Factors Associated with the Efficacy of Trigger Point Injection in Advanced Cancer Patients

Abstract

Few studies have reported the efficacy of trigger point injection (TPI) to myofascial trigger points (MTrPs) in advanced cancer patients. Factors that are associated with TPI efficacy have not yet been elucidated. The study was aimed at evaluating factors that are associated with TPI efficacy to MTrPs in advanced cancer patients. Factors that are associated with TPI efficacy were retrospectively identified based on a comparison between clinically relevant responders and nonresponders by using multivariate regression analysis. One hundred five advanced cancer patients who visited the Palliative Care Department with a chief complaint of pain and who received TPI treatment to the MTrP at the pain site. The TPI efficacy rate on the day after TPI treatment was 0.59 (95% confidence interval [CI]: 0.50-0.68). Significant factors associated with TPI efficacy were coexistence of cancer pain with MTrP at the pain site (odds ratio [OR]: 3.87, 95% CI: 1.21-12.4), MTrP at areas other than lower back or hip (OR: 6.45, 95% CI: 1.98-21.0), and fewer MTrPs (OR: 0.64, 95% CI: 0.42-0.99). Coexistence of cancer pain at the pain site of the chief complaint was observed in 64% of study subjects (95% CI: 0.55-0.73). The TPI efficacy is likely high when advanced cancer patients have fewer MTrPs together with cancer pain at areas other than the lower back or hip. MTrPs in advanced cancer patients are more commonly observed together with cancer pain rather than independently. Healthcare providers should recognize the relationship between MTrP and cancer pain and proactively perform physical examinations to detect MTrPs for potential TPI.