Occupations Involving Manual Labor Increase the Risk for Incident Knee Osteoarthritis

Grace H. Lo¹, Michael T. Strayhorn², Jeffrey B. Driban³, Lori Lyn Price⁴, Charles Eaton⁵ and Timothy E. McAlindon⁶, ¹VA HSR&D Center for Innovations in Quality, Effectiveness and Safety; Medical Care Line and Research Care Line; Department of Medicine, Michael E. DeBakey VA Medical Center, Baylor College of Medicine, Houston, TX, ²VA HSR&D Center for Innovations in Quality, Effectiveness and Safety; Department of Medicine, Michael E. DeBakey VA Medical Center, Baylor College of Medicine, Houston, TX, ³Rheumatology, Tufts Medical Center, Boston, MA, ⁴Clinical Care Research, Tufts Medical Center, Boston, MA, ⁵Center for Primary Care and Prevention, Memorial Hospital of Rhode Island, Providence, RI, ⁶Tufts Medical Center, Boston, MA

Meeting: 2015 ACR/ARHP Annual Meeting

Date of first publication: September 29, 2015

Keywords: Osteoarthritis and physical activity

Session Information

Date: Tuesday, November 10, 2015

Title: Epidemiology and Public Health Poster III (ACR): Gout and Non-Inflammatory Musculoskeletal Conditions

Session Type: ACR Poster Session C

Session Time: 9:00AM-11:00AM

Background/Purpose : CDC guidelines indicate regular physical activity can lead to improved health outcomes. Physically active occupations may contribute toward meeting these guidelines. The impact of this possibility toward the risk of OA has not been tested and is concerning because some jobs are associated with an increased risk of OA (e.g., military, construction, mining). The objective of this study was to evaluate the association between the extent of work-related physical activity and incident knee OA.

Methods : We performed a person-based longitudinal study using Osteoarthritis Initiative (OAI) data. PA semi-flexed knee radiographs were obtained at baseline and annual follow-up visits, centrally assessed for Kellgren-Lawrence (KL) grade (0-4). Question 10 of the Physical Activity Scale for the Elderly (PASE) at baseline and at each annual OAI visit evaluated the prior 7 days for whether people worked (either paid or volunteer). If a participant did work, they were asked about work-related physical activity level, one of 4 levels (see table) and the number of hours worked. People with no evidence of radiographic knee OA at the baseline visit were included. Those who reported no paid or volunteer work were excluded. We performed logistic regression with the predictor being the work level (1-4), and separately, number of hours worked (<20 hours, 20-39 hours, 40-60 hours and >60 hours), with an outcome of incident person-based ROA (KL ≥ 2 in either knee) in the following 12 months. Those who developed ROA were censored from further analysis. We used generalized estimating equations (GEE) to adjust for correlations within person observations over time. We adjusted for age, sex, BMI, injury and the remaining PASE domains. We also tested for interactions between work level and BMI as well as work level and injury.

Results : Of 951 participants (2819 observations), 57.3% were female; baseline mean age was 59.5 (±8.7) years; BMI was 26.8 (±4.5) kg/m². Higher work levels were strongly and significantly associated with incident ROA, even after adjustment for BMI and knee injury, and with a significant dose response relationship (Table). However, there was no relationship with number of hours worked. In the fully adjusted model, both knee injury and BMI were also significant risk factors for incident ROA, with a significant interaction between injury and work level.

Conclusion : People who do physically intensive work have a greater odds of incident knee OA compared to those who do sedentary work. In our study, the relationship was with intensity of the work rather than number of hours worked. Strategies are needed to identify at-risk individuals engaged in heavy work, and to mitigate injuries.

Table. Associations of work-related physical activity with incident ROA.
	n = 2819 observations = 951 people	Incidence of ROA	Unadjusted OR	Adjusted OR*
Work level type	Level 1= Mainly sitting with slight arm movements (e.g., office worker, watchmaker, bus driver)	17/867 (2.0%)	Referent	Referent
	Level 2 = Sitting or standing with some walking (e.g., cashier, light tool and machinery worker)	30/1233 (2.4%)	1.2 (0.7 – 2.3)	1.2 (0.6 – 2.2)
	Level 3 = Walking, with some handling of materials generally weighing less than 50 pounds (e.g., mailman, waiter/waitress, construction worker)	26/649 (4.0%)	2.1 (1.1 – 3.9)	2.0 (1.1 – 3.8)
	Level 4 = Walking and heavy manual work often requiring handling of materials over 50 pounds (e.g., lumberjack, stonemason, farm laborer)	4/70 (5.7%)	3.0 (1.0 – 9.5)	2.9 (0.9 – 9.5)
			p for trend = 0.007	p for trend = 0.009
*Adjusted for age, sex, injury, BMI and the remaining components of the PASE.

Disclosure: G. H. Lo, None; M. T. Strayhorn, None; J. B. Driban, None; L. L. Price, None; C. Eaton, None; T. E. McAlindon, None.

To cite this abstract in AMA style:

Lo GH, Strayhorn MT, Driban JB, Price LL, Eaton C, McAlindon TE. Occupations Involving Manual Labor Increase the Risk for Incident Knee Osteoarthritis [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/occupations-involving-manual-labor-increase-the-risk-for-incident-knee-osteoarthritis/. Accessed .

« Back to 2015 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/occupations-involving-manual-labor-increase-the-risk-for-incident-knee-osteoarthritis/