To the Editor.—
Much of the letter by Jick et al concerns our attempt to explain the variation among studies. As our Table 4 clearly indicated, the listing of proportions of "heavy" coffee-drinkers in various studies was made without precise equilibration of the number of cups of coffee drunk per day. Many persons who answered "yes" to the question "Have you usually, in the past year, drunk more than six cups of coffee per day?" may have imprecisely interpreted the query as "six or more cups per day?"Therefore, we thought that the comparison was appropriate. However, we now agree that a strict interpretation categorizes our positive responders as drinking seven or more cups of coffee per day. Such categorization is closer to Paul's1 200 or more cups per month group that included only 7% of controls.The new Framingham Heart Study data, presented by Jick et al, suggest
Klatsky A, Friedman G, Siegelaub A. Coffee Drinking and Myocardial Infarction. JAMA. 1974;227(7):802–803. doi:10.1001/jama.1974.03230200059022
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