AB1601-HPR CLINICAL, LABORATORY, AND RADIOLOGICAL FEATURES OF PATIENTS WITH UNDIFFERENTIATED CONNECTIVE TISSUE DISEASE: SINGLE-CENTER COHORT

A. Cefle; S. San; D. Temiz Karadağ; A. Yazici

doi:10.1136/annrheumdis-2024-eular.5125

Abstract

Background: Undifferentiated Connective Tissue Disease (UCTD) is a term used for patients who exhibit clinical manifestations of a connective tissue disease but do not meet the classification criteria for any specific connective tissue disease.

Objectives: While some patients with UCTD may evolve into a definite connective tissue disease over time, the majority remain unchanged. This study aims to investigate the clinical, laboratory, and imaging findings of patients followed with a diagnosis of UCTD in our clinic, with a particular focus on those who have evolved into a definite connective tissue disease during their follow-ups.

Methods: Our study included 99 patients diagnosed with UCTD between the years 2004 and 2022. Demographic, laboratory, and clinical data at the time of UCTD diagnosis were retrospectively examined. Patients with negative ANA results but displaying significant referral symptoms for connective tissue diseases were also included in the analysis. Furthermore, the laboratory and clinical data at the time of the definite diagnosis were analyzed for patients who evolved into a connective tissue disease during their follow-ups.

Results: For patients included in the study with a follow-up duration of >1 year, 76 had a positive ANA, while 5 were found to be ANA negative. Among those with a follow-up duration of <1 year, 18 were identified as ANA positive (Figure 1). The average follow-up duration for all UCTD patients was determined to be 53.16±43.68 months (min-max= 6 - 207 months). The demographic, clinical, and laboratory characteristics of the patients are presented in Tables 1 and 2.

The three most commonly observed symptoms during admission were arthralgia (55 patients), Raynaud’s phenomenon (34 patients), and arthritis (28 patients), respectively. Eleven patients (11.1%) had transformed into a definite connective tissue disease within an average of 2.7±2.2 years (min-max= 1-7 years). During their follow-ups, four patients (4%) were diagnosed with mixed connective tissue disease, six (6%) with systemic sclerosis (SSc), and one with systemic lupus erythematosus (SLE).

During the initial admission, only 37 patients (37.4%) underwent thoracic CT scans, and among them, findings consistent with interstitial lung disease (ILD) were observed in 4 cases. During follow-ups, an additional 13 patients had thoracic CT scans, leading to the diagnosis of ILD in 3 more cases. Throughout the patients’ follow-ups, no significant organ involvement other than lung involvement was observed.

Conclusion: In conclusion, we observed that the majority of patients we followed with a diagnosis of UCTD did not experience a change in their diagnosis during the follow-up. The referral symptoms of patients diagnosed with UCTD were generally associated with the musculoskeletal system or vasculopathy, and in most patients, there was no significant organ involvement either at the time of diagnosis or during follow-ups.

While it could be associated with the lack of further investigations due to the mild nature of the initial findings, based on the current evidence, it can be stated that patients diagnosed with UCTD have a favorable clinical course.