Simple scientific questions require simple scientific answers; doctors want unequivocal guidance to their practice so that they do not fumble in the dark. But it is easier to ask questions than to answer them, as two papers published in the same week in the New England Journal of Medicine and the Journal of the American Medical Association attest.

The question asked by the two papers was the optimum level of oxygenation in the blood of pre-term infants. In the past it was rather naively supposed that if oxygen were necessary, then more of it must be better; but premature infants who were exposed to high levels of oxygen developed a condition known as retinopathy of prematurity, often leaving them blind or severely impaired visually.

The two trials, one from Britain, Australia and New Zealand, and the other from the United States, Canada, Argentina, Finland, Germany and Israel, sought to establish whether a higher or lower level of oxygen saturation of the blood was better for infants born very prematurely. The results were different, if not quite diametrically opposed.

The first trial found that babies treated so that their blood oxygen saturation was higher had a lower death rate at 36 weeks than those treated so that their levels were lower. 15.9 per cent in the high saturation group died compared with 23.1 per cent in the lower. You would have to treat 14 babies with the high oxygen saturation to save life more than treating them at the lower level.

Not long ago I bought a book, published in 1922, titled Syphilis of the Innocent. Needless to say, the title implied a corollary: for if syphilis could be contracted by the innocent (as, for example, in the congenital form of the disease), it could also be contracted by the guilty.

In general, however, physicians do not inquire after the morals of their patients, except in so far as those morals have immediate pathological consequences. They do not refuse to treat patients because they find them disgusting, because they find them unappealing, because they are appalled by the way they choose to live. They try to treat them as they find them; they may inform, but they do not reprehend.

However, in practice things are sometimes more complex than this ecumenical generosity of spirit might suggest. According to an article in a recent edition of the New England Journal of Medicine, some doctors have been turning away patients on the grounds that they were too fat (one physician suggested that she did so because, ridiculously, she feared for the safety of her staff once the patients weighed more than 200 pounds), or that their children have gone unimmunized. Is such discrimination by physicians legitimate or illegitimate, legally or morally speaking? Is there not a danger that physicians may hide behind pseudo-medical justifications to express their personal prejudices or to coerce patients into doing what the physicians think is good for them?

Does practice really make perfect? Does it even lead to improvement? One feels instinctively that it should, that the more experience a physician has, the better for the patient. Much of the skill of diagnosis is pattern-recognition rather than complex intellectual detection, and it follows that the longer a physician has been at it, the quicker he will recognize what is wrong with his patients. He has experience of more cases than younger doctors to guide him.

But the practice of medicine is more than mere diagnosis. It often requires manual dexterity as well, and the ability to assimilate new information as advances are made. These may decline rather than improve with age. Too young a doctor is inexperienced; too old a doctor is past it.

A recent paper, whose first author comes from the Orwellianly named Department of Veterans’ Affairs Center for Health Equity Research and Promotion, examined the relationship between the years of an obstetrician’s experience and the rate of complications the women under his care experienced during childbirth. The authors examined the records of 6,705,311 deliveries by 5,175 obstetricians in Florida and New York. No one, I think, would criticize the authors for the smallness of their sample.

They examined the rate of serious complications such as infection, haemorrhage, thrombosis, and tear during or after delivery, divided by obstetrician according to his number of years of post-training experience. Reassuringly, and perhaps not surprisingly, experience reduced the number of such complications decade after decade. The rate of complications was 15 percent in the first ten years after residency; it declined by about 2 percent to 13 percent in the first decade thereafter, by about 1 percent in the subsequent decade to 12 percent, and by  half a percent in the next. In other words, improvement continued, but less quickly as the obstetricians became more experienced; the authors appear not to have continued their study to the age at which the rate of complications started to rise again (if indeed there is such an age).

There was a time in my country when, among other unpleasant duties, the prison doctor was required to assess prisoners for their fitness for execution. Needless to say, not much attention was paid in medical school to this particular skill: the physician was on his own because in those days there were no such things as official guidelines. The rough and ready rule was that a man was fit to be executed if he knew that he was to be executed and why. It was the death-penalty equivalent of informed consent to surgery.

