Polymyalgia rheumatica and diverticular disease: just two distinct age-related disorders or more? Results from a case-control study

In a previous report of two married cohabiting couples affected by polymyalgia rheumatica (PMR), we noticed that the wife of one couple and both members of the other couple suffered from symptomatic diverticular disease (DD), whose diagnosis was made before the onset of PMR. We investigated whether DD might be a risk factor for the development of PMR. We conducted a case-control study informed on a database containing the prospectively collected medical records of consecutive PMR patients. Among comorbidities, attention was focused on symptomatic DD, provided that the diagnosis had been made by colonoscopy and/or computed tomography scan. As controls, we identified one control per case at random among those matched by age and sex attending the ophthalmic and orthopedic outpatient clinics, as long as a PMR diagnosis had been excluded. A logistic regression model was used, following a multiplicative model, and results were presented as odds ratio (OR) and 95% confidence intervals (95% CI). The most frequent comorbidities in the two groups of patients (121 cases and 121 controls) were chronic coronary artery disease, atrial fibrillation, diabetes mellitus, hypertension, DD, hypercholesterolemia, osteoporosis, chronic obstructive pulmonary disease, gastroesophageal reflux disease, and cholelithiasis. The association between PMR and DD (OR = 4.06; 95% CI: 1.76-9.35) was by far stronger than that found comparing PMR with the other comorbidities. The chronic bowel inflammation induced by dysbiosis in patients with symptomatic DD could be a critical immunopathological mechanism supporting the development or exacerbation of PMR in susceptible individuals.