Background Rheumatoid arthritis is an inflammatory musculoskeletal disease, which presents mainly by joint swelling and pain, but also with a variety of other symptoms. Anemia has already been detected as additional marker for disease activity but there is no evidence about the differences between young- (YO) and late-onset (LO) (onset of disease after 60 years of age) RA patients.
Objectives To investigate differences in the prevalence of anemia between YO-RA and LO-RA over the course of the disease and find factors that can be linked to anemia.
Methods We selected an inception cohort of RA patients that was treated with DMARDs for at least a year from a prospective longitudinal database and used data of the first 20 blood draws of these patients, which were performed over up to 7 years of disease course. We used longitudinal, logistic regression and chi-square analyses to determine different aspects of anemia. We evaluated the risk for developing anemia, as well as factors associated with different types of anemia based on the mean corpuscular volume, the mean haemoglobin, kidney function, and disease activity.
Results 326 RA patients were included in this study, 126 patients were late-onset RA (mean±SD: age: 69.4±6.6 years, 71% female, glomerular filtration rate (GFR) 72.5±15.6ml/min, haemoglobin (HB) 13.1±1.3g/dl, 47% rheumatoid factor (RF) positive and 42% anti-citrullinated antibodies (ACPA) positive) and 200 patients young-onset RA (mean±SD: age: 47.4±9.6 years, 75% female, glomerular filtration rate (GFR) 86.6±16.5ml/min, haemoglobin (HB) 13.3±1.4g/dl, 55.5% RF positive and 50% ACPA positive). At baseline there was no significant difference in composite measures of disease activity, however LO-RA showed significant higher acute phase reactants and swollen joints and lower GFR than YO-RA. Over the observation period there was a significant higher prevalence of anemia in LO than in YO (23.4% vs. 17.6%), this relates to an odds ratio (OR) of 1.4 (CI: 1.2–1.7, p<0.001). When using the time point of the lowest haemoglobin level, there was even a higher OR of 1.67 (1.09–2.54) for LO to have anemia. 45% of YO have at least one incident episode of anemia over the follow-up period, whereas this is the case in 54% of LO (p=0.03). This difference increased when looking at the very late-onset patients (age at onset >75years, n=20) to 70%. Anemia was present during 24.2±31.5% versus 17.6±27.6% of the observed time period. Haemoglobin levels were also significantly lower in patents with later onset of RA (p<0.001).
Normocytic normochromic anemia tended to be more prevalent in very-late-onset RA. (see figure 1A). Among patients with anemia impaired kidney function (GFR<60ml/min) was observed in 26% of LO patients and 47% of very-late-onset patients, which was significantly higher compared to 3% in YO (p=0.015; figure 1B).
Conclusions RA patients with late-onset disease show a greater risk of anemia. Anemia in late-onset RA patients is more strongly associated with decreased kidney function, and anemic episodes are longer and more severe.
Disclosure of Interest None declared