Cost effectiveness analysis of drotrecogin alfa (activated) as a treatment for severe sepsis in hospitalised patients

Introduction

Drotrecogin alfa (activated) significantly reduced severe sepsis (SevSep) mortality at 28 days [1]. According to the French budget environment, it is mandatory to evaluate its cost effectiveness ratio on a pragmatic basis.

Methods

All SevSep patients in the Cub-Réa database (1997-1999 period) defined according to PROWESS [1] and with a hospital length of stay (LOS) = 24 hours (n = 10,459) were included. The baseline patients' characteristics are similar to those of the PROWESS criteria study: age (61 years vs 60 years), < 60 years (42% vs 44%), and number of organ failure (2.1 vs 2.4). Key patient data recorded: age, gender, type of admission (medical or surgical), admission mode (direct or transfer), number (1, 2, 3), duration and type of support (respiratory, renal, circulatory) and SAPS II. Stratification according to these criteria and loading of the observed frequencies into a decision-tree for conditional probabilities. Relative risk of death with drotrecogin alfa (activated) estimated according to the observed classification into 11 néoGHM [2] groups (28 days survival represented by the parametric function of Weibull). SevSep impact on long-term mortality estimated by the McCabe score with three hypotheses for life expectancy (LE): unique LE of 5 years, McCabe > 0 (2 years of survival), McCabe = 0 (4 years LE reduction or half LE reduction versus whole population). Costs estimated by subgroups and by a linear equation (nursing workload, LOS, SAPS II, living or dead status). Calculation of a differential cost effectiveness ratio (drotrecogin alpha (activated) price: 7836.95 - for 4 days treatment and a mean patient's weight of 70 kg) and analysis of Monte Carlo's type.

Results

The expected cost in the model of a SevSep patient treated by standard care is 26,983.3 -_FF96 vs 26,373.6 -_FF96 observed from Cub-Réa. The expected cost predicted in the model of a SevSep patient treated by drotrecogin alfa (activated) is 34,605.90 -_FF96. The survivors LE according to the above hypotheses are 5.0, 10.6, and 6.9 years. Corresponding effectiveness differences in favor of drotrecogin alfa (activated) are 0.33, 0.63, and 0.41 years. The cost per additional year of life saved amounts of 18,446.3 -_FF96 including all degrees of severity and co-morbidity. The sensitivity analysis model shows that with an expected threshold of 53,357.1 -_FF96, 96.3% of the bootstrap samples are cost-effective.

Conclusion

The predicted cost effectiveness ratio of drotrecogin alfa (activated) in adult SevSep patients is much lower than the international range considered as acceptable (53,357.10 -). Drotrecogin alfa (activated) is cost-effective when including patients with all degrees of co morbidity.