Efficacy of therapeutic ultrasound vs sham ultrasound on pain and physical function in people with knee osteoarthritis: A meta-analysis of randomized controlled trials

Table 2 Criteria used to classify risk of bias in trials according to components of methodological quality

Random sequence generation
Low risk	Referring to a random number table; Using a computer random number generator; Coin tossing; Shuffling cards or envelopes; Throwing dice; Drawing of lots
High risk	Sequence generated by odd or even date of birth; Sequence generated by some rule based on date (or day) of admission; Sequence generated by some rule based on hospital or clinic record number; Allocation by judgment of the clinician; Allocation by preference of the participant; Allocation based on the results of a laboratory test or a series of tests; Allocation by availability of the intervention
Unclear	Insufficient information
Allocation concealment
Low risk	Central allocation (including telephone, web-based); Sequentially numbered, opaque, sealed envelopes; An equivalent method was used to conceal allocation
High risk	Using an open random allocation schedule (e.g., a list of random numbers); Assignment envelopes were used without appropriate safeguards (e.g., if envelopes were unsealed or nonopaque or not sequentially numbered); Alternation or rotation; Date of birth; Case record number; Any other explicitly unconcealed procedure
Unclear	Insufficient information
Blinding of each of: participant, care provider, outcome assessor
Low risk	Unlikely that the blinding could have been broken
High risk	Likely that the blinding could have been broken
Unclear	Insufficient information
Completeness of outcome data collection
Low risk	No missing outcome data; Reasons for missing outcome data unlikely to be related to true outcome; Missing outcome data balanced in numbers across all groups, with similar reasons for missing data across groups; Missing data have been imputed using appropriate methods; For continuous outcome data, plausible effect size (difference in means or standardized difference in means) among missing outcomes not enough to have a clinically relevant impact on observed effect size
High risk	Reason for missing outcome data likely to be related to true outcome, with either imbalance in numbers or reasons for missing data across intervention groups; "As-treated" analysis done with substantial departure of the intervention received from that assigned at randomization. Potentially inappropriate application of simple imputation. For continuous outcome data, plausible effect size (difference in means or standardized difference in means) among missing outcomes enough to induce clinically relevant bias in observed effect size
Unclear	Insufficient information
Completeness of outcome reporting
Low risk	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; The study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre-specified
High risk	Not all of the study’s pre-specified primary outcomes have been reported; One or more primary outcomes is reported using measurements, analysis methods or subsets of the data (e.g., subscales) that were not pre-specified; One or more reported primary outcomes were not pre-specified (unless clear justification for their reporting is provided, such as an unexpected adverse effect); One or more outcomes of interest in the review are reported incompletely so that they cannot be entered in a meta-analysis; The study report fails to include results for a key outcome that would be expected to have been reported for such a study
Unclear	Insufficient information
Other potential sources
Low risk	The study appears to be free of other sources of bias
High risk	There is at least one important risk of bias. For example, the study had a potential source of bias related to the specific study design used or has been claimed to be fraudulent, or has some other problem
Unclear	Insufficient information