Medical audit: the problem of missing case-notes

This paper reports the results of a case-note audit undertaken to detect the antenatal risk factors found at the initial booking visit, including the subsequent clinical action taken. From a total of 2,139 case-notes of women booked via an obstetric computer system, and delivered between March 1990 and March 1991, 136 (6.4%) were missing. The results showed that these 136 mothers experienced significantly worse delivery outcomes, ie higher incidence of perinatal death; preterm labour; a baby with a low Apgar score and low birth weight. There was also a higher incidence of perinatal death and babies with a low Apgar score for women booked manually compared with those booked via the computer system. These results show that many audit procedures may be the subject of substantial bias due to the problem of missing information. The extended use of a computer-based medical record system should help to resolve this problem, although hybrid information systems can themselves be biased.