Background/Purpose The prevalence of knee arthritis is high in both urban and rural China. Although the association between knee arthritis and limitation of daily activity has been well documented in self-rated studies, no such conclusion has been made based on physical examinations from population-based study in China. 

Methods CHARLS (China Health and Retirement Longitudinal Study) is a population-based longitudinal survey among Chinese retired populations. During the baseline cross-sectional study period between 2011 and 2012, 17708 residents were recruited using door-to-door enumeration in 450 randomly selected communities in China. Subjects completed a home interview with a set of questions on self-rated health status and had a battery of performance-based physical examinations including test of balance, the 5 chair rise test and the gait speed. All the subjects were required to take the balance and the 5 chair rise test, while gait speed was examined only in those aged ≥60 years. Balance was evaluated by asking subjects to keep a stance with heel of one foot pressing the big toe of the other for at least 10 seconds. The 5 chair rise test was conducted using the regular method and gait speed was measured by recording the time each subject needed to pass 2.5 meters. Knee arthritis was only identified when both pain in knees and diagnosis of arthritis/rheumatism by a doctor were present. The association between knee arthritis and gait speed was examined using Linear regression, while the relation of knee arthritis to capacity of balance and the function of repeated sitting to standing was analyzed by Binary logistic regression, adjusting for age, sex, body mass index (BMI), smoking and drinking history, history of injury and hip fracture, and comorbidities.

Results Among 17708 participants (men: 47.9%, mean age: 59.1 years, mean BMI: 23.4 kg/m²), the prevalence of knee arthritis was 9.1%. 13521 (76.4%) and 13240 (74.8%) subjects, respectively, consented to take the test of balance and the 5 chair rise test. 5725 (72.7%) subjects participated the gait speed test. After adjustment for age, sex and other potential confounders, subjects with knee arthritis had increased failure rate of completing the test of balance (odds ratio=1.7, 95% confidence interval (CI): 1.3-2.3) and the 5 chair rise test (odds ratio=2.1, 95% confidence interval (CI): 1.5-2.9), as well as impaired gait speed (mean difference=0.204, 95% confidence interval (CI): 0.003-0.406) (Table).

Conclusion Physical examination outcomes from the CHARLS study indicated that knee arthritis was positively associated with impaired physical function among the residents in China.

Knee arthritis	Number of subjects	Number of subjects with failure	Prevalence (%)	OR (95% CI)*
Test of Balance
Yes	1328	68	5.1%	1.7 (1.3-2.3)
No	12156	292	2.4%	1.0 (reference)
5 Chair Rise Test
Yes	1280	59	4.6%	2.1 (1.5-2.9)
No	11921	243	2.0%	1.0 (reference)
Knee arthritis	Number of subjects	Mean of Gait Speed (Second)	Mean Difference (95% CI)*
Gait Speed
Yes	666	5.019	0.204(0.003-0.406)
No	5061	4.700

*adjusted for age, sex, BMI, smoking and drinking history, history of injury and hip fracture, and comorbidities

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/knee-arthritis-is-positively-associated-with-physical-impairment-conclusion-based-on-physical-examinations-from-a-cross-sectional-study-of-17708-chinese-residents/