Pain
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Randomized Controlled Trial Multicenter Study
Psychosocial factors predict opioid analgesia via endogenous opioid function.
Use of opioid analgesics for management of chronic nonmalignant pain has become common, yet there are presently no well-validated predictors of optimal opioid analgesic efficacy. We examined whether psychosocial factors (eg, depressive symptoms) predicted changes in spontaneous low back pain after administration of opioid analgesics, and whether endogenous opioid (EO) function mediated these relationships. Participants with chronic low back pain but who were not chronic opioid users (N = 89) underwent assessment of low back pain intensity pre- and post-drug in 3 (counterbalanced) conditions: (1) placebo, (2) intravenous naloxone, and (3) intravenous morphine. ⋯ Bootstrapped mediation analyses showed that links between morphine analgesic responses and depressive symptoms, trait anxiety, pain catastrophizing, and perceived disability were partially mediated by EO function. Results suggest that psychosocial factors predict elevated analgesic responses to opioid-based medications, and may serve as markers to identify individuals who benefit most from opioid therapy. Results also suggest that people with greater depressive symptoms, trait anxiety, pain catastrophizing, and perceived disability may have deficits in EO function, which may predict enhanced response to opioid analgesics.
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Attitudes to pain medication are important aspects of adjustment to chronic pain. They are measured by the 47-item Pain Medication Attitudes Questionnaire (PMAQ). To measure those attitudes more quickly and easily, we developed and evaluated a 14-item PMAQ using data from 3 separate surveys of people with pain in the general population. ⋯ Confirmatory factor analysis showed that the 14-item PMAQ retained the 7-factor structure of the 47-item version, and correlations with other measures showed that it retained the validity of the 47-item version. The PMAQ scale Need was the most significant independent predictor of analgesic dependence in each of 4 separate multiple regression analyses. This short form of the PMAQ allows attitudes to pain medications to be measured in a valid and more efficient way.
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Health utilities are a preference-based measure of health-related quality of life that facilitates comparison of disease burden across conditions. We estimated utilities using a population-based, matched sample of adolescents and adults with and without chronic pain, controlling for comorbidity. Ontarians aged ≥12 years with and without chronic pain were identified from the Canadian Community Health Survey (CCHS) 2000-2001 and 2009-2010 and linked to their provincial health care administrative data. ⋯ The matched cohort with chronic pain had a mean utility of 0.59 (95% confidence interval 0.58-0.59), and the decrement associated with chronic pain was 0.32 (95% confidence interval 0.31-0.32). Utilities in people with chronic pain were lower than, and decrements larger than, those seen with most other chronic diseases including heart disease, diabetes, and chronic obstructive pulmonary disease. These data will be useful to inform priorities and future strategies for the prevention and control of chronic pain.
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Chronic pain conditions are often comorbid with alcohol abuse. "Self-medication" with alcohol introduces a host of problems associated with the abuse of alcohol which over time has the potential of exacerbating the painful condition. Despite the prevalence of chronic pain being associated with alcohol abuse, rodent models which mimic the comorbid conditions are lacking. In this study, we model osteoarthritis (OA) in C57BL/6J mice by surgically destabilizing the medial meniscus (DMM). ⋯ Compared with sham controls, DMM mice consumed more EtOH and preferred EtOH over water at the 20% EtOH concentration. Histological analysis verified that the DMM mice exhibited significant damage to the articular cartilage and osteophyte growth compared with sham controls and these measures of the severity of OA correlated with the amount of ethanol intake. Thus, the combination of the DMM model of OA with the enhanced two-bottle ethanol choice is a potential preclinical approach in mice by which the basis of the comorbid association of alcohol abuse and chronic pain conditions can be explored.