The predictors and economic burden of early-, mid- and late-onset cardiac implantable electronic device infections: a retrospective cohort study in Ontario, Canada.

The rate of cardiac implantable electronic device (CIED) infection is increasing with time. We sought to determine the predictors, relative mortality, and cost burden of early-, mid- and late-onset CIED infections. We conducted a retrospective cohort study of all CIED implantations in Ontario, Canada between April 2013 and March 2016. The procedures and infections were identified in validated, population-wide health-care databases. Infection onset was categorized as early (0-30 days), mid (31-182 days) and late (183-365 days). Cox proportional hazards regression was used to assess the mortality impact of CIED infections, with infection modelled as a time-varying covariate. A generalized linear model with a log-link and γ distribution was used to compare health-care system costs by infection status. Among 17 584 patients undergoing CIED implantation, 215 (1.2%) developed an infection, including 88 early, 85 mid, and 42 late infections. The adjusted hazard ratio (aHR) of death was higher for patients with early (aHR 2.9, 95% CI 1.7-4.9), mid (aHR 3.3, 95% CI 1.9-5.7) and late (aHR 19.9, 95% CI 9.9-40.2) infections. Total mean 1-year health costs were highest for late-onset (mean Can$113 778), followed by mid-onset (mean Can$85 302), and then early-onset (Can$75 415) infections; costs for uninfected patients were Can$25 631. After accounting for patient and procedure characteristics, there was a significant increase in costs associated with early- (rate ratio (RR) 3.1, 95% CI 2.3-4.1), mid- (RR 2.8, 95% CI 2.4-3.3) and late- (RR 4.7, 95% CI 3.6-6.2) onset infections. In summary, CIED infections carry a tremendous clinical and economic burden, and this burden is disproportionately high for late-onset infections.

Age-social stratification designs had a negligible impact on income-mortality associations.

OBJECTIVES: Age-social stratification has been used to offset socioeconomic status (SES) misclassification due to cohort effects. This study was to evaluate whether age-income stratification designs generate comparable income-mortality associations as those whose income rankings are based on absolute thresholds. STUDY DESIGN AND SETTING: Using self-reported income as our SES variable, and mortality as our outcome measure, the impact of age-social stratification was examined in two distinct cohorts: one with acute myocardial infarction (AMI) (n=3,138), and the second free of cardiovascular disease (n=15,115). Age-adjusted income-mortality associations were compared between age-social stratification techniques, which used "age-relative" income thresholds and "absolute" income thresholds whose ranks were independent of patient age. RESULTS: In both cohorts, crude mortality inversely correlated with age and income. Techniques using "age-relative" income thresholds yielded similar adjusted odds ratio for mortality as did those that used "absolute" income threshold methods (differences in adjusted odds ratios [+/-95% confidence interval (CI)] between "absolute" and "age-relative" classifications for highest vs. lowest income tertiles: -0.05 [-0.24, 0.12] among patients with AMI and 0.05 [-0.03, 0.13] among patients without cardiovascular disease). CONCLUSION: More complex designs incorporating age-social stratification techniques generate similar income-mortality associations as more simplified approaches, which classified SES using absolute income thresholds.