title: Persistent analgesic use and the association with chronic pain and other risk factors in the population-a longitudinal study from the Tromsø Study and the Norwegian Prescription Database.
abstract: OBJECTIVE
  Analgesics are commonly used drugs. The long-term effectiveness is mostly unproven, while the risk of several serious adverse effects is well established. We aimed to estimate the prevalence and incidence of persistent analgesic use and the association with chronic pain and sociodemographic and comorbid risk factors.
  
  
  METHODS
  The Tromsø Study is an epidemiological, prospective study of health and diseases. We linked the sixth wave (Tromsø 6, 2007-08, n = 12,981) with the Norwegian Prescription Database (NorPD, 2004-13). Persistent analgesic use was defined as the use of analgesics, i.e., either non-steroidal anti-inflammatory drugs, opioids or paracetamol, for ≥90 days with proportion-of-days-covered ≥40 %. The study design provided both cross-sectional and longitudinal data; a cohort of 11,905 persons was followed for 4.5 years.
  
  
  RESULTS
  The prevalence of persistent analgesic use was 4 % in general and 10 % among those reporting chronic pain. The incidence rate of persistent analgesic use was 21 per 1000 person-years in general. Baseline chronic pain doubled the risk of incident persistent analgesic use (HR = 2.05, 95 % CI 1.80-2.33). The risk increased with increasing chronic pain severity, as measured by chronic pain duration, frequency, intensity, and number of body locations. Sociodemographic risk factors were older age, female sex, lower education, and most likely lower physical activity. Psychological distress was not a statistical significant risk factor.
  
  
  CONCLUSIONS
  This study showed a relatively low prevalence of persistent analgesic use and that the majority of persons reporting chronic pain do not use analgesics persistently.
authors.affiliation: Regional Medicines Information and Pharmacovigilance Center (RELIS), University Hospital of North Norway, P.O. Box 79, N-9038, Tromsø, Norway. per-jostein.samuelsen@unn.no.|Department of Community Medicine, UiT-The Arctic University of Norway, Tromsø, Norway. per-jostein.samuelsen@unn.no.
authors.forename: Per-Jostein
authors.initials: PJ
authors.lastname: Samuelsen
authors.affiliation: Tromsø Hospital Pharmacy, Tromsø, Norway.
authors.forename: Kristian
authors.initials: K
authors.lastname: Svendsen
authors.affiliation: Department of Community Medicine, UiT-The Arctic University of Norway, Tromsø, Norway.
authors.forename: Tom
authors.initials: T
authors.lastname: Wilsgaard
authors.affiliation: Department of Pain Management and Research, Division of Emergencies and Intensive Care, Oslo University Hospital, Oslo, Norway.|Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: Audun
authors.initials: A
authors.lastname: Stubhaug
authors.affiliation: Department of Pain Management and Research, Division of Emergencies and Intensive Care, Oslo University Hospital, Oslo, Norway.|Division of Mental Health, Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: Christopher Sivert
authors.initials: CS
authors.lastname: Nielsen
authors.affiliation: Department of Community Medicine, UiT-The Arctic University of Norway, Tromsø, Norway.
authors.forename: Anne Elise
authors.initials: AE
authors.lastname: Eggen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000700:Analgesics / Q000627:therapeutic use*; D059350:Chronic Pain / Q000188:drug therapy* / Q000453:epidemiology; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D011307:Drug Prescriptions; D004363:Drug Utilization / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D012307:Risk Factors
chemical_list: D000700:Analgesics
keywords: Acetaminophen; Analgesics; Chronic pain; Non-steroidal anti-inflammatory agents; Opioids; Persistence; Pharmacoepidemiology