Table 2.

Clinical relevance of FVC changes in patients with chronic respiratory disease and late-onset Pompe disease

Citation	Disease	n	% predicted FVC				Relevance*
			Mean ± SD baseline (m)	Timepoint (m)	Absolute diff. (%)	Relative diff. (%)	Absolute MCID (%)	Relative MCID (%)	Patient notice difference?
[39]	IPF	1156	70 ± 13				2–6	3–9
[40]	IPF	84	73 ± 19		5–10	7–14
					>10	>14
[41]	IPF		67 ± 12		7–12	10–18
					≥12	≥18
[30]	MPS	22	48 ± 15	Week 26: 53 ± 19	5	10	Within	Above	“much better”
[18]	Pompe	60	55 ± 14	Week 78: 57 ± 16	Week 78: 1	2	Below	Below	“much better” to “somewhat better”
[42]	Pompe	2	Pt 1: 81	2 years:	2 years:	2 years:	Pt 1: Below	Pt 1: Below	Pt 1: “much better” to “somewhat better”
			Pt 2: 94	Pt 1: 80	Pt 1: −1	Pt 1: −1	Pt 2: Within	Pt 2: Below	Pt 2: “much better” to “somewhat better”
				Pt 2: 92	Pt 2: −2	Pt 2: −2
[12]	Pompe	74	65 ± 27	67 ± 27	2	3	Within	Within	“much better” to “somewhat better”
[31]	Pompe	44	70	12 months: 70	12 months: 0.5	1	Below	Below	“much better” to “somewhat better”
[13]	Pompe	28	80 ± 14	At 3 years: 77 ± 18	3 years: −4	5	Within	Within	“same” to “much worse”
[43]	Pompe	1	44	42	−2	−5	Within	Within	“somewhat better”
			----------	----------	----------	----------	----------	----------	----------
			31	25	−6	−19	Above	Above	“same” to “much worse”
[44]	Pompe	5		2 years:	2 years:
			Pt 1: 0.0	Pt 1: 8	Pt 1: 8	Pt 1: -	Pt 1: Above	Pt 1: -	Pt 1: “much better”
			Pt 2: 46	Pt 2: 66	Pt 2: 26	Pt 2: 57	Pt 2: Above	Pt 2: Above	Pt 2: “much better”
			Pt 3: 9	Pt 3: 16	Pt 3: 7	Pt 3: 78	Pt 3: Above	Pt 3: Above	Pt 3: “much better”
			Pt 4: 14	Pt 4: 7	Pt 4: −7	Pt 4: 50	Pt 4: Above	Pt 4: Above	Pt 4: “somewhat worse”
			Pt 5: 10	Pt 5: 20	Pt 5: 10	Pt 5: 100	Pt 5: Above	Pt 5: Above	Pt 5: “much better”
[34]	Pompe	1			1.9/year		Below		“much better” to “somewhat better”
[45]	Pompe	1			6 months: 16		Above		“much better”

*MCID of 2–6% and patient classifications based on a study in patients with idiopathic pulmonary fibrosis [39].

FVC forced vital capacity, IPF idiopathic pulmonary fibrosis, MCID minimal clinically important difference, pt patient, diff. difference, % predicted FVC Percentage change in predicted FVC, MPS mucopolysaccharidosis, SD standard deviation.