Risk factors associated with systemic lupus erythematosis in a Mexican population

To assess risk factors associated with systemic lupus erythematosus (SLE) in the Mexican population.

A case-control study was conducted on June 1996, at the Reumathology Clinic of Hospital de Especialidades del Centro Médico Nacional Siglo XXI (HE CMN), Instituto Mexicano del Seguro Social, in Mexico City. Cases were one hundred thirty subjects with four or more SLE criteria and disease evolution of +/- 5 years. Controls were hospitalized patients with acute diseases but without autoimmune diseases. Cases and controls were matched 1:1 by age and gender; both groups were evaluated by direct interview through a structured questionnaire. The following risk factors were assessed: genetic family history of SLE and connective tissue disease; socioedemographic (ethnicity, geographic distribution, education, monthly income); hormonal (use of oral contraceptives, replacement therapy and gynecoobstetric background); environmental (use of hair products, living with dogs, bacterial/viral infections, and allergies). Statistical analysis consisted of odd ratios (OR) with 95% confidence intervals (CI) and multivariate analysis using logistic regression.

The multivariate model showed association with family history of SLE (OR 4.2, CI 95% 1.17-15.2), family history of connective tissue disorder (OR 2.6, CI 95% 1.15-4.5), use of oral contraceptives for more than one year (OR 2.1, CI 95% 1.13-4.3), repetitive pharyngitis (OR 2.1, CI 95% 1.18-3.6), and use of medications (OR 5.0 IC 95% 1.62-21.6). No association was found with socieconomic status, hair dye products, asthma, or allergies.

Genetic factors, such as family history of SLE and connective tissue disease in first-degree relatives, persist as important factors in the development of SLE. Other factors, such as use of some drugs, oral contraceptives, and repetitive pharyngitis, may also favor the onset of disease in genetically susceptible hosts. The English version of this paper is available at: http://www.insp.mx/salud/index.html.