Lung function decline is accelerated in South Africans with cystic fibrosis

Figures & data

Table 1: Demographic data for study population at entry (n = 20)

Variable	Mean (% of total)
Age (years)	16
Age groups
5–9	5 (25)
10–20	10 (50)
> 20	5 (25)
Gender (M/F)	8/12 (40/60)
Mutation
p.F508del homozygous	15 (75)
p.F508del heterozygous	3 (15)
Unidentified	2 (10)
Lung function
FEV1 %	69.0
FEF25-75 %	48.2
Anthropometric measurements
Weight (kg)	41.4
Weight Z-score	–1.0
Height (cm)	145
Height Z-score	–1.5
BMI (kg/m^2)	18.6
BMI Z-score	–0.5

Notes: p.F508del = delta F508 deletion; FEV₁% = percentage predicted forced expiratory volume in one second; FEF_25-75 % = percentage predicted forced expiratory flow during 25–75%; BMI = body mass index.

Table 2: Anthropometry measurements in relation to CF mutation

Variable	Study entry		Study exit		p-value
	Mean	95% CI	Mean	95% CI
Wt — mutation (kg)
p.F508del hete/U	30.5	2.0; 59.0	48.5	7.5; 89.5
p.F508del homo	45.0	37.9; 52.2	54.4	49.2; 59.7	NS
BMI — mutation(kg/m^2)
p.F508del hete/U	16.8	13.1; 20.5	18.8	11.0; 26.6	NS
p.F508del homo	19.1	17.3; 21.0	19.5	17.8; 21.3
BMI Z-score	–0.5	–1.34; 0.33	–1.28	–2.0; –0.56	NS
Ht Z-score	–1.15	–1.6; –0.6	0.86	–0.07; 1.80	0.0005

Notes: CI = confidence intervals; Wt = weight in kilograms; Ht = height in centimetres; BMI = body mass index; p.F508del hete/U = p.F508del heterozygous and unidentified mutations; p.F508del homo = p.F508del homozygous; NS: not statistically significant.

Table 3: Comparison of lung function between mutation and gender

FEV1					FEF25-75
Study time	Mutation/gender	Mean	95% CI	p-value	Study time	Mutation/gender	Mean	95% CI	p-value
Entry	p.F508del hete/U	76.04	35.7; 117.0		Entry	p.F508del hete	56.4	7.3; 120
	p.F508del homo	66.6	51.1; 82.1			p.F508del homo	45.4	28.3; 62.5
	Diff	9.8	–30.0; 49.6	0.54		Diff	11.0	31.4; 64.9	0.67
Exit	p.F508del hete/U	50.8	9.6; 92.0		Exit	p.F508del hete	31.8	6.1; 69.7
	p.F508del homo	40.0	22.0; 58.0			p.F508del homo	23.7	9.2; 38.3
	Diff	10.8	–29.8; 51.4	0.54		Diff	8.0	–29.0; 45.2	0.61
Entry	Female	75.6	56.6; 94.6		Entry	Female	53.1	30.2; 75.8
	Male	59.3	38.3; 80.2			Male	40.7	10.0; 71.5
	Diff	16.3	–9.8; 42.0	0.4		Diff	12.3	–23.1; 47.8	0.5
Exit	Female	47.4	26.3; 68.5		Exit	Female	26.8	10.2; 43.5
	Male	35.6	9.5; 61.8			Male	24.1	0.5; 48.7
	Diff	11.8	–19.2; 42.8	0.4		Diff	2.7	–24.9; 36.3	0.8

Notes: CI = confidence interval; FEV1 = forced expiratory volume; FEF25-75 = forced expiratory flow during 25 – 75%; p.F508del hete/U = p.F508del heterozygous and unidentified mutations; p.F508del homo = p.F508del homozygous; entry = study entry; exit = study exit; Diff = difference between mutations mean or gender mean.

Figure 1: Box plot of relative change of FEV1 (light blue), FEF25/75 (medium blue), BMI Z-score (dark blue) and height according to gender.