What's the evidence that NICE guidance has been implemented? Results from a national evaluation using time series analysis, audit of patients' notes, and interviews

Sir,

The 2000 NICE guidance on the removal of wisdom teeth recommended
that the prophylactic removal of pathology-free wisdom teeth should be
discontinued in the NHS(1).

The analysis presented by Sheldon and colleagues shows a gradual
reduction in the number of wisdom teeth extractions which they suggest
indicates a diffusion of NICE guidance into clinical dental practice (2).
Figure 1 reports the annual number of courses of treatment that included
at least one third molar extraction in the General Dental Service (GDS) in
Scotland and corresponds to Figure 1 in Sheldon et al. 2004.

Figure 1: the annual number of courses of treatment that included at
least one third molar extraction

The raw number of claims per year reported in Figure 1 masks some
underlying trends in the data that are revealed by (a) weighting the data
by the total number of claims made in the GDS over this period and (b)
disaggregating the data into those wisdom teeth extractions that require a
surgical procedure and those that do not.

The left hand scale of Figure 2 shows the number of surgical and non
-surgical third molar treatments per 1000 claims in the Scottish GDS.
The right hand scale of Figure 2 shows the number of general anaesthetic
(GA) treatments per 1000 claims in the Scottish GDS.

Figure 2: the number of surgical, non-surgical 3rd molar extractions
and GA treatmnts per 1000 claims

The rate of both surgical and non-surgical extractions varies around
a constant rate until the end of 1998 when a sharp reduction in the rate
of non-surgical extractions occurs. The suddenness of this change in the
rate of 3rd molar extractions in Scotland seems inconsistent with a
pattern of diffusion.

New guidance for the administration of GAs by dentists in the UK was
issued by the General Dental Council and these came into effect on 10th
November 1998 (3). Since then only anaesthetists on the GMC specialist
register, trainee anaesthetists or non-consultant career grade
anaesthetists working under the supervision of a named consultant in the
same NHS department are able to administer a general anaesthesia in dental
practice. The reduction in the rates of non-surgical extractions
coincides with the change in GDC advice to dentists.

While the evidence in figure 2 does not establish a causal
relationship between GAs and wisdom teeth extractions it does provide some
preliminary evidence that the regulatory framework within which General
Dental Services are provided can affect clinician behaviour. In contrast,
the reduction in third molar extractions since the introduction of the
NICE guideline in 2000 has been less marked.

Research to help clarify the nature of behaviour change in dental
practice is on-going at the Dental Health Services Research Unit in
Scotland.

References

(1) Guidance on the Removal of Wisdom Teeth. NICE 2000

(2) Sheldon TA, Cullum N, Dawson D, Lankshear A, Lowson K, Watt I,
West P, Wright D, Wright J. What’s the evidence that NICE guidance has
been implemented? Results from a national evaluation using time series
analysis, audit of patients’ notes and interviews. BMJ 2004; 329: 999.

(3) Seward M. GA-end of an era. BDJ [editorial] 1998;185:497.

Acknowledgements

The authors gratefully acknowledge the comments of Stephen Goold and
Alison Simpson, NHS National Services Scotland.

Disclaimer

DHSRU is funded by the Chief Scientist Office of the Scottish
Executive and is part of the MRC Health Services Research Collaboration.
The usual disclaimer applies.

Competing interests:
None declared