Costs of hospital-acquired Clostridium difficile infections: an analysis on the effect of time-dependent exposures using routine and surveillance data

Thomas Heister,Philip Hehn,Klaus Kaier,Jan Wolff,Markus Dettenkofer,Martin Wolkewitz,Hajo Grundmann

doi:10.1186/s12962-019-0184-5

Abstract

BackgroundHospital-acquired infections have not only gained increasing attention clinically, but also methodologically, as a time-varying exposure. While methods to appropriately estimate extra length of stay (LOS) have been established and are increasingly used in the literature, proper estimation of cost figures has lagged behind.MethodsAnalysing the additional costs and reimbursements of Clostridium difficile-infections (CDI), we use a within-main-diagnosis-time-to-exposure stratification approach to incorporate time-varying exposures in a regression model, while at the same time accounting for cost clustering within diagnosis groups.ResultsWe find that CDI is associated with €9000 of extra costs, €7800 of higher reimbursements, and 6.4 days extra length of stay. Using a conventional method, which suffers from time-dependent bias, we derive estimates more than three times as high (€23,000, €8000, 21 days respectively). We discuss our method in the context of recent methodological advances in the estimation of the costs of hospital-acquired infections.ConclusionsCDI is associated with sizeable in-hospital costs. Neglecting the methodological particularities of hospital-acquired infections can however substantially bias results. As the data needed for an appropriate analysis are collected routinely in most hospitals, we recommend our approach as a feasible way for estimating the economic impact of time-varying adverse events during hospital stay.

Highlights

Hospital-acquired infections have gained increasing attention clinically, and methodologically, as a time-varying exposure
It shows that Clostridium difficile infections (CDI) increases the costs of hospitalization by €9000, leads to €7800 of additional reimbursement, and prolongs the patients’ hospital stay by 6 days
The marginal effects correspond to a 36% (exp(0.31) − 1) increase in the costs of hospitalization, a 33% increase in reimbursements, as well as a 24% prolongation of hospital stay

Summary

Introduction

Hospital-acquired infections have gained increasing attention clinically, and methodologically, as a time-varying exposure. Estimation of the in-hospital costs of CDI, is challenging for a number of reasons: First, hospital-acquired CDI presents a complication occurring in different and often dissimilar groups of patients. Hospital-acquired CDI often occurs in a relatively late phase of hospitalization, making estimation results ignoring the timing of CDI exposure subject to the time-dependent bias by implicitly assuming that hospital-acquired infections are already present on admission. This bias is always associated with an overestimation of the true effect [11,12,13,14,15,16]

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