Spatial and Temporal Clustering of Anti-Glomerular Basement Membrane Disease.

BACKGROUND AND OBJECTIVES: An environmental trigger has been proposed as an inciting factor in the development of anti-GBM disease. This multicenter, observational study sought to define the national incidence of anti-GBM disease during an 11-year period (2003-2014) in Ireland, investigate clustering of cases in time and space, and assess the effect of spatial variability in incidence on outcome. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We ascertained cases by screening immunology laboratories for instances of positivity for anti-GBM antibody and the national renal histopathology registry for biopsy-proven cases. The population at risk was defined from national census data. We used a variable-window scan statistic to detect temporal clustering. A Bayesian spatial model was used to calculate standardized incidence ratios (SIRs) for each of the 26 counties. RESULTS: Seventy-nine cases were included. National incidence was 1.64 (95% confidence interval [95% CI], 0.82 to 3.35) per million population per year. A temporal cluster (n=10) was identified during a 3-month period; six cases were resident in four rural counties in the southeast. Spatial analysis revealed wide regional variation in SIRs and a cluster (n=7) in the northwest (SIR, 1.71; 95% CI, 1.02 to 3.06). There were 29 deaths and 57 cases of ESRD during a mean follow-up of 2.9 years. Greater distance from diagnosis site to treating center, stratified by median distance traveled, did not significantly affect patient (hazard ratio, 1.80; 95% CI, 0.87 to 3.77) or renal (hazard ratio, 0.76; 95% CI, 0.40 to 1.13) survival. CONCLUSIONS: To our knowledge, this is the first study to report national incidence rates of anti-GBM disease and formally investigate patterns of incidence. Clustering of cases in time and space supports the hypothesis of an environmental trigger for disease onset. The substantial variability in regional incidence highlights the need for comprehensive country-wide studies to improve our understanding of the etiology of anti-GBM disease.

Declining mortality rates despite increases in clinical coronary artery disease among US dialysis patients: a national registry study.

BACKGROUND/AIMS: Coronary artery disease (CAD) is a major risk factor for death on dialysis. The objective of this study was to compare prevalent trends and patterns of survival in successive national cohorts. METHODS: National data on 823,753 incident dialysis patients, aged 18 and over, were analyzed from the US Renal Data System from 1995 to 2004. The prevalence of CAD was compared across calendar years by sex and race categorized as; White, Black, Asian and Native American/Alaskan Native (Native Am). Two-year mortality rates were determined for annual cohorts and multivariable Cox regression compared hazard ratios (HR) and 95% confidence intervals. RESULTS: From 1995 to 2004, the annual prevalence of CAD increased significantly in men from 25.2 to 30.1% and in women from 22.1 to 25.3%, p < 0.001. For men, the rise in prevalence was largely due to increases among Black men and older White men. For women, the pattern was similar. During this period, death rates decreased significantly from 379 to 348 and from 396 to 357 per 1,000 person-years in men and women respectively. Multivariate analysis identified significant reductions in mortality with advancing calendar year for White (HR 0.98 (0.98-0.99)), Asian (HR 0.93 (0.91-0.96)), and Native Am men (HR 0.95 (0.90-0.99)), and for White (HR 0.99 (0.98-0.99)) and Native Am women (HR 0.93 (0.89-0.98)). No significant trends were observed for Black patients. CONCLUSIONS: Despite a rising burden of CAD among incident US dialysis patients, mortality rates have fallen for most groups. Substantial racial disparities remain.