Risk-adjusted sequential probability ratio tests and longitudinal surveillance methods.

Regardless of the exact method employed, the application of statistical process controL SPRTs, or related longitudinal analysis methods can significantly improve the ability to monitor clinical processes and outcomes. Incorporation and adaptation of risk-adjustment and rare events into these methods represent important contributions to their use in health care. Fostering greater and more widespread use of these methods, however, remains a significant challenge. Hopefully studies such as those by Spiegelhalter et al. will lead to more awareness of their value for contributing to a safer health care system.