Table 3.
Risk of Bias Assessments
| Bias | Author’s Judgement | Support for Judgement |
|---|---|---|
| Caballero-Gordo et al, 199112 | ||
| Random sequence generation | Unclear risk | Quote: “the study was prospective, randomized and double blind” Comment: Randomization process not stated |
| Allocation concealment | Unclear risk | Quote: “the study was prospective, randomized and double blind” Comment: Allocation concealment not stated |
| Blinding of participants and personnel | Unclear risk | Quote: “double blind” Comment: Insufficient information to judge |
| Blinding of outcome assessment (lactation) | Unclear risk | Quote: “double blind” Comment: Subjective outcomes may be more vulnerable to bias |
| Blinding of outcome assessment (side effects) | Unclear risk | Quote: “double blind” Comment: Subjective outcomes may be more vulnerable to bias |
| Incomplete outcome data | Low risk | Quote: “9 patients were excluded because of protocol violations, 6 because they did not return for an examination at 14 days and 3 because they used bromoergocryptine after treatment” Comment: 1/20 placebo, 3/40 0.50mg, 4/40 0.75mg and 1/40 1mg group were excluded |
| Selective reporting | Low risk | Comment: No evidence of selective reporting |
| Other bias | Unclear risk | Comment: Number of participants in placebo group were only half of other intervention groups |
| European Multicentre Study Group for Cabergoline in Lactation Inhibition, 199111 | ||
| Random sequence generation | Low risk | Quote: “subjects randomised”. Treatments given “according to a randomised sequence balanced within each centre” |
| Allocation concealment | Low risk | Quote: “treatments were given double blind, using the double dummy technique” “the drugs were provided … in individualized patient kits, which were assigned by the doctor according to the patient’s order of entry to the study” |
| Blinding of participants and personnel | Low risk | Quote: “treatments were given double blind, using the double dummy technique” “in one instance the code was broken before the end of the study for one woman taking cabergoline owing to an unexpected adverse event (hemianopia), the women remained blind to the treatment” Comment: Double-blind, and unlikely that the blinding could have been broken |
| Blinding of outcome assessment (lactation) | Low risk | Comment: Placebo was used to make up for the difference in the duration of treatments between the 2 arms of the trial |
| Blinding of outcome assessment (side effects) | Low risk | Quote: “treatments were given double blind” |
| Incomplete outcome data | Low risk | 6/136 missing from cabergoline group (1 due to “intolerance”, 2 due to “lost to follow up”, 3 due to “other reasons”); 8/136 missing from bromocriptine group (3 due to “intolerance”, 3 due to “lost to follow up”, 2 due to “other reasons”) Comment: Subjects not completing the study protocol were included in analysis as “treatment failure”. Missing data balanced across groups and reasons similar |
| Selective reporting | Low risk | Comment: No evidence of selective reporting |
| Other bias | Unclear risk | 18/136 taking cabergoline and 16/136 taking bromocriptine received concomitant treatment that may have interfered with lactation (ergot derivatives in 28 and oral contraceptives in 6, equally dispensed over the 2 groups) |
| Giorda et al, 199114 | ||
| Random sequence generation | Low risk | Quote: “the women were randomly allocated with random tables” |
| Allocation concealment | Unclear risk | Comment: Allocation concealment not described |
| Blinding of participants and personnel | High risk | Quote: “single-blind” |
| Blinding of outcome assessment (lactation) | Low risk | Quote: “breast engorgement, breast tenderness and milk secretion were assessed clinically by one of us unaware of the type of treatment who recorded the presence or absence of these variables” |
| Blinding of outcome assessment (side effects) | Unclear risk | Quote: “clinical side effects reported by the women either spontaneously or after specific questions were also recorded” Comment: subjective |
| Incomplete outcome data | Low risk | Comment: No missing data |
| Selective reporting | Low risk | Comment: No evidence of selective reporting |
| Other bias | Low risk | Comment: No other sources of bias |
| Melis et al, 198715 | ||
| Random sequence generation | Unclear risk | Quote: subjects were “randomly divided into 3 treatment groups in a single blind fashion” Comment: Randomization process not stated |
| Allocation concealment | Unclear risk | Comment: No information about allocation concealment to permit judgement |
| Blinding of participants and personnel | Unclear risk | Comment: Insufficient information to permit judgement on blinding. Study was labeled as “single blind”, unclear who was blinded and the measure taken to ensure blinding |
| Blinding of outcome assessment (lactation) | Unclear risk | Comment: Insufficient information to permit judgement on blinding. Study was labeled as “single blind”, unclear who was blinded and the measure taken to ensure blinding |
| Blinding of outcome assessment (side effects) | Unclear risk | Comment: Insufficient information to permit judgement on blinding. Study was labeled as “single blind”, unclear who was blinded and the measure taken to ensure blinding |
| Incomplete outcome data | Low risk | Comment: No missing data |
| Selective reporting | Low risk | Comment: No evidence of selective reporting |
| Other bias | Unclear risk | Comment: Insufficient information to assess |
| Melis et al, 198816 | ||
| Random sequence generation | Unclear risk | Quote: “subjects were randomly allocated to four treatment groups of eight subjects” Comment: Randomization process not stated |
| Allocation concealment | Low risk | Quote: “the three doses of Cabergoline and placebo were supplied in identical vials containing a lyophilized powder, which was restored to a liquid state with water immediately before use” |
| Blinding of participants and personnel | Low risk | Quote: “double blind trial” “neither the patients nor the staff administering the solutions were aware of which treatment was being given” |
| Blinding of outcome assessment (lactation) | Unclear risk | Comment: Unclear whether outcome assessors were blinded |
| Blinding of outcome assessment (side effects) | Unclear risk | Comment: Unclear whether outcome assessors were blinded |
| Incomplete outcome data | Low risk | Comment: No missing data |
| Selective reporting | High risk | Quote: “No nausea, vomiting, hypotension, or nasal stuffiness were reported by the subjects who received Cabergoline” Comment: method of measuring side effect measurement was not pre-specified in the methods section. Unclear if there were other side effects sought for but not reported. Unclear if placebo groups had any side effects. |
| Other bias | Low risk | Comment: No other sources of bias |
| Nisha et al, 200913 | ||
| Random sequence generation | Unclear risk | Quote: “they were randomly divided into two groups” Comment: Randomization process not stated |
| Allocation concealment | Low risk | Quote: “a total of 200 opaque white envelopes were sealed, mixed and put in a box” “each woman was asked to open one envelope and recruited in one of the two groups as per instructions inside the envelope” |
| Blinding of participants and personnel | Unclear risk | Comment: No blinding, route of administration was different between the 2 comparison groups (oral form versus IM injection) |
| Blinding of outcome assessment (lactation) | Unclear risk | Comment: No blinding |
| Blinding of outcome assessment (side effects) | Unclear risk | Comment: The study did not address this outcome |
| Incomplete outcome data | Low risk | Comment: No missing data |
| Selective reporting | Low risk | Comment: No evidence of selective reporting |
| Other bias | Low risk | Comment: No other sources of bias |