African Colombians Have Low Incidence of Rheumatoid Arthritis

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African Colombians Have Low Incidence of Rheumatoid Arthritis

A DGReview of : " Rheumatoid arthritis in African Colombians from Quibdo "

Seminars in Arthritis and Rheumatism

01/11/2002

By Rose

Rheumatoid arthritis is rare in residents of Quibdo, Columbia, who are of

African descent.

Researchers from the United States and Colombia, who compared the incidence of

rheumatoid arthritis (RA) in African Colombians and of Mestizo Colombians, found

that the condition lacks association with the HLA-DRB1 and DQB11 alleles.

Furthermore, the found that radiographic damage may be less severe in African

Colombians than in Mestizos. In addition, the authors write, rheumatoid factors

and antikeratin antibodies are not markers of progression and of RA activity in

this population.

There is only limited data available relevant to the prevalence, incidence, and

genetic or environmental factors influencing risk or severity of RA in

non-Caucasian subjects, the investigators write.

Prevalence of RA in Caucasian and some Native Americans is estimated at 1

percent or more. However, it has been reported to be low in some African

populations.

The study aimed to determine the hospital incidence and period prevalence of RA

in African Colombians living in Quibdo. They drew from data collected at a

primary-to-tertiary care centre at Hospital San Francisco de Asis.

Studies were then undertaken relative to genetic and immunologic factors, which

influenced the risk and severity of rheumatoid arthritis (RA). These included

human leukocyte antigen (HLA) genes, immunoglobulin A (IgA) rheumatoid factor

(RF) and antikeratin antibodies (AKA).

Participants included 3.044 patients whose outpatient charts for 1995, relative

to hospital incidence, were reviewed. Stratified sampling of all African

Colombian aged 18 or older having arthralgia assessed the period prevalence

during January to December in 1996. Participants also underwent x-rays of hands

and feet, provided a blood sample, and completed a survey and a pretested

standard questionnaire.

Turbidimetry and enzyme-linked Immunosorbent assay (ELISA), respectively,

measured the total and IgA RF and AKA was assessed by indirect

immunofluorescence on rat oesophagus. Polymerase chain reaction technique with

primers of specific sequence and reverse dot blot determined the HLA-DRB1 and

DQB1 alleles.

Hospital incidence of RA was determined as 0.65 cases per 1.000 person years.

Subjects with arthralgia totaled 321 (0.3 percent 95 confidence interval [CI],

0.28-0.3) and 18 fulfilled the criteria of the American College of Rheumatology

for RA (PP in the general population, 0.01 percent 95 percent CI, 0.008-0.02).

By comparison with Mestizo patients, the erosion scores in African Colombians

were low.

Researchers determined there was no association between any HLA allele, RA risk

or severity, or between autoantibodies and RA severity in African Colombians.

There were no significant differences seen between African Colombians and

Mestizo patients in the presence of RF (total and IgA), AKA, age at onset,

extra-articular manifestations, formal education and history of malaria.

Seminars in Arthritis & Rheumatism Vol 31 No 3 pp 191-198.