Have hospitals adopted managed care's regimen of efficiency as standard operating practice? A new Milliman & Robertson survey suggests that when it comes to hospitalization, medical/surgical lengths of stay are not heavily influenced by what it says on a patient's insurance card. In 11 states where M&R studied discharge data, lengths of stay for commercial patients with indemnity insurance were less than 4 percent higher overall than for patients enrolled in HMOs. Neither HMO nor indemnity LOS reflect retrospectively denied days. Of patients whose cases were studied, 36 percent were enrolled in HMOs.