IJE Advance Access published online on June 25, 2009
International Journal of Epidemiology, doi:10.1093/ije/dyp212
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Elevated serum creatine kinase predicts first-ever myocardial infarction: a 12-year population-based cohort study in Japan, the Suita study
1Department of Preventive Cardiology, National Cardiovascular Center, Osaka, Japan.
2The First Institute for Health Promotion and Health Care, Japan Anti-Tuberculosis Association, Tokyo, Japan.
*Corresponding author. Department of Preventive Cardiology, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan. E-mail: makotow{at}hsp.ncvc.go.jp
 |
Abstract |
|---|
Background In myocardial infarction (MI), it is well known that serum creatine kinase (s-CK) increases after onset, but it is unclear whether s-CK elevates before MI onset. The present analysis examined whether elevated s-CK levels predicted first-ever MI or stroke.
Methods This study was a population-based cohort study in a Japanese urban area. Study subjects were comprised of 5026 initially healthy Japanese (2370 men and 2656 women, mean age: 54.5 years) without a history of MI or stroke. They were followed-up for 11.8 years on average, and 103 MIs (definite: 45; probable: 58) and 168 strokes (definite: 126; probable: 42) were observed. There was no subject who developed MI just at baseline (the follow-up period among those with definite MI was, at earliest, 0.20 years).
Results The adjusted hazard ratio for definite MI was 4.18 (95% confidence interval 1.66–10.53) with s-CK levels of 
200 IU/l, compared with the reference category (s-CK levels of 
99 IU/l), whereas no relationship was observed between s-CK levels and the risk for stroke. With regard to definite MI, an interaction between s-CK levels and dyslipidaemia was observed. Among subjects with hypercholesterolaemia, the hazard ratio linearly elevated with increased s-CK levels. On the other hand, no linear elevation was observed among subjects without hypercholesterolaemia (P for interaction = 0.011).
Conclusions The present study suggested that screening for elevated s-CK levels in initially healthy Japanese subjects was useful to predict first-ever MI in the future, especially in subjects with dyslipidaemia.
Keywords Creatine kinase, myocardial infarction, stroke, cohort studies, urban population
Accepted 21 April 2009