Convergent Validity of Revealed and Stated Recreation Behavior with Quality Change: A Comparison of Multiple and Single Site Demands

Recreation demand, Travel cost method, Convergent validity, Revealed preference, Stated preference,

Initial Invasive versus Conservative Management of Stable Ischemic Heart Disease Patients with a History of Heart Failure or Left Ventricular Dysfunction: Insights from the ISCHEMIA Trial

Background: It is unknown whether an initial invasive strategy in patients with stable ischemic heart disease and at least moderate ischemia improves outcomes in patients with a history of heart failure (HF) or left ventricular dysfunction (LVD) when EF ≥35%, but <45%. / Methods: Among 5179 participants randomized into the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA), all of whom had LVEF ≥35%, we compared cardiovascular outcomes by treatment strategy in those with a history of HF or LV dysfunction (HF/LVD) at baseline versus those without HF/LVD. Median followup was 3.2 years. / Results: There were 398 (7.7%) participants with HF/LVD at baseline of whom 177 had HF/LVEF>45%, 28 had HF/LVEF 35-45% and 193 had LVEF 35-45% but no prior history of HF. HF/LVD was associated with more comorbidities at baseline, particularly prior myocardial infarction (MI), stroke and hypertension. Compared to those without HF/LVD, those with HF/LVD were more likely to experience a primary outcome composite of cardiovascular death, nonfatal MI, or hospitalization for unstable angina, HF, or resuscitated cardiac arrest; four-year cumulative incidence rate (22.7% vs. 13.8%), cardiovascular death or MI (19.7% vs. 12.3%), and all-cause death or HF (15.0% vs. 6.9%). Those with HF/LVD randomized to the invasive versus conservative strategy had a lower rate of the primary outcome (17.2% vs. 29.3%, difference in 4-year event rate -12.1%; 95% CI: -22.6, -1.6%), whereas those without HF/LVD did not (13.0% vs. 14.6%, difference in 4-year event rate -1.6%; 95% CI: -3.8%, 0.7%; p-interaction = 0.055). A similar differential effect was seen for the primary outcome, all-cause mortality, and CV mortality when invasive versus conservative strategy associated outcomes were analyzed with LVEF as a continuous variable for those with and without prior HF. / Conclusions: ISCHEMIA trial participants with stable ischemic heart disease and at least moderate ischemia with a history of HF or LVD were at increased risk for the primary outcome. In the small, high-risk subgroup with HF and LVEF 35-45%, an initial invasive approach was associated with a better event-free survival. This result should be considered hypothesis generating. / Clinical Trial Registration: URL: https://clinicaltrials.gov Unique Identifier: NCT0147152

Are time and money equally substitutable for all commodity groups in the household’s domestic production?

This article uses time-use and household expenditure data to measure the substitutability between time and money within the Beckerian household production framework. The elasticity of substitution is estimated for five commodity groups and across two developing countries: Ecuador and Guatemala. The estimated elasticities are positive, indicating substitutability, and much larger for all other goods compared to food. Our results raise some interesting questions regarding the policy effects of an intervention that does not consider the money/time trade-offs in consumption

Biomechanical characterization of a micro/macroporous polycaprolactone tissue integrating vascular graft

The objective of the present study was to characterize the short-term biomechanical properties of cast micro/macroporous poly(caprolactone) (PCL) tubes intended for application as tissue integrating blood vessel substitutes. Micro/macroporous PCL vascular grafts (5.5 mm internal diameter, 7.5 mm external diameter) with defined macropore structures were produced by rapidly cooling PCL solutions containing dispersed gelatin particles in dry ice, followed by solvent and gelatin extraction. A Bose-Enduratec BioDynamic chamber configured for cardiovascular applications was used to measure the diametrical stability (dilation) of tubular samples under hydrodynamic flow conditions at 37 °C. Microporous PCL tubes withstood the hydrodynamic stresses induced by short, 2-min duration flow rates up to 1000 mL/min, which resulted in estimated internal pressures in excess of arterial pressure (80–130 mmHg). Micro/macroporous PCL tubes having a maximum macroporosity of 23% accommodated the hydrodynamic stresses generated by short duration, flow rates up to 1000 mL/min, which resulted in estimated internal pressures similar to venous pressure (30 mmHg).The dilation of microporous PCL tubes under short, (5 min) pulsatile flow conditions (1 Hz) increased from 10 to 100 μm with increasing mean flow rate from 50 to 500 mL/min. Both microporous and macroporous tubes exhibited a burst strength higher than 900 mmHg under hydrostatic fluid pressure, which is in excess of arterial pressure (80–130 mmHg) by a factor of approximately 7. Quantitative analysis of the macropore structure was performed using micro-computed tomography for correlation with mechanical properties and cell growth rates. Mouse fibroblasts efficiently colonized the external surface of macroporous PCL materials over 8 days in cell culture and cell numbers were higher by a factor of two compared with microporous PCL. These findings demonstrate that micro/macroporous PCL tubes designed for vascular tissue engineering can accommodate the hydrodynamic stresses generated by short duration, simulated blood flow conditions and exhibit good potential for integration with host tissue. © 2010 Biomedical Engineering Society