Table 3 Quality of studies
RCT Studies | Explanation of calculation of sample size | Description of mechanism for patient selection | Explanation of the causes for withdrawal of patients | Statistical analysis adequate to the type of data | Description of the control for confusing factors | Blindness for the evaluation of results | Use of p values or confidence intervals | Evaluation of quality |
|---|---|---|---|---|---|---|---|---|
Nelson 1993 [22] | yes | yes | Yes | yes | yes | no | Yes | High |
Tulloch 1997 [23] | yes | yes | No | yes | yes | no | yes | Medium |
Illing 1998 [24] | no | yes | Yes | yes | yes | no | yes | medium |
O Brien 2003 [19] | yes | yes | Yes | yes | yes | no | yes | high |
Martina 2013 [7] | yes | yes | Yes | yes | yes | no | yes | high |