Is rheumatoid arthritis in African descendants from North and South America the same?

Possible influence of resistance to malaria in clinical presentation of rheumatoid arthritis: biological significance of natural selection

Rheumatoid arthritis (RA) is a common autoimmune disease that affects all ethnic groups. Genetic factors, mainly HLA alleles, are highly associated with increased risk to develop RA. However, there are few available data about the role of these genetic polymorphisms in the prevalence or severity of RA in the Afrodescendant population, who have evolutionarily and by natural selection developed mutations that allowed them to acquire resistance to infectious diseases like malaria. Some of the mechanisms, by which this resistance was developed as a product of natural selection, are involved in different forms of immunological response, many of them of a well-known importance in the pathophysiology of RA. This paper focuses on presenting the known mechanisms of resistance to malaria and their possible contribution to the pathophysiology of RA, including "loss-of-function" mutations, lack of expression of chemokine receptors, decrease of immune complexes clearance by asplenia, or increase of immune reactivity mediated by B cells, among other mechanisms in this special group of patients.

Latitude gradient influences the age of onset in rheumatoid arthritis patients

The mean age of rheumatoid arthritis (RA) onset is around 50 years as reported in several clinical trials involving Caucasian patients. However, clinical observations suggest that Mexican RA patients' disease is initiated at a younger age. The objective of the study was to assess whether the age of onset of RA is different in Mexican and in Canadian RA patients. Certified rheumatologists from Canada and Mexico directly interviewed consecutive RA patients attending their clinics regarding the date patients first noticed a swollen joint. None of the participant rheumatologists were aware of the primary aim of this exploratory study at the time of the interviews. Data was gathered from 161 Mexican (91% women) and 130 Canadian (77% women) RA patients collected by three rheumatologists in each country. Duration since disease onset was not different within countries (mean 95% confidence interval [CI] for differences -10 to 16 years, p = 0.12 for Canadians, and -6 to 10 years, p = 0.26, for Mexicans). However, there was a significant difference between the two countries. Mexicans patients on average developed RA almost 12 years younger than Canadians (95% CI for difference 9 to 15 years, p < 0.001). Frequency distribution showed that 35.5% of Canadians but only 4% of Mexicans had the onset of the disease after the age of 55 (all p < 0.001). It appears that RA begins at a much younger age in Mexican than Canadian patients. If this were confirmed after controlling for different confounders and biases, it would have important societal, economic, and therapeutic implications.

Sociodemographic differences in quality of life in rheumatoid arthritis

Assessment of health-related quality of life (HR-QOL) in people with rheumatoid arthritis (RA) has become important in health research and can inform clinical care. Many studies have found sociodemographic differences in the HR-QOL of people with RA, and interpreting these differences can be challenging. Biological, health disparity, reporting and assessment instrument differences are a few of the possible explanations that should be considered when interpreting results. Our review of the evidence of sociodemographic differences in HR-QOL in people with RA produced 34 articles describing 49 studies.Typically, patients with RA who were older, female, less educated, non-employed and/or less affluent tended to have significantly lower HR-QOL than other groups. Some evidence also indicated that people with RA who are non-White or who live in rural settings may also tend to have lower HR-QOL scores, but the number of studies supporting these findings was sparse. Researchers and clinicians can optimise their assessment of HR-QOL by finding well validated instruments for the context they are working in. Additional research is needed to identify the exact causes of HR-QOL differences so that quality treatment can be provided to those in need.