pain modulation efficiency) were compared using a mixed effect model to examine difference among groups, adjusted for age, sex and race.

Results: No main effects for group assignment were noted (p > 0.05 for all), when considered as 4 groups or 2 collapsed groups (ie propranolol vs placebo or personalized psychologic vs general education). Interaction terms were then entered into our models in an exploratory fashion. For PPT outcomes interactions were noted for, sex and time, and race and time (p<0.015). For temporal summation outcomes, interactions were noted for sex and group and race and group (p < 0.015).

Conclusion: Results indicated no statistically reliable changes in pain sensitivity when considering matched vs unmatched treatment groups. Caution is needed in this interpretation given that the trial was not powered to specifically identify these differences. Exploratory analysis of interactions among ethnic/racial and gender identities by treatment, however, showed the potential for differential effects for specific pain sensitivity measures. Significant interactions across modalities suggest analysis of higher order interactions/intersectionality could be of great interest for testing efficacy of personalized interventions in future trials.