Factors accounting for asthma variability: achieving optimal symptom control for individual patients.

Asthma is a variable disease, and various factors can lead to an increase (or decrease) in asthma symptoms and the level of asthma control. Pub Med was searched for recent articles dealing with asthma variability, environmental factors and co-morbid conditions that affect asthma control, and for publications which identified tools to facilitate patients' response to asthma variability. Variability in asthma symptoms may be a response to the individual's environment (e.g. seasonal variation, cigarette smoke, and air pollutants) or personal factors (e.g. inhaler technique, pregnancy, exercise). Co-morbid diseases such as allergic rhinitis may also impact significantly on asthma variability and control. Documenting asthma variability and assessing both adherence and possible triggers over time may allow patients and physicians to develop treatment programmes that anticipate, rather than follow, changes in the level of asthma symptoms. Personalised asthma control plans which take into account factors affecting symptom variability may enable patients to modify medication and their environment prophylactically in anticipation of a known trigger or at the first sign of an asthma exacerbation.