Abstract:
Pain affects 100 million adults in the United States (US) and costs up to $635 billion annually. Several interventional treatments have been developed to mitigate the negative impacts of pain. Randomized controlled trials (RCTs) provide the strongest
level of evidence to support pain treatment effectiveness. However, the modest effect sizes of most current pain treatments make it essential that RCTs use the most rigorous study design and analytic methods to reduce the likelihood that real treatment effects are obscured by other factors.
A factor that we believe is important to account for in interventional pain trials is the use of concurrent analgesics. Our observation had been that concurrent analgesic use is not well-reported in many RCTs evaluating pain treatments and, even when reported, is not accounted for in ways that optimize the precision of estimated treatment effects. A study by Suri et al., found that ignoring concurrent analgesic use in the analysis of pain RCTs may lead to substantial underestimation or overestimation of treatment effects on pain intensity, as well as affect the power of the study. The authors of that study proposed a new measure to account for concurrent analgesic use, Quantitative Pain and Analgesic Composite outcome (QPAC1.5). The QPAC1.5 combines pain intensity and concurrent
analgesic use into a single numeric rating scale of pain intensity. It may increase precision and accuracy in pain RCTs that do not explicitly account for concurrent analgesic use in the analyses of pain intensity. To our knowledge, there is a lack of evidence in the literature evaluating how often pain RCTs report on concurrent analgesic use or examining what methods they use to account for analgesic use when analyzing pain intensity outcomes.
We conducted a meta-epidemiologic study of concurrent analgesic use reporting among RCTs that were included in a 2021 comprehensive systematic review of emerging non-surgical interventional procedural treatments for pain. The primary study aims were to examine (1) the prevalence of reporting concurrent analgesic use among included RCTs, and (2) the methods used to account for concurrent analgesic use. A secondary aim of the study was to investigate the impact of accounting for concurrent analgesic use on estimated treatment effects on pain intensity using the QPAC1.5 in a subset of
RCTs.