Relationships between slow vital capacity and measures of respiratory function on the ALSFRS-R

Figures & data

Figure 1. Scores of dyspnea (A), orthopnoea (B), and respiratory insufficiency (C) above/at median versus below median percent predicted SVC.

Figure 2. Respiratory insufficiency score 12 (A) or 10 (B): above/at median versus below median percent predicted SVC.

Figure 3. Correlation between percent predicted SVC and total ALSFRS-R score.

Figure 4. Relationship between change from baseline in SVC and changes in ALSFRS-R respiratory sub-score.

Table 1. Difference in percent predicted SVC at the first drop of ALSFRS-R dyspnea/orthopnoea score between patients with slow decline and rapid decline in SVC.

	Dyspnea		Orthopnoea
	Slow* (n = 67)	Rapid (n = 69)	Slow* (n = 41)	Rapid (n = 58)
%predicted SVC, median	81	62	75	58
LS means (SE)	69.1 (4.9)	68.2 (3.6)	74.3 (6.1)	56.0 (5.9)
Differences of LS means		−0.9		−18.3
95% CI		−13.0, 11.2		−35.1, −1.4
p value		0.8813		0.0336

*Patients with a slower rate of decline in SVC are defined as those having a slope larger than the population mean; patients with a rapid decline in SVC are those having a slope smaller than the population mean.

ALSFRS-R, revised ALS Functional Rating Scale; CI, confidence interval; LS, least squares; SE, standard error; SVC, slow vital capacity.