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Rising caesarean section rates: a cause for concern?
BJOG: an International Journal of Obstetrics and Gynaecology October 2003, Vol. 110, pp. 964 –966
CORRESPONDENCE Impact of rising caesarean rate on stillbirths in Merseyside
Zarko Alfirevic & Grace Edwards University of Liverpool, Liverpool, UK
Sir, The authors of the Commentary from Ireland1 suggested an inverse relationship between caesarean rates and intrapartum stillbirth. We examined the trends in caesarean section and intrapartum stillbirths rate in nine maternity units in the Merseyside region, England for the period 1995 and 2001. The data had been submitted annually to the regional Confidential Enquiry into Stillbirths and Deaths in Infancy (CESDI) Office as a part of an ongoing national audit. Prior to the commencement of the CESDI, it was agreed at national level to use the modified Wigglesworth Classifiction1 to ascertain a cause for each death using a standardised approach. There was significant increase correlation between the rate of caesarean section and the rate of intrapartum stillbirths (r ¼ 0.78, P ¼ 0.037) (Fig. 1). Similar trends were not seen for three other Wigglesworth’s groups, prematurity, congenital malformations and unexplained deaths where the correlations were 0.57, 0.12 and 0.62, respectively. The observed reduction in intrapartum stillbirths may be a consequence of a lower threshold for caesarean section both before and during labour. It may also be secondary to other improvements in antenatal and neonatal care such as increased use of antenatal steroids for lung maturity, surfactant for neonatal respiratory distress syndrome, better postgraduate education (mandatory training in CTG interpretation), the introduction of guidelines and labour ward risk management. We did not expect to find such a strong correlation between caesarean section and intrapartum stillbirths and urge others to examine larger data sets for similar trends.
PII: S 1 4 7 0 - 0 3 2 8 ( 0 3 ) 0 3 5 0 7 - 9
Reference 1. Wigglesworth JS. Causes and classification of fetal and perinatal death. In: Wigglesworth JS, Singer DB, editors. Textbook of Fetal and Perinatal Pathology, 1. Boston: Blackwell Scientific Publications, 1991:72 – 92.
Fig. 1. Caesarean section rates (%) and intrapartum stillbirths (%) (Wigglesworth classification) in Merseyside, England between 1995 and 2001.
Rising caesarean section rates: a cause for concern? Sir, ‘Lies, damn lies and statistics’. The paper by Mathews et al.1 purports to link the perinatal mortality rate in normally formed infants > 2.5 kg in the three Dublin maternity hospitals. The hospitals are designated A, B and C. Hospital C was neither involved nor consulted in the study although its data were used, analysed and quoted. We are surprised that a peer review journal would publish a paper where the authors are openly critical of another institution, without that institution being given an opportunity to state its case. The enthusiastic adoption of interventions in medicine, without good scientific evidence of benefit, sometimes does more harm than good. The authors of the paper have produced a weak argument linking trends in perinatal mortality with caesarean delivery rates. The same mistake was made in the 1970s and 1980s with electronic fetal monitoring. The caesarean epidemic is the latest example of an uncontrolled experiment in obstetrics. In the year 2003, it is simply not acceptable to propose that an intervention, associated with at least a fourfold increase in maternal mortality and morbidity, is responsible for less perinatal deaths on such a tenuous premise as temporal association. It has been accepted for some time that comparison of mortality statistics between individual hospitals is unreliable because of differing populations and differing referral patterns. The more complex the case mix, the more likely that mortality and morbidity will be higher. Hospital C is the largest of the three hospitals and receives the greatest number of national in utero transfers and neonatal transfers. Indeed in 2002, five of its perinatal deaths were received from hospital