A navigation engine for medical and/or pharmacy claims (in combination with employer human resource records or on a stand-alone basis) that quantifies healthcare outcomes and ranks healthcare providers and other healthcare items by root diagnosis based on their overall average claims per healthy day (i.e., clinical efficiency). Claims per healthy day is the adjusted claims cost per day to keep a patient healthy (or in the case of an employer, keep an employee at work), so the lower, the better. The navigation engine uses drop-down menus and/or similar techniques that require the user to select a root diagnosis on which to search, as well as other variables (e.g., provider category, geographic proximity, in-network versus in or out of network, etc.), turning an open-ended question, e.g., “Which doctor should I go to for back pain?” to a closed-ended one “Which surgeons in my network within 25 miles have the best outcomes for back surgery?”