The common inflammatory condition of sinusitis is associated with a 40% increased risk of later being diagnosed with a rheumatic condition, according to research published in the open access journal RMD Open.

The researchers used data from the Rochester Epidemiology Project, an interconnected system of medical records for more than 500,000 people living in Olmsted County, Minnesota, from 1966 to 2014. The study sample included 1,729 adults who were newly diagnosed with a systemic autoimmune rheumatic disease, such as rheumatoid arthritis, antiphospholipid syndrome, and Sjogren’s syndrome. Each of these patients was matched with three subjects without rheumatic disease, based on age at diagnosis and sex.

Sinusitis cases were divided into time periods of 1–5 years, 5–10 years, and 10 or more years before the diagnosis of rheumatic disease. Potential confounding factors such as age, weight, and smoking status at rheumatic disease diagnosis, gender, race, and ethnicity were also taken into account.

The researchers found that a history of sinusitis was associated with a 40% increased risk for any new rheumatic disease diagnosis, with the association being strongest for systemic autoimmune rheumatic diseases such as antiphospholipid syndrome (sevenfold increased risk) and Sjogren’s syndrome (more than doubled risk ).

In addition, acute sinusitis was associated with an 18% increased risk of developing seronegative rheumatoid arthritis (having symptoms but no detectable antibodies).

The association between sinusitis and newly diagnosed rheumatic disease was strongest in the 5-10 years preceding symptom onset, where the risk was 70% higher overall, three times higher for Sjogren’s syndrome, and twice as high for polymyalgia rheumatica. The more frequent the sinusitis episodes, the greater the odds of a new diagnosis of rheumatic disease.

However, the researchers clarify that this is an observational study, so no definitive conclusions can be drawn about causative factors. They also acknowledge several limitations to their findings, including the study’s predominantly white population and few cases of certain types of rheumatic diseases. In addition, they add that reverse causation cannot be ruled out, whereby rheumatic diseases themselves increase the risk of sinusitis.