NEW YORK (Reuters Health) – The relationship of measures involving lung function (FEV1) and asthma symptoms may be useful in the construction of decision-analysis based models of asthma interventions, researchers report in the January issue of the Journal of Clinical Epidemiology.
Dr. Karen M. Kuntz, of Harvard School of Public Health, Boston, and colleagues examined data obtained in 15 randomized clinical trials of asthma interventions. These studies were conducted primarily in adults and involved inhaled corticosteroids, long-acting beta-agonists, or leukotriene modifiers.
In particular, the researchers examined FEV1 percent predicted and asthma symptom scores. Most studies used scores measuring symptom severity alone. However, three also gave symptom frequency, seven gave daytime scores, and two provided symptom scores for both day and night. Overall, five adult studies gave the percentage of days with symptoms and 10 reported the percentage of nighttime awakenings.
There was no significant association between FEV1 percentage predicted and the percentage of days with symptoms. However, the researchers found a significant negative association between lung function and symptom scores and the percentage of nocturnal disturbances. Furthermore, at follow-up within the studies, there was a consistent relationship between mean changes in lung function and symptoms.
The investigators thus conclude that such functional relationships "can be useful for inferring the effect on the symptoms of a population associated with overall improvements in lung function."