A. Perinatal mortality data must be based on geographically defined populations in order to have validity. The matter of deaths in normally formed infants is open to varying interpretation. In Fig. 1, the authors display a very simplistic and misleading depiction of deaths per 1000 live births and caesarean sections. Superficial viewing would suggest that increased caesarean section rates are associated with a linear reduction in deaths. The authors fail to acknowledge that many more important factors prevailed over these 21 years including: better nutrition, increased prosperity, antenatal ultrasound, better identification of the compromised fetus, improved management of medical disorders and many advances in neonatal medicine. In addition, the data used are too superficial to answer the question asked. Data would have been needed on antepartum and intrapartum stillbirths as well as neonatal deaths. Caesarean sections are never going to prevent the macerated antepartum stillbirth or neonatal death from sepsis. The paper also fails to address the significant maternal morbidity and mortality associated with caesarean birth. Indeed, from 1999 to 2002, hospital A has had four deaths from the complications of caesarean delivery, a serious omission from the commentary. Finally, the use or abuse of statistics is all too apparent in the article which also fails to acknowledge a fundamental flaw in the
D RCOG 2003 BJOG: an International Journal of Obstetrics and Gynaecology www.bjog-elsevier.com
CORRESPONDENCE
annual reports of hospital A. This hospital fails to include unbooked cases in calculating its perinatal death rate (unlike hospitals B and C). A more accurate interpretation of each hospital’s corrected perinatal mortality rates (excluding malformations) of infants >500 g over the last four years and their caesarean section rates is shown in Tables 1 and 2. While debate on the appropriate use of caesarean delivery is welcome, one would hope for contributions that are more evidence based than evidence biased. One must also make a plea not to forget the mother, after all she is the one on whom the surgery is performed. Finally, to propose that consultants working in hospital C have an attitude to the practice of obstetrics which accepts a higher rate of perinatal death, in order to keep a caesarean section rate low, could be seen as an attempt to discredit their practice. Is this what Matthews et al. intended? D. P. Keane, P. Boylen & J. F. Murphy National Maternity Hospital, Dublin, Ireland
Reference 1. Rising caesarean rates: a cause for concern. Br J Obstet Gynaecol 2003;110:346 – 349.
Editor’s note Whatever the rights and wrongs of the issue underlying this debate, these was no obligation for Mathews et al. to ask Keane et al. for permission to analyse the figures from hospital C. These were already in the public domain. However, it would have been courteous to warn them that they were conducting such an analysis. PII: S 1 4 7 0 - 0 3 2 8 ( 0 3 ) 0 3 8 2 2 - 9
AUTHOR’S REPLY Sir, We are pleased that the accuracy of the data in our paper showing a consistently and persistently higher mortality rate in normally formed babies of more than 2.5 kg in hospital C is not disputed, and we agree about the danger of adopting non-evidence-based interventions obstetrics. Our paper was an attempt to provide data to flesh out the ‘rising caesarean section’ debate. We acknowledge that caesarean section is a major intervention with risks of maternal mortality and morbidity. This is why there is a debate. We had hoped that the important issues we addressed in this paper could be discussed dispassionately without inter-institutional criticism. Table 1. Comparison of corrected perinatal mortality >500 g from 1998 to 2001 (number of deaths/infants delivered).
2001 2000 1999 1998 Total deaths/infants Perinatal mortality rate
Hospital A
Hospital B
Hospital C
46/6600 41/6310 36/6334 32/6387 155/25,631 6.04
44/7684 59/7496 44/7067 47/6997 194/29,244 6.63
51/8142 65/7840 46/7659 42/7917 204/31,558 6.46
D RCOG 2003 Br J Obstet Gynaecol 110, pp. 964 – 966
965
Table 2. Caesarean section rates from 1998 to 2001 (sections/mothers delivered).
