Monday, January 4, 2010

PRESCRIPTION DRUGS KILL OVER 100,000 ANNUALLY

Even higher than the number of people who die from medication errors is the number of people who die from medication, period. Even when a prescription drug is dispensed properly, there's no guarantee it won't end up killing you.

A remarkable study in the Journal of the American Medical Association revealed that prescription drugs kill around 106,000 people in the US every year, which ranks prescription drugs as the fourth leading cause of death. Furthermore, each years sees 2,216,000 serious adverse drug reactions (defined as "those that required hospitalization, were permanently disabling, or resulted in death").



The authors of this 1998 study performed a meta-analysis on
39 previous studies covering 32 years. They factored out such things as medication errors, abuse of prescription drugs, and adverse reactions not considered serious. Plus, the study involved only people who had either been hospitalized due to drug reactions or who experienced reactions while in the hospital. People who died immediately (and, thus, never went to the hospital) and those whose deaths weren't realized to be due to prescription drugs were not included, so the true figure is probably higher.

Four years later, another study in the JAMA warned:

Patient exposure to new drugs with unknown toxic effects may be extensive. Nearly 20 million patients in the United States took at least 1 of the 5 drugs withdrawn from the market between September 1997 and September 1998. Three of these 5 drugs were new, having been on the market for less than 2 years. Seven drugs approved since 1993 and subsequently withdrawn from the market have been reported as possibly contributing to
1002 deaths.

Examining warnings added to drug labels through the years, the study's authors found that of the new chemical entities approved from 1975 to 1999, 10 percent "acquired a new black box warning or were withdrawn from the market" by 2000. Using some kind of high-falutin'
statistical process, they estimate that the "probability of a new drug acquiring black box warnings or being withdrawn from the market over 25 years was 20%."

A statement released by one of the study's coauthors — Sidney Wolfe, MD, Director of Public
Citizen's Health Studies Group — warned:

In 1997, 39 new drugs were approved by the FDA. As of now [May 2002], five of them (Rezulin, Posicor, Duract, Raxar and Baycol) have been taken off the market and an additional two (Trovan, an antibiotic and Orgaran, an anticoagulant) have had new box warnings. Thus, seven drugs approved that year (18% of the 39 drugs approved) have already been withdrawn or had a black box warning in just four years after approval. Based on our study, 20% of drugs will be withdrawn or have a black box warning within
25 years of coming on the market. The drugs approved in 1997 have already almost
"achieved" this in only four years — with 21 years to go.

How does this happen? Before the FDA approves a new drug, it must undergo clinical trials. These trials aren't performed by the FDA, though — they're done by the drug companies themselves. These trials often use relatively few patients, and they usually select patients most likely to react well to the drug. On top of that, the trials are often for a short period of time (weeks), even though real-world users may be on a drug for months or years at a time. Dr. Wolfe points out that even when adverse effects show up during clinical trials, the drugs are sometimes released anyway, and they end up being taken off the market because of those same adverse effects.

Postmarketing reporting of adverse effects isn't much better. The FDA runs a program to collect reports of problems with drugs, but compliance is voluntary. The generally accepted estimate in the medical community is that a scant 10 percent of individual instances of adverse effects are reported to the FDA, which would mean that the problem is ten times worse than we currently believe.

Drugs aren't released when they've been proven safe; they're released when enough FDA bureaucrats — many of whom have worked for the pharmaceutical companies or will work for them in the future — can be convinced that it's kinda safe. Basically, the use of prescription
drugs by the general public can be seen as widespread, long-term clinical trials to determine their
true safety.

We are all guinea pigs.

THE SUICIDE RATE IS HIGHEST AMONG THE ELDERLY

If you judge by the media and the public education programs, you might be inclined to think that teenagers and young adults (aged 15 to 24) are the age group most likely to kill themselves. Actually, they have the second-lowest rate of suicide. (The absolute lowest rate is among kids aged 5 to 14; children younger than that are apparently deemed incapable of consciously choosing to end their lives.) It is the elderly, by far, who have the highest rate of suicide.

In the US, of every 100,000 people aged 75 to 79, 16.5 kill themselves. For those 80 and over, the rate is 19.43. This compares to a rate of 8.15 per 100,000 for people between the ages 15 and
19, and 12.84 for people aged 20 to 24.

As with every age group, men are far more likely to kill themselves, but among the elderly this trend reaches extreme proportions. Of people 65 and older, men comprise a staggering 84 percent of suicides.

