The Knee Clinical Assessment Study – CAS(K). A prospective study of knee pain and knee osteoarthritis in the general population: baseline recruitment and retention at 18 months

Table 6 Association between body mass index and SF-36 physical function in observed target population and CAS(K) clinic attenders*

	Poor physical function	Good physical function	Odds ratio (95% CI†) Unadjusted	Odds ratio (95% CI†) Adjusted‡
Reported knee pain in last 12 months (n = 3106)
Self-reported body mass index
Underweight/normal (<25·0 kg/m²)	550	321	1.00	1.00
Overweight (25·0–29·9 kg/m²)	750	420	1.04 (0.9, 1.3)	1.38 (1.1, 1.7)
Obese (>29·9 kg/m²)	520	164	1.85 (1.5, 2.3)	2.71 (2.1, 3.4)
Attended research clinic (n = 819)
Self-reported body mass index
Underweight/normal (<25·0 kg/m²)	100	83	1.00	1.00
Overweight (25·0–29·9 kg/m²)	216	136	1.32 (0.9, 1.9)	1.41 (1.0, 2.1)
Obese (>29·9 kg/m²)	164	46	2.96 (1.9, 4.6)	3.64 (2.3, 5.8)

* Both SF-36 physical function scores and self-reported body mass index are subject to missing data.
† – 95% confidence interval
‡ – Adjusted for gender and age-group (50–59 yrs, 60–69 yrs, 70–79 yrs, 80+ yrs)

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