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B. J. Lee et al.
severe knee OA. Clinical characteristics according to
the presence or absence of knee OA are shown in Table
I. The prevalence of knee OA was 24.4% (n = 899) in
men and 43.5% (n = 2,092) in women. The prevalence
of severe knee OA among subjects with knee OA were
42.7% (n = 384) in men and 67.2% (n = 1,406) in wo-
men. Compared with subjects who did not have knee
OA (men, 37.8%, women, 33.2%), more subjects with
knee OA were diagnosed with metabolic syndrome,
especially in women (men, 40.6%, women, 52.7%).
The mean number of metabolic syndrome components
was also higher in women with knee OA.
Associations between metabolic syndrome and
the risk of knee osteoarthritis and severe knee
osteoarthritis
In the univariate analysis, metabolic syndrome in-
creased the risk of developing knee OA (OR = 2.24,
95% CI = 1.94–2.58, p-value< 0.001) and severe knee
OA (OR = 2.22, 95% CI = 1.90–2.60, p-value< 0.001)
in women (Table II). After adjusting for age group
(model 1), metabolic syndrome increased the risk of
developing knee OA (OR = 1.64, 95% CI = 1.41–1.91,
p-value < 0.001) and severe knee OA (OR = 1.59, 95%
CI = 1.36–1.87, p-value < 0.001) in women. After
adjusting for all other environmental factors (model
Model 1 a
OR (95% CI)
Osteoarthritis
Men (n = 360) c
1.13 (0.93–1.36)
Women (n = 1,084) c 2.24 (1.94–2.58)*
Severe osteoarthritis
Men (n = 150) d
0.98 (0.76–1.25)
Women (n = 766) d 2.22 (1.90–2.60)*
Model 2 b
OR (95% CI)
1.18 (0.97–1.44) 1.17 (0.96–1.43)
1.64 (1.41–1.91)* 1.61 (1.38–1.87)*
1.03 (0.80–1.33) 1.03 (0.80–1.33)
1.59 (1.36–1.87)* 1.56 (1.33–1.84)*
*p< 0.001. p< 0.05 was considered to be statistically significant.
Model 1 was adjusted for age group.
Model 2 was adjusted for age group, education, smoking, alcohol
consumption, and physical activities.
c
Number of subjects with knee OA and metabolic syndrome.
d
Number of subjects with severe knee OA and metabolic syndrome.
OR: odds ratio; 95% CI: 95% confidence interval.
a
b
2), metabolic syndrome also increased the risk of
developing knee OA (OR = 1.61, 95% CI = 1.38–1.87,
p-value < 0.001) and severe knee OA (OR = 1.56, 95%
CI = 1.33–1.84, p-value < 0.001) in women. However,
these associations were not observed in the univariate
and multivariate analyses in men.
Table III. Odds ratio for development of knee osteoarthritis
(OA) and severe knee osteoarthritis in accordance with number
of metabolic syndrome components
Univariate
Number of analysis
components OR (95% CI)
Model 1 a
OR (95% CI) Model 2 b
OR (95% CI)
1.16 (0.81–1.67) 1.15 (0.80–1.66)
1.40 (0.98–2.00) 1.38 (0.96–1.99)
1.37 (0.93–2.02) 1.33 (0.90–1.97)
1.49 (0.98–2.27) 1.49 (0.97–2.30)
1.80 (1.06–3.08)* 1.82 (1.05–3.17)*
1 (n = 388) c 1.91 (1.41–2.59)*** 1.48 (1.08–2.04)* 1.39 (1.01–1.92)*
Men
Demographics
Univariate
analysis
OR (95% CI)
Osteoarthritis
1 (n = 188) c 1.24 (0.87–1.76)
Table I. Demographics of the participants
Age
50–59 years
60–69 years
70–79 years
80– years
Obesity
Hyperglycaemia
Hypertension
Abdominal obesity
Low HDL
High TG
Metabolic syndrome
Number of metabolic
syndrome component
Smoking
Alcohol intake
Education
≤ Elementary school
Middle school
High school
