Wednesday, April 28, 2010

Worse outcomes when fewer than expected cesareans

In a study that has echoes of the 2003 Healthgrades survey of U.S. hospitals, this month, researchers Srinivas SK et al have published: 'Evaluating risk-adjusted cesarean delivery rate as a measure of obstetric quality'.

In it, they report that when cesarean rates are lower than expected, adverse maternal or neonatal outcomes are higher.

However, as Michael Smith reports in MedPage Today, "the converse isn't true". Higher-than-expected cesareans rates "aren't associated with a protective effect".

IMPORTANT - The study was carried out in the U.S. where emergency and elective cesarean deliveries are not separated in birth records; therefore, it is highly likely, and indeed comparable with what other studies have found, that the protective effect with planned, elective cesareans is higher in these hospitals but they are being tarnished by the inclusion of emergency cesarean outcomes in the data.

MedPage Today report
In his report, Smith explains how: "the researchers constructed a population-based cohort of 845,651 patients from 401 hospitals in California and Pennsylvania. They excluded premature births and those in which C-sections were standard of care (such as for malpresentation and cord prolapse).

As well as analyzing the overall cohort, the researchers looked separately at the 274,371 primiparous patients with full-term singleton pregnancies.

For both groups, they linked birth certificate and hospital admission records to estimate the correlation between risk-adjusted cesarean delivery and a composite of adverse maternal outcomes, adverse neonatal outcomes, and four obstetric patient safety indicators from the Agency for Healthcare Research and Quality (AHRQ).

The composite maternal outcome included such events as wound infection and postdelivery hemorrhage, and the composite neonatal outcome included such things as death and birth injury. The AHRQ indicators included such things as birth trauma and injury with cesarean delivery.

The researchers used logistic regression to calculate an expected rate of C-section for each hospital and compared that with the observed rate.

In both cohorts, there was a negative correlation between the C-section rate and each of the outcomes, which was significant except for one -- AHRQ patient safety indicator 19 (injury with non-instrumented vaginal delivery).

Comparing C-section and adverse events rates showed that, in the general cohort:

•59.8% of the 107 hospitals with lower-than-expected risk-adjusted C-section rates had a higher-than-expected rate of at least one of the six adverse outcomes.
•Only 19.6% of the 102 hospitals with higher-than-expected risk-adjusted C-section rates had a higher-than-expected rate of any of the six adverse outcomes.
•The comparable figure was 36.1% for the hospitals with the as-expected risk-adjusted C-section rates, which was statistically similar to the higher-than-expected group."

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