March 5, 2013 -- Cesarean delivery rates range from as low as 7 percent to as high as 70 percent at U.S. hospitals, a new study found.
The magnitude of the variation was more than could be accounted for by case mix, suggesting a possible quality-of-care problem, study author Katy Backes Kozhimannil of the University of Minnesota School of Public Health in Minneapolis and colleagues reported.
Even among lower-risk pregnancies, "in which more limited variation might be expected," hospital cesarean rates varied 15-fold, from 2 percent to 37 percent.
"Thus, vast differences in practice patterns are likely to be driving the costly overuse of cesarean delivery in many U.S. hospitals," they wrote in the March issue of Health Affairs. "Because Medicaid pays for nearly half of U.S. births, government efforts to decrease variation are warranted."
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C-section is the most common procedure done in the operating room, and boosted the cost of delivery to an average of almost $13,000 compared with $9,000 for vaginal births in 2010, based on a prior study of private health insurance payments.
Both overuse and underuse of cesarean delivery may be clinically harmful as well, with higher risk of infection, injury, and need for emergency hysterectomy for the mother and greater risk of asphyxia, respiratory distress, and other pulmonary disorders for the baby compared with vaginal birth.
The group analyzed inpatient claims data from the 593 hospitals with at least 100 deliveries included in the 2009 Nationwide Inpatient Sample, which covers about 20 percent of all U.S. centers.
The mean cesarean delivery rate across the hospitals was 33 percent, which didn't differ by number of beds, teaching status, or location categories, although rates varied widely within each category.
Small and rural hospitals showed slightly more variability, while teaching hospitals showed less, the researchers noted.
The C-section rate among lower-risk pregnancies (term, singleton, vertex pregnancies without prior cesarean delivery) was lower at 12 percent, but showed even greater variation between hospitals than the overall rate.
Again, ranges were somewhat greater at small and rural hospitals but less among teaching hospitals.
The variation among small and rural hospitals "may be driven in part by the overall volume of deliveries," but none of the factors appeared to explain much of the overall variation, Kozhimannil's group pointed out.
Women asking for C-sections accounts for too small a percentage of these deliveries to drive the variations either, they argued.
That leaves practice patterns as the likely the driver, and one that "ought to be the focus of policy interventions," the researchers wrote.
One solution, they suggested, might be better triage in maternity care so that high-risk pregnancies go to hospitals that can manage them while others go to licensed birth centers that focus on vaginal delivery.
Another would be to start monitoring cesarean section rates as part of a hospital's quality of care reporting, perhaps tied to Medicaid payments, and perhaps with public reporting.
Limitations of the study included inability to identify gestational age at delivery aside from "preterm," whether a woman was a first-time mother, or what the reasons for cesarean section were.
Exclusion of small-volume obstetric units meant the results might not generalize to such hospitals, the researchers added.