Link Between Initial Autoimmune Disorder and Later Autoimmune Disorders

Patients who develop an immune-mediated inflammatory disease (IMID) have a significantly increased risk of developing a subsequent IMID, according to data presented here on February 17 at the 12th Congress of the European Crohn's and Colitis Organisation, Inflammatory Bowel Diseases (ECCO-IBD).

Remo Panaccione, MD, University of Calgary, Calgary, Alberta, and colleagues compared the risk of developing subsequent IMIDs among cohorts of patients with and without an initial IMID, for each of the following IMIDs: ankylosing spondylitis, celiac disease, hidradenitis suppurativa, inflammatory bowel disease (IBD), lupus, psoriatic arthritis, psoriasis, rheumatoid arthritis, and uveitis.

The investigators estimated IMID risk using data from a large United States insurance claims database (January 2001-September 2015).

Up to 1,000 controls were matched with replacement by age, sex, state of residence, and insurance type to case patients aged 18 to 64 years who had an initial incident IMID.

The analysis included a total of 398,935 patients. Across the 9 initial IMID cohorts, the median range of follow-up was 918 to 1,023 days for cases and 883 to 971 days for controls.

The range of percent of patients with ?1 observed secondary IMID was 5.2% to 47.2% for cases and 0.8% to 1.1% for controls.

Compared with matched controls, patients with an initial IMID had a significantly higher risk of developing any of the other 8 secondary IMIDs (P ? .002). Patients with IBD as the primary IMID had 7.5 times the risk of developing any subsequent IMID as controls.

Dr. Panaccione emphasised that the results should be interpreted with caution given that the study was based on insurance claims data which include limited clinical detail, variable patient follow-up, possible coding errors and omissions, and an inability in to validate the onset and presence of medical conditions.

He also noted that the results do not prove causality.

"Causal direction and pathways between IMIDs is unclear," he said. "Documented secondary IMIDS may be more common among cases than controls because cases had more contact with clinicians."

Funding for this study was provided by AbbVie, Inc.

[Presentation title: The Risk of Developing Subsequent Immune-Mediated Inflammatory Diseases: a Retrospective Matched Cohort Study. Abstract P698]