Asthma and EpiCenter

Now that we’ve sprung forward, health care professionals are readying themselves for the yearly increase in seasonal asthma visits. While spring allergens related to pollen do lead to increased ED visits for exacerbation of asthma symptoms, the highest spikes in asthma-related ED visits usually occur each year in the fall, beginning in September.

This has been attributed to fall allergens such as ragweed, mold, and dust mites stirred by awakening heat vents. Among children, the return to school and accompanying influx in flu cases is also cited as a cause of increased asthma symptoms. In addition, schools house their own varieties of dust mites and molds, which can be different than the ones found in students’ homes and therefore more triggering.

According to the CDC’s National Surveillance of Asthma, there was an average of 8.4 ED visits per 100 persons with asthma from from 2001 to 2009. These visits were highest for children aged 0-4 years (20.8 visits per 100 persons with asthma), and lowest for adults aged 65 and older. In 2012, asthma prevalence in the US was at 8% among adults and 9% among children.

US Air Quality

EpiCenter has several tools available that can be useful when looking at asthma-related hospital data. EpiCenter’s “Exacerbation” classification looks for chief complaints with keywords related to the exacerbation of asthma, bronchitis, emphysema, and Chronic Obstructive Pulmonary Disease (COPD). In regions where admissions data is collected, it’s also possible to plot charts for hospital admissions related to the exacerbation classifier. On the Maps page, air quality markers can be plotted geographically for any historic date, enabling users to view air quality data for regions that may have seen an influx in asthma-related ED visits. Air quality data can also be downloaded as a CSV file.

US 5 years by month PER 100,000

While fall and spring are typically where the number of asthma-related ED visits surge, this January we saw a significant influx in ED visits within EpiCenter’s exacerbation classifier. The numbers were particularly high on the coldest days of the Polar Vortex. There are several likely causes for this: First, when very cold air is breathed in through the mouth, the muscles around the airways and bronchial tubes narrow and tighten, and the lungs can spasm and cramp. This can cause a temporary asthma-like effect even in people who do not usually suffer from asthma; it can be extremely triggering for those with asthma or COPD. Alternatively, people are more likely to stay indoors and crank up their furnaces, which can lead to additional exposure to dust and other indoor allergens as they are blown out of heating vents. Chimney smoke is another common asthma trigger, and cold weather also often coincides with an increase in colds and flu, which can exacerbate asthma and COPD symptoms.

The CDC’s National Surveillance of Asthma notes that the number of asthma deaths declined steadily from 2001 (4,269) to 2009 (3,388) at a rate of 3.3% per year. Asthma deaths per million population declined 4.9% per year from 15.0 deaths per million population in 2001 to 10.5 deaths per million population in 2009.

Still, hospitalizations and deaths due to asthma are largely preventable. The study states:

Asthma hospitalizations represent a serious adverse outcome that is theoretically preventable with high-quality health care, patient education, and optimal management of asthma. Furthermore, an asthma hospitalization is a marker for increased risk of future asthma exacerbations.

Asthma deaths are uncommon, especially among children and young adults, but they remain a focus of preventative efforts because high-quality health care and patient education should theoretically prevent asthma-related deaths.

Improvements to our ability to track and analyze hospital admissions and readmissions are the first steps to improving care. As technology continues to develop, we look forward to seeing the number of asthma-related deaths and hospitalizations continue to steadily decrease. As always, HMS will continue to develop and enhance tools that help public health officials track and analyze the relevant data in real time.