What’s in a name? How the definition of “low risk” affects c-section rates

When we hear the cesarean section rate for a hospital, most of us don’t think any further. Obstetricians and hospitals have long sought to reduce the cesarean delivery rate to increase the quality and safety of healthcare for laboring women. However, comparing cesarean rates across hospitals is not so simple! What if one hospital takes care of a “higher risk” group of women, who are more likely to have a medical need for a cesarean. As insurers are moving towards outcome measures (including cesarean rates) to determine payments, hospitals with high-risk populations could be penalized for taking care of the sickest patients.

To help prevent unfair penalties, healthcare organizations have created definitions for “low risk” deliveries. The basic idea is- compare only the “low-risk” deliveries for hospitals to level the playing field. Two organizations have created definitions for “low-risk” deliveries, the Joint Commission and the Agency for Healthcare Research and Quality (AHRQ). The definitions are almost identical, except that the Joint Commission definition only includes mothers who have never given birth before, and the AHRQ definition includes all mothers who haven’t had a c-section in the past.

The Society for Maternal Fetal Medicine (SMFM) published a new definition in the February 2016 Gray Journal (here). SMFM hoped to improve upon the prior two definitions by including some well-accepted contraindications to a vaginal birth and some conditions that increase the risk of cesarean delivery. For instance, the SMFM definition excludes pregnancies complicated by placenta previa, a condition in which the placenta is blocking the baby’s exit from the womb and the only way to deliver the baby is via cesarean section. Another example is HIV infection. Women with HIV infection are not “low-risk” for delivering via cesarean section, but they are included in the existing two definitions. In this case, patients with high-risk conditions could suffer if hospitals are penalized for caring for them. SMFM also created their definitions using ICD-9 codes, so that the data could be easily extracted from medical records.

The SMFM report includes a comparison of their definition with the existing two definitions. They collected data on more than 800,000 births in 612 hospitals and found the low-risk c-section rate for each hospital using the three definitions. The low-risk cesarean delivery rate was lowest for all hospitals using the SMFM definition. However, this rate was not significantly different from the rates found by the other two definitions. Overall, SMFM encourages the use of its new definition because the clinical perspective increases the accuracy and precision of the definition of “low-risk,” and it’s easy to use.