Table 1

Study quality

 /1 /3 /3 /2 /4 /1 /5 /1 /20 Author Objective Study design Study population Intervention Outcomes Statistics Results/conclusions Competing interest/support Total Skarda et al1 1 0 3 1 3 1 3 0 12 Watson et al5 1 1 3 1 4 1 4 0 15 Fortenberry et al8 1 0 3 1 3 1 3 0 12 Steiner et al4 1 0 0 1 3 1 2 0 8
• A score of >14 indicates a study of adequate quality.