Patients taking opioids for chronic fibromyalgia pain who concurrently consumed caffeine experienced a decrease in pain and symptom severity not seen in patients taking opioids without concomitant consumption of caffeine, according to the results of a recent study by J. Ryan Scott, Chronic Pain and Fatigue Research Center, Department of Anesthesiology, University of Michigan, Ann Arbor, and colleagues (Scott JR, et al. J Pain Res. 2017;10:1801-1809).
In their study, Mr Scott and colleagues sought to address a gap in existing research regarding the effects of caffeine on patients with fibromyalgia pain.
“Whereas the role of caffeine as an analgesic adjuvant is well documented, the direct and indirect intrinsic effects of caffeine on pain are complex and remain poorly understood, particularly in chronic pain populations,” they explained.
To assess the effects of caffeine on pain and other symptoms in patients with fibromyalgia receiving opioid analgesics, Mr Scott and colleagues evaluated 962 patients who presented at the University of Michigan Health System Back and Pain Center between November 2010 and February 2014, and who met the American College of Rheumatology 2011 Survey Criteria for fibromyalgia.
Of the patients included in the study, 67% were women, and the mean age was 47.6 years. These patients completed self-report questionnaires that addressed their symptoms, demographics, and medication use, the data of which were then entered into the Assessment of Pain Outcomes Longitudinal electronic data capture system.
Caffeine consumption was assessed by asking patients to indicate whether they consumed caffeinated beverages each day, and to report the average number of cups of caffeinated beverages they consumed daily.
Mr Scott and colleagues stratified the patients by opioid use (ie, opioid user vs opioid nonuser), and—to assist in evaluating for dose-dependent caffeine effects—by the amount of caffeine patients consumed daily (ie, no caffeine, low caffeine, moderate caffeine, or high caffeine). To compare differences in pain and symptom severity between the groups that did and did not consume caffeine, the investigators used Dunnett’s post hoc testing.
Results of the study indicated that, among patients with fibromyalgia who were receiving opioid therapy, caffeine consumption had a significant effect on pain, catastrophizing, and physical function. Furthermore, Mr Scott and colleagues noted a dose-dependent relationship, wherein benefits were seen more consistently among patients who consumed low and moderate doses of caffeine than in those who consumed caffeine at a high dose.
Compared with patients in the no caffeine group, patients with low and moderate caffeine consumption experienced lower levels of pain interference. Higher physical function and lower pain catastrophizing were observed in all groups that consumed caffeine, regardless of dose, compared with those in the no caffeine group. Low pain severity and depression were only observed in the patients who consumed moderate amounts of caffeine.
“The results of this study show that patients using opioids who also consume caffeine reported less pain severity, pain-related interference in daily life, pain catastrophizing, and depression, as well as higher physical function, compared to those patients taking opioids but not consuming caffeine,” Mr Scott and colleagues reported.
In addition, although low caffeine intake was linked to higher physical function among patients who were not using opioids, the investigators observed no other significant effects in this group.
“Patients not on opioid therapy who consume caffeine exhibited no differences in pain and symptoms compared to those not consuming caffeine, except for improved levels of physical function in the caffeine consumers....These results suggest a dose-dependent effect of caffeine on opioid analgesia: low to moderate amounts of caffeine consumption improve symptoms, whereas higher amounts of caffeine typically do not,” they asserted.
Mr Scott and colleagues also suggested that further research into caffeine’s intrinsic properties in chronic pain is necessary.