Because men commit the vast majority of hara-kiri among old people, looking at these male suicide rates makes for extremely depressing reading. For guys aged 75 to 79, the suicide rate is
34.26 per 100,000. In the 80 to 84 group, men's suicide rate is 44.12. When you look at men 85 and older, the suicide rate is a heart-breaking 54.52. Compare this to the suicide rate for dudes in their mid to late teens: 13.22 per 100,000.

It is true that suicide ranks as the second or third most common cause of death in young people (depending on age group), while it is number 15 and under for various groups of the elderly. Still, the suicide rate among the young is equal to their proportion of the population, while the elderly are way overrepresented as a group. And old people are cut down by a great many diseases and disorders virtually unknown to the young, which naturally pushes suicide down in the rankings.

The reasons why this suicide epidemic is ignored are highly speculative and would be too lengthy to get into here. However, we can rule out one seemingly likely explanation — suicide among the aged is invisible because they usually O.D. on prescription drugs or kill themselves in other ways that could easily be mistaken for natural death in someone of advanced years. This doesn't wash, primarily because guns are the most common method of dispatch. Of suicides over
65, men used a gun 79.5 percent of the time, while women shot themselves 37 percent of the time. It's hard to mistake that for natural causes.

The sky-high suicide rate among the elderly applies to the entire world, not just the US. Plotted in a graph, suicide rates by age group around the globe gently curve upward as age increases. When the graph reaches the final age group, the line suddenly spikes, especially for men. Worldwide, men 75 and over have a suicide rate of 55.7 per 100,000, while women in the same age group have a rate of 18.8. This rate for old men is almost three times the global rate for guys aged 15 to 24, while the rate for old women is well over three times the rate for young gals in that age group.

WORK KILLS MORE PEOPLE THAN WAR

The United Nations' International Labor Organization has revealed some horrifying stats:

The ILO estimates that approximately two million workers lose their lives annually due to occupational injuries and illnesses, with accidents causing at least 350,000 deaths a year. For every fatal accident, there are an estimated 1,000 non-fatal injuries, many of which result in lost earnings, permanent disability and poverty. The death toll at work, much of which is attributable to unsafe working practices, is the equivalent of 5,000 workers dying each day, three persons every minute.

This is more than double the figure for deaths from warfare (650,000 death* per year). According to the ILO's SafeWork programme, work kills more people than alcohol and drugs together and the resulting loss in Gross Domestic Product is 20 times greater than all official development assistance to the developing countries.

Each year, 6,570 US workers die because of injuries at work, while 60,225 meet their maker due to occupational diseases. (Meanwhile, 13.2 million get hurt, and 1.1 million develop illnesses that don't kill them.) On an average day, two or three workers are fatally shot, two fall to their
deaths, one is killed after being smashed by a vehicle, and one is electrocuted. Each year, around
30 workers die of heat stroke, and another 30 expire from carbon monoxide.

Although blue collar workers face a lot of the most obvious dangers, those slaving in offices or stores must contend with toxic air, workplace violence, driving accidents, and (especially for the health-care workers) transmissible diseases. The Occupational Safety and Health Administration warns that poisonous indoor air in nonindustrial workplaces causes "[t]housands of heart disease deaths [and] hundreds of lung cancer deaths" each year.

But hey, everybody has to go sometime, right? And since we spend so much of our lives in the workplace, it's only logical that a lot of deaths happen — or at least are set into motion — on the job. This explanation certainly is true to an extent, but it doesn't excuse all such deaths. The International Labor Organization says that half of workplace fatalities are avoidable. In A Job to Die For, Lisa Cullen writes:

In the workplace, few real accidents occur because the surroundings and operations are known; therefore, hazards can be identified. When harm from those hazards can be foreseen, accidents can be prevented....

Most jobs have expected, known hazards. Working in and near excavations, for example, poses the obvious risks of death or injury from cave-in.... When trenches or excavations collapse because soil was piled right up to the edge, there is little room to claim it was an accident.

ONE OF THE HEROES OF BLACK HAWK DOWN IS A CONVICTED CHILD MOLESTER

The movie Black Hawk Down was one of the biggest box office draws of 2001, and it earned its director, Ridley Scott, an Oscar nomination. (He didn't win, but the movie got two Academy Awards for editing and sound.) Based on Mark Bowden's nonfiction book of the same title, it concerns the disastrous raid of Mogadishu, Somalia, by US elite soldiers in 1993.

