One physician’s comments on the Ontario (Canada) CS Rate Variation (OHTAC) Oct 2013

by faithgibson on October 27, 2013

Commentary on the Report of the Cesarean Section  (CS) Rate Variation document (OHTAC Oct 2013) for review

This comprehensive review studied the many factors that can contribute to the rise in the Cesarean Section Rate. After studying the literature, the only firm conclusion is that a policy of induction of labour at 41 weeks can lower the CS rate.

The strengths of this review are its comprehensiveness and detailed structure.

The weakness of this review are:

  • ·       The available literature attempts to isolate factors that individually contribute to the stated outcome, while in reality no single factor contributes to the outcome of interest. The CS rate is influenced by a complex of interacting factors that in the end characterize a style of practice
  •      Review does not deal with the important issue of older mothers and the prevention of unexplained stillbirth. The recommendation is to induce them a week earlier at 40 weeks.
  • ·       The difficulty of this type of review is that it treats all women as the same and therefore suggests that induction at 41 weeks will lower the CS rate, while it will do so for some women and not others. Problems is that we do not know which ones, so we treat all women the same, while we know that some women make a 38, 39, 40, 41 or 41 or even a 43 week placenta, but again we do not know which ones.
  • ·       While the studies cited indicate that induction at 41 weeks will lower the CS rate, in practice, on the “shop floor” so to speak, practitioners know that the opposite is true. In the largest maternity unit in Canada, women undergoing induction for post dates have rates of CS up to 44% while those going into spontaneous labour have raes as low as 8%.
  • ·       See page 37 of the Report showing the variation by Robson group demonstrating the effect of spontaneous labour vs induction
  • ·       Regarding the use of Epidural analgesia as covered in the report, the current Cochrane does not show an increase in CS rate, while again in practice this is not true. This is based in part on the inclusion of studies that ought not be there and exclusion of other that should be there, (1, 2)  The National Attitues and Beliefs study, shows that among younger obstetricians, they believe that epidurals are not a problem in this respect, while the older obstetricians, who have seen the change over their practice lifetime, as epidurals became ubiquitous, see how epidurals have increased the CS rate, even though in individual cases epidurals can lower the CS rate.(3)
  • ·      For reasons that I cannot understand, this review has not addresses to issue of VBAC. In terms of lowering the CS rate, others reviews consistently demonstrate that addressing women with a uterine scar will provide a much larger effect that induction at 41 weeks.
  • ·      Of course the largest way of avoiding CS is to avoid it. And if you fail to avoid it in the first birth, the chances of an increase in CS for subsequent births is huge. As well a number of placentation problems in subsequent pregnancies (previa, accreta, abruption, stillbirth, infertility) are found—leading to an increase in CS.
  • ·       How can this be?  Why is the literature not reflective of practice reality.
  • Largely it is because RCTs and other studies can tightly control the conditions of the study to isolate the outcome of interest, while in real life, its messy.
  • For conditions that are subject to many variables, practice styles and variable provider behaviours and attitudes, it may be that conventional study methodologies do not work.
  • ·       The midwifery literature is ignored and therefore not compared to “conventional” literature.
  • For example, midwives when caring for women at home for home birth or the same midwives in hospital, have substantially lower rates of CS.(4)  This is accomplished, among other methods,  by keeping women out of hospital. Hence the review ought to cite these Canadian references, concluding that midwifery care is in fact much more dramatic in its effect of lowering the CS rate than induction at 41 weeks. The study by EK Hutton et al of Ontario midwives show the same thing.
  • The recent Canadian study of the attitudes and beliefs of maternity care providers shows that obstetricians favour induction at 41 weeks while midwives do not believe in this approach in general.(5)  While it is difficult to directly relate beliefs to action, the midwifery global approach, including reluctance to induce at 41 weeks, results in lower CS rates.

In summary, despite a laudable effort, based on conventional methods of systematic review, this review has failed to include some key studies, such as the home birth and midwifery and VBAC literature, leading to conclusions that are open to criticism. While the method employed is the one used for most purposes, isolation of single factors does not reflect the practice world. It may be that the methodology may be suited to answer the key question. To address the question, other methods need to be included, including qualitative and multivariate approaches.