Longitudinal Relationship Between Physical Activity and Joint Space Narrowing: Forty-Eight-Month Follow-Up Data From the Osteoarthritis Initiative

Abstract

Objective: To determine whether the amount of physical activity (PA) is a determinant of joint space narrowing (JSN) worsening over 48 months in participants with knee osteoarthritis.

Methods: Data were obtained from the Osteoarthritis Initiative. PA, measured using the Physical Activity Scale for the Elderly (PASE), was defined as the mean value of the annual measurements conducted prior to development of worsening JSN. Worsening JSN was defined as at least a partial grade increase in the Osteoarthritis Research Society International JSN score over 48 months, in comparison with baseline. Restricted cubic spline function was used to group participants based on the linear association between PA and JSN worsening. A pooled logistic regression model was used to evaluate the association between PA and JSN worsening adjusted for confounders.

Results: A total of 2,167 participants were included. In total, 625 participants (28.8%) had JSN worsening over 48 months. Compared with a PASE score of 141-180, PASE scores of 101-140 and >220 were associated with an increased risk of JSN worsening in men, with odds ratios (ORs) of 1.73 (95% confidence interval [95% CI] 1.07-2.81) and 1.83 (95% CI 1.14-2.93), respectively. Similarly, in participants with Kellgren/Lawrence (K/L) grade 2, compared with a PASE score of 141-180, PASE scores of ≤100 and >220 were associated with increased risks of JSN worsening, with an OR of 1.69 (95% CI 1.13-2.54) and 1.64 (95% CI 1.05-2.56), respectively.

Conclusion: Compared to moderate PA, higher or lower amounts of PA are associated with an elevated risk for JSN worsening in men and in participants with K/L grade 2 knees.

Trial registration: ClinicalTrials.gov NCT00080171.

Figure 1. Flow chart of the identification of participants for study inclusion.

Abbreviations: PA, physical activity; JSN, joint space narrowing; OAI, Osteoarthritis Initiative; PASE, Physical Activity Scale for the Elderly score; KL grade, Kellgren and Lawrence grading scale; WOMAC, Western Ontario and McMaster Universities Arthritis Index.

Figure 2. Association between PASE score and JSN progression over 48 months using the RCS method (4 nodes) in A) men and B) women.

Abbreviations: PASE, Physical Activity in the Elderly Scale; JSN, joint space narrowing; RCS, restricted cubic spline; CI, confidence interval. Spline plot for adjusted Logistic models. Adjusted for age, sex, race, BMI, knee pain, knee injury. A) For men, test for overall association, p=0.1103; test for nonlinear association p=0.1507 with median PASE score reference value of 155.5. B) For women, test for overall association, p=0.4339; test for nonlinear association p=0.4869 with median PASE score reference value of 134.