Effects of β2 agonists on post-thoracotomy pain incidence.

BackgroundPre-clinical research has shown (2)-adrenoceptors to be essential for the antiallodynic action of antidepressant drugs in murine models of neuropathic pain and that sustained treatment with (2)-agonists has an antiallodynic action. Here, we clinically investigated whether chronic (2)-agonist treatments may influence the incidence of post-thoracotomy chronic pain, defined as pain that recurs or persists along a thoracotomy scar more than 2months after surgery, either neuropathic or non-neuropathic. MethodsWe conducted an epidemiological study on patients operated by thoracotomy. Demographic data, medical history and treatments concomitant to the surgery were recorded at a follow-up visit. Information on perioperative treatments was collected from the anaesthesia records and confirmed by the patients. In patients with pain at the surgery level, post-thoracotomy chronic pain was assessed by clinical examination and numeric scale. Physical examination and DN4 questionnaire were used to discriminate neuropathic and non-neuropathic chronic pain at scar level. ResultsOne hundred and eighty-nine patients were included. Eighty-one patients reported persisting thoracic pain, with neuropathic characteristics in 58 of them (30% of the 189 patients). The most common chronic drugs during the perioperative period were inhaled (2)-agonists (28.6%). The chronic use of (2)-agonists was an independent predictor of thoracic neuropathic pain (but not of non-neuropathic pain) and was associated with a five-fold decrease in the relative incidence of neuropathic pain [OR=0.19 (0.06-0.45)]. ConclusionsThese data suggest a possible influence of chronic (2)-agonist treatments on neuropathic pain secondary to thoracotomy. This apparent preventive effect of (2)-agonist treatments should warrant controlled clinical trials.