Chapter 21: Diagnosis and Management of Asthma

INTRODUCTION TO ASTHMA AND ITS EPIDEMIOLOGY

Asthma is a complex disorder characterized by variable and recurring symptoms, airflow obstruction, bronchial hyperresponsiveness, and underlying airway inflammation. Asthma is one of the most common chronic diseases globally and domestically, affecting 23 million individuals and including 7 million in the United States alone. The prevalence of asthma has been increasing since the early 1980s across all age, gender, and racial groups. Asthma is the most common chronic disease in children and affects more children (7%-10%) than adults (3%-5%). Prevalence by gender varies by age, being more common in boys than girls in childhood but more common in women than men in adulthood. The slightly higher prevalence of asthma among African Americans and Puerto Ricans than Caucasians is highly correlated with socioeconomic status (ie, poverty, urban air quality, indoor allergens, lack of patient education, and inadequate medical care).

Asthma is associated with increased morbidity. Approximately 10 million ambulatory care visits, 2 million emergency department visits, and half a million hospitalizations annually are attributed to asthma. In fact, asthma is the third-ranking cause of hospitalization in children. It is also the leading cause of school absenteeism among children, accounting for >14 million total missed days of school. Meanwhile, in terms of risk by ethnicity, African Americans are also three times more likely to be hospitalized from asthma.

Asthma is also a major cause of mortality. It is the primary cause of more than 4,000 United States annual deaths due to asthma and is a contributing factor for nearly 7,000 other deaths annually. Despite improvements in the understanding of the pathophysiology and the expansion of available effective therapies, overall asthma death rates continue to increase by 50% among all genders, age groups, and ethnic groups since the 1980s. In addition, mortality rates for children younger than 19 years old have increased by nearly 80% percent since then. Mortality rates are higher in women, accounting for nearly 65% of all asthma deaths. African Americans are also three times more likely to die from asthma. In fact, mortality rates are highest in African-American women, whose rate is 2.5 times higher than that of Caucasian women. Aside from gender and ethnicity, risk factors for increased asthma mortality include severe airflow obstruction, multiple recent emergency department visits or hospitalizations in the past year, history of intubation or ICU admission in the past five years, nonuse of inhaled corticosteroids, current smoking, psychosocial stress and depression, socioeconomic factors, and attitudes and beliefs ...