Asthma Epidemiology and Natural History

Floyd J. Malveaux, M.D., Ph.D.Howard University College of Medicine

Asthma Mortality

Hospitalization for Asthma

Epidemiology of Asthma• In the United States Asthma affects an estimated

15-18 million persons.• Of these 5 million are children less than 18 years• Over 10 million days are missed from school due

to asthma• Over 200,000 hospitalizations resulting in 1.9

million days of inpatient care• 1.7 times increase risk of learning disability.

Vital Health Stat 1995; 10:94-95

Epidemiology of Asthma

• Number of persons with Asthma DOUBLED in past 20 years

• Asthma in children <5 y.o. increased 160% between 1980-94

• Children, 5-14 y.o., had a 74% increase• Asthma symptoms more prevalent in

low SES and urban (esp. inner-city)

Hypotheses Underlying Increase in Asthma

• Changes in lifestyle, with more time spent indoors

• Increase exposure to indoor allergens• Lack of exercise• Increase in obesity• Dietary changes

– J Allergy Clin Immunol 2000;105:399-408

Asthma in Inner-CityA recent study found that one out of five children in Baltimore, MD and Washington, DC were receiving the wrong or no treatment for asthma.

Even with high quality care, some cases of asthma are particularly difficult to control; and medications cause adverse side effects in some people.

Moreover, lack of timely surveillance data at the State and local levels impedes planning of intervention efforts.

Socioeconomic Factors and Asthma in Children

• Children living in poverty are more likely to use urgent care for primary care source

• Children living with family income less than $20,000 are twice as likely to be held behind in school than their non asthmatic counterparts

• Allergen sensitization to house dust mite or cockroach is more prevalent in inner city children

• African American children are at increased risk for asthma prevalence, morbidity and mortality– Pediatrics 1993;91:56-61

Origin of Childhood Asthma

• Environmental– Socioeconomic

status– Allergen

Exposure– Infections– Irritants

• Genetic– Twin Studies– Risk to relatives– Increased

susceptibility• Polymorphism• Alteration of

host resistance

Exposure to Allergen

• Concentration X Time = Exposure

Allergen Exposure and Childhood Asthma

• For dust mite and cockroach allergens, there is a dose-response relationship between domestic exposure and sensitization.

• Given that allergen provocation can induce many of the features of asthma, the findings strongly suggest that there is a causal relationship between allergen exposure in the home and asthma.

• J Allergy Clin Immunol 2000; 105(2Pt2):S503-8