Sir.—We found the article by Sly et al1 to be very important. In a similar study that was carried out a few months ago in Greece, we checked the reliability of diary cards compared with peak expiratory flow rates (PEFR) measured at home by 33 asthmatic children aged 6 to 11 years (mean, 8.2 years).
In 26 cases (78.7%) of the studied group, no correlation was found between the scale recorded in the diary and the PEFR. In each of 17 cases (51.5%), the recorded symptoms were moderate or severe while the PEFR was normal or slightly low. In nine cases (27.2%), the patients reported mild symptoms or no symptoms at all while the PEFR was significantly low. We also found that, in all but one case, the values of the PEFR measured at home were not significantly different from those recorded in the clinic (Figure).