Anaesthesia
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We observed survival after scheduled repair of abdominal aortic aneurysm in 1096 patients for a median (IQR [range]) of 3.0 (1.5-5.8 [0-15]) years: 943 patients had complete data, 250 of whom died. We compared discrimination and calibration of an external model with the Kaplan-Meier model generated from the study data. ⋯ Groups with median 5-year predicted mortality of 40% (n = 251), 18% (n = 414) and 8% (n = 164) had lower observed mortality than 114 patients with 70% predicted mortality, hazard ratio (95% CI): 0.58 (0.37-0.76), p = 0.0031; 0.30 (0.19-0.48), p = 1.7 × 10(-12) and 0.19 (0.13-0.27), p = 1.3 × 10(-10) , respectively, test for trend p = 5.6 × 10(-15). Survival predicted by the external calculator was similar to the Kaplan-Meier estimate.
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Comparative Study
Cost comparison of re-usable and single-use fibrescopes in a large English teaching hospital.
A number of studies in the U. S. A. and mainland Europe have described the costs of fibreoptic tracheal intubation. ⋯ An 'isopleth' was identified for this relationship: a line that joined all the points where the cost of re-usable vs single-use fibrescopes was equal. It appears cheaper to use single-use fibrescopes at up to 200 fibreoptic intubations per year (a range commensurate with normal practice) even when the repair rate for re-usable fibrescopes is low. Any centre, knowing its fibrescope use and repair rate, can plot its data similarly to help ascertain which of the re-usable or single-use fibrescope represents better value.
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I simulated survival with and without scheduled repair of abdominal aortic aneurysms with different diameters in different populations. The results imply that scheduled repair should be determined by the combination of a patient's monthly mortality hazard and aneurysm diameter. The median survival of some patients will be extended by the scheduled repair of aneurysms smaller than 55 mm, whereas the median survival of other patients will be curtailed by repair of any aneurysm. ⋯ K. Small Aneurysm Study were reproduced in simulation and are compatible with the repair of aneurysms smaller than 55 mm diameter. Epidemiological simulations suggest that past randomised controlled trials underestimate the effect of aneurysm repair today.