Sjögren's syndrome: An underdiagnosed condition in mixed connective tissue disease

Lung fibrosis is uncommon in primary Sjögren's disease: A retrospective analysis of computed tomography features in 77 patients

PURPOSE

The purpose of this study was to describe lung abnormalities observed on computed tomography (CT) in patients meeting the 2016 American College of Rheumatology/European League Against Rheumatism (EULAR) classification criteria for primary Sjögren's disease (pSD).

MATERIALS AND METHODS

All patients with pSD seen between January 2009 and December 2020 in the day care centre of our National Reference Center for rare systemic autoimmune diseases, who had at least one chest CT examination available for review and for whom the cumulative EULAR Sjögren's Syndrome Disease Activity Index (cumESSDAI) could be calculated were retrospectively evaluated. CT examinations were reviewed, together with clinical symptoms and pulmonary functional results.

RESULTS

Seventy-seven patients (73 women, four men) with a median age of 51 years at pSD diagnosis (age range: 17-79 years), a median follow-up time of 6 years and a median cumESSDAI of 7 were included. Sixty-six patients (86%) had anti-SSA antibodies. Thirty-three patients (33/77; 43%) had respiratory symptoms, without significant alteration in pulmonary function tests. Forty patients (40/77; 52%) had abnormal lung CT findings of whom almost half of them had no respiratory symptoms. Abnormalities on chest CT were more frequently observed in patients with anti-SSA positivity and a history of lymphoma. Air cysts (28/77; 36%) and mosaic perfusion (35/77; 35%) were the predominant abnormalities, whereas lung fibrosis was observed in five patients (5/77; 6%).

CONCLUSION

More than half of patients with pSD have abnormal CT findings, mainly air cysts and mosaic perfusion, indicative of small airways disease, whereas lung fibrosis is rare, observed in less than 10% of such patients.

Towards Early Diagnosis of Mixed Connective Tissue Disease: Updated Perspectives

Mixed Connective Tissue Disease (MCTD) is an autoimmune disease first described by Sharp et al in 1972, characterized by the presence of anti-Ribonucleoprotein antibodies directed against the U1 complex (anti-U1RNP). The condition shares clinical characteristics with Systemic Lupus Erythematosus, Rheumatoid Arthritis, and Systemic Sclerosis. Diagnosis is quite difficult due to its rarity, the lack of validated classification criteria, and its heterogeneous clinical presentation. While in the early stages its nuanced clinical features might lead to it being incorrectly classified as other Connective Tissue Diseases (CTDs) or even not recognized, in cases of longstanding disease its classification as a CTD is clear but challenging to discriminate from overlap syndromes. MCTD should be considered a distinct entity due to the presence of a specific genetic substrate and the presence of the high titer of a specific autoantibody, anti-U1RNP, present in all the commercial kits for Extractable Nuclear Antigens, and almost always associated with Antinuclear Antibody positivity with a coarse speckled pattern. Except for anti-U1RNP, no specific biomarkers are available to guide clinicians to a correct classification of MCTD, which is arrived at by the association of clinical, serological and instrumental evaluation. In the first stages, the disease is mainly characterized by Raynaud's phenomenon, inflammatory arthritis, puffy fingers, myalgia and/or myositis, and rarely, trigeminal neuropathy. Longstanding disease is generally associated with the development of Pulmonary Hypertension and Interstitial Lung Disease, which are the two main causes of mortality in MCTD. The aim of this review is to summarize current knowledge on the early recognition of MCTD.

Ocular Surface Inflammatory Disorders (OSID): A Collective of Systemic Etiologies Which Cause or Amplify Dry Eye Syndrome

The ocular surface inflammatory disorders (OSID) are caused by systemic disorders that conduct a persistent inflammatory reaction in the ocular adnexal connective tissues, such as the conjunctiva, lacrimal gland (LG) and meibomian glands (MGs), which cause an inflammatory dry eye. The etiologies of OSID are a subset of systemic pathologies such as graft versus host disease, Sjögren’s syndrome, allergies, cicatrizing conjunctivitis, and more. These cause a purely inflammatory dry eye syndrome as a consequence of the persistent surrounding inflammation in the adnexal tissues, which is distinct from the age-related dry eye disease. A limitation toward management of these conditions is the lack of available biomarkers that can detect presence of inflammation and quantify damage on the conjunctiva and LG, even though these are considered to be drivers of the inflammatory milieu. The OSID and dry eye syndrome are caused by different immune cells which are not exclusively limited to T cell lymphocytes, but rather derive from an orchestrated multicellular immunologic response. Recognition of this syndrome is crucial to direct research in a direction that clarifies the potential role of inflammation and its associated immune phenotype on the conjunctiva and adnexal ocular tissues in OSID and dry eye syndrome. On this paper, we review the basic and clinical research evidence for the existence of OSID with focus on the different immune cells involved, the target tissues and potential consequences and OSIDs diagnostic and therapeutic implications.

