Incidence and prevalence of lupus in Buenos Aires, Argentina: a 11-year health management organisation-based study.
OBJECTIVE
Studies regarding the epidemiology of systemic lupus erythematosus (SLE) are lacking in Argentina. Our purpose was to estimate the incidence and prevalence of SLE in a university hospital-based health management organisation in Buenos Aires (HIMCP).


METHODS
For incidence calculation, the population at risk included all adult members of the HIMCP, with continuous affiliation for at least 1 year from January 1998 to January 2009. Each person was followed until he/she voluntarily left the HIMCP, death or finalisation of the study. Multiple methods for case finding were used to ensure complete ascertainment: (a) patients with problem SLE, undifferentiated autoimmune disease or mixed connective tissue disease in the Computer-based Patient Record System, (b) patients with positive antinuclear antibody test, anti-Sm antibodies and/or anti-dsDNA antibodies in the laboratory database and (c) patients who consumed hydroxichloroquine, chloroquine, azathioprine, cyclophosphamide, mycophenolate, cyclosporine or rituximab, from the administrative HIMCP drugs database. Medical records of all patients found were reviewed, and only patients fulfilling ACR criteria for SLE were included. Global and gender incidence rate (IR) was calculated. Prevalence was estimated on 1 January 2009, and the denominator population was the number of active members >18 years at that date (n=127 959).


RESULTS
In the study period, 68 patients developed SLE. The observed IR (per 100 000 person-years, (CI 95%)) was 6.3 (4.9 to 7.7) for total population; 8.9 (CI 6.6 to 11.2) for women and 2.6 (1.2 to 3.9) for men. On 1 January 2009, 75 prevalent cases were identified. Prevalence rates (cases per 100 000 habitants, (CI 95%)) were 58.6 (46.1 to 73.5) for total population; 83.2 (63.9 to 106.4) for women and 23 (CI 11.9 to 40.1) for men.


CONCLUSIONS
SLE incidence and prevalence rates in Argentina are in agreement with those of other studies from different parts of the world.
Rheumatology Section, Medical Services , Hospital Italiano de Buenos Aires , and Fundacion Pedro M. Catoggio para el Progreso de la Reumatologia, Buenos Aires , Argentina ; Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
M
M
Scolnik
Rheumatology Section, Medical Services , Hospital Italiano de Buenos Aires , and Fundacion Pedro M. Catoggio para el Progreso de la Reumatologia, Buenos Aires , Argentina ; Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
J
J
Marin
Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
S M
SM
Valeiras
Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
M F
MF
Marchese
Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
A S
AS
Talani
Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
N L
NL
Avellaneda
Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
A
A
Etchepare
Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
P
P
Etchepare
Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
M S
MS
Plou
Rheumatology Section, Medical Services , Hospital Italiano de Buenos Aires , and Fundacion Pedro M. Catoggio para el Progreso de la Reumatologia, Buenos Aires , Argentina ; Instituto Universitario Escuela de Medicina Hospital Italiano de Buenos Aires , Buenos Aires , Argentina.
E R
ER
Soriano
Autoimmune Diseases; Epidemiology; Systemic Lupus Erythematosus