Table 5.

Estimated RLFD^† and samples size requirements^§ by age and risk factors

	Age range, yrs
		≥6	≥13	≥18	≥25	6–12	13–17	18–24
Weight-for-age percentile
≥25th	FEV1 change (% pred/yr)	−3.5	−5.0	−4.7	−3.7	−2.5	−5.2	−5.4
	Sample size	396	192	170	182	787	201	158
<25th	FEV1 change (% pred/yr)	−4.9	−6.9	−7.0	−10.7	−3.8	−6.8	−5.7
	Sample size	255	102	93	58	464	106	109
P. aeruginosa culture history in the past year
All negative	FEV1 change (% pred/yr)	−2.7	−4.8	−4.4	−2.5	−2.0	−4.9	−5.1
	Sample size	691	236	199	499	1208	243	153
Any positive	FEV1 change (% pred/yr)	−5.2	−6.2	−5.8	−6.2	−4.3	−6.4	−5.6
	Sample size	215	124	127	110	364	122	137
IV exacerbations in the past year
0	FEV1 change (% pred/yr)	−3.1	−4.5	−3.7	−3.8	−2.4	−4.7	−3.7
	Sample size	492	211	205	228	852	210	194
1	FEV1 change (% pred/yr)	−4.9	−5.9	−5.8	−6.6	−4.1	−6.1	−5.3
	Sample size	242	134	103	106	386	153	100
2	FEV1 change (% pred/yr)	−5.8	−7.9	−7.7	−8.7	−3.6	−8.1	−7.3
	Sample size	172	73	85	60	519	78	101
≥3	FEV1 change (% pred/yr)	−9.0	−10.3	−9.0	−7.5	−7.4	−11.1	−9.6
	Sample size	98	68	94	108	162	56	92

^†derived from 1.5 years of semiannual measures

^§80% power to detect a 50% change in rate of FEV₁ change over 1.5 years with semiannual FEV₁ measure, α = 0.05, in CF subjects with FEV₁ ≥ 70% predicted.