Dry eye disease, a prominent manifestation of systemic autoimmune disorders

OBJECTIVES

Dry eye disease (DED) is arguably the most frequent ocular disease encountered in ophthalmic clinical practice. DED is frequently an underestimated condition causing a significant impact on visual function and quality of life. Many systemic autoimmune diseases (SAIDs) are related to moderate to severe DED. The main objective of this review is to enhance the awareness among ophthalmologists of the potential association of an underlying SAID in a high-risk patient with DED.

METHODS

An exhaustive literature search was performed in the National Library of Medicine's Pubmed, Scopus, Web of Science, and Google Scholar databases for all English language articles published until November 2021. The main keywords included "dry eye disease" associated with autoimmune, connective tissue, endocrine, gastrointestinal, hematopoietic, vascular, and pulmonary diseases. Case reports, series, letters to the editor, reviews, and original articles were included.

RESULTS

Although DED is frequently associated with SAIDs, its diagnosis is commonly delayed or missed, producing significant complications, including corneal ulceration, melting, scleritis, uveitis, and optic neuritis resulting in severe complications detrimental to visual function and quality of life. SAID should be suspected in a woman, 30 to 60 years old with a family history of autoimmunity, presenting with DED symptoms and extraocular manifestations including arthralgias, dry mouth, unexplained weight and hair loss, chronic fatigue, heat or cold intolerance, insomnia, and mood disorders.

CONCLUSIONS

Establishing the correct diagnosis and treatment of DED associated with SAIDs is crucial to avoid its significant burden and severe ocular complications.

Preliminary Screening Questionnaire for Sjögren's Syndrome in the Rheumatology Setting

OBJECTIVE

Sjögren's syndrome (SS) is frequently undetected or misdiagnosed as other rheumatologic diseases. We aimed to develop an SS screening questionnaire for the rheumatology practice.

METHODS

We developed the Sjögren's Syndrome Screening Questionnaire (SSSQ) via secondary analysis of data from 974 participants referred by rheumatologists to the Sjögren's International Collaborative Clinical Alliance (SICCA) study. Participants answered 88 questions regarding symptoms, medical history, and demographics. They underwent ocular, dental, and serologic tests and were classified as SS or non-SS using the 2016 American College of Rheumatology/European League Against Rheumatism classification criteria. We conducted univariate and multivariate logistic regression to identify questions most discriminative of SS, from which we derived an individual's likelihood of SS ("SSSQ score").

RESULTS

Five questions were significantly discriminative of SS in the multivariate analysis (p < 0.05): (1) Can you eat a cracker without drinking a fluid/liquid? (no: odds ratio [OR], 1.39; 95% confidence interval [CI], 1.06-1.82]); (2) How would you describe your dental and oral health in general? (fair/poor: OR, 1.68; 95% CI, 1.04-2.75); (3) During the last week, have you experienced tearing? (none of the time: OR, 2.26; 95% CI, 1.23-4.34); (4) Are you able to produce tears? (no: OR, 1.62; 95% CI, 1.12-2.37); and (5) Do you currently smoke cigarettes? (no: OR, 2.83; 95% CI, 1.69-4.91). SSSQ score ≥7 (possible range, 0-11) distinguishes SS from non-SS patients with 64% sensitivity and 58% specificity (area under receiver operating characteristic curve, 0.65).

CONCLUSIONS

The SSSQ is a simple 5-item questionnaire designed to screen for SS in clinical practice, with a potential impact to reduce delays in diagnosis.

Transcriptomic Mapping of Human Parotid Gland at Single-Cell Resolution

As the largest salivary gland in oral cavity, the parotid gland plays an important role in initial digesting and lubricating food. The abnormal secretory function of the parotid gland can lead to dental caries and oral mucosal inflammation. In recent years, single-cell RNA sequencing (scRNA-seq) has been used to explore the heterogeneity and diversity of cells in various organs and tissues. However, the transcription profile of the human parotid gland at single-cell resolution has not been reported yet. In this study, we constructed the cell atlas of human parotid gland using the 10× Genomics platform. Characteristic gene analysis identified the biological functions of serous acinar cell populations in secreting digestive enzymes and antibacterial proteins. We revealed the specificity and similarity of the parotid gland compared to other digestive glands through comparative analyses of other published scRNA-seq data sets. We also identified the cell-specific expression of hub genes for Sjögren syndrome in the human parotid gland by integrating the results of genome-wide association studies and bulk RNA-seq, which highlighted the importance of immune cell dysfunction in parotid Sjögren syndrome pathogenesis.

