DISCUSSION
The most common pathological findings in pulmonary involvement of SS are
ILD and small airway defects. HRCT is the most sensitive diagnostic
method for the detection of noninvasive and early parenchymal injury
(9).
The number of studies evaluating the characteristic results of HRCT in
ILD due to primary SS is quite limited. The most common involvement
patterns among the HRCT findings in SS lung involvement are
peribronchial wall thickening, ground glass appearance, nodules and
bronchiectasis (10,11).
It has been reported in a study conducted by Dong et al.with 527
patients diagnosed with primary SS, that SS-related involvement is found
to be widespread and affects multiple anatomical structures (airways,
alveoli, vascular structures and pleura) and also it has been stated
that different histological patterns may be seen simultaneously such as
nonspecific interstitial pneumonia (NSIP), organized pneumonia (OP) and
the union of NSIP and usual interstitial pneumonia (UIP) (12).
In our study, the most common HRCT findings found in patients were
peribronchial thickening (48.6 %), ground glass appearance (28.6%) and
prominence in interstitial scars were, in accordance with the
literature.
We think that the absence of NSIP and OP patterns are due to the fact
that our patients were in the early phase of disease and they had mild
disease findings. Patients with ILD show restrictive functional
dysfunction. PFT data is also a tool used to diagnose this respiratory
disorder ( even in asymptomatic patients) in the early period (13).
Decreased FVC, FEV1 and DLCO in PFT are among the predicted findings.
However, the most important parameter among these is the decreased DLCO
levels that were detected in the early period, and it is associated with
the high mortality rate (13,14).
Although it was not possible to compare PFT results since there was no
control group in our study; there was a significant decrease in FEV1 and
FVC values in older SS patients. However, it was not possible to exclude
possible age-related changes in these patients. In studies carried out,
İt was detected that decreased DLCO is generally associated with
widespread involvement in HRCT (15).
In our study, while the DLCO value in patients with CT findings was
found to be lower, it was not statistically significant. Again, no
substantial difference was observed in our research when the patients
with and without CT findings were compared according to the PFT results.
The relatively younger age of our patients, shorter illness length and
limited involvement in HRCT findings may explain this circumstance. The
inability of PFT to detect early findings, especially in CT, was shown
to be similar to our outcome In the analysis of Palm et al.
While 85% of the patients had HRCT findings in this study, only 15% of
the patients were diagnosed with PFT alone (14).
6MWT is an exercise test used to assess exercise capacity and treatment
response in patients with chronic lung diseases such as chronic
obstructive pulmonary disease (COPD), interstitial fibrosis, pulmonary
arterial hypertension, and it has been used as a prognostic tool in
patients with heart failure and lung disease in recent years (16).
According to the American Thoracic Society guidelines, 6MWT is stated to
be a simple, low-cost, reproducible and easy-to-apply method (17).
Generally, there are studies evaluating pulmonary functional capacity in
conditions such as idiopathic pulmonary fibrosis and chronic obstructive
pulmonary disease (18-20).
However, there are not enough studies on 6MWT data for lung involvement
in SS. In our study, the lack of significant difference between 6MWT and
lung involvement supports the absence of diffuse pulmonary involvement.
The prevalence of pulmonary symptoms in primary SS patients is stated to
be between 9-25%; in the literature consistent with our research
(12,21).
Dry cough and/or effort dyspnea are the most common among the clinical
findings. In a report, it was reported that symptoms were linked to the
underlying chronic respiratory conditions in 1/3 of the patients who had
clinical symptoms (21).
This rate was approximately ¼ in our study. It has been reported in the
literature that respiratory symptoms are observed in 10% of patients
within 1 year after diagnosis, reaching 20% in 5 years (4,12).
In our research, more than half of the patients had CT findings in the
first 3 years. However, its correlation with the clinic could not be
clearly evaluated because of the small number of patients. However,
these results show that, lung involvement in patients typically occurs
in the first years of the illness in line with the literature. In a
study, it was found that 15-20 % of patients had chronic ILD outcomes
even before an overt connective tissue disease develops (22).
In another cohort study, it was demonstrated that 60% of patients were
diagnosed with ILD before the diagnosis of SS in 60% of patients (13).
It was stated in some research, that pulmonary findings did not have a
negative effect on prognosis. In the study of Davidson et al. involving
30 British patients, it was shown that after 10 years of follow-up,
pulmonary functions remained stable in most patients (23).
However, there are several studies contradicting these studies in the
literature. ILD is a poor prognostic factor in SS patients and the
cumulative mortality rate reaches 16% in 5 years (14, 24,25).
In addition, in a study by Chen et al. high HRCT scores were found to be
an independent risk factor for mortality (9).
It is very important to determine the predictive factors of the disease
in the prevention and early treatment of pulmonary disease. Studies
investigating prognostic variables of lung involvement in SS are not
sufficient and the findings are contradictory. Although some studies
have shown that advanced age and long duration of the disease may be
associated with poor prognosis, publication is also available. There are
also researches that indicate that this relationship is not important
(26).
When the laboratory parameters are examined; Although it has been
reported that hypergammaglobulinemia, lymphopenia, rheumatoid factor
(RF) and anti Ro / La positivity may be predictive factors in lung
involvement, the results of the study are not statistically significant
(15).
In our study, the relationship of these parameters with pulmonary
involvement could not be investigated because the patients’ laboratory
parameters were not analyzed in a single center and the findings of
certain patients were not available.
In researches investigating clinical results and lung involvement, it
was observed that the Reynoud syndrome was more prominent in patients
with lung involvement (14,27).
This situation can be interpreted as the development of ischemic process
depends on microangiopathy due to the initiation of ILD development.
Similarly, CT involvement was detected in 6 of 8 patients with the
Reynoud phenomenon in our study.
The treatment of primary SS pulmonary involvement is generally based on
clinical practice and no widely accepted algorithm is currently
available. The use of immunosuppressants such as Cyclophosphamide,
Azathioprine and high-dose steroids and biological agents such as
Rituxumab and Belimumab, along with symptomatic therapy, is used to
manage the treatment of these patients. The most common use in our
patients was hydroxychloroquine and / or low-dose steroid use.
This outcome indicates that there was no widespread intervention and no
associated symptoms in our patients.
Its retrospective nature, the limited number of patients, and the
inability to assess the relationship between autoantibodies and lung
involvement were the limitations of our research.