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Occup Environ Med 2007;64:798-805 doi:10.1136/oem.2006.030148
  • Original article

Workplace policies and prevalence of knee osteoarthritis: the Johnston County Osteoarthritis Project

  1. Jiu-Chiuan Chen1,2,
  2. Laura Linnan3,
  3. Leigh F Callahan2,4,5,6,
  4. Edward H Yelin7,
  5. Jordan B Renner2,8,
  6. Joanne M Jordan1,2,4,5
  1. 1
    Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, NC, USA
  2. 2
    Thurston Arthritis Research Center, School of Public Health, University of North Carolina, Chapel Hill, NC, USA
  3. 3
    Department of Health Behavior and Health Education, School of Public Health, University of North Carolina, Chapel Hill, NC, USA
  4. 4
    Division of Rheumatology, Allergy and Immunology, Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
  5. 5
    Department of Orthopedics, University of North Carolina, Chapel Hill, NC, USA
  6. 6
    Department of Social Medicine, University of North Carolina, Chapel Hill, NC, USA
  7. 7
    Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, CA, USA
  8. 8
    Department of Radiology, University of North Carolina, Chapel Hill, NC, USA
  1. Jiu-Chiuan Chen, Department of Epidemiology, University of North Carolina School of Public Health, 2104G, McGavran-Greenberg, CB#7435, Chapel Hill, NC 27599-7435, USA; jcchen{at}unc.edu
  • Accepted 4 May 2007
  • Published Online First 13 June 2007

Abstract

Objective: Previous studies on work and knee osteoarthritis (KOA) have been primarily focused on physical demands; very little is known about work-related organisational policies and KOA risks and outcomes. We examined the associations between workplace policies and KOA in a community-based population in the USA.

Methods: The associations between employment offering accommodations (switch to physically less demanding jobs; part-time work for people needing reduced time) and benefits policies (paid sick leave; disability payment) with KOA outcomes (knee symptoms; symptomatic KOA [sKOA]; asymptomatic radiographic KOA [rKOA]) were analysed in participants (n = 1639) aged <65 years old and with completed employment histories and knee radiographs at baseline examination of the Johnston County Osteoarthritis Project. Multiple logistic regression models were used to estimate the prevalence odds ratios (ORs) of KOA associated with each workplace policy, adjusting for sociodemographic features, lifestyle factors, knee injuries, body mass index and other workplace characteristics. We used propensity score models to evaluate the differential selection in employment offering favourable policies and adjust for this potential bias accordingly.

Results: Individuals employed in workplaces offering better policies had significantly less knee symptoms. Lower sKOA prevalence was noted in workplaces offering job-switch accommodation (8% vs. 13%), paid sick leave (9% vs. 16%) and disability payment (8% vs. 16%) than their counterparts. In multivariable models, the difference in sKOA prevalence was statistically significant for paid sick leave (adjusted OR 0.58, 95% CI 0.37 to 0.91) and disability payment policies (adjusted OR 0.54, 95% CI 0.35 to 0.85). Even among those without overt knee-related symptoms, a similar pattern of negative association between workplace policies and rKOA was present and remained robust after propensity score adjustment.

Conclusion: The negative associations between KOA and workplace policies raise concerns about possible employment discrimination or beneficial effects of workplace policies. Longitudinal studies are needed to clarify the dynamic complexities of KOA risks and outcomes in relation to workplace policies.

Footnotes

  • Competing interests: All authors have no conflict of interests in conjunction with publishing this research work.

  • Funding: Supported by Centers for Disease Control and Prevention/Association of Schools of Public Health S043, S1733, and S3486 and the National Institute of Arthritis, Musculoskeletal, and Skin Diseases Multipurpose Arthritis and Musculoskeletal Diseases Center 5-P60-AR30701 and Multidisciplinary Clinical Research Center 5-P60-AR049465 (J C C, J M J, L F C, J B R). None of the funding sources is involved in study design, data collection, analysis or interpretation of data related to this manuscript.

  • Abbreviations:
    BMI
    body mass index
    CI
    confidence interval
    HAQ
    Health Assessment Questionnaire
    KL
    Kellgren–Lawrence
    KOA
    knee osteoarthritis
    NHIS-DS
    National Health Interview Survey Disability Supplement
    OR
    odds ratio
    rKOA
    radiographic knee osteoarthritis
    sKOA
    symptomatic knee osteoarthritis

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  4. All Versions of this Article:
    1. oem.2006.030148v1
    2. 64/12/798 most recent

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