Risk of asthma and autoimmune diseases and related conditions in patients hospitalized for obesity

Background. Although there are putative mechanistic links between obesity and autoimmune diseases, obesity is not considered a risk factor for most autoimmune diseases. Methods. Using the nation-wide Hospital Discharge Register we defined a cohort of 29,665 patients hospitalized for obesity since year 1964. The patients were followed for hospitalization for any of 34 autoimmune or related conditions through year 2007. Standardized incidence ratios (SIRs) were calculated for autoimmune diseases in obese individuals compared to those who had not been hospitalized for obesity. Results. Among 22 immune diseases diagnosed after hospitalization for obesity and in at least 5 patients, the overall SIR was 2.05. Of the individual diseases studied, the risk of 16 was significantly increased; none displayed a decreased risk. Psoriasis (4.54) and Behcet's disease (4.49) exhibited the highest risks, followed by Hashimoto's disease/hypothyroidism (4.12) and asthma (3.39). Small but significant increases in SIRs were also noted for the common autoimmune diseases Graves' sdisease/hyperthyroidism (1.28) and rheumatoid arthritis (1.37). Conclusions. The present population of obese individuals, subsequently diagnosed with a number of autoimmune diseases and related conditions, was hospitalized at a relatively young age. Further studies are needed to describe the morbidity in the obese population at large.