The selected studies were graded according to the strength of their evidence according to JBI levels of evidence (Level 1-5) and each intervention given a grade of recommendation according to JBI (A or B).
Styrkleiki rannsókna var metin samkvæmt viðmiðum JBI varðandi gagnreyndar upplýsingar (level 1-5) og lagt mat á íhlutanir samkvæmt viðmiðum JBI (grade A eða B).