title: Physical activity and associations with computed tomography-detected lumbar zygapophyseal joint osteoarthritis.
abstract: BACKGROUND
  There are no previous epidemiologic studies examining associations between physical activity and imaging-detected lumbar zygapophyseal joint osteoarthritis (ZJO) in a community-based sample.
  
  
  OBJECTIVE
  To determine whether physical activity is associated with prevalent lumbar ZJO on computed tomography (CT).
  
  
  METHODS
  A community-based cross-sectional study.
  
  
  METHODS
  Four hundred twenty-four older adults from the Framingham Heart Study.
  
  
  METHODS
  Participants received standardized CT assessments of lumbar ZJO at the L2-S1 levels. Severe lumbar ZJO was defined according to the presence and/or degree of joint space narrowing, osteophytosis, articular process hypertrophy, articular erosions, subchondral cysts, and intra-articular vacuum phenomenon. This definition of lumbar ZJO was based entirely on CT imaging findings and did not include any clinical criteria such as low back pain.
  
  
  METHODS
  Physical activity was measured using the Physical Activity Index, which estimate hours per day typically spent in these activity categories: sleeping, sitting, slight activity, moderate activity, and heavy activity. Participants reported on usual frequency of walking, running, swimming, and weightlifting. We used multivariable logistic regression to examine associations between self-reported activity and severe lumbar ZJO, while adjusting for key covariates including age, sex, height, and weight.
  
  
  RESULTS
  In multivariable analyses, ordinal categories of heavy physical activity duration per day were significantly associated with severe lumbar ZJO (p for trend=.04), with the greatest risk observed for the category 3 or more hours per day, odds ratio 2.13 (95% confidence interval [CI] 0.97-4.67). When heavy activity was modeled as a continuous independent variable, each hour was independently associated with 1.19 times the odds of severe lumbar ZJO (95% CI 1.03-1.38, p=.02). Less vigorous types of physical activity and the type of exercise were not associated with severe lumbar ZJO. Older age, lesser height, and greater weight were independently and significantly associated with severe lumbar ZJO. In multivariable models predicting lumbar ZJO, neither model discrimination nor reclassification improved with the addition of physical activity variables, compared with a multivariable model including age, sex, height, and weight.
  
  
  CONCLUSIONS
  Our findings demonstrate a statistically significant cross-sectional association between heavy physical activity and CT-detected severe lumbar ZJO. However, the additional discriminatory capability of heavy physical activity above and beyond that contributed by other factors was negligible.
authors.affiliation: VA Puget Sound Healthcare System, 1660 S. Columbian Way, RCS-117, Seattle, WA, USA; Department of Rehabilitation Medicine, University of Washington School of Medicine, 325 Ninth Avenue, Box 359612, Seattle, WA 98103, USA. Electronic address: pradeep.suriyaarachchi@va.gov.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Suri
authors.affiliation: Department of Rheumatology, Kolling Institute, University of Sydney, Royal North Shore Hospital, Sydney, Clinical Administration 7C, Pacific Highway, St. Leonards, New South Wales, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Hunter
authors.affiliation: VA Puget Sound Healthcare System, 1660 S. Columbian Way, RCS-117, Seattle, WA, USA; Department of Medicine, University of Washington School of Medicine, RR-512 Health Sciences Building, Box 356420, Seattle, WA 98103, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Boyko
authors.affiliation: New England Baptist Hospital, 125 Parker Hill Ave, Boston, MA 02120, USA.
authors.forename: James
authors.initials: J
authors.lastname: Rainville
authors.affiliation: Department of Radiology, Boston University School of Medicine, 820 Harrison Avenue, FGH Building 3rd Floor, Boston, MA 02215, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Guermazi
authors.affiliation: Division of Rheumatology, Immunology and Allergy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, BC-4-4016, Boston, MA 02446, USA; Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, BC-4-4016, Boston, MA 02446, USA.
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Katz
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D017116:Low Back Pain / Q000209:etiology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D009043:Motor Activity; D016017:Odds Ratio; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D015995:Prevalence; D014057:Tomography, X-Ray Computed / Q000379:methods*; D021801:Zygapophyseal Joint / Q000000981:diagnostic imaging / Q000473:pathology*
keywords: Arthritis; Computed tomography; Exercise; Facet; Lumbar; Rehabilitation