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- Page navigation anchor for Author response to "Pitfalls of Analyzing Healthcare Provider-based Perinatal Outcomes" PART 2Author response to "Pitfalls of Analyzing Healthcare Provider-based Perinatal Outcomes" PART 2
In terms of Dr. Jain’s comment about inaccuracies in BC with coding the delivery provider: We did not use delivery provider as the exposure but solely to exclude births that were not delivered by a primary care provider. For example, we did not want to include midwife or physician patients who were delivered by a nurse or who had no attendant. Given how few births were excluded based on the delivery provider, we do not anticipate that the lower levels of validity reported for this variable by Frost affected our results.
The stringent word limit prevented us from including etiological considerations and a description of different factors that might impact birth outcomes of midwifery or physician clients. We appreciate the etiological consideration Dr. Jain suggested and can also think of factors that might predispose midwifery clients to worse outcomes. For example, midwifery clients routinely decline tests or procedures recommended by a health care provider (e.g. genetic and gestational diabetes testing, induction of labour) and midwives generally support or accept that decision (Stoll et al. (2)). In the current study we reported that 20% of midwifery clients who had a home birth were moderate or high risk. These cases were included in the analysis.
In response to the comment about lack of biological plausibility:
Other research studies and reviews have found reduced perinatal death rates and preterm birth rates for midwife-led continuity of care...
Show MoreCompeting Interests: None declared.References
- 1. Thiessen K, Nickel N, Prior HJ, et al. Understanding the allocation of caesarean outcome to provider type: a chart review. Healthcare Policy. 2018 Nov;14(2):22.
- 2. Stoll K, Wang JJ, Niles P, et al. I felt so much conflict instead of joy: an analysis of open-ended comments from people in British Columbia who declined care recommendations during pregnancy and childbirth. Reproductive health. 2021 Dec;18(1):1-5.
- 3. Bradford BF, Wilson AN, Portela A, et al. Midwifery continuity of care: A scoping review of where, how, by whom and for whom?. PLOS Global Public Health. 2022 Oct 5;2(10):e0000935.
- 4. World Health Organization. WHO recommendations on antenatal care for a positive pregnancy experience. World Health Organization; 2016. https://www.who.int/publications/i/item/9789241549912
- Page navigation anchor for Author response to "Pitfalls of Analyzing Healthcare Provider-based Perinatal Outcomes" PART 1Author response to "Pitfalls of Analyzing Healthcare Provider-based Perinatal Outcomes" PART 1
We appreciate and have carefully considered Dr. Jain’s response.
We opted to reduce (not eliminate) bias caused by the unequal distribution of medical risk factors across MRP groups by using a validated weighted risk score to group birthers into prenatal risk groups. Stratifying the analysis by the antepartum risk score rather than entering it into the model as a covariate largely mitigates the issue of the risk score predicting the outcomes.
In terms of the bias that might be introduced if the 41 individual factors that comprise the antepartum risk score are not present for one or more of the MRP groups: the individual indicators were present across all 3 MRP groups, including for the indicators ‘small for dates’ and ‘malpresentation’. The goal of our paper was not to compare midwives to physicians across all possible risk factors and we have clearly stated the limitations in the paper, i.e. more clients in the OB group might have had more complex medical conditions, explaining differences in outcomes.
With respect to MRP assignment: MRP is a mandatory data field, clearly defined in our paper and in our view the best variable to use when describing outcomes of midwife-led care. We cited the study by Thiessen et al.(1) to show that there might be significant overlap between the prenatal provider type and the MRP. In terms of using the Thiessen study to infer that our study suffers from imprecision in the MRP assignment that ‘can easily account for th...
Show MoreCompeting Interests: None declared.References
- 1. Thiessen K, Nickel N, Prior HJ, et al. Understanding the allocation of caesarean outcome to provider type: a chart review. Healthcare Policy. 2018 Nov;14(2):22.
- 2. Stoll K, Wang JJ, Niles P, et al. I felt so much conflict instead of joy: an analysis of open-ended comments from people in British Columbia who declined care recommendations during pregnancy and childbirth. Reproductive health. 2021 Dec;18(1):1-5.
- 3. Bradford BF, Wilson AN, Portela A, et al. Midwifery continuity of care: A scoping review of where, how, by whom and for whom?. PLOS Global Public Health. 2022 Oct 5;2(10):e0000935.
- 4. World Health Organization. WHO recommendations on antenatal care for a positive pregnancy experience. World Health Organization; 2016. https://www.who.int/publications/i/item/9789241549912
- Page navigation anchor for Pitfalls of Analyzing Healthcare Provider-based Perinatal OutcomesPitfalls of Analyzing Healthcare Provider-based Perinatal Outcomes
The study showed that a substantial reduction in perinatal death (RR 0.44), low birth weight (RR 0.24), preterm birth (RR 0.39), Apgar <7 at 5 min (RR 0.63) and cesarean delivery (RR 0.17) when care was provided by midwives. The analyses were based on most responsible provider (MRP) and risk stratification was carried out with a risk scoring system. There are several potential methodological & analytical errors that need consideration before these inferences can be made.
This risk scoring system could not have reduced the selection bias to any significant degree. Many individual risk factors in this scoring system not only directly associate with specific outcomes but also impact MRP assignment. E.g.,, diagnosis of small for dates (score 3) predetermines one of the primary outcomes, low birth weight, and strongly associates with the other four primary outcomes. In addition, such pregnancies are more likely to be cared for by an obstetrician. On the other hand, malpresentation (score 3), increases the risk of cesarean delivery with no substantial impact on the other four outcomes. Therefore, pregnancies with the exact same antepartum risk score could have a completely different a priori risk of most if not all of the primary outcomes. This creates a very substantial selection bias.
The second major potential error relates to the MRP assignment for in-hospital services. Agreement was 93% for obstetricians and 94% for midwives, this degree of imprecision...
Show MoreCompeting Interests: None declared.References
- 1. Thiessen K, Nickel N, Prior HJ, et al. Understanding the allocation of caesarean outcome to provider type: a chart review. Healthc Policy 2018;14:22-30.
- 2. Frosst G, Hutcheon J, Joseph KS, et al. Validating the British Columbia Perinatal Data Registry: a chart re-abstraction study. BMC Pregnancy Childbirth 2015;15:123.