Table 2

Association between the TRPV1 585 Ile–Ile genotype and symptomatic or asymptomatic knee osteoarthritis (OA) in a crude meta-analysis and in pooled analysis

Groups compared	Sample size	Summary OR (95% CI) (crude Mantel–Haenzsel)	p Value meta‑analysis	Heterogeneity I² p(Cochran's Q)	Pooled analysis OR (95% CI)	p Value pooled analysis
Any knee OA versus controls	4368 cases, 3852 controls	0.83 (0.73 to 0.95)	0.0073	I² =0% p(Q)<0.39	0.84 (0.72 to 0.98)^*	<0.0277^*
Symptomatic knee OA versus controls	3270 cases, 3852 controls	0.74 (0.64 to 0.87)	0.00022	I² =0% p(Q)<0.66	0.76 (0.64 to 0.92)^*	<0.0042^*
Asymptomatic knee OA versus controls	1098 cases, 3852 controls	0.99 (0.81 to 1.22)	0.93	I² =0% p(Q)<0.67	1.01 (0.78 to 1.31)^*	<0.92^*
Symptomatic versus asymptomatic knee OA	3270 symptomatic cases, 1098 asymptomatic cases	0.76 (0.59 to 0.99)	0.0378	I² =0% p(Q)<0.87	0.74 (0.55 to 0.99)^†	<0.0417^†

ORs refer to the risk of individuals carrying the TRPV1 585 Ile–Ile compared with Val–Ile and Val–Val individuals.
↵* Adjusted for age, sex and body mass index (BMI).
↵† Adjusted for age, sex, BMI and Kellgren–Lawrence grade.
‡ All estimates are also adjusted for relatedness between twins.