Bronchodilator Responsiveness Positivity More Likely in Morning

WEDNESDAY, March 12, 2025 (HealthDay News) — Patients are more likely to have positive bronchodilator responsiveness in the morning and in winter months, according to a study published online March 11 in Thorax.

Ben Knox-Brown, Ph.D., from the Royal Papworth Hospital NHS Foundation Trust in Cambridge, England, and colleagues examined the association between time of day and season of testing on the level of bronchodilator responsiveness in a population of 1,620 patients.

The researchers found that the odds of a positive bronchodilator response decreased by 8 percent per one-hour increment in the working day (odds ratio, 0.92). When time of day was dichotomized into morning and afternoon periods, a similar effect was seen, with reduced odds of responsiveness in the afternoon (odds ratio, 0.68). The impact of time of day was only seen in those referred for asthma/query asthma, while no association was seen for those referred for other reasons. Compared with the rest of the year, bronchodilator responsiveness was more common in winter months.

“These findings suggest that performing diagnostic testing when patients are most symptomatic, that is, in the morning, may improve diagnostic testing,” the authors write. “This also reinforces the need to document the timing of spirometry testing whenever possible, and that repeat testing should be done at the same time of day.”

One author disclosed financial ties to ndd Medical Technologies.

Abstract/Full Text