Incidence of outcomes relevant to vaccine safety monitoring in a US commercially-insured population

BACKGROUND

Background incidence rates (IRs) of potential safety outcomes among vaccine eligible individuals can inform assessment of vaccine safety. Vaccine safety surveillance often uses claims databases, but the impact of outcome definitions on background IR estimates is largely unexplored. Using two definitions for each outcome, we estimated background IRs of 32 cardiac, metabolic, allergic, autoimmune, neurologic, hematologic and nephrologic outcomes among individuals eligible to receive pneumococcal vaccination.

METHODS

We defined a cohort of individuals aged 6-100 years in US commercial health plans who had ≥12 months of health plan enrollment between January 2007 and August 2014 and no previous record of conjugate or simple polysaccharide pneumococcal vaccination. We developed a sensitive and a specific definition for each outcome, with the specific definition requiring evidence of additional care consistent with the outcome. IRs per 100,000 person-years for each outcome were presented overall and stratified by age, gender, and invasive pneumococcal disease (IPD) risk category.

RESULTS

We followed 19.9 million individuals for a median of 2.5 years. Wide variation was seen in IRs across different definitions of the 32 outcomes, with 19 (59%) outcomes having a specific definition IR less than half of the sensitive definition IR. IRs were particularly variable by definition for outcomes categorized as either hematologic/nephrologic or neurologic (mean ratio of specific IR to sensitive IR = 0.26 and 0.30, respectively). Across definitions, the IRs of the 32 outcomes were often highest in females, adults ≥65, and those at higher IPD risk.

CONCLUSIONS

Background IRs of safety outcomes relevant to populations indicated for pneumococcal vaccine varied by outcome definitions and population subgroups in this large US commercially-insured population. Given large differences in estimated IRs using sensitive versus specific case definitions, neurologic, and hematologic/nephrologic safety outcomes as compared to allergic and autoimmune outcomes may warrant more refined definitions and medical record validation.

An updated meta-analysis to understand the variable efficacy of drotrecogin alfa (activated) in severe sepsis and septic shock

BACKGROUND

Significant debate continues over the efficacy of drotrecogin alpha activated (DAA) in sepsis. This updated meta-analysis provides an updated summary effect estimate and explores the reasons for outcome heterogeneity in placebo-controlled randomized clinical trials of DAA on 28-day all-cause mortality in patients with severe sepsis or septic shock.

METHODS

Computer searches of MEDLINE, EMBASE, the Cochrane Library, ClinicalTrials.gov, published abstracts from major intensive care meetings and examination of reference lists were used to identify five placebo-controlled randomized clinical trials with 7260 patients. The primary endpoint was 28-day all-cause mortality. Secondary outcomes were 28-day incidence of severe bleeding and intracranial hemorrhage.

RESULTS

DAA was not associated with improved 28-day all-cause mortality in patients with severe sepsis or septic shock (pooled relative risk (RR) of 0.97 [95% CI 0.83-1.14]), and is associated with an increase in serious bleeding. The significant heterogeneity in the pooled RR for 28-day mortality (I2 value of 59.4%, χ2 P-value 0.043) is no longer present with exclusion of the post-study amendment portion of PROWESS (I2 value of 0%, χ2 P-value 0.44 without PROWESS post-amendment). Using meta-regression, the best ranked predictor of outcome heterogeneity was baseline mortality in the placebo arm, which was among the highest in PROWESS.

CONCLUSION

DAA is not associated with improved survival in patients with severe sepsis or septic shock. Further studies should be done to determine whether changes in supportive therapy for sepsis explain the variable efficacy of DAA in randomized controlled clinical trials observed over time.