2001 2000 1999 1998 Total sections/mothers Caesarean rate (%)
Hospital A
Hospital B
Hospital C
1720/6457 1585/6211 1572/6283 1518/6119 6395/25,070 25.5
1412/7546 1252/7389 1137/6970 1015/6918 4816/28,823 16.7
1150/7980 1100/7722 973/7537 1003/7817 4226/31,056 13.6
We cannot provide population-based mortality statistics because women from outside Dublin are free to deliver in any of the Dublin hospitals. If perinatal mortality data ‘must be based on geographically defined populations to have validity’, then why does hospital C bother publishing, and widely disseminating, a non-population-based annual report. Because of the inability to produce population-based data, we have addressed factors that might skew obstetric risks in the various hospitals. We believe that hospital C has the lowest risk population as evidenced by having the lowest percentage of low birthweight babies, the highest percentage of upper socio-economic patients, the highest percentage of fee-paying patients and the lowest percentage of pregnant asylum seekers (28% of births in hospital A compared with 10% in hospital C). Hospital A also has the busiest neonatal intensive care unit which, when full, requires the transfer of high risk patients, explaining the comment regarding high risk transfers from hospital A to hospital C. That transfers are much less frequent in the opposite direction supports our contention that hospital C has the lowest risk population. As babies of 2.5 kg or more are rarely transferred, either in utero or postnatally, these transfers are not contributing to deaths in the 2.5 kg and over category in hospital C. We have responded to the point made by hospital C about the inclusion of unbooked patients by including unbooked cases in the table below. Table 3 supplied by hospital C neatly illustrates one of the key points in our study—that important differences in perinatal mortality are missed by submerging data relating to normally formed babies of 2.5 kg or greater in perinatal mortality statistics for all babies of z500 g. Their comment on statistical abuse in our paper rings a bit hollow given their handling of data relating to the years 1998 – 2001. First, they lump all deaths >500 g together, obscuring important differences in mortality rates. Then they change from ‘lumpers’ to ‘splitters’ and suggest that even if the >2.5 kg mortality rate were relevant, these deaths should be split into multiple subgroups rendering any meaningful analysis impossible. There were indeed four maternal deaths in the years 1999 – 2002 in hospital A. One was due to carcinomatosis, and two were
Table 3. The number of deaths, and number of deliveries in hospitals A and C separated into <2.5 kg and z2.5 kg.
1998 1999 2000 2001 Total Rate
Hospital A z2.5 kg
Hospital A <2.5 kg
Hospital C z2.5 kg
Hospital C <2.5 kg
5/5947 11/5941 9/5874 8/6094 33/23,856 1.38/1000
27/440 24/397 30/436 37/506 118/1779 66/1000
15/7480 20/7261 24/7439 15/7733 74/29,913 2.48/1000
31/468 27/398 30/401 36/409 124/1676 74/1000
CORRESPONDENCE Impact of rising caesarean rate on stillbirths in Merseyside
Zarko Alfirevic & Grace Edwards University of Liverpool, Liverpool, UK
Sir, The authors of the Commentary from Ireland1 suggested an inverse relationship between caesarean rates and intrapartum stillbirth. We examined the trends in caesarean section and intrapartum stillbirths rate in nine maternity units in the Merseyside region, England for the period 1995 and 2001. The data had been submitted annually to the regional Confidential Enquiry into Stillbirths and Deaths in Infancy (CESDI) Office as a part of an ongoing national audit. Prior to the commencement of the CESDI, it was agreed at national level to use the modified Wigglesworth Classifiction1 to ascertain a cause for each death using a standardised approach. There was significant increase correlation between the rate of caesarean section and the rate of intrapartum stillbirths (r ¼ 0.78, P ¼ 0.037) (Fig. 1). Similar trends were not seen for three other Wigglesworth’s groups, prematurity, congenital malformations and unexplained deaths where the correlations were 0.57, 0.12 and 0.62, respectively. The observed reduction in intrapartum stillbirths may be a consequence of a lower threshold for caesarean section both before and during labour. It may also be secondary to other improvements in antenatal and neonatal care such as increased use of antenatal steroids for lung maturity, surfactant for neonatal respiratory distress syndrome, better postgraduate education (mandatory training in CTG interpretation), the introduction of guidelines and labour ward risk management. We did not expect to find such a strong correlation between caesarean section and intrapartum stillbirths and urge others to examine larger data sets for similar trends.
PII: S 1 4 7 0 - 0 3 2 8 ( 0 3 ) 0 3 5 0 7 - 9
Reference 1. Wigglesworth JS. Causes and classification of fetal and perinatal death. In: Wigglesworth JS, Singer DB, editors. Textbook of Fetal and Perinatal Pathology, 1. Boston: Blackwell Scientific Publications, 1991:72 – 92.
