Systemic lupus erythematosus = many concomitant diseases?

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that by nature leads to multiple organ involvement and is associated with a number of typical concomitant diseases (e.g. cardiovascular diseases, kidney diseases). Scientists from our epidemiological department have investigated how often these already exist before the onset of the disease or if they only appear after the onset of the disease, i.e. how often they can be a consequence of the disease. For this purpose, health insurance data of people with new-onset SLE were compared with data of people without known autoimmune diseases or with new-onset diabetes mellitus. Diabetes mellitus was chosen because a set of diagnostic measures are performed at new onset of both diseases. The results show that the increase in other chronic diseases such as hypertension, osteoporosis and depression was observed in both SLE and diabetes.  This was accompanied by a corresponding increase in prescriptions for cardiovascular drugs, painkillers, anti-inflammatories and antidepressants. The comparison between SLE and diabetes mellitus shows that the more intensive diagnostics detect pre-existing chronic diseases, while the comparison with a control group without autoimmune diseases underestimates this “detection bias”. When it comes to estimating the disease burden and treatment of a chronic disease like SLE, the choice of an appropriate control group is of great importance to avoid false conclusions.