Effect of hospital setting and volume on clinical outcomes in women with gestational and type 2 diabetes mellitus.

OBJECTIVE: Efforts to improve health care outcomes in the United States have led some organizations to recommend specific hospital settings or case volumes for complex medical diagnoses and procedures. But there are few studies of the effect of setting and volume on maternal outcomes, particularly in complicated conditions, such as diabetes. Our objective was to estimate the effect of hospital setting and volume on childbirth morbidity and length of stay in pregnancies complicated by type 2 and gestational diabetes.
METHODS: We analyzed Maryland hospital discharge data during 1999-2004. The dependent variables were primary cesarean delivery, episiotomy, a composite variable for severe maternal morbidity, and hospital length of stay. The independent variables were hospital setting (community, non-teaching hospitals, community, teaching hospitals, and academic medical centers) and tertiles of annual hospital diabetes delivery volume. Multivariable regression analysis was used to assess the relation of hospital setting with each outcome, adjusting for hospital volume and maternal case mix.
RESULTS: 5,507 deliveries with type 2 (15%) and gestational (85%) diabetes were analyzed. Primary cesarean delivery rates among women with any diabetes did not vary across settings. After adjustment for volume and patient case mix, the likelihood of severe maternal morbidity was higher among deliveries at academic centers compared to community, non-teaching hospitals (odds ratio [OR], 2.1; 95% confidence interval: 1.0, 4.2). Academic centers had a protective effect (OR, 0.3; 95% CI: 0.2, 0.7) and community teaching hospitals had a borderline protective effect (OR, 0.8; 95% CI: 0.7, 1.0) on episiotomy, compared to community, non-teaching hospitals. Length of stay was greater at academic centers and community, teaching hospitals compared to community, non-teaching hospitals (5.4 days, 3.5 days vs. 2.8 days, respectively). We did not identify an independent association between hospital diabetes volume and clinical outcomes after adjustment for case mix.
CONCLUSIONS: Among women with type 2 and gestational diabetes, hospital setting is associated with a higher likelihood of severe maternal morbidity and length of stay, independent of volume. Patient case mix accounts for some of the variation across settings. The volume-outcome relationship found with other complex medical conditions or procedures was not found among diabetic pregnancies. Further investigations are needed to explain variations in outcomes across hospital settings and volumes.