Fig. 1. Caesarean section rates (%) and intrapartum stillbirths (%) (Wigglesworth classification) in Merseyside, England between 1995 and 2001.
Rising caesarean section rates: a cause for concern? Sir, ‘Lies, damn lies and statistics’. The paper by Mathews et al.1 purports to link the perinatal mortality rate in normally formed infants > 2.5 kg in the three Dublin maternity hospitals. The hospitals are designated A, B and C. Hospital C was neither involved nor consulted in the study although its data were used, analysed and quoted. We are surprised that a peer review journal would publish a paper where the authors are openly critical of another institution, without that institution being given an opportunity to state its case. The enthusiastic adoption of interventions in medicine, without good scientific evidence of benefit, sometimes does more harm than good. The authors of the paper have produced a weak argument linking trends in perinatal mortality with caesarean delivery rates. The same mistake was made in the 1970s and 1980s with electronic fetal monitoring. The caesarean epidemic is the latest example of an uncontrolled experiment in obstetrics. In the year 2003, it is simply not acceptable to propose that an intervention, associated with at least a fourfold increase in maternal mortality and morbidity, is responsible for less perinatal deaths on such a tenuous premise as temporal association. It has been accepted for some time that comparison of mortality statistics between individual hospitals is unreliable because of differing populations and differing referral patterns. The more complex the case mix, the more likely that mortality and morbidity will be higher. Hospital C is the largest of the three hospitals and receives the greatest number of national in utero transfers and neonatal transfers. Indeed in 2002, five of its perinatal deaths were received from hospital A. Perinatal mortality data must be based on geographically defined populations in order to have validity. The matter of deaths in normally formed infants is open to varying interpretation. In Fig. 1, the authors display a very simplistic and misleading depiction of deaths per 1000 live births and caesarean sections. Superficial viewing would suggest that increased caesarean section rates are associated with a linear reduction in deaths. The authors fail to acknowledge that many more important factors prevailed over these 21 years including: better nutrition, increased prosperity, antenatal ultrasound, better identification of the compromised fetus, improved management of medical disorders and many advances in neonatal medicine. In addition, the data used are too superficial to answer the question asked. Data would have been needed on antepartum and intrapartum stillbirths as well as neonatal deaths. Caesarean sections are never going to prevent the macerated antepartum stillbirth or neonatal death from sepsis. The paper also fails to address the significant maternal morbidity and mortality associated with caesarean birth. Indeed, from 1999 to 2002, hospital A has had four deaths from the complications of caesarean delivery, a serious omission from the commentary. Finally, the use or abuse of statistics is all too apparent in the article which also fails to acknowledge a fundamental flaw in the
D RCOG 2003 BJOG: an International Journal of Obstetrics and Gynaecology www.bjog-elsevier.com
CORRESPONDENCE
annual reports of hospital A. This hospital fails to include unbooked cases in calculating its perinatal death rate (unlike hospitals B and C). A more accurate interpretation of each hospital’s corrected perinatal mortality rates (excluding malformations) of infants >500 g over the last four years and their caesarean section rates is shown in Tables 1 and 2. While debate on the appropriate use of caesarean delivery is welcome, one would hope for contributions that are more evidence based than evidence biased. One must also make a plea not to forget the mother, after all she is the one on whom the surgery is performed. Finally, to propose that consultants working in hospital C have an attitude to the practice of obstetrics which accepts a higher rate of perinatal death, in order to keep a caesarean section rate low, could be seen as an attempt to discredit their practice. Is this what Matthews et al. intended? D. P. Keane, P. Boylen & J. F. Murphy National Maternity Hospital, Dublin, Ireland
Reference 1. Rising caesarean rates: a cause for concern. Br J Obstet Gynaecol 2003;110:346 – 349.
