Table 3 Quality assessment of the included RCT studies
From: Clinical effectiveness of Invisalign® orthodontic treatment: a systematic review
Author-year of publication | Study design | Sequence generation (selection bias) | Allocation concealment (selection bias) | Blinding of participants and personnel (performance bias) | Blinding of outcome assessors (detection bias) | Incomplete outcome data (attrition bias) | Selective reporting (reporting bias) | Other sources of bias | Overall risk |
|---|---|---|---|---|---|---|---|---|---|
Hennessy et al. [18] (2016) | RCT | Aj: Low risk Sfj: Although not explicitly stated, sequence generation is very likely due to reference of random picking up of sealed opaque envelopes | Aj: Low risk Sfj: Sealed opaque, envelopes | Aj: Low risk Sfj: Incomplete blinding, but the review authors judge that the outcome is not likely to be influenced by lack of blinding | Aj: Low risk Sfj: No blinding of outcome assessment, but the review authors judge that the outcome measurement is not likely to be influenced by lack of blinding | Aj: Low risk Sfj: Missing outcome data balanced in numbers across intervention groups, with similar reasons for missing data across groups | Aj: Low risk Sfj: The study protocol is available and all of the study’s pre-specified outcomes that are of interest in the review have been reported in the pre-specified way | Aj: Low risk Sfj: The study appears to be free of other sources of bias | Low |
Li et al. [19] (2015) | RCT | Aj: Low risk Sfj: Use of a computer random number generator | Aj: Low risk Sfj: Sequentially numbered, opaque, sealed envelopes | Aj: Low risk Sfj: Blinding ensured and unlikely that the blinding could have been broken | Aj: Low risk Sfj: Blinding of outcome assessment ensured and unlikely that the blinding could have been broken | Aj: Low risk Sfj: No missing outcome data | Aj: Low risk Sfj: The study protocol is available and all of the study’s pre-specified outcomes that are of interest in the review have been reported in the pre-specified way | Aj: Low risk Sfj: The study appears to be free of other sources of bias | Low |
Bollen et al. [20] (2003) | RCT | Aj: Low risk Sfj: Reference to a random number list | Aj: Low risk Sfj: Randomization schedule based on a list of random numbers performed by a calibrated investigator, unaware of the treatment plan | Aj: Low risk Sfj: Incomplete blinding, but the review authors judge that the outcome is not likely to be influenced by lack of blinding | Aj: Low risk Sfj: No blinding of outcome assessment, but the review authors judge that the outcome measurement is not likely to be influenced by lack of blinding | Aj: Low risk Sfj: Missing outcome data balanced in numbers across intervention groups, with similar reasons for missing data across groups | Aj: Low risk Sfj: The study protocol is available and all of the study’s pre-specified outcomes that are of interest in the review have been reported in the pre-specified way | Aj: Low risk Sfj: The study appears to be free of other sources of bias | Low |