Asturias 2007.
Methods |
Study design: open‐label, randomised trial Setting: 3 well‐child public clinics, Guatemala city, Guatemala Study dates: April to November 2004 |
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Participants |
Sample size: 500 healthy, full‐term infants naive to polio vaccination were recruited from April to November 2004 Age: mean = 59.5 days Sex: male = 253, female = 247 Inclusion criteria: "Healthy, full‐term, 6–11‐week old infants attending 3 well‐child public clinics in Guatemala City were eligible" (quote) Exclusion criteria: "(1) received polio, hepatitis B (HB), Haemophilus influenzae type b (Hib), or diphtheria‐tetanus toxoids–pertussis (DTP) vaccines; (2) a history of any disease preventable by these vaccines; (3) a confirmed immunosuppressive condition; (4) received immunosuppressive drugs or blood‐derived products; (5) major congenital defects or serious chronic illness; (6) a history of any neurological disorders or seizures; or (7) allergies to any component of the vaccines." (quote) |
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Interventions |
Group A (n = 166): IIII at 2, 4, 6 and 12 months Group B (n = 168): IIOO at 2, 4,6 and 12 months Group C (n = 166): OOOO at 2, 4, 6 and 12 months |
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Outcomes |
Timing of outcome assessment: 2, 6, 7, 12, and 13 months |
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Notes | ||
Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Low risk |
Quote: "Infants were randomized using a permuted block design of 6–12 at a 1:1:1 ratio within each study" Comment: probably done properly, since the table of baseline characteristics of included participants is balanced |
Allocation concealment (selection bias) | Low risk | Quote: "Allocation to study group was done by opening sealed, sequentially numbered envelopes" |
Blinding of participants and personnel (performance bias) All outcomes | Low risk | Comment: no blinding but performance is not likely to be influenced by lack of blinding in terms of intervention or co‐interventions |
Blinding of outcome assessment (detection bias) All outcomes | Low risk | Comment: no blinding. Objective outcome (antibody titres) is not likely to be influenced by lack of blinding. Diary cards and digital thermometers were used by parents to record adverse events. Diary cards were collected at the next scheduled visit, and the parent was interviewed to ensure completeness of the information. These outcomes could have an unclear risk of bias but they were not meta‐analysed. |
Incomplete outcome data (attrition bias) All outcomes | Unclear risk | Comment: Out of 500 infants enrolled, 444 (88.8%) were available for primary end‐point analysis, and 439 (87.8%) completed the last study visit. |
Selective reporting (reporting bias) | Low risk | Comment: no evidence of selecting reporting |
Other bias | Low risk | Comment: no evidence of other bias |
Conflict of interest | Unclear risk | Financial support: financially supported by Sanofi Pasteur. Independent funds were used to support statistical analyses, and support for one of the authors was provided by a Fogarty International Research Scientist Development Award (grant KO1 TW006659). |