Evidence-Based Complementary and Alternative Medicine / 2013 / Article / Tab 2

Review Article

Chinese Herbal Medicine for Osteoporosis: A Systematic Review of Randomized Controlled Trails

Table 2

The Cochrane Collaboration’s tool for assessing risk of bias.

Random sequence generation

Low risk of biasThe investigators describe a random component in the sequence generation process such as: referring to a random number table; using a computer random number generator.
High risk of biasThe investigators describe a nonrandom component in the sequence generation process. Usually, the description would involve some systematic, nonrandom approach, for example, sequence generated by odd or even date of birth; sequence generated by some rule based on date (or day) of admission.
Unclear risk of biasInsufficient information about the sequence generation process to permit judgement of “Low risk” or “High risk.”

Allocation concealment

Low risk of bias Participants and investigators enrolling participants could not foresee assignment because one of the following, or an equivalent method, was used to conceal allocation: central allocation (including telephone, web-based and pharmacy-controlled randomization); sequentially numbered drug containers of identical appearance.
High risk of bias Participants or investigators enrolling participants could possibly foresee assignments and thus introduce selection bias, such as allocation based on 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).

Blinding of participants and personnel

Low risk of bias Any one of the following: no blinding or incomplete blinding, but the review authors judge that the outcome is not likely to be influenced by lack of blinding; blinding of participants and key study personnel ensured, and unlikely that the blinding could have been broken.
High risk of bias No blinding or incomplete blinding, and the outcome is likely to be influenced by lack of blinding; blinding of key study participants and personnel attempted, but likely that the blinding could have been broken, and the outcome is likely to be influenced by lack of blinding.
Unclear risk of bias Any one of the following: insufficient information to permit judgement of “Low risk” or “High risk”; the study did not address this outcome.

Blinding of outcome assessment

Low risk of bias Any one of the following: no blinding of outcome assessment, but the review authors judge that the outcome measurement is not likely to be influenced by lack of blinding; blinding of outcome assessment ensured, and unlikely that the blinding could have been broken.
High risk of bias Any one of the following: no blinding of outcome assessment, and the outcome measurement is likely to be influenced by lack of blinding; blinding of outcome assessment, but likely that the blinding could have been broken, and the outcome measurement is likely to be influenced by lack of blinding.
Unclear risk of bias Any one of the following: insufficient information to permit judgement of “Low risk” or “High risk”; the study did not address this outcome.

Incomplete outcome data

Low risk of bias Any one of the following: no missing outcome data; reasons for missing outcome data unlikely to be related to true outcome (for survival data, censoring unlikely to be introducing bias).
High risk of bias Any one of the following: 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; for dichotomous outcome data, the proportion of missing outcomes compared with observed event risk enough to induce clinically relevant bias in intervention effect estimate.
Unclear risk of bias Any one of the following: insufficient reporting of attrition/exclusions to permit judgement of “Low risk” or “High risk” (e.g., number randomized not stated, no reasons for missing data provided); the study did not address this outcome.

Selective reporting

Low risk of biasAny of the following: the study protocol is available and all of the study’s pre-specified (primary and secondary) outcomes that are of interest in the review have been reported in the prespecified 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 (convincing text of this nature may be uncommon).
High risk of biasAny one of the following: not all of the study’s prespecified 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 prespecified.
Unclear risk of biasInsufficient information to permit judgement of “Low risk” or “High risk.” It is likely that the majority of studies will fall into this category.
Other bias

Low risk of biasThe study appears to be free of other sources of bias.
High risk of biasThere 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 have been fraudulent; or had some other problem.
Unclear risk of bias There may be a risk of bias, but there is either insufficient information to assess whether an important risk of bias exists or insufficient rationale or evidence that an identified problem will introduce bias.

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