The IL-6 rs12700386 polymorphism is associated with an increased risk of developing osteoarthritis in the knee in the Chinese Han population: a case-control study

Table 5 Genetic (G) and environmental (E) factors 2*4 fork analysis

G^a	E^b	Case	Control	OR (95%CI); P value	Reflecting information
rs12700386
CC vs. GG	Smoking
+	+	19	9	2.86 (1.25,6.56); 0.015	G, E combined effect
+	–	5	7	0.97 (0.30,3.13); 0.602	G alone effect
-	+	78	103	1.03 (0.70,1.50); 0.923	E alone effect
-	–	115	156	1.00 (reference)	Common control
GC vs. GG	Smoking
+	+	13	12	1.47 (0.65,3.34); 0.402	G, E combined effect
+	–	121	122	1.35 (0.95,1.91); 0.111	G alone effect
-	+	78	103	1.03 (0.70,1.50); 0.923	E alone effect
-	–	115	156	1.00 (reference)	Common control
CC vs. GG	Drinking
+	+	13	6	2.90 (1.07,7.83); 0.034	G, E combined effect
+	–	11	10	1.47 (0.61,3.57); 0.495	G alone effect
-	+	71	96	0.99 (0.67,1.45); 1.000	E alone effect
-	–	122	163	1.00 (reference)	Common control
GC vs. GG	Drinking
+	+	39	46	1.13 (0.70,1.84); 0.620	G, E combined effect
+	–	95	88	1.44 (0.99,2.09); 0.058	G alone effect
-	+	71	96	0.99 (0.67,1.45); 1.000	E alone effect
-	–	122	163	1.00 (reference)	Common control

^aG (+): IL-6 gene rs12700386 variants (Heterozygous or homozygous); G (−): wild type
^bE(+): smoking/non-smoking; E(−): non-smoking/non-drinking

ISSN: 1471-2350