Objectives: The aim was to compare students' practical cardiopulmonary resuscitation (CPR) skills and willingness to perform bystander CPR, after a 30 min mobile application (app)-based versus a 50 min DVD-based training.

Settings: Seventh grade students in two Swedish municipalities.

Design: A cluster randomised trial. The classes were randomised to receive app-based or DVD-based training. Willingness to act and practical CPR skills were assessed, directly after training and at 6 months, by using a questionnaire and a PC Skill Reporting System. Data on CPR skills were registered in a modified version of the Cardiff test, where scores were given in 12 different categories, adding up to a total score of 12-48 points. Training and measurements were performed from December 2013 to October 2014.

Participants: 63 classes or 1232 seventh grade students (13-year-old) were included in the study.

Primary and secondary outcome measures: Primary end point was the total score of the modified Cardiff test. The individual variables of the test and self-reported willingness to make a life-saving intervention were secondary end points.

Results: The DVD-based group was superior to the app-based group in CPR skills; a total score of 36 (33-38) vs 33 (30-36) directly after training (p<0.001) and 33 (30-36) and 31 (28-34) at 6 months (p<0.001), respectively. At 6 months, the DVD group performed significantly better in 8 out of 12 CPR skill components. Both groups improved compression depth from baseline to follow-up. If a friend suffered cardiac arrest, 78% (DVD) versus 75% (app) would do compressions and ventilations, whereas only 31% (DVD) versus 32% (app) would perform standard CPR if the victim was a stranger.

Conclusions: At 6 months follow-up, the 50 min DVD-based group showed superior CPR skills compared with the 30 min app-based group. The groups did not differ in regard to willingness to make a life-saving effort.