From the Guidelines
The prevalence of overlapping autoimmune syndrome is estimated to be around 8-13.8% among patients with autoimmune diseases, with the most common combinations being AIH-PBC overlap syndrome and AIH-PSC overlap syndrome. This condition occurs when a patient simultaneously develops two or more distinct autoimmune disorders, such as the co-occurrence of systemic lupus erythematosus with rheumatoid arthritis or Sjögren's syndrome with primary biliary cirrhosis. The exact prevalence varies depending on the specific combination of diseases and the population studied, with some combinations being more common than others, as reported in a study published in 2023 1. Overlapping syndromes are more prevalent in women, particularly during childbearing years, and often have a genetic component with family history being a significant risk factor.
Some key points to consider:
- The prevalence of AIH-PBC overlap syndrome was reported as 8–10% among AIH patients, and 7.4–11.7% in Korean studies 1.
- A retrospective cohort study found that 13.8% of patients were diagnosed with AIH-PBC overlap syndrome, with 7.8% diagnosed simultaneously and 1.8% diagnosed with AIH first, and 4.3% diagnosed with PBC first 1.
- The pathophysiology involves shared genetic susceptibility factors and environmental triggers that lead to dysregulation of the immune system across multiple pathways, as discussed in a study published in 2009 1.
- Diagnosis typically requires comprehensive laboratory testing including autoantibody panels, inflammatory markers, and sometimes tissue biopsies to confirm the presence of multiple distinct autoimmune conditions.
- Treatment approaches generally need to address all present conditions simultaneously, often requiring combination immunosuppressive therapies tailored to the specific autoimmune diseases involved, as recommended in a study published in 2009 1.
From the Research
Prevalence of Overlapping Autoimmune Syndrome
- The prevalence of overlapping autoimmune syndrome is not well-established, as the definitions of these diseases have not been fully established 2.
- However, it is known that autoimmune diseases are multifactorial, with environmental and heritable factors, and the presence of more than one disorder is not uncommon 3.
- Some studies have reported cases of overlap syndrome, including a case of a middle-aged female with celiac disease, primary biliary cholangitis, autoimmune hepatitis, and evolving CREST syndrome 3.
- Another study reported a case of overlap syndrome with autoimmune idiopathic hepatitis and pulmonary idiopathic hypertension 4.
- A review article on overlap syndromes and autoimmune liver disease noted that overlapping autoimmune features are not infrequent, but appropriate diagnosis remains hindered by a lack of standardized diagnostic criteria 5.
Characteristics of Overlapping Autoimmune Syndrome
- Overlapping autoimmune syndrome can involve various combinations of autoimmune diseases, including systemic lupus erythematosus, progressive systemic sclerosis, polymyositis, and dermatomyositis 2.
- The syndrome can also involve autoimmune liver diseases, such as autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis 5.
- Patients with overlapping autoimmune syndrome may experience a range of symptoms, including generalized fatigue, fever, weight loss, and vertigo 3.
- Laboratory tests, such as antinuclear antibodies and anti-extractable nuclear antibody assays, can help diagnose overlapping autoimmune syndrome 3.
Treatment of Overlapping Autoimmune Syndrome
- The treatment of overlapping autoimmune syndrome is guided by small observational studies, and there is a need for more rigorous, quantitative research 6.
- A systematic review and meta-analysis found that combination therapy with ursodeoxycholic acid and corticosteroids and/or antimetabolites may be superior to other treatments for autoimmune hepatitis-primary biliary cholangitis 6.
- However, more studies are needed to determine the optimal treatments for other overlap syndromes 6.