Effect of combined pulmonary fibrosis and emphysema on patients with connective tissue diseases and systemic sclerosis: a systematic review and meta-analysis

Table 4 Meta-analysis on clinical characteristics of the patients with systemic sclerosis (SSc) with combined pulmonary fibrosis and emphysema (CPFE) compared to the patients with SSc with interstitial lung disease (ILD) without emphysema

Characteristics	Number (n = 701)			Pooled mean difference or odds ratio [95% confidence interval]	Heterogeneity
Characteristics	Included study	SSc-CPFE (n = 136)	SSc-ILD without emphysema (n = 565)		I² (%)	P
Age and gender
Age of patients	4	136	565	−0.73 [−3.66, 2.19]	0	0.83
Number of male patients	4	136	565	3.99 [2.62, 6.06]	70	0.02
Smoking history
Number of ever-smokers	4	136	565	3.16 [2.09, 4.78]	64	0.04
Physical characteristics
Number of patients with ACA	2	79	268	0.81 [0.31, 2.13]	0	0.89
Number of patients with digital ulcer	2	52	77	0.64 [0.29, 1.41]	0	0.77
Composite physiologic index	2	70	98	2.46 [−5.33, 10.24]	70	0.07
ILD extent, % of total lung volume	2	57	297	7.02 [−4.53, 18.56]	85	0.009
Number of patients with ILD extent > 20% of total lung volume	2	75	265	1.99 [1.18, 3.37]	22	0.26
Number of patients with pulmonary hypertension	2	73	361	3.36 [1.85, 6.09]	78	0.03
PaO₂ at rest, kPa	2	73	348	−0.94 [−1.41, −0.47]	0	0.84
Pulmonary function test
TLC, % of predicted	2	79	267	−1.93 [−6.73, 2.88]	0	0.68
FEV1, % of predicted	2	77	362	−2.52 [−7.50, 2.45]	0	0.66
FVC, % of predicted	4	136	564	−0.65 [−4.96, 3.66]	0	0.58
FEV1/FVC, % of predicted	2	52	75	−4.62 [−9.41, 0.17]	72	0.06
DLCO, % of predicted	4	136	557	−14.31 [−17.31, −11.32]	0	0.41
FVC/DLCO	2	57	297	0.32 [0.15, 0.48]	0	0.35

SSc-CPFE systemic sclerosis and combined pulmonary fibrosis and emphysema, SSc-ILD sclerosis and interstitial lung disease, ACA anti-centromere antibody, ILD interstitial lung disease, TLC total lung capacity, FEV1 forced expiratory volume in 1 s, FVC forced vital capacity, DLCO diffusing capacity of carbon monoxide