Validation of the Asthma Control Test questionnaire in a North African population.

BACKGROUND

Patient-reported outcome measures are required to measure asthma control. The Asthma Control Test (ACT) is one such measure which was used in the AIRMAG study, a general population study of asthma in the Maghreb. Three dialectal Arabic versions of the ACT (Algerian, Moroccan and Tunisian) were developed.

OBJECTIVE

To perform a psychometric evaluation of the properties of dialectal Arabic versions of the ACT used in the AIRMAG study.

METHODS

The test data came from 624 adult subjects in a random general population sample in Algeria, Morocco and Tunisia. The internal consistency of the ACT was analysed using Cronbach's a coefficient. The factorial structure was explored by primary component analysis with varimax rotation. Test-retest reproducibility was assessed in a subgroup of 61 subjects. Face and discriminant validity were assessed.

RESULTS

Cronbach's a coefficient ranged from 0.58 for the Algerian version to 0.67 for the Moroccan version. The 'use-of-rescue-treatment' item was identified as discordant, since its removal resulted in an increase in Cronbach's a coefficient. The discordance of this item was confirmed by primary component analysis, where the four remaining items were aligned along a single dimension, and the 'use-of-rescue-treatment' item offset along a second dimension. Test and retest scores were well correlated (r =0.704). The ACT showed good face and discriminant validity.

CONCLUSIONS

The ACT is a valid measure of asthma control in a North African context, although its internal consistency is compromised by the 'use-of-rescue-treatment' item, probably due to limited access to care and use of short-acting beta-agonists.