In a recent post on his blog Dr Briffa bemoaned the over-reliance of the modern medical profession on ‘tests’ to the exclusion of the exercise of their clinical skills. His mini rant had been set off by an article in the BMJ by Dr Des Spence accusing modern doctors of being so fearful of sticking their necks out and ‘giving an opinion’ that they had created an endless referral system that is ‘bland, thoughtless, expensive and indecisive’.
Dr Spence is a pretty regular contributor to the BMJ (with whom I have taken issue in the past – see Bad Medicine: food intolerance) but on this occasion I, too, entirely agree with him – especially in the field of food allergy. Even the keenest supporter of skin prick or blood tests will admit that they are far from perfect, turning in a worrying number of both false positives and false negatives, and that the only really reliable method of testing for allergy is a provocation test in which the patient, under medical supervision, actually ingests the allergen.
But, if tests don’t work, how is even an initial diagnosis to be reached?
Drs Briffa and Spence both suggest that the doctor draws on his/her own clinical training and experience before resorting to either a referral or a test. Dr Briffa quotes his experience with a patient who, having suffered from a month long headache, had been referred to a private neurologist and subjected to a battery of tests including an MRI scan without any outcome, positive or negative. When she saw Dr Briffa she explained that the pain ran up the back of her head from her neck up into her skull. A cursory examination revealed, accurately, that she was suffering from muscular tension, yet none of the doctors she had seen previously had either asked in detail about the nature of her pain or given her a physical examination.
In terms of allergy, clinical training and experience is vital but possibly even more important is the ability to think outside the conventional medical box and to be prepared to delve in some depths into both the patient’s and their family’s history.
In a short presentation at a recent Anaphylaxis Campaign conference, allergist Dr Michael Radcliffe illustrated the former with a number of case histories in which testing not only failed to help but actually muddied the picture. Such as, for example:
A patient collapsed after eating spaghetti Bolognese in a restaurant but had no known allergies, and tested negative, to all of the potential allergens in the dish. However, he did have a severe reaction each autumn to the mould/fungus, altenaria. On further investigation it was found that it had been a vegetarian spaghetti Bolognese and that the meat alternative had been Quorn – a fungus which cross reacts with altenaria.
The late, and sadly missed, Dr Harry Morrow Brown, was a stickler not only for eliciting all of the circumstances surrounding each allergic reaction but for a detailed investigation into the family history of the patient. There is a lengthy (and very well worth reading) section on testing for allergy on his website, www.allergiesexplained.com, but a few of his opening remarks well illustrate his approach:
The most important part of an allergy investigation is taking a very detailed case history, always including the family history, because if many family members also have allergies then the patient’s problems are also more likely to be due to allergy. Taking an allergic case-history properly is very interactive and time-consuming, depends on the experience and knowledge of the investigator, and is an example where art of medicine still takes precedence over science.
An experienced Allergist will know the correct questions to ask and how to elicit and detect significant clues in the patient’s answers which may suggest the most likely causes…….
….Observant patients may have noticed important circumstantial evidence relating to their sufferings, but may not mention their experiences unless asked directly by the allergist because they do not realise that their observations are important. For this reason an experienced allergist will ask essential leading questions which are always asked again later to check for consistency.
This is not to say that, even in allergy, tests are useless – Harry Morrow Brown not only used them extensively but invented many of his own. However, tests should remain an adjunct to, not a replacement for, clinical diagnosis. As Dr Radcliffe said:
Both skin prick and blood tests can be used to diagnose and, although neither are totally reliable, they are an easy and cheap guide to allergic sensitivity. However, they should only ever be used in conjunction with the patient’s history which, for an allergist, is the key to making an accurate diagnosis.
Take heed, oh ye doctors!
