• Haili Wang, Christian Fischer, Gang Chen, Nina Weinsheimer, Simone Gantz, and Marcus Schiltenwolf.
• Department of Orthopaedic Surgery and Traumatology, Heidelberg University Hospital, Heidelberg, Germany. haili.wang@med.uni-heidelberg.de
• Pain Physician. 2012 Jul 1;15(3 Suppl):ES135-43.

BackgroundLong-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.ObjectivesIn this study we investigated whether long-term opioid treatment changes pain sensitivity of patients with cLBP.Study DesignA prospective, nonrandomized, cross-sectional study.SettingMultidisciplinary pain management clinic, specialty referral center, university hospital in Germany.MethodsUsing 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).ResultsOP 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.LimitationsLimitations include small numbers of patients with heterogeneous opioid therapy and the nonrandomized observational nature of the study.ConclusionsThe 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.

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