Effect Of Hospital Volume On The Incidence Of Major Complications In Patients Hospitalized With Ovarian Hyperstimulation Syndrome.

A relationship between higher hospital volume and improved outcomes has been established for many medical conditions and surgical procedures. However, it has not been previously studied with regards to ovarian hyperstimulation syndrome (OHSS). This study aimed to elucidate the association between hospital volume and OHSS-related complications in hospitalized patients. A retrospective analysis of the National inpatient Sample from January 2001 to December 2011. Patients hospitalized with OHSS were included. International Classification of Disease 9th edition codes were used to examine incidence of major complications. Major complications were defined by the presence of ICD-9 codes for hypotension, shock or systemic inflammatory response syndrome, hemorrhage, coagulopathy, venous or arterial thromboembolism, pulmonary embolism, stroke, cerebral edema, myocardial infarction, pericardial effusion, pneumonia, respiratory failure, pulmonary edema, ovarian torsion, or ileus/small bowel obstruction. Annualized hospital volume was defined as the average number of patients with OHSS treated by a given hospital per year: low-volume (average 1 case/year), mid-volume (average >1 but <3.5 cases/year), and high-volume (average ≥3.5 cases/year, i.e. the top-decile). Characteristics and major complication rates related to hospital treatment volume were assessed with multivariable analysis. There were 11,968 cases of OHSS treated at 735 hospitals; 2,441 (20.4%) patients were treated at low-volume centers, 5,078 (42.4%) at mid-volume centers, and 4,449 (37.2%) at high-volume centers. Of the entire cohort, 1,625 (13.7%) patients experienced a major complication during hospitalization. Patients treated at high-volume centers had lower rates of major OHSS-related complications (low-volume 15.6%, mid-volume 15.2%, and high-volume 11.0%; P<0.001). On multivariable analysis, treatment at a high-volume center was independently associated with a nearly 20% lower rate of major OHSS-related complications (adjusted-odds ratio 0.82, 95% confidence interval 0.70-0.97, P=0.021). Major complications were common among patients admitted to the hospital with OHSS. Our study suggests that higher hospital volume may be associated with improved outcomes in OHSS.