Editor’s note Whatever the rights and wrongs of the issue underlying this debate, these was no obligation for Mathews et al. to ask Keane et al. for permission to analyse the figures from hospital C. These were already in the public domain. However, it would have been courteous to warn them that they were conducting such an analysis. PII: S 1 4 7 0 - 0 3 2 8 ( 0 3 ) 0 3 8 2 2 - 9
AUTHOR’S REPLY Sir, We are pleased that the accuracy of the data in our paper showing a consistently and persistently higher mortality rate in normally formed babies of more than 2.5 kg in hospital C is not disputed, and we agree about the danger of adopting non-evidence-based interventions obstetrics. Our paper was an attempt to provide data to flesh out the ‘rising caesarean section’ debate. We acknowledge that caesarean section is a major intervention with risks of maternal mortality and morbidity. This is why there is a debate. We had hoped that the important issues we addressed in this paper could be discussed dispassionately without inter-institutional criticism. Table 1. Comparison of corrected perinatal mortality >500 g from 1998 to 2001 (number of deaths/infants delivered).
2001 2000 1999 1998 Total deaths/infants Perinatal mortality rate
Hospital A
Hospital B
Hospital C
46/6600 41/6310 36/6334 32/6387 155/25,631 6.04
44/7684 59/7496 44/7067 47/6997 194/29,244 6.63
51/8142 65/7840 46/7659 42/7917 204/31,558 6.46
D RCOG 2003 Br J Obstet Gynaecol 110, pp. 964 – 966
965
Table 2. Caesarean section rates from 1998 to 2001 (sections/mothers delivered).
2001 2000 1999 1998 Total sections/mothers Caesarean rate (%)
Hospital A
Hospital B
Hospital C
1720/6457 1585/6211 1572/6283 1518/6119 6395/25,070 25.5
1412/7546 1252/7389 1137/6970 1015/6918 4816/28,823 16.7
1150/7980 1100/7722 973/7537 1003/7817 4226/31,056 13.6
We cannot provide population-based mortality statistics because women from outside Dublin are free to deliver in any of the Dublin hospitals. If perinatal mortality data ‘must be based on geographically defined populations to have validity’, then why does hospital C bother publishing, and widely disseminating, a non-population-based annual report. Because of the inability to produce population-based data, we have addressed factors that might skew obstetric risks in the various hospitals. We believe that hospital C has the lowest risk population as evidenced by having the lowest percentage of low birthweight babies, the highest percentage of upper socio-economic patients, the highest percentage of fee-paying patients and the lowest percentage of pregnant asylum seekers (28% of births in hospital A compared with 10% in hospital C). Hospital A also has the busiest neonatal intensive care unit which, when full, requires the transfer of high risk patients, explaining the comment regarding high risk transfers from hospital A to hospital C. That transfers are much less frequent in the opposite direction supports our contention that hospital C has the lowest risk population. As babies of 2.5 kg or more are rarely transferred, either in utero or postnatally, these transfers are not contributing to deaths in the 2.5 kg and over category in hospital C. We have responded to the point made by hospital C about the inclusion of unbooked patients by including unbooked cases in the table below. Table 3 supplied by hospital C neatly illustrates one of the key points in our study—that important differences in perinatal mortality are missed by submerging data relating to normally formed babies of 2.5 kg or greater in perinatal mortality statistics for all babies of z500 g. Their comment on statistical abuse in our paper rings a bit hollow given their handling of data relating to the years 1998 – 2001. First, they lump all deaths >500 g together, obscuring important differences in mortality rates. Then they change from ‘lumpers’ to ‘splitters’ and suggest that even if the >2.5 kg mortality rate were relevant, these deaths should be split into multiple subgroups rendering any meaningful analysis impossible. There were indeed four maternal deaths in the years 1999 – 2002 in hospital A. One was due to carcinomatosis, and two were
Table 3. The number of deaths, and number of deliveries in hospitals A and C separated into <2.5 kg and z2.5 kg.
1998 1999 2000 2001 Total Rate
Hospital A z2.5 kg
Hospital A <2.5 kg
Hospital C z2.5 kg
Hospital C <2.5 kg
5/5947 11/5941 9/5874 8/6094 33/23,856 1.38/1000
27/440 24/397 30/436 37/506 118/1779 66/1000
15/7480 20/7261 24/7439 15/7733 74/29,913 2.48/1000
31/468 27/398 30/401 36/409 124/1676 74/1000