title: Persistent post-surgical pain and experimental pain sensitivity in the Tromsø study: comorbid pain matters.
abstract: In a large survey incorporating medical examination (N=12,981), information on chronic pain and surgery was collected, and sensitivity to different pain modalities was tested. Tolerance to the cold pressor test was analysed with survival statistics for 10,486 individuals, perceived cold pressor pain intensity was calculated for 10,367 individuals, heat pain threshold was assessed for 4,054 individuals, and pressure pain sensitivity for 4,689 individuals. Persistent post-surgical pain, defined by self-report, was associated with lower cold pressor tolerance (sex-adjusted hazard ratio=1.34, 95% confidence interval=1.08-1.66), but not when adjusting for other chronic pain. Other experimental pain modalities did not differentiate between individuals with or without post-surgical pain. Of the individuals with chronic pain (N=3352), 6.2% indicated surgery as a cause, although only 0.5% indicated surgery as the only cause. The associations found between persistent post-surgical pain and cold pressor tolerance is largely explained by the co-existence of chronic pain from other causes. We conclude that most cases of persistent post-surgical pain are coexistent with other chronic pain, and that, in an unselected post-surgical population, persistent post-surgical pain is not significantly associated with pain sensitivity when controlling for comorbid pain from other causes. A low prevalence of self-reported persistent pain from surgery attenuates statistically significant associations. We hypothesize that general chronic pain is associated with central changes in pain processing as expressed by reduced tolerance for the cold pressor test.
authors.affiliation: Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway Department of Community Medicine, University of Tromsø, Norway Division of Cardiothoracic and Respiratory Medicine, University Hospital of North Norway, Tromsø, Norway Department of Clinical Medicine, University of Tromsø, Tromsø, Norway Department of Pain Management and Research, Division of Emergencies and Critical Care, Oslo University Hospital, Rikshospitalet, Oslo, Norway Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway Division of Mental Health, Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: Aslak
authors.initials: A
authors.lastname: Johansen
authors.forename: Henrik
authors.initials: H
authors.lastname: Schirmer
authors.forename: Audun
authors.initials: A
authors.lastname: Stubhaug
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Nielsen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059350:Chronic Pain / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology*; D003080:Cold Temperature / Q000009:adverse effects; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D010147:Pain Measurement / Q000379:methods / Q000523:psychology*; D010149:Postoperative Pain / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology*; D057566:Self Report
keywords: Chronic pain; Cold pressor test; Comorbidity; Epidemiology; Pain sensitivity; Pain tolerance; Persistent post-surgical pain; Postoperative pain