title: Psychological predictors of change in the number of musculoskeletal pain sites among Norwegian employees: a prospective study.
abstract: The pathogenesis of syndromes of widespread musculoskeletal pain remains an enigma. The present study sought to determine if psychological states, job satisfaction, pain intensity, and sleep problems contributed to the spread and decline of the number of musculoskeletal pains.
  
  
  
  A sample of 2989 Norwegian employees completed a questionnaire at baseline and follow-up 2 years later. Data were analyzed with multinomial and ordinal logistic regression analyses to determine effects on direction and degree of change of number of pain sites (NPS).
  
  
  
  After adjustment for sex, age, skill level, and number of pain sites at baseline, increases in the number of pain sites from baseline to follow-up were predicted by emotional exhaustion, mental distress, having little surplus, feeling down and sad, sleep disturbances, and intensity of headache. Decreases were predicted by low levels of emotional exhaustion, mental distress, sleep disturbances, restlessness, and lower intensity of headache, neck pain, shoulder pain, and back pain. Higher numbers of pain sites at baseline were associated with reduction of number of pain sites and lower likelihood of spread. Some factors that did not predict whether decrease or increase occurred were nevertheless associated with the degree of decrease (depression, anxiety, having surplus, self-efficacy) or increase (anxiety).
  
  
  
  Several psychological and physiological factors predicted change in the number of pain sites. There is a need for further investigations to identify possible mechanisms by which psychological and behavioral factors propagate the spread of pain.
authors.affiliation: Department of Work Psychology and Physiology, The National Institute of Occupational Health, Oslo, Norway. joc@stami.no.
authors.forename: Jan Olav
authors.identifier: 0000-0001-5530-7526
authors.initials: JO
authors.lastname: Christensen
authors.affiliation: Oslo and Akershus University College of Applied Sciences, Faculty of Social Sciences, Department of Social Work, Child Welfare and Social Policy, Oslo, Norway.
authors.forename: Sissel
authors.initials: S
authors.lastname: Johansen
authors.affiliation: Department of Work Psychology and Physiology, The National Institute of Occupational Health, Oslo, Norway.
authors.forename: Stein
authors.initials: S
authors.lastname: Knardahl
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007588:Job Satisfaction; D008297:Male; D008875:Middle Aged; D059352:Musculoskeletal Pain / Q000453:epidemiology / Q000209:etiology / Q000523:psychology*; D009664:Norway / Q000453:epidemiology; D011446:Prospective Studies; D012893:Sleep Wake Disorders / Q000150:complications*