The number of articles included in this review
|Interventions||Class of evidencea||Total|
|Safe landing strategy||0||4||9||0||13|
|Vitamin D intake||8||1||0||0||9|
aClass 1: randomized controlled trials. Class 2: non-randomized controlled trials. Class 3: experimental studies with no control group. Class 4: studies not belonging to Class 1, 2, and 3 (i.e., case study).