Introduction: Cost analysis is complicated by the fact that patients acquire infections during their hospital stay, having already spent time at risk without having an infection. Multi-state models (MSM) accounts for this time at risk treating infections as time-dependent exposures from ICU admission.
Aim of the study: To estimate ventilator-associated events (VAEs) direct additional cost in ICU patients.
Material and Methods: This was a prospective, observational study carried out for a two-year period in four medical-surgical ICUs of Athens, Greece. The sample consisted of adult patients who received mechanical ventilation for ≥4 days and were followed until discharge from the ICU or until death. CDC standard definitions were used to diagnose VAEs. To estimate VAEs additional length of stay (LOS), we used a four-state model that accounted for the time of VAEs. The direct hospital cost was calculated, consisting of the fixed and variable cost. The direct additional cost per VAEs episode was calculated by multiplying VAEs extra LOS by cost per day of ICU hospitalization.
Results: In the final analysis were included 378 patients with 9,369 patient-days. The majority of patients were male (58.7%) with a median age of 60 years. Of 378 patients 143 (37.8%) developed 143 episodes of VAEs. VAEs crude additional LOS was 17 days, while VAE mean additional LOS after applying MSM was 6.55±1.78 days. The direct cost per day of ICU hospitalization was € 492.80. The direct additional cost per VAEs episode was € 3,227.84, € 885.56 the fixed and € 2,342.28 the variable cost. Antibiotic cost was € 1,570.95 per VAEs episode. The total direct additional cost for the two-year period was € 461,581.12.
Conclusions: These results confirm the importance of estimating VAEs real cost using micro-costing for analytical cost allocation, and MSM to avoid additional LOS and cost overestimation.