Evaluating guidelines across primary care-secondary care interfaceBMJ 2001; 323 doi: https://doi.org/10.1136/bmj.323.7316.808 (Published 06 October 2001) Cite this as: BMJ 2001;323:808
Methodological weaknesses and poor reporting undermine authors' conclusions
- Nick Freemantle, professor (N.Freemantle@bham.ac.uk),
- John Wood, principal statistician
- Department of Primary Care and General Practice, University of Birmingham, Birmingham B15 2TT
- GlaxoSmithKline, Harlow CM19 5AW
- Department of General Practice, University of Glasgow, Glasgow G12 0RR
- MRC Social and Public Health Sciences Unit, University of Glasgow, Glasgow G12 8RZ
- Health Services Research Unit, University of Aberdeen, Aberdeen AB25 2ZD
EDITOR—Readers' ability to extract information from Morrison et al's study is impeded by errors in analysis and reporting.1 The trial evaluated clinical guidelines on the management of subfertility for doctors in general practice. The hope was that consequent improvements to procedure in primary care would affect processes in secondary care after referral, with more efficient management overall.
The subjects of the study were healthcare professionals, and the focus (the object of the intervention and the outcomes measured) was on their behaviour. All the results, however, are given as aggregated patient referrals, which does not respect the structure of the experiment.
Although one can compare case mix through aggregated patient characteristics (table 1), it is wrong to assess and report the effects of the intervention on this basis.2 The authors adjust for within practice correlation in their analysis, but at a level that is inappropriate. Two important consequences …