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Most drugs don’t work…

Posted by medconsumers on May 15, 2011

“Most drugs don’t work on most patients.” When I first read this statement many years ago in the British Medical Journal, a light bulb went off. I’d been a medical writer for a long time and knew it to be true. Yet I had never seen prescription drug effectiveness summed up so accurately. In a medical journal, no less! Unfortunately, drug study results are routinely reported in statistical terms known to make the drug’s benefit appear larger than it really is. More on that later.

The trigger for my light bulb moment was a 2003 editorial entitled, “Drug Don’t Work” by Richard Smith, MD, who explained, “This is of course no news to doctors. Anybody familiar with the notion of ‘number needed to treat’ (NNT) knows that it’s usually necessary to treat many patients in order for one to benefit. NNTs under 5 are unusual, whereas NNTs over 20 are common.”

The latest research, however, indicates that Dr. Smith may have overestimated physician understanding of medical statistics. A new Cochrane review of all relevant studies found that the most common statistical terms for expressing drug study results—in medical journals and the media—are misunderstood by doctors and consumers alike. In fact there was no difference in understanding between physicans and the lay public.

For the Cochrane review entitled, “Using different statistical formats for presenting health information,” the authors identified the 35 best studies designed to evaluate how well people understood the different ways of expressing the same study results. This review came down in favor of absolute risk reduction rather than relative risk reductions (RRR), as described below:

“You read that a study found that an osteoporosis drug cuts the risk of having a hip fracture in the next three years by 50%. Specifically, 10% of the untreated people had a hip fracture at three years, compared with 5% of the people who took the osteoporosis drug every day for three years. Thus 5% (10% minus 5%) less people would suffer a hip fracture if they take the drug for 3 years. In other words, 20 patients need to take the osteoporosis drug over 3 years for an additional patient to avoid a hip fracture. ‘Cuts the risk of fracture by 50%’ represents a relative risk reduction. ‘Five per cent less would suffer a fracture’ represents an absolute risk reduction. ‘Twenty patients need to take the osteoporosis drug over 3 years for an additional patient to avoid a hip fracture’ represents a number needed to treat.”

To people without statistical training—and that includes most physicians—the “cuts your risk by 50%” RRR example appears more impressive. And too often this is the sole way drug study results are described in medical journals, as well as ads aimed at physicians and the general public. Rarely is it explained that the 50% simply represents the difference between the treated and the untreated.

Here’s a real world example: Your doctor says, “You have mild hypertension and should go on a blood pressure lowering drug for the rest of your life because it will cut your risk of stroke by 50%.” Sounds good, maybe even worth the risk of sexual dysfunction and depression—two common side effects of anti-hypertensives. But here’s the other side of the story: A person with mild hypertension has only an infinitessimal chance of having a stroke, so the drug will reduce that infinitessimal risk by 50%

The common usage of RRR comes from the biostatisticians and the methodologists whose job it is to determine whether studies are conducted rigorously and results reported accurately. The fact that the Cochrane Collaboration’s own biostatisticians and methodologists are concerned enough to have produced this new review signals some recognition that it’s time for a change. (Long overdue, given that the sole use of RRR serves the pharmaceutical industry’s interest.) The Cochrane Collaboration itself has produced too many drug reviews with results expressed solely as RRR. Here’s one improvement under consideration because it is better understood: 100 of 1,000 untreated people will have a hip fracture in the next three years; 50 of 1,000 people taking an osteoporosis drug will have a hip fracture in the next three years.

The most easily understood way of expressing “most drugs don’t work on most people” can be found at this website: www.TheNNT.com Say, you are suffering from acute sinusitis but wary of taking an antibiotic for this distressing condition. You want to know how well the drug is likely to work and the likelihood of harm. TheNNT.com shows that 93% will not benefit from antibiotics; nearly 7% saw a faster resolution of their symptoms; and just over 1% were harmed by the antibiotics (e.g., diarrhea, vomiting). Even more interesting, four out of five people (in the placebo group) got better without antibiotics.

Maryann Napoli, Center for Medical Consumers(c)

6 Responses to “Most drugs don’t work…”

  1. This statistical information is absolutely correct, but that doesn’t mean everyone should avoid taking medications. The problem with saying “MOST drugs don’t work” is that people may conclude that ALL the drugs their doctors prescribe won’t work.
    Especially if you have a condition that could worsen without treatment, it’s wise to weigh the benefits and risks of a trial of medication that has proven effective in a high percentage of people. To take just a few examples, would you choose to die from a serious infection that has known susceptibility to a particular antibiotic? Would you want your child to suffer from a leukemia that is usually cured by a specific anti-cancer drug? Would you want joints throughout your body to be destroyed by rheumatoid arthritis when new biologic drugs are now available to stop disease progression?
    Yes, these medications may not work for every patient. Yes, they may cause unwanted side effects. But yes, they are usually worth a trial.
    Be skeptical, but keep an open mind.

    • Dr. Richard Smith, former editor of the British Medical Journal, who was quoted approvingly in this article, did not say, “Most drugs don’t work.” Rather, he wrote, “Most drugs don’t work in most people.” That’s an important distinction. The overwhelming majority of people do not benefit from most drugs. (For examples, see the recommended website link within this article http://www.TheNNT.com) And wouldn’t it be great if, as you say, we could weigh the benefits with the risks of all drugs, but it is common for drug industry-conducted clinical trials, now the majority, to either withhold all serious adverse effects or selectively report (i.e., cherry picking) more favorable results. (See this report of 102 drug trials that appeared in JAMA, May 26, 2004 http://www.ncbi.nlm.nih.gov/pubmed/15161896) Moreover, the harms related to most drugs do not become appearent until years after they go on the market and are taken by thousands of people who are not like the population represented in clinical trials. You are probably right to assume that most people in dire circumstances would take the drug no matter what. We want to encourage the growing number of people who want to be given some idea what that chance of benefit actually is. Moreover, refusing drug therapy is often a reasonable decision.

  2. L Robertson said

    This rant is perhaps more of an amplification of your article than a comment. But relevant.
    I live with my sister and a friend in her 90s who is bright and active, but has some health challenges. The other two of us are in our 60s and have relatively few health challenges. All 3 are blessed with Good Health Care. All of us are boggled by how many prescriptions we have stopped using because the effects were worse than the symptoms (serious migraines, for example, stopped when sis stopped taking pepcid). Our elder finds virtually every Rx makes her asthma worse, her skin inflamed/itchy, or causes dizziness – besides not working. Literally dozens of bottles and tubes of discarded prescriptions leave our household. Our HMO physicians have never had any interest in tracking this. The grief and the inconvenience are bad enough, but the money! and the environmental impact of all of it!!! Ack!

  3. I agree with Margaret Farnsworth 100%.

  4. Margaret Farnsworth said

    This is why I use homeopathy as my main medical treatment. Excellent results and no side affects. Of course I use standard medical practices for broken bones or things that need surgery, but homeopathy stands me in good stead to withstand the afteraffects of operations and to heal more quickly.

    • Mary,

      I would agree with you about 50%! Homeopathy has no side affects, but as far as excellent results, I’d beg to differ. We all must be careful to not only agree with studies that support our points of views and beliefs, but also studies that fail to support the ideas that we like. We need to apply the same critical eye with regards to homeopathy that we do with pharmaceutical medicines.

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