The problem of what to believe
In the Salt Skip Program at the Menzies Research Institute in Hobart the two salt-related health problems with the most dramatic response to good salt control are:
- the severe vertigo attacks of Meniere’s Disorder
- the mood changes and fluid retention of severe premenstrual syndrome
But we are only reporting clinical experience. Likewise two professors at one of Sydney’s big teaching hospitals were only reporting clinical experience when they wrote this about the vertigo of Meniere’s Disorder:
Strict dietary sodium restriction aiming for a urinary sodium less than 50 mmol/day is the most effective medical therapy (there has been no proper clinical trial), more effective and less troublesome than diuretics. Surgery can stop the vertigo attacks but can’t restore the hearing [1].
Would it amaze you to discover that surgery has not been given a ‘proper clinical trial’? If so, read on to find out why.
A PROPER CLINICAL TRIAL
The founding father of ‘proper clinical trials’ was the late Dr Archie Cochrane. As an early champion of Britain’s National Health Service (that provided free drugs) he was reluctant to charge taxpayers for drugs that only had a placebo effect.
Cochrane pioneered the randomised controlled trial, where a drug is compared with a placebo (a dummy tablet containing no drug). Patients are randomly allocated to a treatment group that receives the real drug and a control group that receives the placebo. The tablets have code numbers and even the doctors and nurses cannot tell who had the real drug until the results are in and the code is broken.
The often-surprising findings of ‘proper clinical trials’, such as more side effects with the placebo—believe it or not—have revolutionised modern medicine.
SURGERY AND VERTIGO
A randomised controlled trial of surgery for vertigo would require a sham operation on the control group. Even after recovering from the anaesthetic nobody would know if the real procedure had been done after the surgical incision had been made. That would have to wait until the results were in.
Obviously no surgeon would agree to this, no patient would give informed consent and no ethics committee would ever permit such a trial, so it would never be funded. For practical and ethical reasons there will never ‘a proper clinical trial’ of surgery for vertigo. We have the same problem with controlling salt intake.
SALT AND VERTIGO
It has been known since 1934 that the vertigo of Meniere’s Disorder can be induced at will by salt loading and virtually abolished at sodium excretion rates below 50 mmol/day [2, 3] and this has been confirmed in London [4]. In Hobart we have dramatic clinical results [5] but we have never been able to recruit any volunteers for a ‘proper clinical trial’ because no volunteer has ever given informed consent to any procedure that might induce vertigo. In London, where they did recruit volunteers in the 1960s, the ethics committee intervened in the middle of a trial and stopped it [6].
Clinical experience does have some validity of course. If salt had been a harmless food additive it would certainly not have caused ethical problems serious enough to make it impossible to conduct ‘proper clinical trials’ comparing two levels of intake (under 50 and over 50 mmol/day).
People who find they are able to control their severe vertigo attacks by simply choosing healthier food—without drugs or surgery—have no interest in ‘proper clinical trials’. They tell us they have no problem with what to believe!
References
1. Halmagyi GM, Cremer PD. Assessment of dizziness. J Neurol Neurosurg Psychiatry 2000;68:129–134.
2. Furstenberg AC, Lashmet FH, Lathrop F. Ménière’s symptom complex: medical treatment. Annals of Otology, Rhinology and Laryngology 1934;43:1035–46.
3. Boles R, Rice DH, Hybels R, Work WP. Conservative management of Ménière’s disease: Furstenberg regimen revisited. Annals of Otology 1975;84:513–17.
4. Harrison MS, Naftalin L. Meniere’s disease: mechanism and management. Springfield, Illinois: Charles C Thomas; 1968:85–101.
5. Beard TC. Chapter 13. Salt and other health problems. In: Salt Matters: a consumer guide. Melbourne: Lothian Books; 2004:157–174.
6. Gibson WPR. Royal Prince Alfred Hospital, Sydney. Personal communication 1999.
Page last modified on: Tuesday 06 Nov, 2007