One of the last British executioners, Albert Pierrepoint, who hanged about 600 people, wrote in his memoirs that he was often asked if people struggled on their way to the gallows. He replied that he had known only one do so; to which he added, by way of explanation, “And he was a foreigner.” However, foreign nationality was not in itself a contraindication to execution. Pierrepoint was one of the executioners at Nuremberg.

An article in a recent edition of the New England Journal of Medicine draws attention to the ethical and practical dilemmas of American physicians asked to assess people for fitness to carry concealed weapons. Again this is not a skill taught in medical schools. No firm criteria, beyond those of common sense (which have not been validated by research), have been laid down. It seems obvious that people with paranoid personalities or psychoses, gross depression or mania, those who take cocaine, amphetamines, or other stimulants, and alcoholics should be refused permission to carry concealed weapons. But many of those conditions (if taking cocaine can properly be called a condition) are easy to conceal or difficult to detect. How far is the doctor to go in attempting to detect them? Interestingly, or curiously, the authors do not mention hair or blood tests, which could certainly help the doctor detect drug and alcohol abuse. 

Pain is obviously one of the most important symptoms with which doctors deal, but measuring its severity objectively is difficult. Some people turn a twinge into agony, while others raise not a murmur in the last extremities of torture. And it is universally accepted that a person’s psychological state or disposition has a profound effect on his perception of pain.

Philosophers, indeed, have used the phenomenon of pain to debate what seemed to them an important question, namely whether there were such things as private languages or inner states inaccessible to others.

Clever experiments reported in a recent issue of the New England Journal of Medicine offer the hope, perhaps illusory, that brain imaging techniques might one day distinguish between real and severe pain on the one hand from exaggerated or false pain on the other (people may exaggerate or lie about pain for a variety of reasons).

Having recently returned from Madrid, I confess that I saw little evidence of the Mediterranean diet being consumed there (apart, that is, from the red wine): though, of course, Madrid is in the middle of the peninsula, far from the Mediterranean. Perhaps things are different on the coast. Nevertheless, at over 80 years, Spain has one of the highest life expectancies in the world.

Is this because of the much-vaunted Mediterranean diet? Spanish research recently reported in the New England Journal of Medicine provides some – but not very much – support for the healthiness of that diet.

The researchers divided 7000 people aged between 55 and 80 at risk of heart attack or stroke because they smoked or had type 2 diabetes into three dietary groups. One group (the control) was given dietary advice concerning what they should eat; the two other two groups were cajoled by intensive training sessions into eating a Mediterranean diet, supplemented respectively by extra olive oil or nuts, supplied to them free of charge.

They were then followed up for nearly five years, to find which group suffered from the most (or the least) heart attacks and strokes. The authors, of whom  there were 18, concluded:

Among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.

The authors found that the diets reduced the risk of the subjects suffering a heart attack or stroke by about 30 percent. Put another way, 3 cardiovascular events were prevented by the diet per thousand patient years. You could put it yet another way, though the authors chose not to do so: 100 people would have to have stuck to the diet for 10 years for three of them to avoid a stroke or a heart attack. This result was statistically significant, which is to say that it was unlikely to have come about by chance alone, but was it significant in any other way?

The unexamined life, said Socrates, is not worth living; but sometimes I wonder whether the too-closely examined life is not worth living either, for examination uncovers dilemmas where none existed before.

Two articles in a recent edition of the New England Journal of Medicine ask the question of whether employers should, or have the right to, refuse to employ smokers, as increasing numbers do in the 21 states that permit such discrimination against them.

As is by now no secret, smokers are more likely to suffer from many types of illness than non-smokers, and their health insurance is therefore considerably more expensive than that of non-smokers. They impose costs on their employers which weigh upon all workers, smokers or not. (The authors do not take into account that smokers not only contribute to taxes by their habit but, by dying early, reduce pension costs.)

The authors worry that refusal to hire smokers would be discriminatory against people of lower social class, since it is among the latter that smoking is most prevalent. I am not sure that this is right: the majority of people in all social classes now do not smoke, while people who apply for jobs at any particular level are likely to be of the same social class. Except in the case where there is only one applicant for a job, then, it is likely that there will always be an applicant of any given social class who does not smoke. The discrimination remains against smokers, therefore, and not by proxy against members of lower social class.

