Table 2

Assessment of risk of bias

RCTsAdequate sequence generation?Allocation concealment?Blinding (of outcome assessors)?Incomplete outcome data addressed?Overall assessment of risk of bias
Krugman et al19UnclearUnclearYesUnclearUncertain
De Miranda et al20UnclearUnclearUnclearNoHigh
Stipancic et al21NoNoUnclearUnclearHigh
Sorensen et al22UnclearUnclearUnclearYesUncertain
Simpson and Dryden23NoNoUnclearUnclearHigh
Pre-post study designsReporting (10 items)External validity (3 items)Internal validity: bias & confounding (13 items)Power (1 item)Total score (27 items)
Einspruch and Forman2431206
Timpany2521205
Konefal and Duncan26604010
Gray2722408
Bigley et al28814013
  • RCT = randomised controlled trial.