Provider volume and maternal complications after Caesarean section: results from a population-based study

Table 4 Odds ratios (ORs) and 95% confidence intervals (CIs) for likelihood of maternal post-operative complication after Caesarean section with provider case volume categories – nonlinear volume effects (n = 20,914 patients)

	Model 1^a			Model 2^b			Model 3^c
	OR	95% CI		OR	95% conf. Int.		OR	95% CI
Provider annual volume (vs. 1–25)
25–50	1.135	0.895	1.376	1.098	0.857	1.339	1.078	0.836	1.321
50–75	0.804	0.528	1.080	0.818	0.542	1.094	0.771	0.489	1.053
75+	0.802	0.458	1.146	0.851	0.506	1.196	0.762	0.404	1.120
Provider years since graduation	0.965	0.956	0.975	0.963	0.954	0.972	0.966	0.956	0.975
Provider not specialized in maternal-fetal medicine or obstetrics & gynecology	1.446	1.029	1.864	1.455	1.026	1.884	1.618	1.177	2.058

^aAdjusted for patient age, diabetes status, elective/urgent admission status, and comorbidity and annual dummy variables
^bAdjusted additionally for neighbourhood characteristics (income quintile and population size)
^cAdjusted additionally for hospital volume

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