Table 5. Understanding of study design and randomisation*.
Developed country studies | Developing country studies | ||||
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Author | Country | Understood study design | Author | Country | Understood study design |
Van Stuijvenberg et al, 199853 | The Netherlands | 88% placebo design | Moodley et al, 200527 | South Africa | 49% knew they had a 50% chance of receiving placebo; 19% understood placebo |
Criscione et al, 200344 | USA | 87% placebo design | Hill et al, 200823 | Ghana | 13% understood ‘not all trial capsules were the same’ |
Howard et al, 198163 | USA | 86% double blind design | Leach et al, 199933 | The Gambia | 10% placebo design† |
Harrison et al, 199555 | USA | 79% | |||
Pope et al, 200346 | Canada | 76% placebo design | |||
Bergler et al, 198064 | USA | 64% (at start), 28% (3 months later) | |||
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Developed country studies | Developing country studies | ||||
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Author | Country | Understood randomisation | Author | Country | Understood randomisation |
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Ravina et al, 201036 | USA | 90%, yet only 67% understood there was a 1 in 3 chance of receiving placebo | Ellis et al, 201018 | Mali | 80% of adults 90% of parents |
Simon et al, 200348 | USA | 68% of majority English speakers | Krosin et al, 200626 | Mali | 68% |
26% of minority English speakers | |||||
14% of minority non-English speakers | |||||
Bergenmar et al, 200837 | Sweden | 85% | Pace et al, 200528 | Thailand | 31% |
Gammelgaard et al, 200441 | Denmark | 79% | Moodley et al, 200527 | South Africa | 21% |
Criscione et al, 200344 | USA | 50% | Pace et al, 200529 | Uganda | 19% |
Van Stuijvenberg et al, 199853 | The Netherlands | 50% | |||
Kodish et al, 200442 | USA | 50% | |||
Howard et al, 198163 | USA | 43% | |||
Pope et al, 200346 | Canada | 39% | |||
Benson et al, 198560 | USA | 33% of depression study, 16% of schizophrenia study | |||
Hietanen et al, 200051 | Finland | 23% | |||
Schats et al, 200347 | The Netherlands | 22% |
Arranged from highest to lowest %.
When broken down into those who had received a written information sheet at least a week before consent, 15% of those who had received the sheet understood that there was a placebo group versus 4% of those who had not received prior written information.