MD, PhD, FMedSci, FRSB, FRCP, FRCPEd.

false negative

Whenever we consider alternative medicine, we think of therapeutic interventions and tend to forget that alternative practitioners frequently employ diagnostic methods which are alien to mainstream health care. Acupuncturists, iridologists, spiritual healers, massage therapists, reflexologists, applied kinesiologists, homeopaths, chiropractors, osteopaths and many other types of alternative practitioners all have their very own ways of diagnosing what might be wrong  with their patients.

The purpose of a diagnostic test or technique is, of course, to establish the presence or absence of an abnormality, condition or disease. Conventional doctors use all sorts of validated diagnostic methods, from physical examination to laboratory tests, from blood pressure measurements to X-rays. Alternative practitioners use mostly alternative methods for arriving at a diagnosis, and we should ask: how reliable are these techniques?

Anyone trying to answer this question, will be surprised to find how very little reliable information on this topic exists. Scientific tests of the validity of alternative diagnostic tests are a bit like gold dust. And this is why a recently published article is, in my view, of particular importance and value.

The aim of this study was to evaluate the inter-rater reliability of pulse-diagnosis as performed by Traditional Korean Medicine (TKM) clinicians. A total 658 patients with stroke who were admitted into Korean oriental medical university hospitals were included. Each patient was seen by two TKM-experts for an examination of the pulse signs – pulse diagnosis is regularly used by practitioners of TKM and Traditional Chinese Medicine (TCM), and is entirely different from what conventional doctors do when they feel the pulse of a patient. Inter-observer reliability was assessed using three methods: simple percentage agreement, the kappa value, and the AC(1) statistic. The kappa value indicated that the inter-observer reliability in evaluating the pulse signs ranged from poor to moderate, whereas the AC(1) analysis suggested that agreement between the two experts was generally high (with the exception of ‘slippery pulse’). The kappa value indicated that the inter-observer reliability was generally moderate to good (with the exceptions of ‘rough pulse’ and ‘sunken pulse’) and that the AC(1) measure of agreement between the two experts was generally high.

Based on these findings, the authors drew the following conclusion: “Pulse diagnosis is regarded as one of the most important procedures in TKM… This study reveals that the inter-observer reliability in making a pulse diagnosis in stroke patients is not particularly high when objectively quantified. Additional research is needed to help reduce this lack of reliability for various portions of the pulse diagnosis.”

This indicates, I think, that the researchers (who are themselves practitioners of TCM!) are not impressed with the inter-rater reliability of the most commonly used diagnostic tool in TCM/TKM. Imagine this to be true for a commonly used test in conventional medicine; imagine, for instance, that one doctor measuring your blood pressure produces entirely different readings than the next one. Hardly acceptable, don’t you think?

And, of course, inter-rater reliability would be only one of several preconditions for their diagnostic methods to be valid. Other essential preconditions for diagnostic tests to be of value are their specificity and their sensitivity; do they discriminate between healthy and unhealthy, and are they capable of differentiating between severely abnormal findings and those that are just a little out of the normal range?

Until we have answers to all the open questions about each specific alternative diagnostic method, it would be unwise to pretend these tests are valid. Imagine a doctor prescribing a life-long anti-hypertensive therapy on the basis of a blood pressure reading that is little more than guess-work!

Since non-validated diagnostic tests can generate both false positive and false negative results, the danger of using them should not be under-estimated. In a way, invalid diagnostic tests are akin to bogus bomb-detectors (which made headlines recently): both are techniques to identify a problem. If the method generates a false positive result, an alert will be issued in vain, people will get anxious for nothing, time and money will be lost, etc. If the method generates a false negative result, we will assume to be safe while, in fact, we are not. In extreme cases, such an error will cost lives.

It is difficult to call those ‘experts’ who advocate using such tests anything else than irresponsible, I’d say. And it is even more difficult to have any confidence in the treatments that might be administered on the basis of such diagnostic methods, wouldn’t you agree?

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