Early diagnosis and treatment for Sjögren's syndrome: current challenges, redefined disease stages and future prospects

There are some challenges and unmet needs in the early diagnosis and management of Sjögren's syndrome (SjS) such as prominent glandular dysfunction at diagnosis and long diagnostic delay. Those challenges are partly attributed to the lack of a good knowledge of the early stages of SjS, which is a major obstacle to delivering appropriate care to SjS patients. Findings from both clinical and experimental studies suggest the plausibility of a redefined SjS course consisting of 4 stages, which includes initiation stage, preclinical stage, asymptomatic SjS stage and overt SjS stage. More studies focusing on the pathological processes and changes during the early stages of SjS are needed. To enable early diagnosis and treatment for SjS, more useful biomarkers of the early stages of SjS need to be identified, and individuals at high risk of SjS development need to be identified. Appropriate screening can be performed to facilitate the early diagnosis of SjS among those high-risk individuals.

Mixed connective tissue disease: Not always an obvious diagnosis

Mixed connective tissue disease (MCTD) is characterized by a mixture of clinical features. The initial presentation is often incomplete, and the features of MCTD usually develop as the disease evolves. We present a 37‐year‐old female patient with overlapping symptoms. The most plausible diagnosis was MCTD.

Salivary gland ultrasound in the diagnostic workup of juvenile Sjögren's syndrome and mixed connective tissue disease

BACKGROUND

Juvenile Sjögren's Syndrome (jSS) is a rare phenomenon that may appear as primary jSS or associated with mixed connective tissue disease (MCTD) and other autoimmune diseases as secondary jSS. With currently no standard diagnostic procedures available, jSS in MCTD seems to be underdiagnosed. We intended to describe and identify similar distinct salivary gland ultrasound (SGUS) findings in a cohort of primary and secondary jSS patients, focusing on sicca like symptoms and glandular pain/swelling in the patients'history.

METHODS

We present a single-center study with chart data collection. B-mode examinations of salivary glands were obtained with a linear high-frequency transducer and evaluated using the scoring-system of Hocevar. Inclusion criteria were: (i) primary or secondary jSS and/or (ii) diagnosis of MCTD and additionally (iii) any presence of sicca like symptoms or glandular pain/swelling.

RESULTS

Twenty five patients with primary (pjSS) and secondary jSS (sjSS) were included in the study (n = 25, 21 female, 4 male), with a median age of 15.3 years at the time of first visit and a mean disease duration of 4.9 years. Pathologic SGUS findings were observed in 24 of 25 patients, with inhomogeneous parenchymal appearances with hypoechoic lesions present in 96% of patients. At least one submandibular gland was affected in 88.5% of the whole group, and all patients in the MCTD-group. Twenty of twenty five patients were scanned and scored on a second visit. Pre-malignancies or mucosa-associated lymphoid tissue (MALT) were detected in biopsies of three patients (Hocevar scoring of 40, 33, and 28).

CONCLUSION

SGUS in patients with pjSS and sjSS is a helpful first-line tool to detect and score salivary gland involvement, in particular when keratoconjunctivitis sicca, xerostomia, or glandular swelling occurs. Juvenile MCTD patients have a significant risk of developing secondary jSS. We propose SGUS as a method in the diagnostic workup and screening for inflammatory changes. Further studies have to determine the predictive value of SGUS for follow up.

