Intercurrent autoimmune conditions in classic and non-ulcer interstitial cystitis

Interstitial cystitis (IC) is known to be one of the most bothersome conditions encountered in urological practice. It is frequently divided into two subtypes: classic and non-ulcer. Several authors have reported on autoantibodies in patients with IC and clinical and histopathological findings show similarities with those in some autoimmune disorders. Furthermore, IC has been shown to be associated with autoimmune diseases such as systemic lupus erythematosus, Sjögren's syndrome and autoimmune diseases of the thyroid gland. Our aim was to study the occurrence of associated autoimmune conditions in patients with IC diagnosed according to the National Institutes of Health/National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases criteria.

Our sample of IC patients consisted of 129 with classic IC and 93 with non-ulcer IC. Clinical records, including micturition charts, were surveyed, and a more in-depth interview was obtained by means of a telephone call. Autoimmune disorders, diagnosed by Swedish clinicians according to acknowledged diagnostic criteria, were registered.

Allergy was the most common IC-associated condition, 41% of all patients with classic IC and 47% of all patients with non-ulcer IC having some type or degree of hypersensitivity/allergy. Rheumatoid arthritis occurred in 13% of patients with classic IC and in 4% with non-ulcer IC. Inflammatory bowel disease was not diagnosed in any of the patients with non-ulcer IC whereas 2.3% of the patients with classic IC had either ulcerative colitis or Crohn's disease, approximately 33 times the prevalence seen in the general population.

It appears that systemic and autoimmune disorders are more prevalent in the IC population than in the general population.