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Calcium channel blockers and myocardial infarction: a case–control study in a Japanese hospital
Author(s) -
Ohyama Yoshiharu,
Funao Kazuhiro,
Kawabe Eri,
Hayashi Doubun,
Yamazaki Tsutomu,
Iga Tatsuji,
Koide Daisuke,
Ohe Kazuhiko,
Kubota Kiyoshi
Publication year - 2002
Publication title -
pharmacoepidemiology and drug safety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.023
H-Index - 96
eISSN - 1099-1557
pISSN - 1053-8569
DOI - 10.1002/pds.743
Subject(s) - medicine , myocardial infarction , odds ratio , confounding , calcium channel , angina , cardiology , blood pressure , diabetes mellitus , calcium , endocrinology
Purpose To examine the relationship of the use of calcium channel blockers (CCBs) in hypertensive patients to myocardial infarction in Japan, where CCBs are prescribed much more frequently than in Europe and America. Design We conducted a nested case–control study using a hospital information system in Japan. Subjects Cases were hypertensive patients who were repeat visitors to Tokyo University Hospital as of April 1996 and had an incidence of fatal or non‐fatal myocardial infarction between 1996 and 1999. Controls were hypertensive patients individually matched to cases by sex, age and history of angina pectoris. Results The study consisted of 16 cases, who were matched to 80 controls. Of the 80 control patients, 54 (68%) received CCBs. On the other hand, all but one of 16 cases received CCBs and the crude odds ratio of myocardial infarction associated with the use of calcium channel blockers was as high as 7.0 (0.9–55.3). The odds ratio was reduced to 4.9 (0.6–42.4) when adjusted by diabetes and diastolic blood pressure. Conclusions Although the crude odds ratio of myocardial infarction associated with CCBs was high, the ratio was reduced when adjusted by known confounding factors, suggesting a mechanism of confounding by indication. In addition, the results obtained in this study using records from a single hospital should not be generalized. Copyright © 2002 John Wiley & Sons, Ltd.