Computerised cardiotocography—study design hampers findings

Cardiotocography is a diagnostic tool, not a therapeutic modality. Diagnostic tests are unlikely to improve outcomes unless followed by specific and effective therapeutic interventions. When the management of highly specific abnormalities is not specified in a study protocol but is instead left to the individual discretion of many providers with very different management approaches, the chance that all of them will react in the same way is small. In The Lancet, the INFANT collaborative group reports the results of a randomised controlled trial 1 in which women in labour undergoing electronic cardiotocographic monitoring were randomly allocated with or without assessment by a decision-support system. The decision-support software extracted data including baseline heart rate, heart-rate variability, accelerations, type and timing of decelerations, the quality of the signal, and the contraction pattern, analysed these data along with the quality of the signals, and then presented the findings as a series of colour-coded alerts, the most serious of which was a red alert. No specific actions on the part of the providers were defined as a result of receiving these alerts. The primary outcomes were a composite of poor neonatal outcome or significant morbidity, and developmental assessment at age 2 years in a subset of surviving children. The authors found no significant difference in the incidence of poor neonatal outcome between the groups (adjusted risk ratio 1·01, 95% CI 0·82–1·25). Furthermore, they found no differences in most of the secondary maternal, neonatal, or long-term outcomes. They concluded that no evidence currently supports the use of computerised interpretation of cardiotocography in labour to improve clinical outcomes for mothers or babies. The IQR of time from identification of the last red level of concern to birth was 13–279 min. This finding suggests widely disparate approaches to even severe cardiotocographic abnormalities in the study. The INFANT trial seems to be open to the same criticism levelled at studies 2,3 in which women in labour were randomly assigned to auscultation or cardiotocography. Without an unambiguous reaction to clearly defined abnormal patterns, these studies could compare outcomes only between women who did or did not wear a monitor belt during labour, rather than show any intrinsic value of cardiotocographic technology. 2,3 We also question the authors' apparent dismissal of the value of computerised cardiotocographic interpretation simply because the algorithm used in their trial was not beneficial. This dismissal would be a substantial problem even in the setting of …