Purpose of the study: Smartphone apps are an important and recent medium for training in basic life support (BLS). Conformity to guidelines is not the only main quality. Usability matters as well. To develop easy-to-use and accurate BLS apps, usability evaluation tools are mandatory.
 
Materials and Methods: Usability was defined by a questionnaire, called Features Evaluation Questionnaire (FEQ), considering 4 principal criteria: comprehensibility, presentation (image and text), ease to use and general characteristics. Each main criterion is divided into 1-3 subcriteria with a specific description. Four BLS apps were taken into account and five ALS expert instructors rated each subcriterion by a 5-point Likert scale. The scores of the main criteria were calculated from the mean of the respective subcriteria. Total scores were calculated from the mean of the main criteria. Meanwhile, 200 student nurses participated to BLS courses. They were randomized to use an app during training and their practical abilities were finally scored. R statistical program was used for analysis.
 
Results: Evaluations of all five experts were averaged. From all categories a total usability score was calculated for each app. Basing on subcriteria, usability of each app was compared to the others in a colored table (the “traffic lights” of usability). Moreover, an interesting relationship was found between skill and FEQ scores (Spearman correlation, p-value=0.043). A simple menu structure (p=0.018), an instant and easily understandable feedback (p=0.036), an intuitive usability (p=0.011) and a high fault tolerance (p=0.041) revealed to be subcriteria closely related to skill scores (Spearman correlations).  
 
Conclusions: FEQ showed to be an interesting tool to evaluate the usability of each selected app, basing on 9 subcriteria, and to compare them in a “traffic light” table. Moreover, the study allowed to identify which features need to be improved to develop apps that actually enhance practical skills.

3 - Features Evaluation Questionnaire (FEQ): validation of a new tool for testing usability of BLS apps