Standard survival data measure the time span from some time origin until the occurrence of one type of event. If several types of events occur, a model describing progression to each of these competing risks is needed. Multi-state models generalize competing risks models by also describing transitions to intermediate events. Methods to analyze such models have been developed over the last two decades. Fortunately, most of the analyzes can be performed within the standard statistical packages, but may require some extra effort with respect to data preparation and programming. This tutorial aims to review statistical methods for the analysis of competing risks and multi-state models. Although some conceptual issues are covered, the emphasis is on practical issues like data preparation, estimation of the effect of covariates, and estimation of cumulative incidence functions and state and transition probabilities. Examples of analysis with standard software are shown.

The two implications of the loss of one-to-one correspondence between cause-specific hazard and cumulative incidence should be kept in mind when deciding on how to make inference in a competing risks situation.

mon and potentially lethal disorder. 1 In the United States alone, more than 50 000 patients are admitted with acute pancreatitis each year. 2 One of the most dreaded complications in these patients is infected necrotizing pancreatitis that leads to sepsis and is often followed by multiple organ failure. 3 In these patients interventions are necessary to debride the infected necrosis, but the interventions themselves cause substantial morbidity. 4-6 The treatment of infected necrotizing pancreatitis has undergone fundamental changes in recent years. Whenever possible, intervention is postponed until the collections with necrosis are demarcated. 7,8 Demarcation facilitates necrosectomy and reduces complications related to the drainage and debride-ment procedures. 9 A recent randomized trial demonstrated that a step-up approach of percutaneous catheter For editorial comment see p 1084.