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.
Key words: Pain sensitivity, opioid treatment, chronic low back pain (cLBP), quantitative
sensory testing (QST)
CYP2D6 genotype can help to predict effectiveness and safety during opioid treatment for chronic low back pain: results from a retrospective study in an Italian cohort