Allied Disorders and Complications of Rheumatoid Arthritis - A Statistical Comorbidity Study of 234 Autopsy Patients
Authors: Bely Miklos 
Published: August 2021

Objective : The incidence of co - morbidities is higher in rheumatoid arthritis (RA) than in the general population. Associated diseases accompanying RA may modify the clinical course and symptoms of RA and may influence the prevalence and mortality of complications related to the basic diseases and vica versa. The aim of this study was t o determine statistically the possible effect of certain allied disorders: type 2 diabetes mellitus (DM), atherosclerosis (Ath) , hypertension (HT), tuberculosis (Tb) with miliary dissemination (mTb), and malignant tumours (mTu) on the prevalence and mortal ity of RA related complications: systemic autoimmune vasculitis (AV), AA amyloidosis (AAa), lethal cardiac insufficiency (CI) caused by endo - , myo - or pancarditis, with or without interstitial pneumonitis, furthermore lethal septic infection (SI) combined with septic vasculitis (SV) or purulent arthritis (PA) Patients a nd Methods : Twohundred thirty four (234) non - selected autopsy patients with RA were studied. RA was confirmed clinically according to the criteria of the American College of Rheumatology (A CR). The presence of DM, Ath, HT, Tb, mTb, or mTu was determined and analyzed retrospectively, reviewing the clinical and pathological reports. The prevalence and mortality of AV, AAa, CI, SI, SV and PA was determined at autopsy and confirmed by a detailed review of extensive histological material. Demographics of different patient cohorts were compared with the Student (Welch) t - probe. The link between Ath, HT, DM, Tb, mTb, or mTu and AV, AAa, CI, SI, SV or PA was analyzed by Pearson's chi - squared (χ2) tes t. Results : RA associated with DM in 41 (17.52%), with severe Ath in 107 (45.72%), with HT in 41 (17.52%), with with Tb in 28 (11.96%), including active disseminated mTb in 9 (3.85%), and with mTu in 27 (11.54%) of 234 patients. RA was complicated by AV in 43 (18.38 %), by AAa in 48 (20.51%), by CI in 15 (6.41%), and by lethal SI in 33 (14.10%) of 234 patients. SI was combined with PA in 15 (6.41% of 234; 45.45% of 33) or with SV in 7 (2.99% of 234; 21.21% of 33) patients; PA or SV did not occur without gen eralized SI. The relationship between Ath and AV, AV (lethal), AAa, AAa (lethal), CI, SI, PA or SV was consequently inverse and mostly significant. There was a positive and significant correlation between Tb or mTb and AV, furthermore between mTb and mortality of AV. Discussion and Conclusions : The consequently inverse and (in most cases) significant correlation between atherosclerosis and autoimmune vasculitis, amyloidosis or sepsis shows that the prevalence or mortality of AV, AAa and SI wa s not influenced by Ath. RA patients with Ath may represent a special group, characterized by lower incidence of SV, AAa, SI, CI, and carry a better prognosis. Ath is basically an age - dependent phenomenon, characteristically present in RA patients with adv anced age, while AV, AAa (with or without lethal outcome) and SI are complications of RA, and characterize severe forms of disease, mostly in younger patients and with an earlier onset (without pronounced atherosclerosis). The positive and significant corr elation between Tb or mTb and AV suggest a positive influence of Tb or mTb on the prevalence of vasculitis, e.g. the presence of Tb or endogenous exacerbation and miliary dissemination of Tb may promote the AV. The significant connection between mTb and mo rtality of AV indicates an increased risk of lethal outcome.