Association between Caesarean delivery mode of anaesthesia and maternal morbidity should not overlook conversions

Abstract

We read with interest the retrospective study by Abe and colleagues1Abe H. Sumitani M. Uchida K. et al.Association between mode of anaesthesia and severe maternal morbidity during admission for scheduled Caesarean delivery: a nationwide population-based study in Japan, 2010–2013.Br J Anaesth. 2018; 120: 779-789Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar on the association between mode of anaesthesia for scheduled Caesarean delivery and maternal morbidity. As expressed here and in the accompanying editorial,2Butwick A.J. Palanisamy A. Mode of anaesthesia for Caesarean delivery and maternal morbidity: can we overcome confounding by indication?.Br J Anaesth. 2018; 120: 621-623Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar a randomised trial would generate the most rigorous data, but cannot ethically be performed. With a very large data set, Abe and colleagues1Abe H. Sumitani M. Uchida K. et al.Association between mode of anaesthesia and severe maternal morbidity during admission for scheduled Caesarean delivery: a nationwide population-based study in Japan, 2010–2013.Br J Anaesth. 2018; 120: 779-789Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar accounted for over 30 co-morbidities with propensity-score matching. Whilst the editorial by Butwick and Palanisamy2Butwick A.J. Palanisamy A. Mode of anaesthesia for Caesarean delivery and maternal morbidity: can we overcome confounding by indication?.Br J Anaesth. 2018; 120: 621-623Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar addresses the possibility of residual confounding by indication, we would like to draw attention to another potential limitation in the methodology of the study: failure to analyse the data by the intended anaesthetic. The authors excluded cases requiring both neuraxial and general anaesthesia from their analysis, stating that these patients could not be accurately categorised. However, whilst in some cases both neuraxial and general anaesthesia might have been planned, these patients most likely received a neuraxial anaesthetic before conversion to general anaesthesia, and not the reverse. The authors acknowledge this when they state that conversions usually occur when ‘neuraxial anaesthesia is insufficient or critical vital signs emerge’. Whilst the conversion group likely represents a small proportion of their data set (<233 of 95 232 scheduled Caesarean deliveries), our data3Markley J.C. Farber M.K. Perlman N.C. Carusi D.A. Neuraxial anesthesia during Cesarean delivery for placenta previa with suspected morbidly adherent placenta: a retrospective analysis.Anesth Analg. 2018; (Access published on February 23)https://doi.org/10.1213/ANE.0000000000003314Crossref PubMed Google Scholar and the data of others4Guasch E. Gilsanz F. Treatment of postpartum hemorrhage with blood products in a tertiary hospital: outcomes and predictive factors associated with severe hemorrhage.Clin Appl Thromb Hemost. 2015; 22: 685-692Crossref PubMed Scopus (12) Google Scholar indicate that these cases include a disproportionate number of morbid outcomes compared with neuraxial anaesthesia alone. Given that the 10 046 cases with neuraxial anaesthesia contained only 76 cases of severe morbidity, it is possible that the inclusion of patients receiving both neuraxial and general anaesthesia significantly increased this number if analysed as a presumed intended neuraxial anaesthetic. This potential bias should be considered when interpreting the results of Abe and colleagues.1Abe H. Sumitani M. Uchida K. et al.Association between mode of anaesthesia and severe maternal morbidity during admission for scheduled Caesarean delivery: a nationwide population-based study in Japan, 2010–2013.Br J Anaesth. 2018; 120: 779-789Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar None declared. Association between mode of anaesthesia and severe maternal morbidity during admission for scheduled Caesarean delivery: a nationwide population-based study in Japan, 2010–2013British Journal of AnaesthesiaVol. 120Issue 4PreviewAlthough the incidence of maternal mortality during Caesarean delivery remains very low, the rate of severe maternal morbidity is increasing. Improvements in obstetric anaesthetic practice have resulted in a dramatic reduction in the risk of maternal death from general anaesthesia. Less clear is whether the risk of severe maternal morbidity differs according to mode of anaesthesia for women undergoing Caesarean delivery. We analysed the association between the mode of anaesthesia and severe maternal morbidity during Caesarean delivery using a nationally representative inpatient database. Full-Text PDF Open Archive