Trends and Associations of Chilblains Prevalence with Connective Tissue Diseases, Including COVID-19 Incidence

Chillblains, also known as perniosis, are inflammatory skin lesions that have long been associated with exposure to low temperatures. However, their co-occurrence with autoimmune illnesses and viral infections, particularly COVID-19, has received increased attention. This study was designed to examine chilblains' documented prevalence and association with autoimmune diseases and COVID-19.

This was a descriptive cross-sectional study carried out at Mass General Brigham (MGB), an extensive integrated healthcare system situated in Greater Boston, Massachusetts. The study included patients with a confirmed diagnosis of chilblains from 2014 to 2021 and COVID-19 from 2020 to 2021. The study was approved by the Mass General Brigham Human Research Committee, ensuring compliance with ethical standards.

During the study, 24,711 charts were reviewed, identifying 1478 patients with chilblains, resulting in an overall registered prevalence of 0.02463%. The majority of chilblains patients were female (72.5%), with the highest proportion in the 31-30-year age group (31.3%). 169 (11.43%) patients were identified with autoimmune diseases, predominantly females (94.1%). The most prevalent condition among them was systemic lupus erythematosus (SLE) (52.6%). Among COVID-19-positive patients (n = 88,763), 30 were diagnosed with chilblains, leading to a prevalence of 0.033%. Females (66.7%) and individuals aged 40-50 (56.7%) were predominantly affected.

This study found a low prevalence primarily among young females and a significant correlation with connective tissue disorders like SLE. The study also notes a rare occurrence of chilblains in COVID-19 patients, suggesting a possible association that requires further investigation, particularly regarding demographic patterns within this subgroup.