E_cs and PVI for covariate groups^a

	No.	Ecs		PVI
		Slope ± SEM	Correlation Coefficient	Slope ± SEM	Correlation Coefficient
Age group (yr)
Younger than 30	39	0.34 ± 0.04	0.89 (0.79–0.94)	−20.1 ± 5.9	−0.48 (−0.69 to −0.20)
30–39	44	0.27 ± 0.05	0.67 (0.47–0.81)	−13.0 ± 7.0	−0.35 (−0.58 to −0.06)
40–49	24	0.28 ± 0.06	0.59 (0.25–0.80)	−10.5 ± 8.5	−0.24 (−0.59 to −0.18)
50 and olderb	9	0.10 ± 0.08	0.31 (−0.44–0.81)	10.6 ± 11.7	0.20 (−0.54 to 0.76)
BMI group (kg/m2)
< 30	8	0.44 ± 0.14	0.57 (−0.23–0.91)	−19.1 ± 19.6	−0.62 (−0.92 to 0.14)
30–39	20	0.20 ± 0.07	0.60 (0.21–0.82)	−2.7 ± 9.3	−0.11 (−0.53 to 0.35)
40–49	34	0.29 ± 0.05	0.79 (0.62–0.89)	−16.4 ± 6.3	−0.33 (−0.60 to 0.01)
≥50	12	0.20 ± 0.08	0.67 (0.16–0.90)	−1.6 ± 10.5	−0.08 (−0.63 to 0.51)
Race group
Black	70	0.27 ± 0.04	0.69 (0.54–0.80)	−12.5 ± 5.3	−0.32 (−0.52 to −0.10)
White	39	0.28 ± 0.04	0.66 (0.44–0.81)	−11.8 ± 6.2	−0.24 (−0.52 to 0.08)
Procedural sedation group
Yes	46	0.28 ± 0.05	0.60 (0.37–0.76)	−19.0 ± 6.5	−0.32 (−0.56 to −0.04)
No	70	0.28 ± 0.03	0.77 (0.66–0.85)	−10.2 ± 4.5	−0.34 (−0.53 to −0.11)
CSF volume removed (mL)
<20	27	0.38 ± 0.06	0.64 (0.34–0.82)	−14.0 ± 10.3	−0.27 (−0.59 to 0.12)
20.0–24.9	27	0.37 ± 0.05	0.79 (0.59–0.90)	−8.6 ± 8.8	−0.18 (−0.53 to 0.21)
25.0–29.9	30	0.38 ± 0.05	0.87 (0.75–0.94)	−18.3 ± 8.7	−0.53 (−0.75 to −0.21)
≥30	32	0.29 ± 0.04	0.90 (0.80–0.95)	−18.9 ± 6.2	−0.41 (−0.67 to −0.08)

Note:—SEM indicates standard error of the mean.

^aThe slope indicates the average change in the measure for a 1 cm H₂O change in opening pressure. The Pearson correlation coefficient reflects the correlation between the measure and opening pressure.

^bComparing 50 years and older with younger than 30 years (P = .01), 30–39 years (P = .09), and 40–49 years (P = .08).