Tissue-Specific Autoantibodies Improve Diagnosis of Primary Sjögren's Syndrome in the Early Stage and Indicate Localized Salivary Injury

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease characterized by lymphocytic infiltration of exocrine glands. Due to the absence of specific clinical manifestations and biomarkers in the early stage, pSS is generally underrecognized. To elucidate the role of the tissue-specific autoantibodies (TSAs), i.e., anti-CA6, anti-SP1, and anti-PSP antibodies, we enrolled 137 pSS patients, 32 secondary Sjögren's syndrome (sSS) patients, and 127 healthy controls (HCs), whose serum and saliva samples were collected. TSA levels were detected by ELISA, and the clinical and laboratory data was reviewed from the medical records. The analysis results showed the following: (1) Compared to HCs, the serum IgA levels of anti-CA6, anti-SP1 and anti-PSP were significantly higher in pSS as well as in sSS patients, and anti-CA6 IgG was also notably higher in pSS patients. (2) The positivity of anti-CA6, anti-PSP and all the three antibodies together were significantly increased in anti-SSA-negative pSS patients. (3) The average IgM levels of anti-CA6 and anti-SP1 decreased as the disease duration extended. (4) The anti-CA6-positive patients have significantly higher levels of serum IgA, while the anti-PSP-positive group has a notably higher serum IgM level. (5) Another autoantibody specific to the salivary glands, anti-α-fodrin antibody, was elevated in TSA-positive patients, especially in the anti-CA6-positive group. (6) Preliminary detection of saliva TSAs showed that all the IgG levels of these three antibodies increased significantly in pSS patients. In conclusion, TSAs improve diagnosis of pSS in the early stage, especially in anti-SSA-negative patients, and their tissue-specific nature indicates localized salivary injury, which deserves further studies to clarify the mechanism.

Association between B Cell Growth Factors and Primary Sjögren's Syndrome-Related Autoantibodies in Patients with Non-Hodgkin's Lymphoma

Despite the overall success of using R-CHOP for the care for non-Hodgkin's lymphoma patients, it is clear that the disease is quite complex and new insight is needed to further stratify the patient for a better personized treatment. In current study, based on previous studies from animal model, new panels combining well-established cytokine (BAFF) and autoantibodies (anti-SSA/Ro) with newly identified cytokine (IL14) and autoantibodies (TSA) were used to evaluate the association between B cell growth factor and Sjögren's related autoantibodies in NHL patients. The result clearly indicates that there was a unique difference between BAFF and IL14 in association with autoantibodies. While serum BAFF was negatively associated with the presence of both traditional anti-SSA/Ro and novel TSA antibodies in GI lymphoma patient, IL14 was positively associated with the presence of both traditional anti-SSA/Ro and novel TSA antibodies in non-GI lymphoma patient. Long-term follow-ups on these patients and evaluation of their response to the R-CHOP treatment and recurrence rate will be very interesting. Our result provides a solid evidence to support using novel diagnostic panel to better stratify the NHL patients.

Emergence of Smoldering ANCA-associated Glomerulonephritis during the Clinical Course of Mixed Connective Tissue Disease and Sjögren's Syndrome

A 67-year-old woman presented with hematuria and proteinuria 16 and 11 months ago, respectively. She had been followed up as mixed connective tissue disease and Sjögren's syndrome for over 19 years. Blood chemistry showed no elevated serum creatinine or C-reactive protein but did reveal myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) of 300 U/dL. A kidney biopsy showed pauci-immune focal necrotizing glomerulonephritis. She was treated with prednisolone and rituximab, resulting in normal urinalysis and decreased MPO-ANCA. The complication of ANCA-associated glomerulonephritis should not be overlooked when abnormal urinalysis findings appear in the course of connective tissue disease, irrespective of the presence of rapidly progressive glomerulonephritis.

Autoantibodies, detection methods and panels for diagnosis of Sjögren's syndrome

The presence of autoantibodies is one of several hallmarks of Sjögren's Syndrome, the detection of serum autoantibodies has a central role in the diagnosis and classification of Sjögren's syndrome. In this review, we will discuss autoantibodies that are helpful in the diagnosis of Sjögren's syndrome. This includes the traditional autoantibodies for disease classification (ANA, Anti-Ro/SSA, Anti-La/SSB, RF), autoantibodies identified from mouse models (Anti-SP1, Anti- PSP, Anti-CA6, and anti-alpha fodrin) and autoantibodies associated with other autoimmune disease (ACA, AMA, and Anti-CCP). We will also review the methods for the detection of autoantibodies and associated challenges for clinical results reporting. The significance of using an autoantibody panel for the diagnosis of SS will be also be reviewed.