One of these Special Forces soldiers underwent a name-change as he moved from the printed page to the big screen. Ranger John "Stebby" Stebbins became Ranger Danny Grimes when played by Scottish heartthrob Ewan McGregor. Why? Because in 2000, Stebbins was court- martialed and sent to the stockade for rape and sodomy of a child under twelve.

This decidedly unheroic turn of events was confirmed by the Army, the Fort Leavenworth military prison (Stebby's home for the next 30 years), and Black Hawk Down's author. Bowden told the New York Post that the Army asked him to change Stebbins' name in the screenplay in order to avoid embarrassing the military.


In an email to the newspaper, Stebby's ex-wife, Nora Stebbins, wrote: "They are going to make millions off this film in which my ex-husband is portrayed as an All-American hero when the truth is he is not."

CARL SAGAN WAS AN AVID POT-SMOKER

When you're talking about scientists who achieved rock-star status in the second half of the twentieth century, the late astronomer and biologist Carl Sagan is right up there with Stephen Hawking. His Cosmos (1980) is one of the most popular science books ever written, planting itself on the New York Times bestseller list for 70 weeks and staying perpetually in print ever since. It was a companion for the PBS television series of the same name, which — along with numerous Tonight Show appearances — introduced Sagan and his emphatically stated phrase "billions and billions" into pop culture. His sole novel, Contact, was turned into a love-it-or-hate-it movie starring Jodie
Foster as an erstwhile scientist searching for extraterrestrial life, with Matthew McConaughey as a New Age flake who, inevitably, makes his own form of contact with her.

Besides his pop-culture credentials, Sagan was pals with numerous legendary Nobel
Prize-winners while still in college, picked up a Pulitzer Prize for his book Dragons of Eden, and consulted for NASA, MIT, Cornell, and RAND. He designed the human race's postcards to any aliens that might be out there — the plaque onboard the Pioneer space probes and the record on the Voyager probes.

So it might come as a bit of a surprise that Sagan was an avid smoker of marijuana. Some might even call him a pothead.

In his definitive biography of the celebrity scientist, Keay Davidson reveals that Sagan started toking regularly in the early 1960s and that Dragons of Eden — which won the Pulitzer — "was obviously written under the inspiration of marijuana." Davidson says of Sagan:

He believed the drug enhanced his creativity and insights. His closest friend of three decades, Harvard psychiatry professor Dr. Lester Grinspoon, a leading advocate of the decriminalization of marijuana, recalls an incident in the 1980s when one of his California admirers mailed him, unsolicited, some unusually high-quality pot. Grinspoon shared the joints with Sagan and his wife, Anne Druyan. Afterward, Sagan said, "Lester, I know you've only got one left, but could I have it? I've got serious work to do tomorrow and I could really use it."

Perhaps letting Sagan bogart the pot was Grinspoon's way of returning a favor, since Sagan had contributed an essay to Marihuana Reconsidered, Grinspoon's classic 1971 book on the benefits and low risks of reefer. For almost three decades, the author of this ode to Mary Jane was anonymous, but in 1999 Grinspoon revealed that "Mr. X" was Sagan.


In the essay, Sagan wrote that weed increased his appreciation of art, music, food, sex, and childhood memories, and gave him insights into scientific and social matters:

I can remember one occasion, taking a shower with my wife while high, in which I had an idea on the origins and invalidities of racism in terms of Gaussian distribution curves. It was a point obvious [sic] in a way, but rarely talked about. I drew curves in soap on the shower wall, and went to write the idea down. One idea led to another, and at the end of about an hour of extremely hard work I found I had written eleven short essays on a wide range of social, political, philosophical, and human biological topics.... I have used them in university commencement addresses, public lectures, and in my books.

The staunchly atheistic/humanistic Sagan comes perilously close to mysticism in some passages:

I do not consider myself a religious person in the usual sense, but there is a religious aspect to some highs. The heightened sensitivity in all areas gives me a feeling of communion with my surroundings, both animate and inanimate. Sometimes a kind of existential perception of the absurd comes over me and I see with awful certainty the hypocrisies and posturing of myself and my fellow men. And at other times, there is a different sense of the absurd, a playful and whimsical awareness....

I am convinced that there are genuine and valid levels of perception available with
cannabis (and probably with other drugs) which are, through the defects of our society and our educational system, unavailable to us without such drugs. Such a remark applies not only to self-awareness and to intellectual pursuits, but also to perceptions of real people, a vastly enhanced sensitivity to facial expression, intonations, and choice of words which sometimes yields a rapport so close it's as if two people are reading each other's minds.

