title: When it hurts, a positive attitude may help: association of positive affect with daily walking in knee osteoarthritis. Results from a multicenter longitudinal cohort study.
abstract: OBJECTIVE
  While depressive symptoms and knee pain are independently known to impede daily walking in older adults, it is unknown whether positive affect promotes daily walking. This study investigated this association among adults with knee osteoarthritis (OA) and examined whether knee pain modified this association.
  
  
  METHODS
  This study is a cross-sectional analysis of the Multicenter Osteoarthritis Study. We included 1,018 participants (mean ± SD age 63.1 ± 7.8 years, 60% women) who had radiographic knee OA and had worn a StepWatch monitor to record their number of steps per day. High and low positive affect and depressive symptoms were based on the Center for Epidemiologic Studies Depression Scale. Knee pain was categorized as present in respondents who reported pain on most days at both a clinic visit and a telephone screening.
  
  
  RESULTS
  Compared to respondents with low positive affect (27% of all respondents), those with high positive affect (63%) walked a similar number of steps per day, while those with depressive symptoms (10%) walked less (adjusted β -32.6 [95% confidence interval (95% CI) -458.9, 393.8] and -579.1 [95% CI -1,274.9, 116.7], respectively). There was a statistically significant interaction of positive affect by knee pain (P = 0.0045). Among the respondents with knee pain (39%), those with high positive affect walked significantly more steps per day (adjusted β 711.0 [95% CI 55.1, 1,366.9]) than those with low positive affect.
  
  
  CONCLUSIONS
  High positive affect was associated with more daily walking among adults with painful knee OA. Positive affect may be an important psychological factor to consider for promoting physical activity among people with painful knee OA.
authors.affiliation: Boston University, Massachusetts, USA. dwtbn@bu.edu
authors.forename: Daniel K
authors.initials: DK
authors.lastname: White
authors.forename: Julie J
authors.initials: JJ
authors.lastname: Keysor
authors.forename: Tuhina
authors.initials: T
authors.lastname: Neogi
authors.forename: David T
authors.initials: DT
authors.lastname: Felson
authors.forename: Michael
authors.initials: M
authors.lastname: LaValley
authors.forename: K Doug
authors.initials: KD
authors.lastname: Gross
authors.forename: Jingbo
authors.initials: J
authors.lastname: Niu
authors.forename: Michael
authors.initials: M
authors.lastname: Nevitt
authors.forename: Cora E
authors.initials: CE
authors.lastname: Lewis
authors.forename: Jim
authors.initials: J
authors.lastname: Torner
authors.forename: Lisa
authors.initials: L
authors.lastname: Fredman
mesh_terms: D056044:Actigraphy / Q000295:instrumentation; D000339:Affect; D000368:Aged; D000407:Alabama; D018771:Arthralgia / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000523:psychology; D003430:Cross-Sectional Studies; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007484:Iowa; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020370:Osteoarthritis, Knee / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D010147:Pain Measurement; D011859:Radiography; D018570:Risk Assessment; D012307:Risk Factors; D016138:Walking