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Rapid Responses: Rapid Responses published:
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risk of obstetric morbidity associated with caesarian section
- Julian Brown (8 May 2001)
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Incidence and predictors of severe obstetric morbidity - a response!!
- Molly Anderson (11 May 2001)
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Assessing predictors of maternal morbidity
- Shantini Paranjothy (17 May 2001)
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Severe maternal morbidity in Europe
- Bouvier-Colle (15 July 2001)
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Julian Brown, specialist registrar in anaesthesia department of anesthesia, bristol royal infirmary, malborough st, bristol BS2 8HW
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Editor-Waterstone et al present the results of their case control study of obstetric morbidity1. They found an association between emergency caesarian section and severe maternal morbidity (with an odds ratio of 4.31).They conclude that attempts to reduce the emergency caesarian section rate would result in a reduction in severe maternal morbidity.This assumes a causal relationship which cannot be determined from their data. It would be surprising if an association wasn't found when the indications for emergency caesarian section include maternal morbidity.If the caesarian section rate is rising despite no evidence of a rise in morbidity then it would be unlikely if caesarian section was contributing to this morbidity. A study directly comparing emergency caesarian section and conservative management would be needed to quantify these risks. References: Waterstone M, Bewley S, Wolfe C. Incidence and predictors of severe obstetric morbidity: case-control study BMJ 2001;322:1089-94 |
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Molly Anderson, 3rd Year Medical Student Dept of Epidemiology and Public Health, Newcastle University
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Editor, Regarding the Waterstone et al (1) case-control study into the incidence and predictors of severe obstetric morbidity, we felt there were several points to be raised. Overall, the study improved upon previous work carried out in this difficult field by the use of a large multi-centered study group. The omission of embolic disease is understandable due to the difficulty in diagnosis. Yet, without this data the study is of diminished value to clinical practice. However, if a method of accurately diagnosing emboli were available, a study into the importance of this factor alone would be of real worth. The study showed that a major predictor of obstetric morbidity was social exclusion. This grouping appeared too broad to be of any significance. Also, this information has been taken from medical notes. Therefore any factor not recorded would not be taken into account in the study. A questionnaire could have been used to provide fuller and more standardised information. A reproducible measure of social class may have given a more accurate, and hence reliable, predictor. This study provides an interesting prelude to further work. We suggest that a future study should include clear definitions of social groupings and an emphasis on embolic disease. Molly Anderson, Cara Jennings, Christopher Lehane, Adam McDiarmid
& Michelle Warden
(1) Waterstone M., Bewley S. and Wolfe C. (2001) ‘Incidence and predictors of severe obstetric morbidity: case-controlstudy’ BMJ 322 1089- 1093 |
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Shantini Paranjothy, Clinical Research Fellow Royal College of Obstetricians and Gynaecologists Clinical Effectiveness Support Unit
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The study by Waterstone et al1, which reports the incidence and predictors of severe obstetric morbidity, contributes significantly to our understanding of maternal health in the U.K. and is welcomed. We would, however, urge caution in the interpretation of some of the reported results, particularly with regard to potential pathways of effects. For instance, all these examples of serious obstetric morbidity have multiple causes, and these causes may occur at different points before or during pregnancy, and during or after labour. What happens at a later stage may be conditional on what has happened earlier. There is no indication that this temporal sequence was considered in the model. Many factors may contribute independently to the outcomes. For example, a plausible explanation for the relatively low odds ratio (1.36; 95% confidence interval 0.99 to 1.88) for post term induction of labour is that the association is masked by the inclusion of emergency caesarean section in the statistical model. Induction of labour is independently associated with emergency caesarean section, which in turn is associated with haemorrhage and infection. Its inclusion in the model would be justified if emergency caesarean section behaved as a confounder in the relationship between induction of labour and maternal morbidity. We would suggest that emergency caesarean section is on the causal pathway and its inclusion in the model makes it impossible to determine the true effect of induction of labour as a predictor for maternal morbidity. The odds ratio for emergency caesarean section suggests that women