Table 4.

Prevalence of symptomatic knee osteoarthritis in NHSS follow‐up study, Singapore (n = 3364)

	Unweighted prevalence, % (95% CI)			Weighted prevalence, %
	n	Model 1a	Model 2b	Model 1a	Model 2b
Overall	3364	5.8 (5.1–6.6)	14.3 (13.2–15.5)	4.7	11.0
By gender
Female	1822	7.1 (6.0–8.4)	17.5 (15.8–19.3)	5.6	13.1
Male	1542	4.2 (3.3–5.3)	10.5 (9.1–12.1)	3.7	8.8
By age groups
18–29 years	424	0.7 (0.2–2.1)	2.4 (1.3–4.3)	0.8	1.6
30–39 years	465	1.3 (0.6–2.8)	7.5 (5.5–10.3)	0.6	5.7
40–49 years	828	4.3 (3.2–6.0)	12.1 (10.0–14.5)	4.4	9.7
50–59 years	830	7.5 (5.9–9.5)	18.3 (15.8–21.1)	6.4	15.7
60–69 years	527	9.5 (7.3–12.3)	21.3 (18.0–24.9)	8.7	18.4
≥70 years	290	13.1 (9.7–17.5)	24.8 (20.2–30.1)	10.8	21.5
By age categories
<60 years	2547	4.2 (3.5–5.1)	11.7 (10.5–13.0)	3.3	8.6
≥60 years	817	10.8 (8.8–13.1)	22.5 (19.8–25.5)	9.5	19.7
By ethnicity and age groups
Chinese
Total	1989	5.1 (4.2–6.1)	10.9 (9.6–12.3)	4.3	9.3
<40 years	450	0.9 (0.3–2.3)	2.9 (1.7–4.9)	0.7	2.6
40–59 years	967	4.7 (3.5–6.2)	10.5 (8.7–12.5)	4.9	10.5
≥60 years	572	9.1 (7.0–11.7)	17.8 (14.9–21.9)	8.4	16.7
Malay
Total	746	5.2 (3.8–7.1)	18.5 (15.9–21.4)	4.8	17.7
<40 years	243	0.8 (0.2–3.0)	6.6 (4.1–10.4)	0.5	5.9
40–59 years	381	5.8 (3.8–8.6)	22.6 (18.7–27.0)	5.3	20.8
≥60 years	122	12.3 (7.6–19.3)	29.5 (22.1–38.1)	12.0	33.6
Indian
Total	456	10.1 (7.6–13.2)	23.0 (19.4–27.1)	9.2	20.3
<40 years	147	2.0 (0.7–5.8)	9.5 (5.8–15.4)	1.2	9.1
40–59 years	222	12.2 (8.5–17.1)	25.2 (20.0–31.3)	11.5	23.9
≥60 years	87	18.4 (11.6–27.8)	40.2 (30.6–50.7)	19.6	35.5

^aModel 1 = algorithm 3 of Instrument 3, sensitivity 0.44, specificity 0.95 for symptomatic knee osteoarthritis.

^bModel 2 = algorithm 3A of Instrument 3, sensitivity 0.62 and specificity 0.87 for symptomatic knee osteoarthritis.