RESUMO
Objective Anemia of chronic disease is a frequent consequence in rheumatoid arthritis and is associated with major clinical and patient outcomes. The present cross-sectional study explored the role of hepcidin (HEP) in anemia of chronic disease in rheumatoid arthritis by studying its relationships with markers of anemia, iron metabolism, inflammation, and erythropoiesis. Methods Blood samples from anemic ( n = 43) and nonanemic ( n = 43) rheumatoid arthritis patients were analyzed for markers of anemia (hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red cells distribution width, and reticulocyte hemoglobin), iron metabolism (iron, total iron binding capacity, ferritin, transferrin saturation, soluble transferrin receptor), inflammation (erythrocyte sedimentation rate, C-reactive protein, and interleukin 6), and erythropoiesis (erythropoietin and HEP). Correlation analysis was used to identify relationships between HEP and all other variables. Principal component analysis was used to identify common underlying dimensions representing linear combinations of all variables. Results HEP had statistically significant mostly moderate-to-large correlations with markers of anemia (0.30-0.70, all p < 0.01), small correlation with markers of iron metabolism and markers of inflammation ( r = 0.20-0.40, all p < 0.01), and moderate correlations with markers of erythropoiesis. Principal component analysis revealed two underlying components (factors) capturing approximately 50% of total variability. Factor 1 comprised mainly of markers of anemia, iron metabolism, and erythropoiesis and was related to "erythrocyte health status," while factor 2 comprised mainly markers of inflammation and iron metabolism and was related to "acute phase reactants." HEP was the only variable demonstrating substantial loadings on both factors. Conclusions HEP is related to markers of anemia, iron metabolism, inflammation, and erythropoiesis. In addition, when all variables are "reduced" to a minimum number of two "latent" factors, HEP is loaded on both, thus underlying its pivotal role in the complex interaction of the erythropoietic response in inflammation-induced anemia and/or functional iron deficiency.
RESUMO
Psoriatic arthritis (PsA) is a specific form of inflammatory arthritis associated with skin psoriasis. PsA makes part of a heterogeneous group of arthritides called the spondyloarthropathies. Several studies regarding the prevalence and incidence of PsA have been published during the last decades, showing a considerable variation of the disease occurrence among different populations. The purpose of this review is to discuss recent observations of epidemiological features for PsA patients. Thus, the literature was reviewed until May 2018 for studies regarding PsA epidemiology, classification criteria and risk factors for PsA development. Systematic reviews based on the international bibliography, are reporting the prevalence of the disease from 1/100.000 inhabitants in Japan to as high as 420/100.000 inhabitants in Italy. The annual incidence also varies, ranging from 1 to 23/100.000 inhabitants, while the average incidence rate is 6.5 cases/100.000 inhabitants. The random effect pooled PsA prevalence and incidence rates are 133/100.000 and 83/100.000 subjects respectively. Thus, a large heterogeneity between studies is observed. This variability could be explained by a number of factors such as the use of multiple and different classification criteria in the studies. Geographical variations are also observed regarding disease occurrence. Differences were found not only between different continents, but also within the same geographic regions. This could be explained by the different genetic background especially the distribution of the human leucocyte antigens. In addition, other factors such as environmental (infections, climate, sun exposure), dietary habits (fish oil consumption, Mediterranean diet) or life style habits (obesity, smoking), could explain the geographic variability in the prevalence estimates. The implementation of unanimous classification criteria and the conformation by the scientific community could lead to a better understanding of the disease epidemiology.
