Assessment of risk of bias in studies included in review.

Legend.
Studies are listed by year (y) of publication, in decreasing order. A tick indicates that specific criteria were fulfilled. Blinding: whether patients, care providers and outcome assessors were blinded. Attrition: loss of data (≥20% = significant). Intention-to-treat (ITT): whether trial authors performed analyses (e.g. last value carried forward) to take into account all patients who began the intervention regardless of protocol violations, drop-outs or loss of follow-up [11], [12].
Abbreviations: US = United States; NL = The Netherlands; UK = United Kingdom; ZA = South Africa; RU = Russia; I = Inadequate; A = Adequate; U = Unclear; NP = Not Performed; NR = Not Reported; Funding = Government (G), Industry (Ind.) or Private (P) grant.
* report the inclusion criteria only.
†used intention-to-treat (ITT) strategies but type not reported.
‡adjusted for cluster effect or intra-class cluster correlation.
§cluster RCT.
||trials for which not all factors tested at baseline were comparable (i.e. ≤10% difference between groups in the factors tested).
¶reached the least target sample required to achieve power in at least one outcome.
** single blinded, nurses and physicians were not aware of patient allocation.
††only patients were blinded.
‡‡data analysts were partly blinded.
§§Huber-White cluster effect approach.
*** intra-class cluster correlation approach not reported.