The Potential Role for Early Biomarker Testing as Part of a Modern, Multidisciplinary Approach to Sjögren's Syndrome Diagnosis

Sjögren's syndrome (SS) is a chronic and progressive multisystem autoimmune disease typically managed by rheumatologists. Diagnostic delays are common, due in large part to the non-specific and variable nature of SS symptoms and the slow progression of disease. The hallmark characteristics of SS are dry eye and dry mouth, but there are a broad range of other possible symptoms such as joint and muscle pain, skin rashes, chronic dry cough, vaginal dryness, extremity numbness or tingling, and disabling fatigue. Given that dry eye and dry mouth are typically the earliest presenting complaints, eye care clinicians and dental professionals are often the first point of medical contact and can provide critical collaboration with rheumatologists to facilitate both timely diagnosis and ongoing care of patients with SS. Current diagnostic criteria advocated by the American College of Rheumatology are predicated on the presence of signs/symptoms suggestive of SS along with at least two objective factors such as traditional biomarker positivity, salivary gland biopsy findings, and/or presence of keratoconjunctivitis sicca. Traditional biomarkers for SS include the autoantibodies anti-Sjögren's syndrome-related antigen A (SS-A/Ro), anti-Sjögren's syndrome-related antigen B (SS-B/La), antinuclear antibody (ANA) titers, and rheumatoid factor (RF). While diagnostically useful, these biomarkers have low specificity for SS and are not always positive, especially in early cases of SS. Several newly-identified biomarkers for SS include autoantibodies to proteins specific to the salivary and lacrimal glands [SP-1 (salivary gland protein-1), PSP (parotid secretory protein), CA-6 (carbonic anhydrase VI)]. Data suggest that these novel biomarkers may appear earlier in the course of disease and are often identified in cases that test negative to traditional biomarkers. The Sjö^® test is a commercially available diagnostic panel that incorporates testing for traditional SS biomarkers (anti-SS-A/Ro, anti-SS-B/La, ANA, and RF), as well as three novel, proprietary early biomarkers (antibodies to SP-1, PSP, and CA-6) which provide greater sensitivity and specificity than traditional biomarker testing alone. Timely diagnosis of SS requires appropriate clinical vigilance for potential SS symptoms, referral and collaborative communication among rheumatology, ophthalmology, and oral care professions, and proactive differential work-up that includes both physical and laboratory evaluations.

Diffusional kurtosis imaging of parotid glands in Sjögren's syndrome: Initial findings

PURPOSE

To explore the role of diffusion kurtosis imaging (DKI) of parotid glands in diagnosing Sjögren's syndrome (SS).

MATERIALS AND METHODS

A total of 40 patients with SS and 40 healthy volunteers underwent 3.0T magnetic resonance imaging (MRI) including DKI, which generated the apparent diffusion coefficient (ADC), corrected diffusion (D), and diffusional kurtosis (K) values. The MR nodular grade was determined on the basis of MR morphological findings.

RESULTS

The parotid ADC, D, and K values in patients with SS were significantly higher than those of healthy volunteers (P = 0.011, < 0.001, 0.022, respectively). The parotid ADC and D values in patients with SS of MR nodular grade 0 were significantly higher than those of healthy volunteers (all P < 0.001). The parotid D value showed an accuracy of 75.0% and 87.9% in diagnosing patients with SS and MR nodular grade 0, respectively. The parotid ADC and D values correlated negatively, while the K values correlated positively with the MR nodular grade significantly in patients with SS (r = -0.741, -0.605, 0.424, all P < 0.001). All parotid DKI parameters differed significantly among patients with SS at different MR nodular grades (all P < 0.001).

CONCLUSION

Parotid DKI parameters hold great potential in diagnosing SS, especially in early-stage SS without MR morphological changes.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1409-1417.

Orofacial manifestations in patients with inflammatory rheumatic diseases

The main orofacial manifestation of the inflammatory rheumatic diseases is that of Sjögren's syndrome. In addition, there is a constellation of orofacial manifestations of the inflammatory rheumatic diseases, many of which are extra-articular with some constituting presenting signs of the underlying rheumatic disease. This review will discuss the orofacial manifestations in a variety of connective tissue diseases and will also allude to the oral adverse drug reactions that may occur as a consequence of therapy.

Use of T1ρMR imaging in Sjögren's syndrome with normal appearing parotid glands: Initial findings

PURPOSE

To explore the feasibility of parotid spin-lattice relaxation time in the rotating frame (T1ρ) MR imaging in the diagnosis of Sjögren's syndrome (SS) without morphological changes of the parotid glands.

MATERIALS AND METHODS

The study enrolled 32 consecutive SS patients without morphological changes of parotid glands and 32 age- and gender-matched healthy volunteers who underwent parotid 3.0 Tesla MR imaging, including T1ρ sequences. Follow-up imaging was performed at 3 months. T1 signal intensities and T1ρ values of bilateral parotid glands were compared using paired samples t-test. Parotid T1 signal intensities and T1ρ values were compared using two independent samples t-test. Diagnostic performance of the parotid T1ρ values was evaluated by receiver operating characteristic analysis. The intraclass correlation coefficient (ICC) was calculated to evaluate the reproducibility of parotid T1ρ measurements.

