Recruitment of pre-dementia participants: main enrollment barriers in a longitudinal amyloid-PET study

Table 1 Sociodemographic and clinical differences between individuals who consented and declined participation in the AMYPAD-PNHS

	Research cohorts			Clinical cohorts			All cohorts
	Consented	Declined	Test statistic	Consented	Declined	Test statistic	Consented	Declined	Test statistic
Female	572/1001 (57.1)	173/287 (60.3)	ns	156/283 (55.1)	22/54 (40.7)	ns	728/1284 (56.7)	195/341 (57.2)	ns
Family history (≥ 1 parent dementia)	662/976 (67.8)	190/287 (66.2)	ns	118/216 (54.6)	4/31 (12.9)	X²(1) = 18.88, p < .001	780/1192 (65.4)	194/318 (61.0)	ns
Age (years)	67.6 ± 7.33	68.3 ± 8.00	ns	72.0 ± 9.96	77.1 ± 8.46	t(335) = -3.53, p < .001	68.6 ± 8.18	69.7 ± 8.67	t(1623) = -2.18, p < .05
Education (years)	14.6 ± 3.78	14.3 ± 3.89	ns	15.0 ± 4.30	13.3 ± 4.07	t(335) = 2.75, p < .01	14.7 ± 3.90	14.2 ± 3.93	t(1623) = 2.36, p < .05
MMSE (score)	28.1 ± 1.54	28.6 ± 1.48	ns	28.4 ± 1.98	27.0 ± 2.44	t(335) = 3.75, p < .001†	28.7 ± 1.65	28.4 ± 1.76	t(1622) = 3.13, p < .01†
Mean nr. of prior visits^‡	3 ± 1	3 ± 1	ns	6 ± 2	4 ± 2	U = 4132.5, p < .001	3 ± 1	3 ± 2	ns

Continuous variables are reported in mean ± sd and categorical variables in n (%). As external factors (Fig. 1) are expected to universally affect participants irrespective of individual characteristics, participants assigned to this reason of decline were excluded from these analyses (n = 95). Not all PCs provided data for both consented and declined participants: missing cases are reported in Supplementary Table S2. ^†Equal variances not assumed. ^‡Reported in median ± IQR and Mann–Whitney U test due to non-normality of the variable. MMSE, Mini-Mental State Examination

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