CALGARY, ALBERTA—Identification of risk factors for near-fatal asthma (NFA) is important for the assessment of all patients with asthma. In a population-based study of asthma patients in Alberta, Ian Mitchell, MD, and colleagues identified a number of risk factors for NFA, such as being younger than 5 years at asthma diagnosis and having a history of life-threatening allergic reactions.[1]

The study was one of the few to garner such data prospectively from a diverse population. “Most of the research in this area has been retrospective and included patients in a single intensive care unit,” said Dr. Mitchell, a Professor of Pediatrics in the Child Health Research Unit at the University of Calgary.

TWO COMPARISON GROUPS

During a 20-month period, the investigators followed 45 Alberta residents who had suffered an episode of NFA requiring assisted ventilation in an intensive care unit. These cases were compared to two other groups in Alberta—197 patients who had visited the emergency department for and received a discharge diagnosis of asthma (but not NFA) and a random sample of 303 asthma patients in a community control group.

Each group completed a questionnaire asking for the following asthma-related data: age at diagnosis, symptom duration before diagnosis, self-assessment of asthma severity and symptom frequency, medication use, allergic disease history, asthma triggers, the trigger for the current asthma episode, and feelings of vulnerability to asthma.

NFA RISK FACTORS

The three groups had similar age distributions and no significant differences in exposure to pets or secondhand cigarette smoke in the home. Similar proportions of each group were current smokers.

However, the patients with NFA were more likely to have received an asthma diagnosis before the age of 5 years and to report moderate to severe disease. They also had more frequent asthma symptoms. For example, 33% reported having symptoms three or more times weekly versus 26% of the emergency care group and 22% of the community controls.

In addition, the NFA group was more than five times as likely as either of the other two groups to report a history of life-threatening allergic reactions. They were also markedly more likely than the community controls, but not the emergency care group, to report feeling vulnerable to asthma.

About 80% of the patients with NFA said that they had increased their asthma medication use in the last 12 months; only about 60% of the emergency care group and 39% of the community controls made such a claim. In addition, the NFA patients were much more likely than the other two groups to be using oral or inhaled corticosteroids daily.

The patients in the NFA group were also more likely than were those in the emergency care group to link their current asthma attack to stress, a food allergy, or going out to a bar, restaurant, or party. “Being at a bar, restaurant, or party was presumably associated with asthma because it led to smoke exposure,” Dr. Mitchell told RESPIRATORY REVIEWS. The emergency care group, on the other hand, was more likely to list the preceding event as either physical activity or a respiratory tract infection.

Dr. Mitchell recommended that physicians attempt to identify these risk factors for NFA during all patient encounters. Patients who have such risk factors require intensive assessment and long-term follow-up, he stressed.

—Timothy Begany