Operator ‘source of error’

Press, 22 July 1986, Page 25

Operator ‘source of error’

In the United States, the Food and Drug Administration says there is insufficient evidence of diagnostic or therapeutic effectiveness of the Dermatron to justify approval of its marketing in America as a diagnostic instrument.

The task force says that instrument response obtained during the Dermatron’s operation is subject to significant operator bias.. The movement of the indicator needle will be “strongly influenced” by the degree of pressure applied to the probe electrode by the machine’s operator. "In fact, an operator can deliberately or unconsciously cause the indicator needle to fluctuate widely, as was noted by operators other than Dr Tizard during the course of the visit to him,” says the report. That source of error is recognised by. electro-acupuncture operators, who claim to have overcome the problem by applying considerable pressure to the acupuncture point and moistening the measurement probe. Dr Peter Madill, an electroacupuncture operator for five years, says his experience shows that claims made in German literature about “the purported pressure independence of the method of point measurement” are not substantiated.

Operator bias is "seldom recognised by the operator,” says the task force, which believes that Dr Tizard- has “adopted an uncritical attitude” to the question of bias. Dr Tizard himself had told the task force that some weeks or months of practice with the instrument were needed to ob-

tain satisfactory responses. In general, says the task force, descriptions of electro-acupunc-ture theory “show a lack of understanding of electrical theory and an attempt to shape the facts according to the required conclusion." For example, theory says that the acupuncture point behaves like a battery when a current is applied from an external source. Task force comment: If a bat-tery-like component does exist, it should be measurable with a standard voltmeter. It is well established that no such readings can be obtained.

Glass causes

problems

Theory says that the acupuncture point is negatively-charged to the skin and its. surroundings within the body. For, this reason, the measurement probe of the Dermatron is connected to the positive terminal of the apparatus so that “balancing” of charges may occur. Task force comment: If the site is negatively charged, then the voltage reading at the site should be negative. In fact, the measured potential is positive

which is consistent with the site being purely passive in nature. Theory says that homeopathic medicine testing according to electro-acupuncture relies on the insertion into the circuit of glass vials containing various homeopathic preparations. However, glass is not a conductor of electricity. In conventional electrical terms, the contents of the glass vials cannot affect the current or applied DC voltage. The technique’s originator recognised this problem, and proposed that the observed effect is a result of “radiation”' arising from the homeopathic preparations to effect changes in the body, which is then able to generate the necessary electrical potential to "balance” the applied potential. Task force comment: The concept of homeopathic preparations not in direct contact with an electrical measuring circuit (but close to it) altering the measured voltage when a small current is applied has no scientific basis. No such radiation as is suggested has been detected, and there is no known mechanism for its generation. In the absence of controlled clinical trials, says the task force, neither apparent cures nor symptomatic improvement can be distinguished from the placebo effect of non-specific treatment, nor from spontaneous im-

provement over time. “I think that whenever someone comes out with a new tech-nique-analytical, healing, identifying or assessing something — that technique must be open to scrutiny to see whether it is valid or not,” says Dr Max Robertson, a Government analyst at the D.S.I.R.’s chemical division in Christchurch. He is a member of the New Zealand Sceptics.

Chance not

enough

For example with a technique that measures a certain level of toxins, a number of healthy people and an equal number with, say, M.E. should be mixed up to see if the technique can sort them out, he says. “The technique must be tested with large numbers,” adds Dr Robertson, “to show that results are not just chance. You have to do analyses of the normal population and those identified as having contact with toxins.” A former boss used to tell him that 60 per cent of the people who go to a doctor because they feel sick would get better eventually whether or not the doctor does anything. In about 20 per cent of such cases, the doctor is

required to carry out a treatment to make the patient better. In the other 20 per cent, there is nothing that can be done.

“On the law of averages, then, any person who sets himself up as curing people will have a 60 per cent success rate even if he does nothing,” says Dr Robert-, son. “Their symptoms, could be relieved by someone who treats them expertly, but they will get better eventually.?': : .<-<« Dr David Marks, a University of ’ Otago psychologist ■ who is head of the New Zealand Sceptics, says that doctors have problems with psychosomatic illnesses which are difficult to treat. Patients want to be treated as persons, as individuals, and homeopaths, for Instance, fulfill a need.

“On the periphery of medicine, we are seeing the reflection of medicine’s failure,” he says. “Alternative medicine, even if it is pseudo-science, is servicing that need. Perhaps, in the end, the pseudo-science is pushing the orthodox to come up with better solutions. That is a positive side.” Dr Marks says that a' better dialogue is needed between the advocates of both sides. He acknowledges the possible nonspecific treatment effects of alternative medicine and thinks that orthodox medical practitioners might offer their patients more by listening better.