Multilevel competing risks in the evaluation of nosocomial infections: time to move on from proportional hazards and even from hazards altogether.

Alvaro Muñoz,Nicole Mongilardi,William Checkley

doi:10.1186/cc13892

Abstract

A competing risk is an event (for example, death in the ICU) that hinders the occurrence of an event of interest (for example, nosocomial infection in the ICU) and it is a common issue in many critical care studies. Not accounting for a competing event may affect how results related to a primary event of interest are interpreted. In the previous issue of Critical Care, Wolkewitz and colleagues extended traditional models for competing risks to include random effects as a means to quantify heterogeneity among ICUs. Reported results from their analyses based on cause-specific hazards and on sub-hazards of the cumulative incidence function were indicative of lack of proportionality of these hazards over time. Here, we argue that proportionality of hazards can be problematic in competing-risk problems and analyses must consider time by covariate interactions as a default. Moreover, since hazards in competing risks make it difficult to disentangle the effects of frequency and timing of the competing events, their interpretation can be murky. Use of mixtures of flexible and succinct parametric time-to-event models for competing risks permits disentanglement of the frequency and timing at the price of requiring stronger data and a higher number of parameters. We used data from a clinical trial on fluid management strategies for patients with acute respiratory distress syndrome to support our recommendations.

Highlights

A competing risk is an event that hinders the occurrence of an event of interest and it is a common issue in many critical care studies
Reductions of up to 70% have been achieved via infection control strategies for specific Nosocomial infection (NI) [3], but this has not been universal across settings
Competing risks in critical care Competing risks are important in the ICU because a large proportion of patients may be discharged or die before developing the event of interest

Summary

Introduction

A competing risk is an event (for example, death in the ICU) that hinders the occurrence of an event of interest (for example, nosocomial infection in the ICU) and it is a common issue in many critical care studies. It is important to define both high-risk patients and high-risk settings and identify interventions that prevent NIs, for which data analysis methods to determine risk factors for specific events are pertinent.

Results

Conclusion