Dima AL, et al. - Considering that while it is widely recognized that asthma outcomes fluctuate over time, data on within-person change predictors are scarce, researchers quantified these variations as well as the longitudinal associations between inhaled corticosteroids (ICS) adherence and outcomes at both between- and within-person levels. A prospective cohort of persistent asthma patients in France and the United Kingdom (N = 847, age 6 to 40 years) provided 3,756 reports over a period of up to 2 years through computer-assisted telephone interviews and text messages on ICS adherence, asthma control, use of reliever medication, and exacerbations. Over time, patients with high adherence to ICS have better control of asthma. Temporarily increasing adherence to ICS tends to be simultaneous with higher use of relievers and subsequently reduces the use of relievers. Causes of within-person variation in outcomes need further study.