Table 4.

Pooled ORs for association of commonly studied risk factors with knee OA (case–control studies)

Risk factors	NO of studies	Pooled OR	Lower CI	Upper CI	P value	I squared (%)
Exercise	5	0.75	0.62	0.91	0.003	25.0
High school	2	0.49	0.30	0.79	0.003	0.0
University	2	0.22	0.06	0.86	0.030	65.0
Living environment	3	2.05	0.66	6.34	0.210	0.0
Drinking	2	1.60	0.40	6.45	0.510	0.0
Trauma history	2	1.53	0.71	3.33	0.280	0.0
BMI ≥ 24 kg/m2	6	1.32	1.00	1.74	0.050	0.0
Junior high school	2	1.21	0.62	2.36	0.570	0.0
Agricultural labour	2	1.17	0.54	2.56	0.690	0.0
Manual labour	4	1.11	0.93	1.31	0.250	0.0
Smoking	3	1.09	0.84	1.41	0.530	0.0
Gender	8	1.05	0.99	1.12	0.090	55.0
Family history	4	1.04	0.98	1.10	0.220	0.0
Age	7	1.01	1.00	1.01	0.140	0.0