Risk Factors:

About 22 million Americans have asthma.

Gender

Before puberty, asthma occurs more often in males, but after adolescence, it is common in females. In adults with similar cases of actual airway obstruction, women are likely to report more severe symptoms than men.

Hormonal fluctuations or changes in hormone levels may play a role in the severity of asthma in women. Between 30 - 40% of women with asthma experience fluctuations in severity that are associated with their menstrual cycle. Some women first develop asthma during or shortly after pregnancy, while others first develop it around the time of menopause (perimenopause).

Race and Ethnicity

African-Americans have higher rates of asthma than Caucasians or other ethnic groups. They are also more likely to die of the disease. Ethnicity and genetics, however, are less likely to play a role in these differences than socioeconomic differences, such as having less access to optimal health care, and greater likelihood of living in an urban area (another asthma risk factor).

Obesity

Studies report a strong association between obesity and asthma. Evidence also suggests that people who are overweight (body mass index greater than 25) have more difficulty getting their asthma under control. Weight loss in anyone who is obese and has asthma or shortness of breath helps reduce airway obstruction and improve lung function. [For more information, see In-Depth Report #53: Weight control and diet.]

Other Risk Factors

GERD. At least half of patients with asthma have gastroesophageal reflux disease (GERD), the cause of heartburn. It is not entirely clear which condition causes the other or whether they are both due to common factors. Treating GERD does not appear to improve asthma control. [For more information, see In-Depth Report #85: Heartburn and gastroesophageal reflux disease.]

Aspirin-Induced Asthma. About 10% of adults and fewer children have aspirin-induced asthma (AIA). With this condition, asthma gets worse when patients take aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). AIA often develops after a viral infection. It is a particularly severe asthmatic condition, associated with many asthma-related hospitalizations. In about 5% of cases, aspirin is responsible for a syndrome that involves multiple attacks of asthma, sinusitis, and nasal congestion. Such patients also often have polyps (small benign growths) in the nasal passages. Patients with aspirin-induced asthma (AIA) should avoid aspirin and other NSAIDs, including ibuprofen (Advil) and naproxen (Aleve).