who underwent the procedure were four times more likely to suffer morbidity, when compared to women who did not. The commentary that follows this paper by D.Murphy2, states that because the odds ratio reported is adjusted, it reflects the additional risk of the procedure itself. However, the estimated effect of emergency caesarean section reported in the study actually represents the combined effect of emergency caesarean section and those confounding variables that had not been accounted for. Drawing a causal interpretation from this four-fold odds ratio is incorrect and we regard the statement in the Abstract that ‘Caesarean section quadruples the risk of morbidity’ as misleading, particularly since no mention is made of the fact that this statement really only applies to emergency caesarean sections. There is an upward trend in published caesarean section rates; this increase may in part reflect changes in clinical beliefs about the relative safety of caesarean section and vaginal birth. There is a paucity of data available to help inform decision-making in this area and there is an urgent need for further research to evaluate maternal morbidity for caesarean section in comparison to vaginal delivery. References: 1. Waterstone M., Bewley S. and Wolfe C. (2001) ‘Incidence and predictors of severe obstetric morbidity: case-control study’ BMJ 322 1089-1093. 2. Murphy DJ. Commentary: Obstetric morbidity data and the need to evaluate thromboembolic disease. BMJ 322 Authors: Shantini Paranjothy
Christ Frost
Diana Elbourne
Jane Thomas
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Bouvier-Colle , INSERM-U149 Paris
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Given their comments about the small size of previous studies, we are very surprised that the authors of the paper on severe obstetric morbidity1 did not mention that it was undertaken as part of an European Union Concerted Action on Maternal Mortality and Severe Morbidity (MOMS). Although they ‘ searched Medline using key words’ and ‘selected definitions that were clinically based and routinely measurable and that did not include management process.’, the definitions they used were, not surprisingly the same as those used by other participants in our European collaborative study. These were published in our final report2 and are appended. They were developed by the participants at meetings which two of the authors attended. As they state, at the outset, there was no agreed definition of severe maternal morbidity. The project leader had proposed a definition previously used in a French survey on intensive care admissions of obstetric patients.3 The group rejected this for the reasons stated in the author’s paper1 and instead developed an approach based on three major conditions which can lead to mortality, haemorrhage, eclampsia and infections. The definition of severe hemorrhage has been used in a French evaluation of quality of obstetric care, which is currently in press. 4 The agreed definitions were then used, not only by the authors, but also in ten other simultaneous population-based studies in regions within countries of Europe in order to compare rates of severe maternal morbidity. As four of the surveys were small, we have given aggregated totals for the three conditions in Table 1. Major differences were seen in incidence and these form an important baseline for future investigations of possible factors which could have led to them. Although the authors’ survey was the largest, sizeable surveys were done in Belgium, Finland and France. It is a pity that they did not consider the collaboration, their involvement in it and the contribution made by collaborators to the development of the indicators they used worthy of mention in their paper. Sophie ALEXANDER Marie-Hélène
Bouvier-Colle, References 1- Waterstone M, Bewley S, Wolfe C. “ Incidence and predictors of severe obstetric morbidity : case-control study. BMJ 2001, 322 : 1089-92 2-(MH Bouvier-Colle for the MOMS group ) Frequency and risk factors of maternal morbidity and mortality- avoidable diseases and evaluation of care- MOMS . Final report (Contract n° MMH1-CT93-1064 & (PECO) CIPD- CT94-0279) 6 avril 1998. 3- Bouvier-Colle MH, Varnoux N, Salanave B, Ancel PY, Bréart G and the maternal morbidity group. Case-control study of risk factors for obstetric patients’ admission to Intensive care units. Eur J Obstet Gynecol Reprod Biol 1997 ; 74 : 173-77. 4- Bouvier-Colle MH, Ould El Joud D, Varnoux N, Goffinet F, and the study group of haemorrhages. Evaluation of care for severe obstetric haemorrhages in three French Regions. BJOG in press Table 1 Incidence of severe obstetric morbidity in 11 regions in Europe , by main obstetrical complications, according to the MOMS-B Survey. Incidence per 1000 European Regions Number of cases of severe morbidity Births or deliveries TOTAL Severe PET HAEMOR-RHAGE SEPSIS UK, South East Thames 608 48 262 12,6 5,0 7,3 0,3 Austria 36 6 022 6,0 5,3 - - Belgium 272 17 500 15,5 5,9 5,9 3,6 Finland 263 17 249 15,3 4,9 9,0 1,3 Hungary, Budapest area 117 13 667 8,6 5,8 2,3 0,4 Irland 11 1 800 6,1 5,0 - - Italia 23 3 170 7,2 6,0 - - Norway 27 3 010 8,9 2,3 2,6 4,0 France, Champagne-Ard. 113 16 806 6,7 2,4 3,1 1,1 France, Centre 149 27 231 5,5 2,4 2,7 0,3 France, Lorraine 224 27 872 8,0 3,7 3,9 0,4 TOTAL 1843 182 589 10,1 4,3 4,9 0,9 |
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