Reading a Regressin Model for Effect Size

Antidepressant drugs accept been getting a bad rap in the media. I'll just give 3 examples:

• On the Today prove, prominent medical expert 🙂 Tom Cruise told us Brooke Shields shouldn't have taken these drugs for her postpartum depression.
• In Natural News, "Health Ranger" Mike Adams accused pharmaceutical companies and the FDA of covering up negative information well-nigh antidepressants, proverb information technology would exist considered criminal activity in whatsoever other manufacture.
• And an article in Newsweek said  "Studies propose that the popular drugs are no more than effective than a placebo. In fact, they may be worse."

Even so psychiatrists are convinced that antidepressants work and are notwithstanding routinely prescribing them for their patients. Is it all a Big Pharma plot? Who ya gonna believe? Inquiring minds want to know:

• Are antidepressants more than effective than placebo?
• Has the efficacy of antidepressants been exaggerated?
• Is psychotherapy a meliorate treatment choice?

The science-based answers to the first two questions are clearly "Yes." The best answer to the third question is "It depends."

In 2008, Erick Turner and iv colleagues published an article in The New England Journal of Medicine (NEJM) entitled "Selective Publication of Antidepressant Trials and Its Influence on Apparent Efficacy." The FDA is able to make sure that drug companies don't pick and cull which trials, and which outcomes within those trials, get seen. Using clinical trial data from the FDA as a gold standard, Turner, et. al. examined how these aforementioned trials were reported in published journal articles, They institute that:

…according to the published literature, the results of almost all of the trials of antidepressants were positive. In contrast, FDA assay of the trial data showed that roughly half of the trials had positive results.

And some of the negative trials were published with a "spin" that made them announced positive. The data did show that each drug was superior to placebo, but the truthful magnitude of that superiority was less than a diligent literature review would indicate. They warned that

By altering the apparent adventure–benefit ratio of drugs, selective publication tin lead doctors to make inappropriate prescribing decisions that may not be in the all-time interest of their patients and, thus, the public health.

Irving Kirsch has been outspoken about antidepressants' declared lack of efficacy. In a controversial meta-assay published in 1998, he found that placebos provided approximately 75% of the comeback provided by agile drug. He suggested that the other 25% is debatable and could be due to an enhanced placebo response when patients experience side effects that convince them they are getting an active drug. In a further study in 2002, he "questioned the clinical significance of antidepressants."

Kirsch recently looked at the FDA data for 4 of the 12 drugs that Turner examined. In spite of the smaller sample, where Turner establish an effect size of 0.31, Kirsch got 0.32. And so they got almost exactly the aforementioned result. But information technology was their interpretations of that result that were very dissimilar. Kirsch ended that antidepressants are ineffective, while Turner found that the drugs were indeed superior to placebo. As the figure below shows, each drug's effect size was positive. Likewise, none of the confidence intervals overlapped zero. This ways that, while there is some probability that the truthful effect size is zero, significant that antidepressants and placebo are equal in efficacy, that probability is negligibly small.

The discrepancy between Turner's and Kirsch'due south interpretations hinges on what these effect size numbers mean in terms of clinical significance,. Values of 0.2, 0.5, and 0.8 were once proposed every bit pocket-sized, medium, and large upshot sizes, respectively. The psychologist who proposed these landmarks admitted that he had picked them arbitrarily and that they had "no more reliable a basis than my ain intuition." After, without providing any justification, the UK'south National Institute for Health and Clinical Excellence (Nice) decided to turn the 0.v landmark (why non the 0.2 or the 0.8 value?) into a one-size-fits-all cut-off for clinical significance. In an editorial published in the British Medical Journal (BMJ), Turner explains with an elegant metaphor: journal articles had sold usa a glass of juice advertised to comprise 0.41 liters (0.41 being the effect size Turner, et al. derived from the journal manufactures); merely the truth was that the "glass" of efficacy contained only 0.31 liters. Considering these amounts were lower than the (arbitrary) 0.five liter cut-off, NICE standards (and Kirsch) consider the glass to be empty. Turner correctly concludes that the glass is far from full, just it is also far from empty. He also points out that patients' responses are non all-or-none and that fractional responses can be meaningful.

Incidentally, Prissy is no longer using the 0.5 result size cutoff.

If nosotros followed Kirsch's interpretation and rejected antidepressants, how would we treat low? Psychotherapy avoids the side furnishings of drugs, but information technology has its own drawbacks: it is expensive, fourth dimension-consuming, and variable in quality. How effective is psychotherapy? Psychotherapy trials likewise suffer from publication bias, just like antidepressant drugs. And when one weeds out low quality studies, psychotherapy has an effect size of merely 0.22, lower than the value for antidepressants reported by Kirsch himself, So if we reject whatsoever handling below the (capricious) 0.v cutoff, when a mental health care provider is faced with a patient in need of help, is he or she to do cipher at all?

I don't doubt that antidepressants have sometimes been over-prescribed and used inappropriately for lesser levels of depression where they are less effective or even ineffective, only this is probably truthful for psychotherapy, also. On the other hand, it has been estimated that just about half of depressed patients are getting any kind of treatment. Severe depression is a life-threatening disease. A recent written report showed that antidepressants reduced the gamble of suicide by 20% in the long term. The risk/benefit ratios are still non clear cut for either course of treatment.

Once more, science fails to give united states the black-and-white answers we crave. And once again we are reminded that nosotros can't rely on the media for accurate, nuanced information about medical science.

For his assistance in preparing this article and for providing the figure, I desire to give thanks Erick Turner, M.D., Department of Psychiatry, Oregon Health and Science University; Staff Psychiatrist, Portland Veterans Affairs Medical Middle; One-time reviewer, FDA.

• Harriet Hall, MD also known as The SkepDoc, is a retired family unit doctor who writes near pseudoscience and questionable medical practices. She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so),  and was the showtime female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Forcefulness physician, she held diverse positions from flight surgeon to DBMS (Managing director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52. She retired with the rank of Colonel.  In 2008 she published her memoirs, Women Aren't Supposed to Fly.

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Source: https://sciencebasedmedicine.org/antidepressants-and-effect-size/

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