Mason 2001.
| Methods | Study design: ITS | |
| Participants | Physicians Clinical speciality: not clear Level of training: fully trained Setting/country: not clear/UK |
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| Interventions | An NHS Effective Health Care bulletin (November 1992) on the treatment of glue ear in children (EHC‐OM bulletin) was distributed nationally to NHS decision makers in 1992. Based on systematic review, the bulletin concluded that surgery should be restricted to children with an extended period of substantial hearing impairment, with persistence and severity established by watchful waiting | |
| Outcomes | 1 process outcome: use of surgery for glue ear (mean number of procedures per 1000 habitants under 15 years old for 14 regions) | |
| Notes | ‐ | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Intervention independent of other changes ‐ ITS | High risk | Quote, pg. 1097: "the change cannot be attributed to the bulletin alone, which was commissioned because of preexisting concerns about appropriate use of the procedure. Its publication received coverage in the medical and academic press,4 possibly encouraging doctors to examine their own practices and bring about behavioural change" |
| Shape of Intervention effect pre‐specified ‐ ITS | Unclear risk | Quote, pg. 1096: "based on systematic review, the bulletin concluded that surgery should be restricted to children with an extended period of substantial hearing impairment, with persistence and severity established by watchful waiting. We evaluated surgery rates before and after distribution of the bulletin" |
| Intervention unlikely to affect data collection ‐ ITS | Low risk | The intervention (Effective Health Care bulletin) did not affect either the source or the method of data collection |
| Blinding of outcome assessors (detection bias) ‐ ITS All outcomes | Low risk | The outcome was objective |
| Incomplete outcome data (attrition bias) ‐ ITS All outcomes | Low risk | Quote, pg. 1096: "quarterly numbers of D151 procedures—insertion of a ventilation tube through the tympanic membrane — performed in children aged under 15 in England from 1989 to 1996 were obtained from the hospital episodes system. We calculated per capita regional and national rates for this procedure" COMMENT: missing data, if any, were likely to be similar pre‐ and post‐intervention |
| Selective reporting (reporting bias) ‐ ITS | Low risk | All relevant outcomes in the methods section were reported in the results section |
| Other bias ‐ ITS | Low risk | There was no evidence of other risks of bias |