Methods: During 28 days, four different turning schemes were used: turning every 2h on a standard institutional (SI) mattress (n=65), turning every 3h on a SI mattress (n=65), turning every 4h on a viscoelastic foam (VE) mattress (n=67), and turning every 6h on a VE mattress (n=65). The remaining patients (n=576) received standard preventive care.