Does Anesthetic Relief Correspond to Future Pain Relief?: A Prospective Trial Examining Future Pain Relief for Ultrasound-Guided Corticosteroid-Anesthetic Injections.

OBJECTIVES

The aim of the study was to prospectively evaluate the association between immediate pain relief from injections of local anesthetic with corticosteroid and subsequent pain relief up to 3 mos. The secondary aim was to examine the time until subjective pain relief after these injections.

DESIGN

This was a single-center, prospective study of patients undergoing ultrasound-guided corticosteroid injections for musculoskeletal pain. Subjects completed follow-up surveys at 2 wks, 1 mo, and 3 mos postinjections. χ 2 tests and sensitivity analysis were used to examine the primary outcome, at least 50% relief from the injection. Regression modeling examined the effects of demographic and injection-related variables on outcome measures.

RESULTS

A total of 132 patients were enrolled (55% female, mean age 52 yrs). Response rates were 87.1% at 2 wks and 77.2% at 3 mos. The positive likelihood ratios from 50% initial pain relief ranged from 1.22 to 1.29 at the three time points, whereas the negative likelihood ratios ranged from 0.54 to 0.63. More than 75% of participants reported subjective pain relief by day 4 after injection.

CONCLUSIONS

The predictive value of immediate pain relief for subsequent longer-term pain relief from corticosteroid-anesthetic injections is not particularly high. Most patients will obtain pain relief within 4 days of a corticosteroid injection.