Table 2.

Effect of dFEV₁ on the Absolute Difference in Exacerbation Rates

Inclusion	No. of Trials	No. of Comparisons	No. of Subjects	Slope (b) Estimate (95% CI)	RR = Exp(b) Estimate (95% CI)	P	R2
All studies	94	167	119,227	–0.16 (–0.21 to –0.1)	0.86 (0.81 to 0.91)	< .001	0.20
Only two arms	49	49	45,371	–0.19 (–0.31 to –0.07)	0.82 (0.73 to 0.93)	.002	0.24
BD only	49	76	80,718	–0.23 (–0.31 to –0.16)	0.79 (0.73 to 0.86)	< .001	0.39
ICS only	27	35	32,354	–0.12 (–0.25 to 0.01)	0.89 (0.78 to 1.01)	.078	0.18
PDE4 only	13	14	14,523	–0.25 (–0.92 to 0.42)	0.78 (0.4 to 1.52)	.463	0.00
Non-BD	57	91	56,715	–0.1 (–0.19 to –0.01)	0.91 (0.83 to 0.99)	.036	0.06
≥ 1 Exacerbation in previous year	27	47	31,055	–0.07 (–0.17 to 0.04)	0.93 (0.84 to 1.04)	.204	0.00

For this analysis, the model is ln(RR) = a + b*dTreat, where RR = rate ratio. The unit for dTreat unit is 100 mL. See Table 1 legend for expansion of abbreviations.