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Background: Appropriate periprocedural management for chronically anticoagulated patients requires assessment of patient‐specific thrombosis and bleeding risks. However, predictors of post‐procedure bleeding are unknown. Objectives: To determine the 3‐month cumulative incidence and independent predictors of peri‐procedural bleeding in chronically anticoagulated patients requiring temporary warfarin interruption for an invasive procedure. Methods: In a protocol driven, cohort study design, all patients referred to the Mayo Clinic Thrombophilia Center for peri‐procedural anticoagulation management (1997–2007; n = 2182), were followed forward in time to determine the 3‐month cumulative incidence of peri‐procedural bleeding (Kaplan–Meier product limit) and potential predictors of bleeding (Cox proportional hazards). Decisions to ‘bridge’ with low‐molecular‐weight heparin were based on estimated thromboembolism and bleeding risk. Results: Indications for chronic anticoagulation included venous thromboembolism (38%), atrial fibrillation (30%) and mechanical heart valves (27%). Of these, 1496 (69%) patients received bridging therapy. The 3‐month cumulative incidence rates of major and overall bleeding were 2.1% and 5.1%, respectively. Major bleeding occurred more frequently in patients receiving bridging therapy (3% vs. 1%; P = 0.017). Independent predictors (hazard ratio; 95% confidence interval) of major bleeding included mitral mechanical heart valve (2.2; 1.1–4.3), active cancer (1.8; 1.0–3.1), prior bleeding history (2.6; 1.5–4.5) and re‐initiation of heparin therapy within 24 h after the procedure (1.9; 1.1–3.4). Conclusion: Factors predisposing to peri‐procedural bleeding are primarily patient‐specific. Premature heparin re‐initiation is an avoidable provider‐specific variable to consider.

Several ground-based ultraviolet (UV) monitoring networks exist in the United States, each of which is unique in the instrumentation employed for measurements. Two of these UV networks are the U.S. Environmental Protection Agency’s (EPA’s) Brewer Spectrophotometer Network and the U.S. Department of Agriculture’s (USDA’s) UV-B monitoring network, with a combined instrument total of 52 sites, with 32 sites located in the mainland United States. The Brewer records full sky spectra from 287 to 363 nm with 0.55-nm resolution, whereas the USDA instrument is a broadband device that measures broadband erythemally weighted UV data. To date, limited comparisons of data collected from these networks have been analyzed for comparative and quality assurance (QA) purposes. The data we use is taken from sites where instruments from each program are colocated, namely, Big Bend National Park, Texas, and Everglades National Park, Florida. To reduce the contribution of errors in the Brewer-based instruments, the raw data is corrected for stray light rejection, the angular response of the full sky diffuser, the temperature dependence of the instruments, and the temporal variation. This reduces the estimated errors of the absolute irradiance values of each Brewer spectral measurement to approximately ±5&percent;. The estimated uncertainty of the USDA instruments is approximately ±6&percent; with a systematic bias of (−13 to 5&percent; depending on the total ozone) and is comprised of (1) standard lamp measurement errors, (2) spectral response determination, and (3) the angular response of the diffuser. We perform comparisons between the Brewer spectrally integrated and erythemally weighted UV irradiance measurements and the data collected by the broadband erythemal UV meters at colocated sites between 1997 through to 2002. © 2005 Society of Photo-Optical Instrumentation Engineers.