Participant recruitment, baseline characteristics and at-home-measurements of cardiometabolic risk markers: insights from the Supreme Nudge parallel cluster-randomised controlled supermarket trial

Table 1 Overview of recruitment investments and yields in the Supreme Nudge trial

			Completed eligibly assessment (n = 664)				Eligible (n = 602)				Included (n = 421)				Baseline measurement completion of primary trial outcome (n = 391)
	Total material cost (€)	Total time (hours)	n	(%)	Material cost per participant (€)	Time per participant (hours)	n	(%)	Material cost per participant (€)	Time per participant (hours)	n	(%)	Material cost per participant (€)	Time per participant (hours)	n	(%)	Material cost per participant (€)	Time per participant (hours)
Media news article	0	10	49	(7.4)	0.0	0.2	44	(7.3)	0.0	0.2	31	(7.4)	0.0	0.3	31	(7.9)	0.0	0.3
Flyers in the supermarket	640	22	79	(11.9)	8.1	0.3	71	(11.8)	9.0	0.3	52	(12.4)	12.3	0.4	52	(13.3)	12.3	0.4
Posters	290	22	18	(2.7)	16.1	1.2	15	(2.5)	19.3	1.5	11	(2.6)	26.4	2.0	10	(2.6)	29.0	2.2
Mailing of flyers and recruitment letters	27,981	1120	477	(71.8)	58.7	2.4	433	(71.9)	64.6	2.6	314	(74.6)	89.1	3.6	288	(73.7)	96.5	3.9
Social media advertisements	3100	10	27	(4.1)	114.8	0.4	24	(4.0)	129.2	0.4	16	(3.8)	193.8	0.6	15	(3.8)	206.7	0.7
Email to supermarket customer panel	0	2	16	(2.4)	0.0	0.1	14	(2.3)	0.0	0.1	11	(2.6)	0.0	0.2	11	(2.8)	0.0	0.2
Advertisement on website of the Dutch Heart Foundation	0	2	17	(2.6)	0.0	0.1	16	(2.7)	0.0	0.1	12	(2.9)	0.0	0.2	11	(2.8)	0.0	0.2
Word of mouth	0	8	34	(5.1)	0.0	0.2	32	(5.3)	0.0	0.3	24	(5.7)	0.0	0.3	24	(6.1)	0.0	0.3
In-store recruitment	1583	276	68	(10.2)	23.3	4.1	67	(11.1)	23.6	4.1	32	(7.6)	49.5	8.6	30	(7.7)	52.8	9.2
Total	33,594	1472

ISSN: 1745-6215