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Rapid Responses: Rapid Responses published:
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Is EEG access helpful?
- Henry Smithson (26 April 2001)
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Audit or Value Judgement?
- Jerry Heath (27 April 2001)
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EEG as a diagnostic tool?
- Shalini Pooransingh, Sam Ramaiah (11 May 2001)
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Henry Smithson, General practitioner Escrick York
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Sir The paper by Smith and colleagues outlining the results of an audit of requests for electroencephalography in one district general hospital in 1994 and 1996 emphasises the poor predictive value of EEG and the low sensitivity and specificity of the test results. It was pleasing that Smith's team showed such a drop in inappropriate EEG requests. But can we be sure that it was their intervention that made the difference? Literature on the success of educational initiatives to change behaviour suggests that Smith's attempt - one clinical meeting per hospital and an issuing of guidelines which the team had already written before the meeting - would have little impact. Clinical meetings at our district general hospitals are only partially attended, and junior staff predominate, most of whom would have moved on in the two years that the study covered. Surely there are many other confounding variables that have not been tested for and which escaped mention in the paper, such as changes in referral patterns due to the increasing popularity of fund-holding, the activity of pharmaceutical companies in raising the profile of epilepsy during the two year study period with possible resultant changes in delivery of service and the seasonal differences in experience of junior staff in August and March cohorts. Requests for EEG services may also depend on availability of neuro- physiology and neurology opinions, accessibility of support professionals such as specialist nurses, professional communication and seasonality. The audit shows that general practitioners rarely request EEGs and understandably so. The diagnosis of epilepsy depends on a careful subject and witness history taken as soon as possible after the episode and GPs are best placed to elicit this valuable information. The frustrations lie in unacceptable waiting times for first appointment with epilepsy experts. This may result in referral to colleagues who may have a limited interest in the condition. With the advent of responsive services in district hospitals generated by co-operation between primary and secondary care (Doncaster, Bradford, North Wales) the time is right to reassess the delivery of epilepsy services as a whole rather than simply requests for EEG. Yours sincerely Henry Smithson Bill Hall Refs Wensing M, Van der Wiejden T, Grol R. "Implementing guidelines and innovations in general practice: which interventions are effective?" Brit J Gen Pract 1998; 48: 991-7. Grimshaw JM, Russell IT. "Effect of clinical guidelines on medical practice: a systematic review of rigorous evaluations." Lancet 1993; 342(8883); 1317 -22 |
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Jerry Heath, Consultant Neurophysiologist University Hospital of Wales
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Requests for electroencephalography in a district general hospital: retrospective and prospective audit. Editor: Audits of investigations are complex as their value to the physician depends on numerous factors not least confidence in their own clinical diagnosis and the report. Many different specialities use EEG services. This audit imposes the "values" of an individual without references to practice guidelines and requires critical appraisal. Smith et al (1) suggest that the unrestricted access and non specialist reporting in their North Wales DGH is typical but fail to mention these practices are contrary to the regional guidelines which their Trusts helped to formulate (2).All 7 EEG departments in South East Wales comply. One author (DS) is credited with grouping EEG requests into "influenced management", "justifiable" and "inappropriate". Requests were considered inappropriate "when a diagnosis (epilepsy) had been made on clinical grounds ...or there had been an unsatisfactory attempt to achieve a clinical diagnosis, usually failure to obtain an eyewitness account of the attack." No rationale is given. At the time of audit six leading UK epileptologists, including the authors senior colleague outlined best practice as "every newly diagnosed case will require at least one standard EEG and up to 50% a second" (3). The authors confidence in their own clinical judgment is admirable but is it reasonable to expect less expert users of the EEG service to ignore such eminent advice? The very personal and subjective nature of the audit is highlighted by the 24% of requests by peers at the neuroscience centre also considered inappropriate. Epilepsy is difficult to diagnose clinically; 20% of patients referred with intractable epilepsy prove to have pseudoseizures.