Sb. Kritchevsky et al., Definition and adjustment of Cesarean section rates and assessments of hospital performance, INT J QUAL, 11(4), 1999, pp. 283-291
Background. Demand is growing for comparative data such as Cesarean section
rates, but little effort has been made to develop either standardized defi
nitions or risk adjustment approaches.
Objective. To determine to what extent a seemingly straightforward indicato
r like Cesarean section rate will vary when calculated according to differi
ng definitions used by various performance measurement systems.
Design. Retrospective data abstraction of 200 deliveries per hospital. Sett
ing. Fifteen acute care hospitals including two from outside the USA.
Measurements. Four widely-used performance measurement systems provided spe
cifications for their Cesarean section indicators. Indicator specifications
varied on inclusion criteria whether the population was defined using Diag
nostic Related Groups or ICD-9-CM procedure codes or ICD-9-CM diagnosis cod
es) and risk-adjustment methods and factors. Rates and rankings were compar
ed across hospitals using different Cesarean section indicator definitions
and indicators with and without risk adjustment.
Results. Calculated Cesarean section rates changed substantially depending
on how the numerator and denominator cases were identified. Relative perfor
mance based on Cesarean section rankings is affected less by differing indi
cator definitions than by whether and how risk adjustment is performed.
Conclusions. Judgments about organizational performance should only be made
when the comparisons are based upon identical indicators. Research leading
to a uniform indicator definition and standard risk adjustment methodology
is needed.