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Evidence based medicine

Dear bpac,

Thank you for your Upfront article on practising evidence based medicine in last months Best Practice Journal. It was pleasing to see the sacred cow of evidence based medicine revealed as a false idol. For too long we have kowtowed ourselves to the practitioners of this cult. Although in the medical profession we see ourselves as honest and wise in our practice we have been exposed as human after all.

The Emperors New Clothes fable has revisited us with bpac publishing this article. Hopefully it might help us pause and ask what it is in human nature that allows the many to be persuaded by the few? History is rich in what it can teach us in this regard. What safeguards might we use to prevent this happening again in medicine?

For me the answer lies in focusing on practising the Art of Medicine, on the surface quite the antithesis of Evidence Based Medicine. However this is not so as the Art of Medicine encompasses both. The humanity of medical care is the major part of the discipline with science an ingredient only.

Our professional ethos of care and beneficence is best served by practitioners who practise the art of medicine with wisdom, humility, compassion and above all a healthy scepticism for new knowledge.

Ken Greer, GP, Wellington

Thanks for your comments Ken. Bpac strongly believes that clinicians should base their recommendations on the best available evidence. To do this they need to be able to appraise the evidence for its strength and relevance for the patient sitting in front of them and be alert for new evidence. We believe evidence-based medicine and patient-centred medicine are two sides of the same coin.

Using dexamethasone for otitis externa

Dear bpac,

Why do we use dexamethasone (as in sofradex) for otitis externa? Why should we be suppressing the inflammation reaction?

GP, Bay of Plenty

Definition: Otitis externa is inflammation, often with infection, of the external ear canal.1

Solutions containing an anti-infective and an anti-inflammatory are used in otitis externa when infection is present with inflammation and eczema.2

A recent meta-analysis suggests minimal or no difference in clinical outcomes when various topical agents including, antiseptics, antimicrobials and steroid-antimicrobial combinations were compared for otitis externa.3

Other studies suggest that the addition of a steroid:

  • Shortens time to treatment response and resolution of symptoms4
  • Reduces inflammation and itching3

Presumably the steroid helps with associated pain and it is reasonable to suppress an inflammatory reaction if antiinfectives are present to treat any concurrent infection.

Prolonged use of topical anti-infectives is discouraged as excessive use may result in fungal infections.

References

  1. Hajioff, D. Otitis externa. BMJ Clin Evid 2007;12:510
  2. British National Formulary (BNF). London: BMJ Publishing Group and Royal Pharmaceutical Society of Great Britain. September 2007
  3. Rosenfeld L, Brown C, Cannon R, et al. Clinical practice guideline: Acute otitis externa. Otolaryngol Head Neck Surg 2006; 134(4): S4 - S23
  4. van Balen F, Smit W, Zuithoff N, Verheij T. Clinical efficacy of three common treatments in acute otitis externa in primary care: randomised controlled trial. BMJ 2003; 327:1201-1205.

Lithium: Baseline ECG may be required

Re: Lithium in General Practice, BPJ 3, Feb 2007. Why is a baseline ECG required in a patient with no cardiac history?

Clinical Manager, Central Otago

Benign, reversible ECG changes occur in 20–30% of people receiving lithium. Other cardiac changes, particularly arrhythmias, may rarely occur at therapeutic and toxic serum lithium concentrations.1

Lithium should be used cautiously in patients with preexisting cardiovascular disease. Patients with underlying cardiovascular disease should be observed carefully for signs and symptoms of arrhythmia (including ECG measurement).1

Information regarding baseline ECG testing for all patients before commencing lithium therapy is inconsistent. The Handbook of Psychotropic Drugs, 13th Edition, 2003, recommends a baseline ECG for people over 45, or in a person with a history of cardiac problems. The Lithicarb FC and Priadel datasheets recommend a baseline assessment of cardiac function and periodic reassessment.

There are several reasons for conducting a baseline ECG in patients (over 45 years) with no history of cardiac problems, including:

  1. Lithium treatment has been associated with arrhythmias, even at therapeutic doses.
  2. Baseline ECG is useful for future comparison should lithium related arrhythmias occur.
  3. People over 45 years have a higher likelihood of underlying cardiac problems.
  4. A baseline ECG can be useful if other medications are added. For example, thyroxine can precipitate atrial fibrillation or angina in patients with ischemic heart disease.2

For further details about the management of patients taking lithium see BPJ 3, February 2007.

References

  1. American Society of Health-System Pharmacists. AHFS Drug Information 2007. Available from http://www.medicinescomplete.com/. Accessed April 2008.
  2. Livingstone C, Rampes H. Lithium: a review of its metabolic adverse effects. Psychopharmacol 2006;20(347):347-355.

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