Tuesday, March 9, 2010
Coffee and the Heart - Researchers are Getting Paid Way Too Much to Rehash Old Data
This post by Westby Fisher, MD, originally appeared at Better Health.
This week, coffee seems to be good for the heart: "People who are moderate coffee drinkers can be reassured that they are not doing harm because of their coffee drinking," said Arthur Klatsky, the study's lead investigator and a cardiologist at Kaiser's Division of Research.
These "surprising" data were presented at the American Heart Association meeting on March 5th. 
But a quick Google search on Dr. Klatsky's earlier studies using the same questionnaire database shows the problems with using questionnaire data to make such sweeping conclusions. Take, for instance, these findings from 1973: Coffee drinking is not an established risk factor for myocardial infarction.
And yet a bit later, in 1990, there's a flip flop: Because of conflicting evidence about the relation of coffee use to coronary artery disease, the authors conducted a new cohort study of hospitalizations among 101,774 white persons and black persons admitted to Kaiser Permanente hospitals in northern California in 1978-1986. In analyses controlled for eight covariates, use of coffee was associated with higher risk of myocardial infarction (P=0.0002). (By the way, British researchers failed to find a similar correlation in instant coffee drinkers.)
So what, really, do these data from the Kaiser questionnaire data regarding heavy coffee consumption and the heart say?
What they say is:
1) Questionnaire data crunched to suggest correlations are insufficient to mean causation, irrespective of how the media parses it.
2) Questionnaire data are subject to significant sampling and reporting biases.
3) Rehashing the same old questionnaires using the same samples with newer data can dramatically alter prior findings.
4) Researchers are getting paid way too much to keep rehashing the same data for large health systems.
5) On the lighter side, college undergrads and medical students should note that they could use these types of questionnaire data to justify significant caffeine consumption along with alcohol to protect themselves from developing cirrhosis.
Sigh. 
This post originally appeared on Better Health, a network of popular health bloggers brought together by Val Jones, MD. Better Health's mission is to support and promote health care professional bloggers, provide insightful and trustworthy health commentary, and help to inform health policy makers about the provider point of view on health care reform, science, research and patient care.
Labels: alcohol abuse, cardiology, coffee, evidence-based medicine, heart, heart disease
posted by the Better Health network at
2:00 PM
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Friday, February 20, 2009
Brain food
Food studies are a staple (pun intended) of medical conferences, and International Stroke Conference 2009 is no exception. As usual, tea and coffee are front and center in the research, though fast food gives them a run for their money. Without further ado:
--Three cups of green or black tea per day lower one's risk of ischemic stroke by 21%, according to a meta-analysis of tea studies from around the world. Pooled results of the 10 studies that examined tea consumption and ischemic stroke found black tea reduced risk by 24%, and green tea by 21%.
--Lest you think you need to swap your morning cuppa joe for tea, take heart: Coffee is also associated with reduced stroke prevalence, an analysis of national health survey data (NHANES III) found. The more you drink, the lower your risk--despite the fact that many heavy coffee drinkers also smoke. Stroke prevalence went from 5% for those who drank 1-2 cups per day, to 2.9% for those who drank more than six cups a day. Cardiac disease, diabetes and hypertension also declined as cups of coffee went up. Could it be that the fountain of youth spurts coffee instead of water?
--To avoid temptation, you might want to skip buying that coffee (or tea) at a fast food restaurant: People who live in neighborhoods with lots of fast food restaurants have a higher stroke risk. Specifically, for each fast food restaurant in a neighborhood, the relative risk rose by 1%. Authors cautioned that this is a correlation--they don't know if the fast food causes the higher risk, or if fast food restaurants are merely a marker of unhealthy neighborhoods. Admittedly, these results seem sort of obvious, but it's interesting that they held up even after researchers controlled for demographic and socioeconomic factors.
Labels: coffee, Stroke 2009, tea
posted by Jessica Berthold at
9:30 AM
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