A survey of health care practitioners' knowledge of the QT interval

To assess health care practitioners' ability to correctly measure the QT interval, and to identify factors and medications that may increase the risk of QT-interval prolongation and torsades de pointes.

A cross-sectional analysis of a survey administered between April 2002 and March 2003.

Health care practitioners attending Grand Rounds Conferences at 6 academic institutions in the United States in internal medicine and psychiatry and at 6 community hospitals in the same geographical areas as the academic institutions.

Anonymous, self-administered questionnaire that included 20 questions on the QT interval.

Of approximately 826 attendees, 517 (63%) completed the survey. Of about 608 attendees of internal medicine conferences, 371 (61%) responded, and of about 208 attendees of psychiatry conferences, 146 (67%) responded. Of a total number of 20 questions, the median number of correct answers for the whole group was 10 (interquartile range 7-13). The median number of correct answers for internists was 12 (interquartile range 9-13), for psychiatrists 10 (interquartile range 7-13), and for other specialists 10 (interquartile range 5-13). Respondents who graduated between 1990 and 1999 and academicians performed significantly better overall than other respondents. Of the 517 respondents, 224 (43%) measured the QT interval correctly. Physicians in training and academicians were more likely to measure the QT interval correctly.

The majority of health care practitioners cannot correctly measure the QT interval and cannot correctly identify factors and medications that can prolong the QT interval. Our findings suggest that greater attention to the QT interval is warranted to ensure safer use of QT prolonging medications.