Prevalence and Risk Factor Determining Autoimmune Rheumatic Disease and Malignancy

Background: A determine prevalence and identify risk factors of malignancy in autoimmune rheumatic diseases were important for raising awareness of the association between autoimmune rheumatic diseases and malignancy leading to more effective treatments.

Objective: To determine prevalence and risk factors of malignancy in autoimmune rheumatic diseases patients.

Methods: A cross-sectional study was conducted on medical records of patients diagnosed with autoimmune rheumatic diseases and malignancy based on the ICD-10 coding system from January 1, 2013-May 31 2020, at a tertiary referral hospital in Bangkok.

Results: From records of patients diagnosed with autoimmune rheumatic diseases, most were patients with systemic lupus erythematosus (n=2,277), rheumatoid arthritis (n=530), spondyloarthritis (n=379), systemic sclerosis (n=290), dermato/ polymyositis (n = 108), Sjögren syndrome (n=95), and overlap syndrome (n=54). The overall prevalence rate of malignancy in autoimmune rheumatic diseases was 4.2%. Lung and breast were the most common sites. Types of autoimmune rheumatic diseases, age groups, comorbid, and medications were risk factors that could heighten malignancy risk in autoimmune rheumatic diseases. Amongst types of autoimmune rheumatic diseases, demato/ polymyositis and rheumatoid arthritis were heighten risk of malignancy up to 3.88 and 2.60 times over systemic lupus erythematosus. Patients with over 60 years had the higher risk at 3.21 times over those age between 15-25 years. Comorbid disease brought 1.50 times higher risk. As cyclophosphamide, corticosteroids and methrotrexate, some medications increased the risk ranged between 2.79, 1.93 and 0.56 times, respectively.

Conclusions: Evidence confirmed the association of malignancy with all kinds of autoimmune rheumatic diseases, especially rheumatoid arthritis and dermato/ polymyositis, at the highest risk. The study indicated an increased risk of malignancy among elders, patients with comorbid, and corticosteroids, cyclophosphamide, and methrotrexate users.