Trends of asthma in Mexico: an 11-year analysis in a nationwide institution

STUDY OBJECTIVES: Asthma prevalence is increasing in many countries. Some recent articles, however, claim that this tendency is ending. Our aim was to investigate asthma trends in Mexico. DESIGN: Annual data on health services provided to asthmatic patients were retrospectively analyzed from 1991 to 2001. SETTING: The Instituto Mexicano del Seguro Social, the largest nationwide medical institution in Mexico (approximately 24 to 32 million insured subjects). PARTICIPANTS: Health services provided to subjects of any age. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Asthma-associated health services, either expressed as absolute number or as rate per insured subjects, progressively increased until 1997 in family physician office visits (FPOVs) [newly diagnosed cases only], emergency department visits (ERVs), and hospital discharges (HDs). From that year onward, the number and rates of asthma-associated health services decreased. The same trends were observed for age groups 0 to 4 years, 5 to 14 years, 15 to 44 years, and 45 to 64 years. Using a different approach, asthma was diagnosed each year in approximately 0.4% of all FPOVs, but a decrease in this percentage was observed from 1997 onward. Likewise, asthma caused increasing percentages of all ERVs and HDs until 1997, followed by a sharp decline thereafter. CONCLUSIONS: A decline in absolute and relative numbers of asthma-associated health services occurred over recent years in all medical settings, suggesting that the epidemic of new asthma cases is ending and/or that better control of the disease has been achieved.