Patients undergoing procedures in a hospital-based outpatient surgery center are more than 30 times more likely to be hospitalized if they have four or more risk factors for complications and adverse outcomes, according to a new study published in Archives of Surgery. The researchers assigned one point to the following risk factors: being 65 or older, having a surgery time of two-plus hours, cardiac diagnosis, peripheral vascular disease, cerebrovascular disease, malignancy, HIV seropositive, and having regional anesthesia, reports MedPage Today. Having a surgical procedure under general anesthesia was assigned two points. The researchers then calculated the likelihood that a patient having an outpatient surgical procedure would have to be admitted to the hospital based on the patient’s risk score. “This is not to suggest that patients with an outpatient surgery admission index of four or higher should universally undergo inpatient surgery,” the researchers wrote. “Rather, clinicians should consider performing surgery on these patients in a setting where there is additional medical support to treat acute adverse events and to permit rapid transfer to an inpatient hospital.”