Effectiveness of guidelines on persistent glue ear in childrenBMJ 2002; 324 doi: http://dx.doi.org/10.1136/bmj.324.7338.673 (Published 16 March 2002) Cite this as: BMJ 2002;324:673
Authors' estimates of size of impact are probably excessive
- Nick Black ([email protected]), professor of health services research,
- Andrew Hutchings, lecturer
- Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, London WC1E 7HT
- Medical Care Research Unit
- Sheffield School for Health and Related Research, University of Sheffield, Sheffield S1 4DA
- Faculty of Medicine
- University of New South Wales, Kensington, 2052 New South Wales, Australia
EDITOR—Mason et al have shown how the Effective Health Carebulletin on treating persistent glue ear in children was associated with a subsequent significant decline in rates of surgery for this condition.1 Their estimates of the size of the impact, however, are probably excessive. This illustrates the dangers of undertaking short time series analyses.
They compared surgical rates after publication of the bulletin with the rates in the preceding three years. They report that during the preceding years the rate rose from about 1.7 to 2.1 per 1000 children. The rise over this period, however, does not reflect the longer term trends in the surgical rate observed in children aged under 10 in the districts covered by the old Oxford and East Anglian regions: the rate peaked in the mid-1980s and then fell slowly but steadily during the following six years.2 Mason et al seem to have based their claim that the rate increased greatly during the 1980s on a paper that covered the period only up to 1982.3
The upturn during 1989-92 has to be seen in the context of an overall decline from 1985 to the present day. The reason for the short …
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