The pain quality response profile of a corticosteroid injections and heated lidocaine/tetracaine patch in the treatment of shoulder impingement syndrome.

OBJECTIVES: To describe the effects of 2 pain treatments for shoulder impingement syndrome (SIS), and illustrate how investigators can use pain quality information to understand treatment response differences.

MATERIALS AND METHODS: This study presents pain quality data from a randomized open-label study comparing the effects of an injection of triamcinolone and up to twice daily application of a heated lidocaine/tetracaine (Trilexis) patch in individuals with SIS. Study participants completed a measure of pain quality at baseline and again on study days 14, 28, and 42 following initiation of 2 treatments for SIS. Baseline and posttreatment pain quality scores were graphed to provide a visual representation of treatment-associated changes. Analyses of variance were used to examine the differences between treatment conditions in changes in pain quality with treatment.

RESULTS: Both treatments resulted in substantial (and similar) pretreatment to posttreatment improvements in many pain qualities. However, differences in the time course of treatment effects were observed for itchy and heavy qualities.

DISCUSSION: Although 2 different pain treatments appear to have the same effects when only pretreatment to posttreatment changes are examined, treatment differences emerged when the time course of treatment is examined. The findings support the importance of assessing both pain qualities and time course of treatment as outcome domains. The results illustrate how investigators can use data from clinical trials to provide a more fine-tuned description of treatment effects, providing knowledge that could be helpful in selecting treatment options at the individual patient level.

SUMMARY: Examination of the effects of pain treatments on pain qualities over time will help researchers and clinicians understand if certain pain quality domains respond faster to one treatment versus another, and may identify differences between treatments that would not be observed by measures of global pain intensity alone.