Incidence, prevalence, and demographic characteristics of ocular cicatricial pemphigoid in Colombia: data from the National Health Registry 2009-2019

AIM: To provide an epidemiological characterization of ocular cicatricial pemphigoid (OCP) in Colombia. METHODS: We conducted a cross-sectional study using SISPRO. We applied the specific code of the International Classification of Diseases for Ocular Pemphigoid, from 2009-2019 to estimate prevalence, incidence, and the demographic status of the disease in Colombia. RESULTS: The estimated average prevalence was 0.22 per 1 000 000 inhabitants, and the estimated average incidence was 0.24 per 1 000 000 inhabitants. With a female predominance of 62.5%, and a male/female ratio of 1:1.6. The group of patients diagnosed with the disease after the age of 80 presented the highest prevalence. The departments with the highest prevalence were Antioquia, Bogotá, and Santander. CONCLUSION: There are important differences between worldwide and Colombian prevalence and incidence data, which may be related to genetic and epigenetic factors, and the possible underdiagnosis of the disease. According to the results, OCP is an extremely rare disease in Colombia. Nevertheless, it is important to encourage awareness of the disease due to its devastating consequences.

IgM Deficiency in Autoimmune Blistering Mucocutaneous Diseases Following Various Treatments: Long Term Follow-Up and Relevant Observations

IgM deficiency has been reported in patients with many autoimmune diseases treated with Rituximab (RTX). It has not been studied, in detail, in autoimmune mucocutaneous blistering diseases (AIMBD). Our objectives were: (i) Examine the dynamics of IgM levels in patients with and without RTX. (ii) Influence of reduced serum IgM levels on clinical and laboratory parameters. (iii) Explore the possible molecular and cellular basis for reduced serum IgM levels. This retrospective study that was conducted in a single-center from 2000 to 2020. Serial IgM levels were studied in 348 patients with five AIMBD (pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, mucous membrane pemphigoid, and ocular cicatricial pemphigoid) and found decreased in 55 patients treated with RTX, IVIG, and conventional immunosuppressive therapy (CIST). Hence the incidence of decreased serum IgM is low. The incidence of decreased IgM in patients treated with RTX was 19.6%, in patients treated with IVIG and CIST, it was 52.8% amongst the 55 patients. IgM levels in the post-RTX group were statistically significantly different from the IVIG group (p<0.018) and CIST group (p<0.001). There were no statistically significant differences between the groups in other clinical and laboratory measures. Decreased serum IgM did not affect depletion or repopulation of CD19+ B cells. Patients in the three groups achieved clinical and serological remission, in spite of decreased IgM levels. Decrease in IgM was isolated, since IgG and IgA were normal throughout the study period. Decreased IgM persisted at the same level, while the patients were in clinical remission, for several years. In spite of persistent decreased IgM levels, the patients did not develop infections, tumors, other autoimmune diseases, or warrant hospitalization. Studies on IgM deficiency in knockout mice provided valuable insights. There is no universally accepted mechanism that defines decreased IgM levels in AIMBD. The data is complex, multifactorial, sometimes contradictory, and not well understood. Nonetheless, data in this study provides novel information that enhances our understanding of the biology of IgM in health and disease.