Table 1 Differences between responders and non‐responders to the risk factor questionnaire.

	Controls (n = 394)		Difference (95% CI)	Cases (n = 1018)		Difference (95% CI)
	Responders (n = 209)	Non‐responders (n = 185)		Responders (n = 712)	Non‐responders (n = 306)
Median age	8.5	9.0	–0.3 (–1.0 to 0.4)*	6.3	7.1	–0.5 (–0.9 to –0.1)*
Median Townsend deprivation score of ward of residence	7.0	7.6	–0.2 (–0.8 to 0.2)*	7.6	7.6	0.1 (–0.2 to 0.4)*
Boys	138 (66%)	101 (55%)	11.4 (1.8 to 21.1)	445 (63%)	188 (61%)	1.1 (–5.4 to 7.6)

*Hodges‐Lehmann median differences.²¹