Table 1.

Recruitment strategies for Study 1 mail-out pilot and Study 2 of three enhanced mail-out strategies

Study and intervention arm of study	Date mailed out	Cost per unit received ($AU)	Responses 30 days after questionnaire mail-out	Overall RR (%) and 95 % CI	Gender				AGE
					Males		Females		Aged 45–64 years		Aged 65+ years
					Responded	RR	Responded	RR	Responded	RR	Responded	RR
Study 1 pilot
5000 Questionnaire	Questionnaire (Q) sent 24 March 2010	$4.19	2084	41.7 %* [40.3–43.5]	961	41.2 % [39.2–43.2]	1123	42.1 % [40.2–43.9]	1233	42.6 % [40.8–44.4]	851	40.4 % [38.3–42.5]
Study 2 enhanced mail-out
Strategy A 1000 Postcard + Questionnaire	Postcard 30 June 2010 + Q 7 July 2010	$3.13	505	50.5 %** [47.4–53.5]	229	48.8 % [44.3–53.3]	276	52.0 % [47.7–56.2]	315	52.2 [48.2–56.2]	190	48.0 % [43.1–52.9]
Strategy B 1000 Questionnaire + Reminder	Q 7 July 2010 + Reminder 21 July 2010	$3.20	541	54.1 % [51.0–57.2]	278	52.4 % [48.1–56.6]	263	56.1 % [51.6–60.5]	330	55.6 % [51.6–59.6]	211	51.8 % [47.0–56.7]
Strategy C 1000 Postcard + Questionnaire + Reminder	Postcard 30 June 2010 + Q 7 July 2010 + Reminder 21 July 2010	$3.78	564	56.4 % [53.3–59.4]	242	60.0 % [55.2–64.7]	322	53.9 % [49.9–57.9]	350	57.7 % [53.7–61.5]	214	54.5 % [49.5–59.3]

Q questionnaire mailed out; RR response rate (computed as at 30 days from sending the invitation/questionnaire pack)

* Study 1 different to all arms of Study 2, p < 0.05; ** Unadjusted (Strategy A) versus (Strategy C) p = 0.004; (Strategy A) versus (Strategy B) p=0.053