≥ College/university
Physical activity
Vigorous a
Moderate b
Walking c
Table II. Odds ratio for development of knee osteoarthritis (OA)
and severe knee OA in metabolic syndrome patients
2 (n = 260) c 1.46 (1.03–2.07)
Male (n = 3,684) Female (n = 4,807)
Non-OA
OA
(n = 2,785) (n = 899) Non-OA
OA
(n = 2,715) (n = 2,092)
1,199 (58.4)
974 (27.4)
559 (12.6)
53 (1.6)
842 (31.5)
1,341 (47.6)
1,616 (57.1)
751 (26.7)
937 (34.0)
1,075 (43.0)
1,019 (37.8)
154 (28.5) 1,487 (62.8)
409 (24.8)
313 (34.4)
816 (24.3)
750 (33.0)
366 (31.0)
370 (11.5)
774 (33.6)
66 (6.1)
42 (1.4)
159 (8.6)
346 (39.9)
800 (29.8)
991 (47.3)
439 (47.7)
870 (32.0)
893 (43.5)
614 (66.9) 1,370 (49.2) 1,471 (68.8)
321 (37.1)
776 (29.3)
999 (47.6)
326 (35.5) 1,469 (53.0) 1,284 (62.4)
287 (35.3)
824 (31.5)
712 (35.2)
360 (40.6)
905 (33.2) 1,084 (52.7)
2.08
2.22
932 (37.5) 238 (31.2)
1,126 (43.3) 362 (45.1)
770
534
876
605
(27.1)
(20.5)
(32.9)
(19.5)
384
170
234
111
1.95
114 (5.7)
155 (6.5)
2.57
64 (3.6)
113 (5.9)
(40.1) 1,278 (46.9) 1,524 (73.2)
(20.9)
499 (20.5)
278 (13.5)
(27.6)
685 (24.7)
231 (10.4)
(11.5)
253 (7.9)
59 (2.9)
439 (16.5) 131 (15.9) 301 (11.1) 171 (8.0)
243 (9.2) 240 (8.4) 195 (9.4)
965 (35.7) 711 (33.9)
101 (11.0)
1,153 (40.1) 417 (46.4)
a
At least 20 min vigorous activity on 3 or more days per week.
b
At least 30 min moderate-intensity activity on 5 or more days per week.
c
At least 30 min walking on 5 or more days per week.
Values are expressed as numbers (%).
OA: osteoarthritis; HDL: high-density lipoprotein; TG: triglycerides.
www.medicaljournals.se/jrm
3 (n = 203) c 1.38 (0.95–2.00)
4 (n = 115) c 1.51 (1.00–2.28)
5 (n = 42) c
Women
1.59 (0.97–2.62)
2 (n = 503) c 2.71 (1.99–3.67)*** 1.74 (1.26–2.42)*** 1.59 (1.14–2.21)**
3 (n = 53) c
4.15 (3.05–5.65)*** 2.37 (1.70–3.30)*** 2.17 (1.56–3.03)***
4 (n = 389) c 4.85 (3.54–6.65)*** 2.63 (1.89–3.66)*** 2.45 (1.75–3.43)***
5 (n = 162) c 4.50 (3.00–6.76)*** 2.40 (1.56–3.71)*** 2.14 (1.38–3.30)***
Severe osteoarthritis
Men
1 (n = 70) d
0.84 (0.51–1.38)
0.77 (0.46–1.28) 0.77 (0.46–1.28)
1.09 (0.68–1.76) 1.10 (0.68–1.78)
0.93 (0.57–1.50) 0.91 (0.55–1.51) 0.91 (0.55–1.52)
1.10 (0.64–1.89) 1.08 (0.62–1.89) 1.09 (0.62–1.92)
0.93 (0.45–1.90) 1.02 (0.49–2.13) 1.04 (0.49–2.19)
1 (n = 234) d 1.83 (1.24–2.69)** 1.34 (0.89–2.02) 1.24 (0.82–1.86)
2 (n = 119) d 1.16 (0.74–1.84)
3 (n = 85) d
4 (n = 50) d
5 (n = 15) d
Women
2 (n = 348) d 2.97 (1.98–4.46)*** 1.82 (1.19–2.79)** 1.62 (1.05–2.48)*
3 (n = 359) d 3.91 (2.65–5.75)*** 2.05 (1.36–3.08)*** 1.84 (1.22–2.77)**
4 (n = 282) d 5.37 (3.63–7.94)*** 2.74 (1.84–4.08)*** 2.51 (1.67–3.78)***
5 (n = 125) d 5.47 (3.54–8.44)*** 2.81 (1.77–4.46)*** 2.43 (1.52–3.88)***
*p < 0.05, **p < 0.01, ***p < 0.001. p <
0.05 was considered statistically
significant.
a
Model 1 was adjusted for age group.
b
Model 2 was adjusted for age group, education, smoking, alcohol consumption,
and physical activities
c
Number of subjects with knee OA and each number of metabolic syndrome
components
d
Number of subjects with severe knee OA and each number of metabolic
syndrome components.
Odds ratio was in comparison with knee OA and severe knee OA individuals
with no component of metabolic syndrome. OR: odds ratio; 95% CI: 95%
confidence interval.