First in a series of columns that will examine how new health information should or should not affect personal decisions about health and prevention.
While the air is thick with information, advice and recommendations about health practices, at times the “facts” seem unclear, confusing and contradictory. We would like clear prescriptions for what is beneficial and what is harmful so that we can decide what to incorporate into our personal health practices.
Why is the picture so murky and ever changing and what can we do to deal with it? The picture is murky because the evidence is murky. At any moment we have an incomplete and flawed picture, which is constantly evolving in small, slow, irregular and sometimes erroneous steps.
Most medical issues, especially relating to prevention, are not as well worked out as we would like. In fact, behind widely held beliefs and practices is a mixture of evidence of varying strengths.
Medical research is being conducted vigorously and new information is being reported weekly. Good research often creates more new questions than answers. Often only those people most familiar with the field can fully appreciate the new results in their proper context.
Yet, all sorts of sources — news media, advertisers, governmental organizations, and private interests — offer to provide the latest story or recommendation. While some issues may be clear and widely accepted, some remain controversial even among experts. The public is not always aware of the uncertainties or controversies, and may be led to believe something is advantageous at a time when many experts disagree.
Prostate specific antigen (PSA) screening for hidden prostate cancer is an example of this. There was sufficient question and concern about the balance of benefits and harms of PSA screening for prostate cancer that the National Cancer Institute initiated a randomized controlled trial in 1990 (still ongoing), eventually involving nearly 77,000 men, to study it. Meanwhile, in December 2002, after a careful review of the available evidence, the U. S. Preventive Services Task Force concluded, “…the evidence is insufficient to recommend for or against routine screening for prostate cancer.”
In spite of this uncertainty and what some would consider a lack of proof, PSA screening has been vigorously recommended and utilized for the past decade. Only recently have the doubts and controversy about PSA screening come into the view of the general public.
Information about ways to “cut your risk” of unwanted health outcomes abound in the media in the form of news, ads and public health recommendations or warnings.
What can you do to sort through this deluge of medical information? You cannot chat with your physician every time a three-sentence bite about wine, broccoli or hormones is broadcast in the morning news. Even if you could, you may not get the answers you seek. While practicing physicians are well aware of established medical guidelines, it is virtually impossible for them to read and fully appreciate the significance and context of every new study as it appears. Thousands of scientific articles are published yearly. Each individual study is of very limited significance by itself. Furthermore, practicing physicians may not always have the background to decipher the nuances of study design and statistics that may make all the difference in the meaning of each new report.
But take heart. There are sources that carefully and thoughtfully review the whole body of evidence around individual prevention and treatment issues, evaluating the strength of that evidence and assessing the size of the benefits and harms. The results of such evaluations are increasingly available to the public.
In this series, we will look at some individual issues that have arisen recently. There is new evidence about effects of foods, vitamins and alcohol on health. There are questions about the balance of harms and benefits of hormone therapy for postmenopausal women. Controversy about mammography, PSA testing and whole-body scanning has raised questions about the value of early detection of disease (especially cancer) and the advisability of screening for hidden disease.
Using some of these examples, we will explore the strength of the evidence that studies commonly provide. Furthermore, we’ll consider the beliefs and myths that color our interpretation of the evidence and how to go about evaluating what the evidence might mean.
It is my belief that understanding more about the nature of the information can help in the decision to consider a health measure. Recognizing common myths and sources of confusion, along with having access to thoughtful reviews that look at the entire issue, can provide individuals with a good framework to consider the options and benefits, either on their own or in cooperation with their physicians.
Mark Zweig, MD, previously a staff physician at NIH, has more than 35 years of experience in medical research and 25 years in patient care. He has particular interest in medical decision-making and preventive medicine.