Strength of Evidence
All publications were scrutinized for study design and ordered
according to the hierarchical strength of evidence,
from the strongest level (type-1 evidence) to the weakest
(type-5) evidence, in accordance with the principles of evidence-based
medicine (EBM).10 Systematic reviews of
RCTs were considered to be type-1 evidence; RCTs, type-
2; and studies with a nonrandomized design, type-3. Type-4
evidence, as presented previously,10 was not used in this
study, because it is intended for well-designed nonrandomized
studies from different research groups on a specific
topic. Thus, all nonrandomized studies were grouped together
on the type-3 level, with the exception of descriptive
studies that were assigned the lowest (type-5) level of
evidence.10
Methodological Ass