LSD HAS BEEN USED SUCCESSFULLY IN PSYCHIATRIC THERAPY

Given the demonization of the psychedelic drug LSD, it may seem inconceivable that mainstream , psychiatrists were giving it to patients during sessions. Yet for at least 20 years, that's exactly what happened.

Created in 1938, LSD was first suggested as a tool in psychotherapy in 1949. The following year saw the first studies in medical/psychiatric journals. By 1970, hundreds of articles on the uses of LSD in therapy had appeared in the Journal of the American Medical Association, the Journal of Psychology, the Archives of General Psychiatry, the Quarterly Journal of Studies of Alcoholism, many non-English-language journals, and elsewhere.

Psychiatric and psychotherapeutic conferences had segments devoted to LSD, and two professional organizations were formed for this specialty, one in Europe and the other in North America. International symposia were held in Princeton, London, Amsterdam, and other locations. From 1950 to 1965, LSD was given in conjunction with therapy to an estimated
40,000 people worldwide.

In his definitive book on the subject, LSD Psychotherapy, transpersonal psychotherapist
Stanislav Grof, MD, explains what makes LSD such a good aid to headshrinking:

...LSD and other psychedelics function more or less as nonspecific catalysts and amplifiers of the psyche.... In the dosages used in human experimentation, the classical psychedelics, such as LSD, psilocybin, and mescaline, do not have any specific pharmacological effects. They increase the energetic niveau in the psyche and the body which leads to manifestation of otherwise latent psychological processes.

The content and nature of the experiences that these substances induce are thus not artificial products of their pharmacological interaction with the brain ("toxic psychoses"), but authentic expressions of the psyche revealing its functioning on levels not ordinarily available for observation and study. A person who has taken LSD does not have an "LSD experience," but takes a journey into deep recesses of his or her own psyche.

When used as a tool during full-scale therapy, Grof says, "the potential of LSD seems to be extraordinary and unique. The ability of LSD to deepen, intensify and accelerate the psychotherapeutic process is incomparably greater than that of any other drug used as an adjunct to psychotherapy, with the exception perhaps of some other members of the psychedelic group."

Due to bad trips experienced by casual users, not to mention anti-drug hysteria in general, LSD was outlawed in the US in 1970. The Drug Enforcement Agency declares: "Scientific study of LSD ceased circa 1980 as research funding declined."

What the DEA fails to mention is that medical and psychiatric research is currently happening, albeit quietly. Few researchers have the resources and patience to jump through the umpteen hoops required to test psychedelics on people, but a few experiments using LSD, ecstasy, DMT, ketamine, peyote, and other such substances are happening in North America and Europe. Universities engaged in this research include Harvard, Duke, Johns Hopkins, University College London, and the University of Zurich.


We're presently in the dark ages of such research, but at least the light hasn't gone out entirely.

THE BAYER COMPANY MADE HEROIN

Now let's turn our attention to the last member of our trifecta of defective tests — the polygraph, more commonly referred to as the lie detector. Invented by the same person who created Wonder Woman and her golden lasso that makes you tell the truth (I'm not kidding), the polygraph is said to detect deception based on subtle bodily signals, such as pulse rate and sweatiness. Its proponents like to claim that it has a success rate of 90 percent or more. This is pure hogwash. While the evidence against lie detectors is way too voluminous to get into here, it will be very instructive to look at a statement from Dr. Drew Richardson. Richardson is a scientist who was
an FBI agent for 25 years; in the late 1980s and early 1990s, he dealt with polygraphs.

In fall 1997, a Senate Judiciary subcommittee held hearings regarding the FBI Crime Lab. Richardson gave scorching testimony about polygraphs. Referring specifically to the practice of using lie detectors to question people in sensitive positions, he said under oath:

It is completely without any theoretical foundation and has absolutely no validity. Although there is disagreement amongst scientists about the use of polygraph testing in criminal matters, there is almost universal agreement that polygraph screening is completely invalid and should be stopped. As one of my colleagues frequently says, the diagnostic value of this type of testing is no more than that of astrology or tea-leaf reading.

If this test had any validity (which it does not), both my own experience, and published scientific research has proven, that anyone can be taught to beat this type of polygraph exam in a few minutes.

