Tag Archives: statistics

July 1 marks a big day for health reform

Pia Christensen

About Pia Christensen

Pia Christensen (@AHCJ_Pia) is the managing editor/online services for AHCJ. She manages the content and development of healthjournalism.org, coordinates AHCJ's social media efforts and edits and manages production of association guides, programs and newsletters.

Scott Hensley, on NPR’s Shots blog, has a nice rundown of the health care provisions that go into effect today, including the so-called tanning tax, high-risk insurance pools and the new healthcare.gov website.

For reporters writing about the tanning tax, we  remind you to look carefully at the numbers and be sure to accurately report the data behind this policy decision. Much of the reporting we’ve seen cites numbers presented by the World Health Organization: “use of sunbeds before the age of 35 is associated with a 75% increase in the risk of melanoma.” But that statistic represents the relative risk, while the absolute risk – the chance of something happening – is far different. Reuters Health Editor Ivan Oransky, M.D., has written about the subject for Covering Health:

“You can see how if someone is lobbying to ban something – or, in the case of a new drug, trying to show a dramatic effect – they would probably want to use the relative risk.”

For a detailed explanation, be sure to read Oransky’s post about the statistics on tanning.

If you’re reporting on the high-risk insurance pools that go into effect today, don’t miss our tip sheet on the topic, with story tips, suggestions and resources from four experience reporters. Apart from being a policy story, it’s of great interest to all your readers, viewers or listeners who have pre-existing conditions and are struggling to find coverage.

Another tip sheet addresses what needs to be covered now that the Patient Protection and Affordable Care Act has been passed and begins to be implemented.

A recent briefing, “Reporting on health reform between now and 2014,” offers further advice and resources from some top Washington, D.C.-based journalists on implementation deadlines, how to cover local issues, Medicare reimbursement rates, what reporters should look for in their states and more.

Tanning beds: What do the numbers really mean?

Pia Christensen

About Pia Christensen

Pia Christensen (@AHCJ_Pia) is the managing editor/online services for AHCJ. She manages the content and development of healthjournalism.org, coordinates AHCJ's social media efforts and edits and manages production of association guides, programs and newsletters.

This is a guest post from Ivan Oransky, M.D., editor of Reuters Health and AHCJ’s treasurer, written at my invitation.

May has been declared “Melanoma Awareness Month” or “Skin Cancer Awareness Month” – depending on which group is pitching you – and reporters are doubtlessly receiving press releases and announcements from a number of groups, including the Melanoma Research Foundation, the Skin Cancer Foundation, hospitals, doctors and other organizations.

Those press releases often point to the World Health Organization, which reports that “use of sunbeds before the age of 35 is associated with a 75% increase in the risk of melanoma” – a statistic often repeated in news stories about tanning beds.

tanning-bedPhoto by Whatsername? via Flickr

But what does that really mean? Is it 75 percent greater than an already-high risk, or a tiny one? If you read the FDA’s “Indoor Tanning: The Risks of Ultraviolet Rays,” or a number of other documents from the WHO and skin cancer foundations, you won’t find your actual risk.

That led AHCJ member Hiran Ratnayake to look into the issue in March for The (Wilmington, Del.) News Journal, after Delaware passed laws limiting teens’ access to tanning salons. The 75 percent figure is based on a review of a number of studies, Ratnayake learned. The strongest such study was one that followed more than 100,000 women over eight years.

But as Ratnayake noted, that study “found that less than three-tenths of 1 percent who tanned frequently developed melanoma while less than two-tenths of 1 percent who didn’t tan developed melanoma.” That’s actually about a 55 percent increase, but when the study was pooled with others, the average was a 75 percent increase. In other words, even if the risk of melanoma was 75 percent greater than two-tenths of one percent, rather than 55 percent greater, it would still be far below one percent.

For some perspective on those numbers, Ratnayake interviewed Lisa Schwartz, M.D.,M.S., whose work on statistical problems in studies and media reports is probably familiar to many AHCJ members. “Melanoma is pretty rare and almost all the time, the way to make it look scarier is to present the relative change, the 75 percent increase, rather than to point out that it is still really rare,” Schwartz, a general internist at Veterans Affairs Medical Center in White River Junction, Vt., told him.

In a nutshell, the difference between skin doctors’ point of view and Schwartz’s is the difference between relative risk and absolute risk. Absolute risk just tells you the chance of something happening, while relative risk tells you how that risk compares to another risk, as a ratio. If a risk doubles, for example, that’s a relative risk of 2, or 200 percent. If it halves, it’s .5, or 50 percent. Generally, when you’re dealing with small absolute risks, as we are with melanoma, the relative risk differences will seem much greater than the absolute risk differences. You can see how if someone is lobbying to ban something – or, in the case of a new drug, trying to show a dramatic effect –  they would probably want to use the relative risk.

This is not an argument for or against tanning beds. It’s an argument for clear explanations of the data behind policy decisions. For some people, the cosmetic benefits of tanning beds – and the benefit of vitamin D, for which there are, of course, other sources – might be worth a tiny increase in the risk of melanoma. For others, any increased risk of skin cancer is unacceptable. (And of course, for the tanning industry, the benefits can be measured in other ways – dollars.) But if reporters leave things at “a 75 percent increase,” you’re not giving your readers the most important information they need to judge for themselves.

So when you read a study that says something doubles the risk of some terrible disease, ask: Doubles from what to what?

Related

These numbers also might come up in reporting about the health reform bill as it does in “Indoor Tanning Getting Moment in the Sun” (March 26, 2010). From the story:

Over the past decade, indoor tanning has increasingly been likened to other maligned habits, cigarette smoking in particular.

