Current Bronchodilator Responsiveness Criteria Underestimate Asthma in Older Adults.

BACKGROUND: Asthma is common in older adults and is confirmed by demonstration of variable expiratory air-flow limitations, typically evaluated by spirometric assessment of bronchodilator responsiveness. However, many patients with clinically suspected asthma and documented air-flow obstruction do not exhibit a post-bronchodilator response that meets or exceeds current established guidelines. We investigated if extending the time from bronchodilator administration to assessment of bronchodilator response increases the yield of spirometry for the diagnosis of asthma in older adults. METHODS: This was a cross-sectional study. The subjects were non-smokers, ≥ 60 y old, and with suspected asthma. Subjects were characterized as (1) those with a positive bronchodilator response on the 30-min post-bronchodilator spirometry, (2) those with a positive bronchodilator response on the 60-min post-bronchodilator spirometry, and (3) those without a positive bronchodilator response but with a positive methacholine challenge test. Factors associated with a late response to bronchodilator were evaluated by using bivariate analysis and by multivariate analysis by using a logistic regression model. RESULTS: This study enrolled 165 subjects. Of these, 81 (49.1%) had a positive bronchodilator response on 30-min post-bronchodilator spirometry; 25 (15.2%) had a positive bronchodilator response on the 1-h post-bronchodilator spirometry; and 59 (35.8%) had no positive bronchodilator response but had a positive methacholine challenge test. On multivariable regression analysis, those with a higher baseline percentage of predicted FEV1, higher scores on a standard asthma control test, and wheezing and/or cough after exercise were more likely to either have a late bronchodilator response or no bronchodilator response. CONCLUSIONS: Our study showed that a late positive response to bronchodilator use was more common than previously presumed in older subjects with suspected asthma. Pulmonary function testing laboratories should consider routinely reassessing spirometry at 1 h after bronchodilator use if the earlier assessment did not reveal a significant response.

Predicting asthma in older adults on the basis of clinical history.

BACKGROUND: The diagnosis of asthma is not always straightforward and can be even more challenging in older adults. Asthma is ideally confirmed by demonstration of variable expiratory airflow limitation. However, many patients with asthma do not demonstrate airflow obstruction nor show bronchodilator reversibility. We aimed to investigate predictors for a positive bronchial challenge test with methacholine in older adults being evaluated for asthma. METHODS: This is a diagnostic accuracy study with a cross-sectional design. Participants ≥60 years with suspected asthma and a negative postbronchodilator response on spirometry were included. All participants underwent a methacholine challenge test (MCT). We assessed the value of standard asthma screening questions and additional clinical questions to predict the MCT results. A multivariable logistic regression model was developed to assess the variables independently impacting the odds of a positive MCT result. RESULTS: Our study included 71 participants. The majority were female (n = 52, 73.2%) and the average age was 67.0 years. Those with a positive MCT (n = 55, 77.5%) were more likely to have wheezing or coughing due to allergens (n = 51, 92.7% vs. n = 12, 75.0%; P = 0.004) and difficulty walking several blocks (n = 14, 25.5% vs. n = 1, 6.3%, P = 0.009). After adjustment, having wheezing or coughing due to allergens (OR = 4.2, 95% CI 1.7-7.8, P = 0.012) remained the only significant independent predictor of a positive MCT. CONCLUSIONS: In older adults with suspected asthma, questioning about wheezing or coughing due to allergens provides a modest independent value to predict a MCT result in those who previously had a negative postbronchodilator response on spirometry.