title: Positive and negative affect dimensions in chronic knee osteoarthritis: effects on clinical and laboratory pain.
abstract: OBJECTIVE
  This study investigated whether daily and laboratory assessed pain differs as a function of the temporal stability and valence of affect in individuals with chronic knee osteoarthritis (KOA).
  
  
  METHODS
  One hundred fifty-one men and women with KOA completed 14 days of electronic diaries assessing positive affect (PA), negative affect (NA), and clinical pain. A subset of participants (n =79) engaged in quantitative sensory testing (QST). State PA and NA were assessed prior to administration of stimuli that induced suprathreshold pain and temporal summation. Multilevel modeling and multiple regression evaluated associations of affect and pain as a function of valence (i.e., positive versus negative) and stability (i.e., stable versus state).
  
  
  RESULTS
  In the diary, stable NA (B = -.63, standard error [SE] = .13, p < .001) was a stronger predictor of clinical KOA pain than stable PA (B = -.18, SE = .11, p = .091), and state PA (B = -.09, p < .001) was a stronger predictor of concurrent daily clinical pain than state NA (B = .04, SE = .02, p = .068). In the laboratory, state PA (B = -.05, SE = .02, p = .042), but not state NA (p = .46), predicted diminished temporal summation of mechanical pain.
  
  
  CONCLUSIONS
  Stable NA is more predictive of clinical pain than stable PA, whereas state PA is more predictive of both clinical and laboratory pain than state NA. The findings suggest that dynamic affect-pain processes in the field may reflect individual differences in central pain facilitation.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Dr., Suite 100, Baltimore, MD 21224, USA. pfinan1@jhu.edu
authors.forename: Patrick H
authors.initials: PH
authors.lastname: Finan
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Quartana
authors.forename: Michael T
authors.initials: MT
authors.lastname: Smith
mesh_terms: D000339:Affect; D000368:Aged; D002908:Chronic Disease; D059026:Diagnostic Self Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D055361:Multilevel Analysis; D020370:Osteoarthritis, Knee / Q000503:physiopathology* / Q000523:psychology; D010146:Pain / Q000523:psychology*; D010147:Pain Measurement / Q000379:methods*; D012044:Regression Analysis; D055500:Resilience, Psychological; D012720:Severity of Illness Index; D013694:Temperament
keywords: chronic pain; daily diary; negative affect; positive affect; quantitative sensory testing; temporal summation