Predictors of long-term outcome of undifferentiated inflammatory arthritis

Abstract

Inflammatory arthritis is a type of joint inflammation caused by overactivity of the immune system. It usually affects many joints of the body at the same time, but it can affect only one joint. Due to insufficient clinical or laboratory information, a number of patients with inflammatory arthritis do not provide the necessary diagnostic criteria to classify them in a specific clinical group of the disease. The level of disease in these people may improve or progress to a well-defined condition such as rheumatoid arthritis or remain undifferentiated inflammatory arthritis. It is absolutely necessary to evaluate the course of this disease and the effective factors in determining the prognosis of these patients in order to prevent the risk of permanent joint damage, disability, or the transformation of the disease into other connective tissue diseases by identifying and starting appropriate treatment in the targeted people. The study of the effective factors in the long-term prognosis of inflammatory arthritis was not differentiated. Materials and methods: All patients with undifferentiated inflammatory arthritis under observation at the Clinic of Research Center for Connective Tissue Diseases, Imam Reza Hospital, located in Tabriz, were included in the study after obtaining an informed consent form (193 patients). The inclusion criteria are: 1. suffering from inflammatory arthritis based on clinical criteria, 2. having at least 1 year of follow-up with regular visits at least 3 times a year. Exclusion criteria included not completing the patient information and not following the treatment. By studying the patient's file, demographic characteristics, clinical characteristics, laboratory findings, treatment regimen and response to treatment were examined. The treatment protocol was first performed with Prednisolone and then with DMARDs according to the clinical condition and the expert doctor's opinion. Prognosis of the disease was evaluated based on transformation to other rheumatic diseases or recovery. The regression model was used to examine the independent variable (disease status) with the dependent variable (time). Findings: Recovery without medication occurred in 42 cases (20.7%). In 24 cases (11.8%), this disease met the criteria of other rheumatic diseases, of which rheumatoid arthritis was the most common. In addition, in 33 (16.3%) cases, poor joint response occurred. The predictors of recovery without medication were the absence of underlying disease and the start of treatment within 3 months. Factors associated with disease progression to rheumatoid arthritis include rheumatoid factor and anti-citrullinated peptide antibody (ACPA), lack of sustained remission, and disease recurrence. Treatment delay of more than 3 months and ACPA positivity were predictive of poor joint response.