Methods and accuracy of coding

Most population based studies make use of the Minnesota Code, first introduced in 19606 and subsequently extended to incorporate serial comparison in 1983.7 An updated manual is due for publication shortly. Coding of an ECG can be done manually as in the paper of De Bacquer and colleagues3 or it can be done by automated methods.8 Both approaches, however, are subject to error9 ,10 and 100% reliance cannot be placed on either the coding of one individual or an automated technique. In the case of manual coding, it is better to have two individuals coding independently and then reaching a consensus in the event of disagreement, or if the coding centre is large enough, a third (more experienced) observer can adjudicate. Automated codings should be reviewed by an observer who effectively provides a second opinion. Even then, a second observer is also of value when there is disagreement between an automated report and the first observer. There is much that can be regarded as subjective in coding …