Systematic review and consensus definitions for the Standardised Endpoints in Perioperative Medicine initiative: patient-centred outcomes

BACKGROUND: Patient-centred outcomes are increasingly used in perioperative clinical trials. The Standardised Endpoints in Perioperative Medicine (StEP) initiative aims to define which measures should be used in future research to facilitate comparison between studies and to enable robust evidence synthesis. METHODS: A systematic review was conducted to create a longlist of patient satisfaction, health-related quality of life, functional status, patient well-being, and life-impact measures for consideration. A three-stage Delphi consensus process involving 89 international experts was then conducted in order to refine this list into a set of recommendations. RESULTS: The literature review yielded six patient-satisfaction measures, seven generic health-related quality-of-life measures, eight patient well-being measures, five functional-status measures, and five life-impact measures for consideration. The Delphi response rates were 92%, 87%, and 100% for Rounds 1, 2, and 3, respectively. Three additional measures were added during the Delphi process as a result of contributions from the StEP group members. Firm recommendations have been made about one health-related quality-of-life measure (EuroQol 5 Dimension, five-level version with visual analogue scale), one functional-status measure (WHO Disability Assessment Schedule version 2.0, 12-question version), and one life-impact measure (days alive and out of hospital at 30 days after surgery). Recommendations with caveats have been made about the Bauer patient-satisfaction measure and two life-impact measures (days alive and out of hospital at 1 yr after surgery, and discharge destination). CONCLUSIONS: Several patient-centred outcome measures have been recommended for use in future perioperative studies. We suggest that every clinical study should consider using at least one patient-centred outcome within a suite of endpoints

The relative connectivity-tortuosity tensor for conduction of water in anisotropic unsaturated soils

The hydraulic conductivity of unsaturated anisotropic soils has recently been described with a tensorial connectivity–tortuosity (TCT) concept. We present a mathematical formalization of the connectivity–tortuosity tensor, assuming that its principal axes coincide with those of the hydraulic conductivity tensor at saturation. The hydraulic conductivity tensor of such unsaturated anisotropic soils is given as the product of a scalar variable, the symmetric connectivity–tortuosity tensor, and the hydraulic conductivity tensor at saturation. The influence of the degree of saturation on hydraulic conductivity is illustrated for four well-defined synthetic soils through radial plots of the hydraulic conductivity scalar and of the reciprocal hydraulic resistivity scalar, both as a function of saturation. The resulting curves are ellipses. The eccentricity of these ellipses is a measure of the degree of anisotropy of the soil at a given saturation