RESULTS
Patients were divided into two groups; SSc patients with any typical
morphological findings of PF on HRCT (n=41) and patients without any
typical morphological findings of PF on HRCT (n=94). These were compared
with healthy controls (n=38). These three groups were comparable in age
and gender distribution (49.8±15.4, 50.2±11.5, 52.2±5.80,p =0.563; female 85.4%, 88.3%, 89.5%, p =0.840,
respectively). Baseline demographic and clinical characteristics and
laboratory results of the SSc patients with and without PF are shown in
Table 1. The patients with PF had more diffuse cutaneous involvement,
lower FVC and DLCO, and were more likely to be Scl-70 autoantibody
positive. Pulmonary artery diameter was higher in the patients with PF,
and more patients had pulmonary artery dilatation when a cut-off value
of 30 mm was used (p <0.001 and p =0.002,
respectively). Synovitis was more common in patients without PF.
The soft-ware analysis was performed on HRCT images of the 135 patients
with SSc and 38 controls (Figure 2). Analysis of the right and left lung
density, right and left lung volume derived from the baseline HRCT
scanning in SSc patients with PF, SSc patients without PF, and control
group was performed (Table 2, Figure 2). Comparison of the lung
measurements showed the right and left lung densities were significantly
increased, and the right and left lung volumes were significantly
decreased in SSc patients with PF than SSc without PF and controls. The
pairwise comparisons between the groups revealed
there were no differences between
the SSc patients without PF and controls in terms of right and left lung
densities (p =1.000 and p =1.000, respectively); there was a
significant difference between SSc patients with and without PF in terms
of right and left lung volumes (p =0.005 and p =0.003,
respectively).
Patients without evidence of PF were sub-grouped into limited (n=71) and
diffuse (n=23) cutaneous involvement. This showed that the right and
left lung densities (p =0.002 and p <0.001,
respectively), and the right and left lung volumes differed
significantly between the groups (p =0.045 and p =0.044,
respectively) (Table 3).
Sixteen out of 56 (28.6%) patients without any signs of PF at initial
evaluation and who had an annual follow-up CT scans developed abnormal
imaging after a mean duration of 10±5 years. Baseline lung densities and
volumes were compared between these sub-groups. This revealed that the
baseline right and left lung densities were significantly lower in the
patients who developed signs of PF during follow-up than those who did
not (p =0.016 and p =0.014, respectively) (Table-4).
The correlation between FVC and DLCO and lung densities and volumes in
patients with and without PF was analyzed separately. Spearman rank
correlation demonstrated negative correlation between the FVC and left
lung density (r =-0.230, p =0.043) and positive correlation
between FVC and right and left lung volumes (r =0.331,p =0.003; r =0.299, p =0.008, respectively) in the
patients without PF signs while DLCO correlated only with left lung
volume in these patients (r = 0.248, p =0.032). In the
patients with PF, FVC correlated negatively with right and left lung
densities (r = -0.601, p =0.001; r = -0.507,p =0.005, respectively) and positively with left lung volume
(r = 0.500, p =0.006). Similarly, DLCO correlated negatively
with right and left lung densities (r =-0.487, p =0.012;r = -0.393, p =0.047, respectively) and positively with left
lung volume in these patients (r = 0.402, p =0.042) (Table
5).