Effectiveness of Immunoglobulins for the Prevention of Systemic Infections : A Meta-Analysis of 8 Clinical Studies in Premature Infants

Improved outcome of APACHE II score-defined escalating systemic inflammatory response syndrome in patients post cardiac surgery in 1996 compared to 1988-1990: the ESSICS-study pilot project

OBJECTIVE

Cardiac surgery using extracorporeal circulation leads to the release of cytokines and subsequently to a systemic inflammatory response syndrome, which is thought to be a negative prognostic factor for patients' outcome. A stratification for the risk of an escalating systemic inflammatory response syndrome had been achieved in a monocenter study carried out in 1988-1990, using APACHE II scoring on the morning of the 1st postoperative day. We now re-evaluated this concept prospectively in three independent centers.

METHODS

The APACHE II based risk stratification was put to test in three independent heart surgery centers in the period from June to December 1996. Nine hundred and forty-five patients after elective cardiac surgery (excluding heart transplantation) with the assistance of the cardiopulmonary bypass were prospectively monitored.

RESULTS

We found an increase in mortality with higher APACHE II score values determined on the 1st postoperative day. The mortality rose to nearly 50% with an APACHE II score of > or = 28. Patients at high risk for the development of a systemic inflammatory response syndrome (APACHE II score > or = 24) significantly differed from patients at lower risk (APACHE II score < 19) in the duration of mechanical ventilation and extracorporeal circulation, age and New York Heart Association (NYHA) classification (P < 0.05).

CONCLUSION

The APACHE II score determined on the morning of the 1st postoperative day helps identifying the subgroup of patients with escalating systemic inflammatory response syndrome. Comparison with the data obtained in the years 1988-1990, suggests a better prognosis in the current trial for patients at high risk with a similar degree of escalating systemic inflammatory response syndrome.

Supplemental immune globulins in sepsis

Intravenous immune globulins are widely used as supplemental treatment of sepsis, septic shock and systemic inflammation in the critically ill, although this indication has at best been validated in part. Likely beneficial mechanisms of action may include the improvement of serum bactericidal activity due to neutralizing and opsonizing immunoglobulin (Ig)G- and IgM-antibodies, as well as stimulation of phagocytosis and neutralization of bacterial endo- and exotoxins; another attractive mode of action may represent immune globulin-mediated modification and specific suppression of proinflammatory cytokine release from endotoxin- and superantigen-activated blood cells. For the "entire group of patients with sepsis and septic shock" a reduction in mortality by intravenous immune globulin could not be documented; however, in the score-based immunoglobulin in sepsis (SBITS)-study with 653 patients included, a moderate improvement in sepsis morbidity and multiple organ dysfunction syndrome was demonstrated. In defined sepsis subgroups, a reduction in mortality by intravenous immune globulin has been seen in individual small, not yet confirmed trials. Finally, the incidence of some severe infections in well characterized "patients at risk" and "operations at risk" is reduced by intravenous immune globulin prophylaxis. Thus, intravenous immune globulin is not a "magic bullet"of sepsis treatment, but it may reduce morbidity and thereby represent a useful piece of stone in the therapeutic mosaic of sepsis treatment.

Survival curve fitting using the Gompertz function: a methodology for conducting cost-effectiveness analyses on mortality data

The analysis of published survival curves can be the basis for incremental cost-effectiveness evaluations in which two treatments are compared with each other in terms of cost per life-year saved. The typical case is when a new treatment becomes available which is more effective and more expensive than the corresponding standard treatment. When effectiveness is expressed using the end-point of mortality, cost-effectiveness analysis can compare the (incremental) cost associated with the new treatment with the (incremental) clinical benefit measured in terms of number of life-years gained. The (incremental) cost-effectiveness ratio is therefore quantified as cost per life-year gained. This pharmacoeconomic methodology requires that the total patients years for the treatment and the control groups are estimated from their respective survival curves. We describe herein a survival-curve fitting method which carries our this estimation and a computer program implementing the entire procedure. Our method is based on a non-linear least-squares analysis in which the experimental points of the survival curve are fitted to the Gompertz function. The availability of a commercial program (PCNONLIN) is needed to carry out matrix handling calculations. Our procedure performs the estimation of the best-fit parameters from the survival curve data and then integrates the Gompertz survival function from zero-time to infinity. This integration yields the value of the area under the survival curve (AUC) which is an estimate of the number of patients years totalled in the population examined. If this AUC estimation is performed separately for the two survival curves of two treatments being compared, the difference between the two AUCs permits to determine the incremental number of patient years gained using the more effective of the two treatments as opposed to the other. The cost-effectiveness analysis can consequently be carried out. An example of application of this methodology is presented in detail.