ABSTRACT
Objective To determine the clinical significance of pulmonary function test(PFT)in evaluating the features and severity of lung impairments associated with connective tissue diseases(CTD)by comparing the differences of pulmonary function test parameters among groups of CTD associated pulmonary disorders.Methods Cases of CTD associated pulmonary disorders were prospectively enrolled and assigned into 3 groups according to their lung impairments:CTD associated pulmonary arterial hypertension group (CTD-PAH,n=29),CTD associated interstitial lung disease group(CTD-ILD,n=35),CTD associated PAH plus ILD group(CTD-PAH+ILD,n=16)and CTD control group(n=34).Pulmonary function test parameters,including total lung capacity(TLC % predicted),forced vital capacity(FVC % predicted),forced expiratory volume in the first second(FEV_(1.0)% predicted),FE_(1.0)%/FVC and diffusing capacity of the lung for carbon monoxide(DLco,% predicted)were measured and compared among the four groups.Results One hundred and forteen eases were included and predominantly female with average onset age of 35～39 years old.CTDs that were predisposed to lung diseases were mixed connective disease(MCTD),systemic sclerosis(SSc),systemic lupus erythematosus(SLE)and primary Sj(o)ren syndrome(pSS),in order.There were 10,29 and 46 percent of patients presented with decreased TLC% in CTD-PAH,CTD-ILD and CTD-PAH+ILD group respectively,50,36 and 71 percent of patients with decreased FVC% respectively,54,47 and 71 percent of patients with decreased FEV_(1.0)% respectively,and 100,82 and 100 percent with decreased DLco% respectively.ANOVA analysis demonstrated that TLC%,FVC%,FEV_(1.0)%,DLco% had significant differences between CTD control group and each of the CTD associated lung disease group(P＜0.05),although none of them was lack of difference between the PAH and ILD groups.TLC% was significantly higher in CTD-PAH group than CTD-PAH+ILD group[(89±15)% vs(79±12)%,P＜0.05],while FVC% was significantly lower in CTDPAH+ILD group either than CTD-PAH group or than CTD-ILD group[(81±13)%,(80±16)% vs(65±22)%,P＜0.05].ConclusionPulmonary function test may be valuable in early screening for CTD associated lung disorders than distinguishing CTD-PAH from ILD,which usually reveal restrictive ventilation dysfunction and/or diffusing capacity dysfunction.