Table 2.
Quality assessment of trials meeting inclusion criteria
| Author(s), Year, and Country | Quality Assessment | Allocation Concealment | Additional Comments |
| Cluster RCT | |||
| White 41 2001 United States | Study was described as randomized however did not explain method of randomization; participants and study-coordinators were blinded; description of withdrawals and dropouts provided: of the 72 initial classes (1626 students), 32 classes (16 target and 16 control; 769 students) participated (remainder dropped from analysis) | Unclear | Sample size calculation not defined; statistical methods unclear; parents required to sign detailed informed consent form; study reviewed and approved by the two school boards; soap and handwashing not monitored; clustering not accounted for |
| Crossover | |||
| Dyer 27 2000 United States | Study was not formally randomized; neither participants or study-coordinators were blinded; description of withdrawals and dropouts provided: no exclusions from the population were necessary | Not Relevant | Sample size calculation not defined; statistical methods unclear; no parental consent form; study not approved by a formal university institutional review board (approved by school board of education); limited SES diversity; soap and handwashing not monitored; clustering not accounted for |
| Morton 16 2004 United States | Study was described as randomized however did not explain method of randomization; neither participants or study-coordinators were blinded; description of withdrawals and dropouts provided: of the 17 initial classes (285 students), 17 classes ((253 students, 120 girls and 133 boys), non-consent = 22 children, adverse-events = 10 children) | Unclear | Sample size calculation not defined; data not in a format which could be easily extracted; study approved by Board of Education, and the Institutional Review Board at the state's largest hospital; a consent form was sent to all parents and guardians; clustering not accounted for |
| Cluster NRCTs | |||
| Hammond 31 2000 United States | Study was not formally randomized; neither participants or study-coordinators were blinded; description withdrawals and dropouts provided: 1 school district did not comply with protocol; 25/3080 students did not participate or complete the protocol (in each case, data was not used for results) | Not Relevant | Sample size calculation not defined; no parental consent form; formal review not mentioned; clustering not accounted for |
| Guinan 10 2002 United States | Study was not formally randomized; participants and study-coordinators were not blinded; description withdrawals and dropouts not provided | Not Relevant | Sample size calculation not defined; statistical methods unclear; no parental consent form; formal review not mentioned (approved by each school); limited SES diversity (high SES); performed in peak absenteeism season; clustering not accounted for |