(3) The false positive rates of properly reported EEG is 0.5%.(4) A diagnosis supported by EEG is far more robust. Smith et al make several false assertions most remarkably that "a single EEG cannot diagnose epilepsy". Spike and wave activity is diagnostic of epilepsy as has been recognised by the DVLA. Furthermore the authors themselves diagnosed epilepsy on this very basis in three children presenting with "funny turns" in their retrospective audit. Ironically as this was not considered a valid reason for referral it appears that such children will in future remain undiagnosed. The results of diagnostic tests are by definition unpredictable and access guidelines will inevitably fail some patients, often those who cannot articulate a good history. The financial savings identified in this audit are likely to be trivial in comparison to social and medicolegal costs associated with misdiagnosis. Jerry Heath Benny Thomas 1 Smith D, Bartolo R, Pickles RM, Tedman BM. Requests for electroencephalography in a district general hospital: retrospective and prospective audit. BMJ 2001;322:954-7(21 April) 2 "Healthcare for people with epilepsy in Wales". A report prepared for the Welsh Medical Committee by the working party on epilepsy. Published by The Welsh Office, October 1994 3 Brown S, Betts T, Chadwick D, Hall B, Shorvon S, Wallace S. An epilepsy needs document. Seizure 1993; 2: 91-103 4 Hopkins A. The first seizure and the diagnosis of epilepsy. In A Hopkins, S Shorvon, G Cascino, eds Epilepsy 2nd ed Chapman & Hall Medical, 1995:105-121 5 Gregory RP, Oates T, Merry RTG. Electroencephalogram epileptiform abnormalities in candidates for aircrew training. Electroencephalogr Clin Neurophysiol 1993;86:75-7 |
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Shalini Pooransingh, (1) Specialist registrar in public health medicine (2) Director of Public Health Department of Public Health Medicine, Walsall Health Authority, Sam Ramaiah
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EEG AS A DIAGNOSTIC TOOL? Smith et al’s(1)article was read with great interest not only because what they report was informative and demonstrated a change in clinical practice, but also because one of us was involved in a similar study back in 1989.(2) The study was undertaken in Clwyd, North Wales and 300 referrals were examined for referral source, reason for referral and results obtained on electroencephalography (EEG). 54% of referrals were in patients aged 15 – 59 years old and 54% were out patients. Positive results were found in 71% of all referrals. (A positive result equated to a definitive finding compatible with a specific diagnosis). Epilepsy was a major reason for referral. The main source of EEG referrals was from psychiatrists and physicians. One possible explanation given for the high referral rate by psychiatrists was the location of the EEG centre in the psychiatric hospital. Despite their high referral rates, the positive results were lowest in this group of referring doctors. A reason put forward for this was an indiscriminate use of the test. For example non specific symptomatic groups such as those with headaches, alcohol abuse and behavioural problems were referred. Added to this junior psychiatric doctors were involved in many of the referrals. The study therefore recommended the use of referral criteria for EEG use and it is heartening to read that Smith et al have not only recommended the use of referral criteria, but have demonstrated the value of such an intervention. Smith et al rightly point out that an EEG is rarely the sole determinant of a diagnosis and its value is therefore limited in clinical practice. Nevertheless, if used appropriately it can be a helpful tool. Both studies have shown that the ready availability of EEG tests can lead to their indiscriminate widespread use. Smith et al have managed to effect a change in EEG use in practice and merit our commendation. As public health doctors, we like to see consistent guidelines being utilised in an effort to improve the quality of care given to patients and to reduce unnecessary costs, whether monetary or psychological, by not performing tests without clinical indication. Dr Shalini Pooransingh
Dr Sam Ramaiah
Department of Public Health Medicine, Walsall Health Authority, Lichfield House, 27-31 Lichfield Street, Walsall WS1 1TE References 1 Smith D Bartolo R Pickles RM Tedman BM Requests for electroencephalography in a district general hospital: retrospective and prospective audit BMJ 2001; 322: 954-7. 2 Rao K Ramaiah R Davies N An analysis of 300 EEG referrals The Practitioner 1989; 233:320-2. |
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