Because of the nature of this type of examination, it would normally be expected to produce large numbers of false positive results (falsely accusing an examinee of lying about some issue). As a result of the great consequences of doing this with large numbers of law enforcement and intelligence community officers, the test has now been manipulated to reduce false positive results, but consequently has no power to detect deception in
espionage and other national security matters. Thus, I believe that there is virtually no probability of catching a spy with the use of polygraph screening techniques. I think a careful exam-ination of the Aldrich Ames case will reveal that any shortcomings in the use of the polygraph were not simply errors on the part of the polygraph examiners involved, and would not have been eliminated if FBI instead of CIA polygraphers had conducted these examinations. Instead I believe this is largely a reflection of the complete lack of validity of this methodology. To the extent that we place any confidence in the results of polygraph screening, and as a consequence shortchange traditional security vetting techniques, I think our national security is severely jeopardized.

After he ripped polygraphs a new one, the FBI silenced Richardson, refusing to let him speak publicly about the subject again.

AN FBI EXPERT TESTIFIED THAT LIE DETECTORS ARE WORTHLESS FOR SECURITY SCREENING

Now let's turn our attention to the last member of our trifecta of defective tests — the polygraph, more commonly referred to as the lie detector. Invented by the same person who created Wonder Woman and her golden lasso that makes you tell the truth (I'm not kidding), the polygraph is said to detect deception based on subtle bodily signals, such as pulse rate and sweatiness. Its proponents like to claim that it has a success rate of 90 percent or more. This is pure hogwash. While the evidence against lie detectors is way too voluminous to get into here, it will be very instructive to look at a statement from Dr. Drew Richardson. Richardson is a scientist who was
an FBI agent for 25 years; in the late 1980s and early 1990s, he dealt with polygraphs.

In fall 1997, a Senate Judiciary subcommittee held hearings regarding the FBI Crime Lab. Richardson gave scorching testimony about polygraphs. Referring specifically to the practice of using lie detectors to question people in sensitive positions, he said under oath:

It is completely without any theoretical foundation and has absolutely no validity. Although there is disagreement amongst scientists about the use of polygraph testing in criminal matters, there is almost universal agreement that polygraph screening is completely invalid and should be stopped. As one of my colleagues frequently says, the diagnostic value of this type of testing is no more than that of astrology or tea-leaf reading.

If this test had any validity (which it does not), both my own experience, and published scientific research has proven, that anyone can be taught to beat this type of polygraph exam in a few minutes.

Because of the nature of this type of examination, it would normally be expected to produce large numbers of false positive results (falsely accusing an examinee of lying about some issue). As a result of the great consequences of doing this with large numbers of law enforcement and intelligence community officers, the test has now been manipulated to reduce false positive results, but consequently has no power to detect deception in
espionage and other national security matters. Thus, I believe that there is virtually no probability of catching a spy with the use of polygraph screening techniques. I think a careful exam-ination of the Aldrich Ames case will reveal that any shortcomings in the use of the polygraph were not simply errors on the part of the polygraph examiners involved, and would not have been eliminated if FBI instead of CIA polygraphers had conducted these examinations. Instead I believe this is largely a reflection of the complete lack of validity of this methodology. To the extent that we place any confidence in the results of polygraph screening, and as a consequence shortchange traditional security vetting techniques, I think our national security is severely jeopardized.

After he ripped polygraphs a new one, the FBI silenced Richardson, refusing to let him speak publicly about the subject again.

DNA MATCHING IS NOT INFALLIBLE

Speaking of tests that aren't all they're cracked up to be, let's look at DNA testing. This is supposed to be the absolute silver bullet of criminal justice, an incontrovertible way to pin guilt on someone. After all, the chances of a mismatch are one in a billion, a quadrillion, a jillion! Some experts have testified under oath that a false match is literally impossible.

Not quite. As he did with HIV testing, risk scholar Gerd Gigerenzer of the Max Planck Institute punches a hole in the matching of genetic material:

In the first blind test reported in the literature, three major commercial laboratories were each sent 50 DNA samples. Two of the three declared one false match; in a second test one year later, one of the same three laboratories declared a false match. From external tests conducted by the California Association of I Crime Laboratory Directors, the Collaborative Testing Services, and other agencies, the psychologist Jonathan Koehler and
his colleagues estimated the false positive rate of DNA fingerprinting to be on the order of 1 in 100. Cellmark Diagnostics, one of the laboratories that found matches between O.J. Simpson's DNA and DNA extracted from a recovered blood stain at the murder scene, reported its own false positive rate to the Simpson defense as roughly 1 in 200.

