RESUMO
BACKGROUND AND AIMS: This living and systematic review aimed to provide an updated summary of the available evidence on pain undertreatment prevalence in patients with cancer; correlations with some potential determinants and confounders were also carried out. MATERIALS AND METHODS: We updated a systematic review published on 2014, including observational and experimental studies reporting the use of the pain management index (PMI) in adults with cancer and pain, from 2014 to 2020. We conducted searches in PubMed/MEDLINE, Embase, and Google Scholar. We performed univariate and multivariable regression analyses to describe the relationship between PMI and a list of potential explanatory variables. RESULTS: Twenty new papers were identified, yielding a total sample size of 66 studies. The proportion of patients classified as undertreated according to the year of study publication shows a higher decrease from 1994 to 2013 (-13% as relative change) than the most recent years 2014-2020 (-11%). The quality of the included studies has increased over the years (from 80% to 93%). At the multivariable analysis, a statistically significant relationship was confirmed between undertreatment and the year of the publication of the study and with a low-medium economic level of the countries, where the studies were conducted. DISCUSSION: Despite the improvement when compared to the period 1994-2000, still about 40% of the cases identified received an analgesic treatment inadequate to the intensity of pain, according to the PMI. Despite its intrinsic limitations, PMI continues to be widely used, and it could allow a continuous monitoring of pain management across a different mix of studies and patients.