When we consult a health care provider because we feel unwell, the first step invariably is to arrive at a diagnosis. Sometimes this is fairly obvious but often it is not. Typically the health care provider will do a few tests to aid the process. This may involve doing some physical examinations, or taking a blood sample, or ordering some high tech investigation, like a scan, for instance.
All these tests have to fulfil certain criteria to be valid. The most basic of these is that repeated tests should produce roughly the same result. If not, the test is not reproducible, i.e. it is not better than pure guess-work.
Alternative practitioners often use diagnostic tests that are unknown in conventional medicine. But this fact does not mean that these test do not need to be as valid as any other test used in medicine. If the alternative tests are not reproducible, the diagnosis of the alternative practitioner is likely to be pure invention. And if the diagnosis is just a figment of imagination, the treatment aimed at curing it will be nonsense as well.
So, how reliable are those tests used by alternative practitioners? Amazingly, this fundamental question has attracted very little research. I have repeatedly investigated this area and found that, generally speaking, alternative diagnostic techniques are bogus. And because there is so little research, every new trial of alternative diagnostic methods is important.
A brand-new study assessed the inter-rater reliability of Ayurvedic pulse (nadi), tongue (jivha), and body constitution (prakriti) assessments. Fifteen registered Ayurvedic practitioners with 3-15 years of experience independently examined 20 healthy subjects. Subjects completed self-assessment questionnaires and software analyses for prakriti assessment. Weighted kappa statistics for all 105 pairs of practitioners were computed for the pulse, tongue, and prakriti data sets.
These pairwise kappas ranged from poor to slight, slight to fair, and fair to moderate for pulse, tongue, and prakriti assessments respectively. The average pairwise kappas for pulse, tongue, and prakriti were 0.07, 0.17, and 0.28, respectively. For each data set and pair of practitioners, the null hypothesis of random rating was rejected for just 12 pairs of practitioners for prakriti, one pair of practitioner for pulse examination, and no pairs of practitioner for tongue assessment.
The authors of this investigation conclude that the results demonstrate a low level of reliability for all types of assessment made by doctors.
This is worrying, I think. It is comparable to a situation where you go to see your GP and he measures your blood pressure, or weight, or cholesterol, or any other parameter with a test that produces a different result each time someone tries to repeat it. Your blood pressure could be 160/90 when measured with this fictionally unreliable test and 110/ 60 when repeated two minutes later by the practice nurse, for instance. Any treatment based on such random numbers would be idiotic…and so, it seems, is any Ayurvedic treatment based on the pulse (nadi), tongue (jivha), and body constitution (prakriti).