It gets even worse. In 1999, the College of American Pathologists performed its own secret tests of 135 labs. Each lab was sent a DNA sample from the "victim," some semen from the "suspect," and a fake vaginal swab containing DNA from both parties. They were also sent a strand of the "victim's" hair. The object was to see how many of the labs would make the matches (ie, match the two sperm samples of the man, and match the hair and DNA sample of the woman). But something unexpected happened: Three of the labs reported that the DNA from the suspect matched the victim's DNA! Obviously, they had mixed up the samples. Only fourteen labs tested the hair, but out of those, one screwed it up by declaring a match to the "suspect."

These kind of switches don't happen only during artificial situations designed to gauge a lab's accuracy (which are usually performed under ideal conditions). During a 1995 rape trial, a lab reversed the labels on the DNA samples from the victim and the defendant. Their testing then revealed a match between the defendant's alleged DNA (which was actually the victim's) and the DNA on the vaginal swab, which didn't contain any semen from the rapist. Luckily, this boneheaded move was caught during the trial, but not everyone is so lucky.

The Journal of Forensic Science has reported an error that was discovered only after an innocent man had been convicted of raping an 11-year-old girl and sentenced to prison, where lie was undoubtedly brutalized in ways that would give you nightmares for the rest of your life, were
you to hear them described in detail. After four years, he was released because the lab hadn't completely separated the real rapist's DNA (extracted from his semen) from the victim's DNA. When the two were swirled together, they somehow matched that of the poor bastard whose eleven alibi witnesses failed to sway the jury. But when the semen DNA was checked properly, it was beyond doubt that a match didn't exist.

While most false matches are the result of human error, other factors do come into play. Some testing techniques are more definitive than others. In the case of one innocent man — Josiah Sutton, found guilty of rape based primarily on DNA evidence — criminology professor William C. Thompson said: "If police picked any two black men off the street, the chances that one of them would have a DNA profile that 'matched' the semen sample as well as Sutton's profile is better than one in eight." Also, we mustn't forget about corruption. In some known cases, DNA analysts have misrepresented (ie, lied about) their findings in order to obtain convictions.

FOR LOW-RISK PEOPLE, A POSITIVE RESULT FROM AN HIV TEST IS WRONG HALF THE TIME

Although a lot of progress has been made in improving the length and quality of life for people with AIDS, getting a positive result from an HIV test must still rank as one of the worst pieces of news a person can get. It's not uncommon for people to kill themselves right after hearing the results, and those who don't commit suicide surely go through all kinds of mental anguish. But
the accuracy of these tests is lower than generally believed. In fact, if you test positive but you're not a member of a high-risk group (such as non-monogamous gay men and intravenous drug users), the odds are 50-50 that you actually have the virus.

To be declared HIV-positive, your blood goes through three tests — two ELISA tests and one more sensitive and costly Western Blot test. Makers of the tests trumpet a 99.99 percent accuracy rate when all three are used. Many AIDS counselors even tell people that the tests never give a false positive (that is, the tests don't indicate that someone is HIV-positive when he or she really isn't). The test manufacturers' claim is misleading, and the counselors' claim is flat-out BS. Cognitive scientist Gerd Gigerenzer — who specializes in risk and uncertainty — explains the reality in plain English:

Imagine 10,000 men who are not in any known risk category. One is infected (base rate) and will test positive with practical certainty (sensitivity). Of the 9,999 men who are not infected, another one will also test positive (false positive rate). So we can expect that two men will test positive.

Out of these two men, only one actually carries the virus. So, if you're a low-risk man who tests positive, the chances are even — the same as a coin flip — that the result is right. It's highly advisable that you take the tests again (and again). The results are even less reliable for women in low-risk groups, since they have a still lower rate of HIV.

Of course, this doesn't apply to an HIV-negative result. If you test negative, the odds are overwhelmingly good (9,998 out of 9,999) that this is correct. It also doesn't hold for people in high-risk categories. For example, if we accept the estimate that 1.5 percent of gay men are HIV- positive, this means that out of every 10,000, an average of 150 are infected. An HIV test will almost surely pick up on all 150, and out of the remaining 9,850 uninfected men, one will incorrectly be labeled positive. This means that only one out of 151 gay men will be falsely diagnosed as having HIV A false positive is thus still possible but much more unlikely.