Tick-Tock...genes working round the clock: associations with sleep and acute and chronic post-thoracotomy pain

Patients undergoing thoracotomy reportedly have up to 75% risk of developing chronic post-operative pain secondary to this life-saving surgery. Multiple factors have been implicated for increased risk of worse post-operative pain (POP) trajectory including baseline pain sensitivity, pre-existing conditions, negative affect and maladaptive coping. Additionally, sleep disruptions are common and quite significant among post-operative patients, but only recently have investigators considered multiple facets of sleep, pain and genetic susceptibility to dysfunction in both as potentially contributing risks for increased post-surgical acute and chronic pain. This new study employs a comprehensive, prospective, longitudinal model to examine the relationship between genes, sleep and pain in a thoracotomy population. 37 patients were recruited pre-operatively and followed for 6-months. Subjects underwent extensive baseline psychosocial/sleep assessments, QST, and DNA. Day-of-surgery included immediate pre-operative mood, blood-draws, plus all surgical factors. Post-operative assessments of pain and sleep were conducted at multiple time-points in-hospital (ICU, Days 1-5), follow-up at weeks 2, 6, and monthly to 6-months. Disrupted sleep was nearly ubiquitous in-hospital, but two-thirds developed lasting sleep disturbances that maintained through months 3-6. This correlated strongly (p<.01) with increased and persistent POP patterns in approximately 50% with notable distinctions after 120-days. Sleep genes were analyzed for associations with subjective disturbance and POP. Several trends emerged with the most striking, consistent pattern among "gg" homozygotes on PER1, who reported significant sleep disruptions across nearly all domains and consistently higher acute and chronic POP lasting to 6-months (p's <.05 to .001). Future research will need to confirm such patterns in larger samples and populations, but these preliminary findings reveal significant associations between pain, sleep and genes in a thoracotomy population. Identifying risk factors and potential avenues for prophylactically treating pain and/or sleep could lead to a better recovery from invasive procedures and potentially disrupt a tragic trajectory to chronic pain.