And with the passage of the new health care bill, government officials are prepared to take that comparison one step further. A 10 percent tax could be levied on indoor tanning as early as July, in an effort to offset some of the health care bill’s multi-billion-dollar budget.

AHCJ resources on writing about medical studies:

In addition, look for a slim guide about covering medical studies that AHCJ will publish this summer.

In 2008, fewer preterm babies, more cesareans

Pia Christensen

About Pia Christensen

Pia Christensen (@AHCJ_Pia) is the managing editor/online services for AHCJ. She manages the content and development of healthjournalism.org, coordinates AHCJ's social media efforts and edits and manages production of association guides, programs and newsletters.

Births in the United States went down nearly 2 percent in 2008, according to new figures [PDF] from the CDC’s National Center for Health Statistics.

Among the report’s highlights:

  • The birth rate for U.S. teenagers fell 2 percent, reversing a two-year increase.
  • The birth rate for Hispanic teenagers declined to an historic low.
  • The cesarean delivery rate rose for the 12th straight year, to 32.3 percent of all births.
  • The percentage of births born preterm declined 3 percent.

Health Journalism 2010

Learn more about “Pregnancy and childbirth trends: Issues of safety and choice,” a panel featuring Mark R. Chassin, M.D., president of The Joint Commission; Julie Deardorff, health and fitness reporter at the Chicago Tribune; Alan M. Peaceman, M.D., professor of obstetrics and gynecology at Northwestern University’s Feinberg School of Medicine and chief of the Division of Maternal-Fetal Medicine at Northwestern Memorial Hospital; and moderated by Deborah L. Shelton, a Chicago Tribune health reporter.

Duo writes about how health statistics can mislead

Andrew Van Dam

About Andrew Van Dam

Andrew Van Dam of The Wall Street Journal previously worked at the AHCJ offices while earning his master’s degree at the Missouri School of Journalism.

Writing in mathematics-focused Plus Magazine, Mike Pearson (bio) and David Spiegelhalter (bio|wikipedia) examine not only the variety of methods used to report health statistics, but also just how each of those methods is employed to mislead physicians, patients and journalists alike. The piece was adapted from their Understanding Uncertainty Web site. The site, which is aimed in part at helping journalists understand statistics and probability, is profiled in this story.

The duo point out and illustrate common pitfalls and summarize relevant research. Not only do they point out fundamentals such as advantages that “number needed to treat,” and to a lesser extent absolute risk (1 in 100,000), numbers have over the popular relative risk (30 percent more likely), they also go much deeper. For example:

stats
Photo by Letting Go of Control via Flickr.

One of the most misleading, but rather common, tricks is to use relative risks when talking about the benefits of a treatment, for example to say that “Women taking tamoxifen had about 49% fewer diagnoses of breast cancer”, while potential harms are given in absolute risks: “The annual rate of uterine cancer in the tamoxifen arm was 30 per 10,000 compared to 8 per 10,000 in the placebo arm”. This tends to exaggerate the benefits, minimise the harms, and in any case make it hard to compare them. This way of presenting risk is known as mismatched framing, and was found in a third of studies published in the British Medical Journal.

And mixing and matching numbers isn’t the only way statistics can be misleading; the writers list many. Even the humble denominator can be manipulated.

For example, people have been offered a prize for drawing a red ball from a bag, and then given the choice of two bags: one containing 1 red ball and 9 white balls, the other containing 8 red balls and 92 white balls. The majority chose the bag with 8 red balls, presumably reflecting a view that it gave more opportunities to win, even though the chance of picking a red ball was lower for this bag. Similarly, people confronted with the statement “Cancer kills 2,414 people out of 10,000,” rated cancer as more risky than those told “Cancer kills 24.14 people out of 100”. The potential influence of the size of the numerator and denominator is known as the ratio bias. Frequencies are generally used in risk communication, but it is important to keep a common denominator in all comparisons.

For a thorough primer on statistics and health, the authors highly recommend Helping Doctors and Patients Make Sense of Health Statistics (pdf), an engaging 2008 paper that makes heavy use of examples and anecdotes to illustrate key issues in the interpretation of statistics.

That paper’s authors recommend the following best practices for writing about health statistics:

We recommend using frequency statements instead of single-event probabilities, absolute risks instead of relative risks, mortality rates instead of survival rates, and natural frequencies instead of conditional probabilities.

Also of interest is this related editorial (pdf) in which media are described as “enablers” of statistical illiteracy. The author also points out that, even if journalists communicate risk in the most objective possibly fashion, folks from different cultural backgrounds will still perceive it differently. It includes an interesting side note about the far-reaching impact of how physicians are allowed to define their own legal standard of care.

Related

AHCJ tip sheets

AHCJ articles

Improving reporting on medical studies (#ahcj09)

Pia Christensen

About Pia Christensen

Pia Christensen (@AHCJ_Pia) is the managing editor/online services for AHCJ. She manages the content and development of healthjournalism.org, coordinates AHCJ's social media efforts and edits and manages production of association guides, programs and newsletters.

“It is possible for good health journalists to provide spectacular stories on health,” said David Henry, CEO of the Institute for Clinical Evaluative Sciences.

During the afternoon panel on “Statistics, Conclusions, Limitations: Reporting on Medical Studies” at the annual Association of Health Care Journalists meeting in Seattle both Henry and moderator Gary Schwitzer, concurred that most health and medical reporting is inaccurate, imbalanced and incomplete. “After three years and 750 stories reviewed there is still a ‘kid-in-the-candy-store projection of health’ in most health news,”Schwitzer said shortly before he launched into a dissection of several news stories.

Independent journalist Christy Fricks writes about the panel – links to the speakers’ presenations are included.