The Net Promoter Score (NPS) – a 14-year-old metric that's traditionally managed by insights and marketing departments – is driving growth and direction at a healthcare company that occupies sixth spot on the Fortune 500, has an operating income of $13 billion, and boasts 260,000 staff (including 60,000 physicians and nurses).

"Everything we do comes back to NPS," insists one doctor in the senior management group of UnitedHealth Group. "It's the number that counts on one-to-one physician-to-patient care; it's the number that tells us how we're aligning with our corporate partners.

"It's the number that's everywhere – from the very bottom to the very top of this organization."

The primary purpose of the Net Promoter Score is to evaluate customer loyalty to a brand or company. And, according to John Walthour, VP/Strategic Insights Group, Consumer Insights in Health Services at UnitedHealth, it's a powerful driver in an industry where overall public perceptions are "right there at the bottom, just ahead of the cable guy.

John Walthour