Introduction: For many complex surgical procedures, high volume centers have been shown to have less morbidity and mortality than low volume centers. No studies to date have examined the affect of case volume on morbidity and mortality for paraesophageal hernia (PEH) repair. The aim of this population-based study is to assess the impact of hospital case volume on inpatient morbidity and mortality following PEH repair. Methods: The Nationwide Inpatient Sample database was queried from 1996-2006 by ICD-9 diagnosis and procedure codes for laparoscopic, transthoracic, and open abdominal approaches to PEH repair. Institutional volumes were classified by increasing case volume in increments of five cases per year. The corresponding morbidity and mortality was assessed for each increment. Data was analyzed using Rao-Scott Chi-Squared test.Results: 97,757 PEH repairs were performed during the study interval: 9,577 laparoscopic repairs, 74,949 repairs by laparatomy and 13,231 repairs were completed by a transthoracic approach. Overall morbidity and mortality are shown and were significantly different across approaches, p<0.0001 and p=0.004 respectively (see table). For laparoscopic and open abdominal repairs, mortality was significantly different across the procedural increments. For the transthoracic approach, only morbidity was different. Hospitals that performed greater than 15 laparoscopic PEH repairs per year had no associated mortality compared to hospitals that performed 15 or fewer cases per year (p=0.004).Conclusion: This data demonstrates that institutional case volume impacts inpatient morbidity and mortality after PEH repairs. However, the impact of case volume is not equivalent for all surgical approaches. The laparoscopic approach had the lowest overall morbidity and mortality and had no associated mortality at institutions performing greater than 15 cases per year. These results suggest that for laparoscopic PEH repairs, the best morbidity and mortality are seen at institutions with annual volumes of greater than 15 cases per year.
Outcomes by Annual Case Volume

			Cases/Year
	Overall	< 5	6-10	11-15	16-20	>20	p
Morbidity(%)
Laparoscopic	7.6	10.9	8.3	6.3	9.4	4.0	0.0603
Open Abdominal	9.8	14.2	11.1	10.4	8.7	6.1	<0.0001
Transthoracic	12.8	16.3	14.9	8.6	15.9	9.5	0.0051
Mortality(%)
Laparoscopic	0.9	1.7	0.8	1.3	0.0	0.0	0.0278
Open Abdominal	1.3	2.3	1.1	0.8	1.5	0.4	<0.0001
Transthoracic	1.4	2.0	1.0	1.9	0.5	0.6	0.2837