Overview of Asthma

Upon completion of this section, you will be able to

• Define asthma
• Identify environmental factors that trigger asthma

This Case Study in Environmental Medicine focuses specifically on the environmental factors that contribute to asthma expression and severity. The goal is to identify those factors, with the hope of moderating or eliminating exposures or reducing their effect.

This case study is not a comprehensive review of asthma, nor a complete review of asthma management. Many excellent texts and articles have covered this topic. The Global Initiative for Asthma (GINA) updated the Global Strategy for Asthma Management and Prevention in 2011. This document provides recommendations on

• Asthma assessment,
• Monitoring,
• Pharmacotherapy,
• Asthma education and,
• Implementation of asthma guidelines in health care systems.

The NIH Guidelines for Diagnosis and Management of Asthma provide key recommendations about the disease. This Report was developed by a panel convened by the National Asthma Education and Prevention Program (NAEPP), coordinated by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health. The third and most recent report, Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma (EPR-3) was released in August 2007. The full report is available online at http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.htm.

The National Heart, Lung, and Blood Institute defines asthma as “…a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role, in particular

• Mast cells,
• Eosinophils,
• T lymphocytes,
• Airway Macrophages,
• Neutrophils, and
• Epithelial cells.

In susceptible individuals, this inflammation causes recurrent episodes of

• Wheezing,
• Breathlessness,
• Chest tightness, and
• Coughing,

particularly at night or in the early morning. These episodes are usually associated with widespread but variable airflow obstruction that is often reversible, either spontaneously or with treatment. The inflammation also causes an associated increase in the existing bronchial hyper responsiveness to a variety of stimuli.” [NHLBI 2007].

Allergic diseases such as asthma, rhinitis, and eczema are increasing in prevalence.

• Asthma is a worldwide problem, with an estimated 300 million affected individuals [GINA 2011].
• The increasing incidence of asthma in many parts of the world continues to make it a global health concern [NHLBI 2003]. Asthma is one of a few diseases in the United States that is increasing in incidence among children and adults. This is despite scientific advances in improving treatment outcomes and understanding the pathogenesis [IOM 2000].
• During 2008-2010, an estimated 8.2% of the U.S. population had current asthma.
• Asthma prevalence was higher among Puerto Rican Hispanics (16.1%) and non-Hispanic blacks (11.2%) than among non-Hispanic whites (7.7%).
• Current asthma prevalence was also higher
  • Among children (9.5%) than among adults (7.7%),
  • Among females (9.2%) than among males (7.0%), and
  • Among persons with family income below 100% of the federal poverty threshold (11.2%) than among persons with family income at or above the federal poverty threshold (8.5% for 100% to less than 250% of the poverty threshold, 7.8% for 250% to less than 450% of the poverty threshold, and 6.7% for at or above 450% of the poverty threshold) for the United States [CDC 2012].

Environmental factors that contribute to asthma symptoms and severity include

• Viral infections [Gern 2004; Martinez 2003; Lemanske 2003],
• Allergens, such as
  • Cockroaches,
  • Dust mites,
  • Pollens,
  • Animal dander, and
  • Molds [Murray et al. 2001; Togias 2003; Jaakkola et al. 2005],
• Environmental tobacco smoke (ETS) (passive and active smoking),
• Indoor and outdoor air pollution,
• Occupational sensitizers: more than 300 substances were identified (including many chemical substances) causing occupational asthma or exacerbating its symptoms such as
  • Isocyanates,
  • Platinum salts and
  • Animal biological products [GINA 2011], and
• Miscellaneous causes such as
  • Exercise,
  • Food allergies,
  • Gastroesophageal reflux,
  • Aspirin, or
  • Other nonsteroidal anti-inflammatory drug (NSAID) sensitivity, sulfite sensitivity, and others [Weinberger 2003; NHLBI 1997].

This Case Study focuses on preventable environmental asthma triggers and measures that may decrease their effects on patients.

• Asthma is a chronic inflammatory disease. It is
  • Increasing in prevalence and
  • Triggered by many various environmental factors.