Table 2.

Generalized estimating equations logistic regression analyses of association between knee pain status among nonfrail participants at baseline and prefrailty/frailty over time

Knee Pain, Past 12 Months	Prefrailty		Frailty
	OR (95% CI)	P	OR (95% CI)	P
Model 1*
No knee pain (reference)	1.00		1.00
Unilateral	1.16 (1.01–1.31)	0.025	1.90 (1.37–2.63)	0.001
Bilateral	1.40 (1.23–1.60)	<0.001	2.20 (1.62–3.00)	<0.001
Unilateral* time	1.01 (0.98–1.03)	0.40	0.96 (0.88–1.05)	0.36
Bilateral* time	0.97 (0.94–0.99)	0.54	1.00 (0.93–1.08)	0.84
Model 2†
No knee pain (reference)	1.00		1.00
Unilateral	1.14 (1.01–1.27)	0.022	1.89 (1.38–2.62)	0.001
Bilateral	1.41 (1.24–1.62)	<0.001	2.21 (1.63–3.01)	<0.001
Unilateral* time	0.95 (0.96–1.03)	0.29	0.96 (0.87–1.03)	0.37
Bilateral* time	0.97 (0.93–0.98)	0.99	1.00 (0.93–1.08)	0.86

OR = odds ratio; CI = confidence interval.

^*Model 1: levels of knee pain and interaction between levels of knee pain and time.

^†Model 2: adjusted for model 1 plus age, sex, race, education, marital status, smoking status, comorbidity, and body mass index.