How should we quantify asthma control? A proposal

Current asthma guidelines suggest a series of criteria to assess if asthma is controlled. However, there is a need to develop a simple and practical method to quantify the degree of such control, both in clinical practice and research.

This report describes a new method to quantify asthma control based on a percentage score. It also aims at comparing the percentage scores obtained with patient's self-evaluation of asthma control and a current validated Mini Asthma Quality of Life (MAQOL) questionnaire.

Forty-two subjects (25 female and 17 male patients) with asthma of different severity recruited from a tertiary center asthma clinic.

The asthma scoring method provided a percentage control for symptoms, baseline expiratory flows and, an optional parameter, for airway inflammation assessed from induced-sputum eosinophil count. These control parameters were compared to an overall assessment of asthma control by the patient (also on a 100% scale) and the score obtained from a validated MAQOL questionnaire.

Mean +/- SEM scores for symptoms, expiratory flows, and airway eosinophilia (last 2 weeks) were 87.8 +/- 1.4%, 88.6 +/- 1.8%, and 66.2 +/- 3.9%, respectively. No significant correlation was found between these three parameters (p > 0.05). The mean global asthma control score and the score estimated by the patient were 80.9 +/- 1.5% and 91.7 +/- 1.5%, respectively (not significantly different). There was a significant correlation between asthma control score (percentage) and percentage symptom score (p < 0.001), while it almost achieved significance for FEV(1) (p = 0.05). Only symptom scores correlated with the MAQOL questionnaire.

We developed a simple easy-to-use asthma control scoring system based on a percentage of optimal control. The percentage symptom score but not the global control score of this new method correlated with patient's global assessment of asthma control. This could be a simple tool that is potentially useful both for the clinician and for research purposes, to quantify global or specific aspects of asthma control.