RESULTS

There were no significant differences of T1 signal intensities and T1ρ values between bilateral parotid glands in SS patients and healthy volunteers (P = 0.170, 0.886 and 0.942, 0.229). The parotid T1ρ values of SS patients (96.47 ± 15.38 ms) were significantly higher than those of healthy volunteers (84.25 ± 6.11 ms) (P < 0.001), while there were no significant differences of T1 signal intensities between SS patients and healthy volunteers (P = 0.655). With a cutoff value of 88.02 ms, the sensitivity and specificity of the parotid T1ρ value was 75.0% and 100.0% in the diagnosis of SS. The reproducibility of parotid T1ρ measurement was excellent (ICC: 0.934-0.995).

CONCLUSION

Parotid T1ρ MR imaging held a potential role in diagnosing SS without morphological changes of parotid glands.

LEVEL OF EVIDENCE

2 J. Magn. Reson. Imaging 2017;45:1005-1012.

Making the diagnosis of Sjögren's syndrome in patients with dry eye

Sjögren’s syndrome (SS) is a chronic and progressive systemic autoimmune disease that often presents initially with symptoms of dry eye and dry mouth. Symptoms are often nonspecific and develop gradually, making diagnosis difficult. Patients with dry eye complaints warrant a step-wise evaluation for possible SS. Initial evaluation requires establishment of a dry eye diagnosis using a combination of patient questionnaires and objective ocular tests, including inflammatory biomarker testing. Additional work-up using the Schirmer test and tear film break-up time can differentiate between aqueous-deficient dry eye (ADDE) and evaporative dry eye. The presence of ADDE should trigger further work-up to differentiate between SS-ADDE and non-SS-ADDE. There are numerous non-ocular manifestations of SS, and monitoring for SS-related comorbid findings can aid in diagnosis, ideally in collaboration with a rheumatologist. The clinical work-up of SS can involve a variety of tests, including tear function tests, serological tests for autoantibody biomarkers, minor salivary gland and lacrimal gland biopsies. Examination of classic SS biomarkers (SS-A/Ro, SS-B/La, antinuclear antibody, and rheumatoid factor) is a convenient and non-invasive way of evaluating patients for the presence of SS, even years prior to confirmed diagnosis, although not all SS patients will test positive, particularly those with early disease. Recently, newer biomarkers have been identified, including autoantibodies to salivary gland protein-1, parotid secretory protein, and carbonic anhydrase VI, and may allow for earlier diagnosis of SS. A diagnostic test kit is commercially available (Sjö^®), incorporating these new biomarkers along with the classic autoantibodies. This advanced test has been shown to identify SS patients who previously tested negative against traditional biomarkers only. All patients with clinically significant ADDE should be considered for serological assessment for SS, given the availability of new serological diagnostic tests and the potentially serious consequences of missing the diagnosis.

Association between Sjogren's syndrome and respiratory failure: put airway, interstitia, and vessels close together: a national cohort study

Objectives

Few studies have evaluated the association between Sjogren's syndrome (SS) and respiratory failure (RF). Thus, we conducted a retrospective national cohort study to investigate whether Sjogren's syndrome (SS) increases the risk of respiratory failure (RF).

Methods

The cohort consisted of 4954 newly diagnosed patients with SS but without a previous diagnosis of RF, and 19816 patients as the comparison cohort from the catastrophic illnesses registry, obtained from the 2000–2005 period. All of the study participants were followed from the index date to December 31, 2011. We analyzed the association between the risk of RF and SS by using a Cox proportional hazards regression model, controlling for sex, age, and comorbidities.

Results

The overall incidence rate of RF showed a 3.21-fold increase in the SS cohort compared with the comparison cohort. The adjusted HR of RF was 3.04 for the SS cohort compared with the comparison cohort, after we adjusted for sex, age, and comorbidities. The HRs of RF for patients with primary SS and secondary SS compared with the comparison cohort were 2.99 and 3.93, respectively (P for trend <.001). The HRs of RF increased as the severity of SS increased, from 2.34 for those with no inpatient care experience to 5.15 for those with inpatient care experience (P for trend <.001).

Conclusion

This study indicates that clinical physicians should not only consider secondary SS but also primary SS as a critical factor that increases the risk of RF.