Twenty-seven years ago I found what seemed to be the only functioning storm-drain in Tanzania, in East Africa, and fell down it, severely injuring a knee in the process. The journey to the mission hospital in the back of a pick-up truck over sixty miles of rutted laterite road was one of the more agonising experiences of my life.

I had an arthroscopy when I returned home several weeks later — I could not even hobble until then — and the orthopaedic surgeon told me that unless I did physical therapy every day for a very long time it was inevitable that I should be crippled by arthritis within twenty years.

It was equally inevitable that I would not do physical therapy every day for a long time; and here I am, twenty-seven years later, without so much as a twinge from my knee. My faith in the predictive powers of orthopaedic surgeons has been somewhat dented.

That was why I read with interest a paper in a recent edition of the New England Journal of Medicine comparing physical therapy with surgery for meniscal tears in the knees of people with osteoarthritis. To cut a long story short, there was no difference in outcome, an important finding, since 465,000 people undergo operations for precisely this situation every year in the United States alone.

Actually, the uselessness of operation had been established before — the uselessness from the patients’ point of view, that is. Two previous trials had compared real with sham operations, and with no operations at all, and found no difference in the outcome two years later. One might suppose that, in the light of these findings, the 465,000 operations still performed annually constituted something of a scandal.

The clinical trial reported in the NEJM is, like all such trials, not definitive. The follow-up period was only 6 months, relatively few patients were recruited to it, and some patients initially allocated to physical therapy had an operation nonetheless for reasons that are not entirely clear. Moreover, the trial is only that of operation versus physical therapy; strictly speaking, there should also be a comparison with patients who had no treatment at all.

The Duke of Wellington, surveying his soldiers before the Battle of Waterloo, famously said that he did not know what they did to the enemy, but by God they frightened him.

No one thought in those days of the psychological effect upon the soldiers of witnessing so much violence (more than 30,000 were killed during the battle, about one in six of those who took part in it); nor could anyone have done so if he had thought of it. But it is now accepted wisdom that active military service leads men subsequently to commit crimes of violence, though the reasons for this are unknown.

A recent paper in The Lancet examined the association of military service and subsequent crimes of violence, which turned out to be much weaker than suspected. The authors examined the criminal records of 8,280 British soldiers who had served in Iraq and Afghanistan with that of 4,080 of those who had not. When controlled for such factors as age, level of education, pre-service record of violent offenses, rank, and length of service, there was no significant difference in the criminal records of those who had served in Iraq and Afghanistan and those who had not.

When, however, those who were deployed in a combat role were compared with those who had not been so deployed, it was found that the former had higher levels of violent offending as measured by their criminal records. Interestingly, however, those who were involved in actual fighting had considerably higher prior levels of violent offending than those not so involved, suggesting that more aggressive types either volunteered or were selected for combat service. Somewhat alarmingly, nearly half of soldiers involved in the fighting had criminal records for violence.

For a long time doctors were subject to contradictory imperatives with regard to AIDS. On the one hand they were enjoined to treat it as they would treat any other disease, without animadversion on the way in which the patient had caught it; on the other hand they had, before testing for the presence of HIV, to seek special permission of the patient and to ensure that he or she had had counselling before the test was taken – quite unlike the testing for any other disease, syphilis for example. So AIDS was at the same time a disease like any other and also in a completely different category from all other diseases.

It cannot be said that pre-test counseling is universally popular among patients. There was an Australian clinic that famously offered the test with “guaranteed no counseling” and it did not lack for clients. For quite a number of years, however, HIV-test counselling has provided a living for the kind of people who like to hover around the edges of human catastrophe.

However, the recommendation by the United States Preventive Services Task Force (USPSTF), reported in an article in a recent edition of the New England Journal of Medicine, that henceforth the screening of adults for HIV infection should be routine will, if adopted, put paid to all such pre-test counseling. One cannot counsel scores or hundreds of millions of people.

Seven years ago the USPSTF came to a different conclusion on the question of screening for HIV, believing that the benefits were insufficient to recommend it. Since then, however, evidence has accumulated that treating people early in the course of their infection not only prolongs their life but reduces spread of the infection.