Table 6.

Black proportion estimates overall, by phase, multi-institutional status, tier assessment, masking, and year.

	Frequency (%), studies	Total number of participants	Estimated proportion (95% CI)	P-value compared to reference category (*)	P-value compared to 2010 Census proportion (12.3%)	$I^2$(%)
Black
Overall	–	–	17.0% (15.9–18.1)	–	< 0.0001	98.3%
Phase
II*	1094 (68.9%)	103,813	16.5% (15.3–17.8)	–	< .0001	98.3%
III	495 (31.2%)	220,155	18.0% (16.1–19.9)	0.220	< .0001
Institution status
Single*	682 (42.9%)	102,520	19.4% (17.7–21.2)	–	< .0001	98.3%
Multi-institutional	907 (57.1%)	221,448	15.3% (14.0–16.7)	0.0002	< .0001
Tier assessment
1*	824 (51.9%)	57,943	17.9% (16.4–19.5)	–	< .0001	98.3%
2	765 (48.1%)	266,025	16.1% (14.6–17.6)	0.091	< .0001
Masking
No masking*	341 (21.5%)	55,000	13.9% (11.8–16.1)	–	< .0001	98.3%
Single	107 (6.73%)	22,081	22.4% (18.1–27.1)	0.0005	< .0001
Double	389 (24.5%)	79,017	16.2% (14.1–18.4)	0.130	< .0001
Triple	287 (18.1%)	72,527	18.5% (16.0–21.1)	0.0065	< .0001
Quadruple	465 (29.3%)	95,343	17.9% (15.9–19.9)	0.0077	< .0001
Study start year
2008*	121 (7.61%)	35,685	13.7% (10.4–17.4)	–	0.200	98.2%
2009	156 (9.82%)	30,239	14.5% (11.5–17.8)	0.738	0.0500
2010	134 (8.43%)	45,381	21.0% (17.2–25.0)	0.0070	< .0001
2011	145 (9.13%)	17,765	22.5% (18.8–26.5)	0.0010	< .0001
2012	159 (10.0%)	29,668	17.3% (14.0–20.7)	0.155	0.0003
2013	189 (11.9%)	32,347	15.1% (12.3–18.2)	0.545	0.0107
2014	169 (10.6%)	25,349	18.6% (15.4–22.1)	0.0495	< .0001
2015	177 (11.1%)	29,085	14.5% (11.6–17.6)	0.749	0.0427
2016	150 (9.44%)	41,432	14.5% (11.4–17.8)	0.753	0.0584
2017	128 (8.06%)	23,619	19.1% (15.3–23.2)	0.0441	< .0001
2018	47 (2.96%)	10,243	20.7% (14.5–27.7)	0.0584	0.0026
2019	14 (0.88%)	3155	15.8% (6.31–28.2)	0.719	0.419