Abstract
BackgroundIncreased pain sensitivity is a putative risk factor for chronic pain and consequently for analgesic use. Conversely, analgesic use may be a cause of increased pain sensitivity, e.g., through opioid-induced hyperalgesia. We aimed to study the association between pain sensitivity and analgesic use in a general population, and to test the hypothesis that increased baseline pain sensitivity is a risk factor for future persistent analgesic use.MethodsThe Tromsø Study (2007–08), a population-based health study, was linked with eight years of prescription data from the Norwegian Prescription Database. The cold pressor test was completed in 10,486 participants aged 30+ years, and we used cold pressor endurance time as a proxy measure of pain sensitivity. Cross-sectional associations with different measures of analgesic use were assessed. Furthermore, a cohort of 9,657 persons was followed for 4.5 years.ResultsIn the cross-sectional analysis, increased pain sensitivity was associated with analgesic use; regular users of opioids alone were more pain sensitive than regular users of non-opioid analgesics. Increased baseline pain sensitivity was a risk factor for persistent analgesic use, i.e., using non-steroidal anti-inflammatory drugs, paracetamol, or opioids for ≥ 90 days and proportion-of-days-covered ≥ 40% (HR = 1.22, 95% CI 1.06-1.40), although not statistical significant after confounder adjustment.ConclusionsIncreased pain sensitivity was associated with analgesic use in general, and reduced pain tolerance was found for both opioid and non-opioid analgesic users. The data suggest that hyperalgesia is an effect of analgesics, whereas pain tolerance has little impact on future analgesic use.
Highlights
Increased pain sensitivity is a putative risk factor for chronic pain and for analgesic use
We have previously shown that the prevalence of persistent prescription (Rx) analgesic use is only ten percent among those reporting chronic pain, and we suggest that this group may represent those who benefit from long-term treatment and have not discontinued due to adverse effects [12]
Main findings In this large population-based linkage study, the main findings were that increased pain sensitivity is associated with analgesic use at the cross-sectional level, regular users of opioids alone were more pain sensitive than regular users of non-opioid analgesics, i.e., non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol, and that increased baseline pain sensitivity was a risk factor for future persistent analgesic use in crude analysis, but not in multivariable analyses
Summary
Increased pain sensitivity is a putative risk factor for chronic pain and for analgesic use. Analgesic use may be a cause of increased pain sensitivity, e.g., through opioid-induced hyperalgesia. We aimed to study the association between pain sensitivity and analgesic use in a general population, and to test the hypothesis that increased baseline pain sensitivity is a risk factor for future persistent analgesic use. Long-term analgesic use and use in chronic pain have limited evidence of efficacy or effectiveness [2,3,4,5,6,7]. Samuelsen et al BMC Pharmacology and Toxicology (2017) 18:45 persistent use of analgesics may not necessarily reflect an adequate and prolonged treatment effect but may be due to irrational use, or, sometimes for the opioids, due to drug abuse. A growing body of evidence shows that opioid use may paradoxically increase pain sensitivity through opioid-induced hyperalgesia (OIH) [15,16,17,18]
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