Background: Nocturnal symptoms of asthma are a cause of significant morbidity and are included as a central feature in the categorization of asthma severity.
Objectives: Data from the Childhood Asthma Management Program were used to estimate the prevalence of nocturnal awakenings in 1041 children with mild-to-moderate asthma and to investigate the relationships between awakenings and peak flows, severity of asthma, and allergen sensitivity and exposure.
Methods: Daily diary care data were recorded during a 28-day interval in the Childhood Asthma Management Program screening process. The data on morning and evening peak flows, overall symptom codes, albuterol use for symptoms, and nocturnal awakenings for asthma symptoms were analyzed and compared with measures of personal characteristics, pulmonary function, and environmental characteristics of the patients.
Results: Three hundred fifty-one (33.7%) children experienced 1 or more night awakenings caused by asthma during the 28-day screening period while not taking any maintenance medications. Greater risk of night awakening was associated with more severe asthma (greater responsiveness to bronchodilator, airway reactivity to methacholine, peak flow variability, and use of albuterol for symptoms, all P <.0001) and atopy (increased IgE and allergy skin test reactivity, both P =.0002). Those with a positive skin test response to dog and a high level of dog allergen in the home had a greater risk of night awakening caused by asthma (P =.01), as did those with a positive skin test response to cat and a high level of cat allergen in the home (P =.04). Mean daily symptom code and use of albuterol for asthma symptoms increased in the 3 days immediately before a single awakening compared with in the 4 to 6 days before the awakening (P =.02 and P =.01, respectively); however, both morning and evening peak flows as a percentage of personal best were similar in both intervals. Mean daily symptom code and daily use of albuterol were greater in the 3 days after an awakening than in the 3 days before (P <.0001 and P =.0002, respectively). Mean evening peak flow percentage of personal best the day after an episode of awakening was lower when a second consecutive awakening occurred than when there was only a single awakening (P =.01).
Conclusions: Nocturnal awakening occurred in one third of the children with mild-to-moderate asthma during a month of relative stability and appears to be an indicator of asthma that is becoming increasingly severe.