Does Long-Term Opioid Therapy Reduce Pain Sensitivity of Patients with Chronic Low Back Pain? Evidence from Quantitative Sensory Testing

Abstract

BACKGROUND: Long-term opioid treatment has been used extensively in treatment of chronic low back pain (cLBP) in the last decades. However, there are serious limitations to the long-term efficacy of opioids and related side effects.

OBJECTIVES: In this study we investigated whether long-term opioid treatment changes pain sensitivity of patients with cLBP.

STUDY DESIGN: A prospective, nonrandomized, cross-sectional study.

SETTING: Multidisciplinary pain management clinic, specialty referral center, university hospital in Germany.

METHODS: Using quantitative sensory testing (QST), we compared the pain sensitivity of the low back bilaterally among 3 groups: 35 patients with cLBP undergoing a long-term opioid therapy (OP); 35 patients with cLBP administered no opioids (ON), and 28 subjects with neither pain nor opioid intake (HC).

RESULTS: OP patients showed significantly higher bilateral thermal detection thresholds to warm stimuli on the back as compared to both ON (P = 0.009 for left low back, P = 0.008 for right low back) and HC subjects (P = 0.004 for left low back, P = 0.003 for right low back). Pain thresholds for cold and heat on the hand were similar in OP and ON groups; both showed, however, significantly reduced heat pain thresholds in comparison with HC participants (P = 0.012 for OP, P = 0.001 for ON). Factors such as age, sex, duration and dose of opioid intake, and self-reported pain intensity, but not depression and pain duration, correlated significantly with QST results.

LIMITATIONS: Limitations include small numbers of patients with heterogeneous opioid therapy and the nonrandomized observational nature of the study.

CONCLUSIONS: The current study demonstrated that chronic opioid intake may only reduce the temperature sensitivity but not pain sensitivity measured by QST which is a useful tool in detecting characteristic changes in pain perception of patients with chronic low back pain after long-term opioid intake.