ABSTRACT
Our objective was to identify predictors of severe acute respiratory infection in hospitalised patients and understand the impact of vaccination and neuraminidase inhibitor administration on severe influenza. We analysed data from a study evaluating influenza vaccine effectiveness in two Michigan hospitals during the 2014-2015 and 2015-2016 influenza seasons. Adults admitted to the hospital with an acute respiratory infection were eligible. Through patient interview and medical record review, we evaluated potential risk factors for severe disease, defined as ICU admission, 30-day readmission, and hospital length of stay (LOS). Two hundred sixteen of 1119 participants had PCR-confirmed influenza. Frailty score, Charlson score and tertile of prior-year healthcare visits were associated with LOS. Charlson score >2 (OR 1.5 (1.0-2.3)) was associated with ICU admission. Highest tertile of prior-year visits (OR 0.3 (0.2-0.7)) was associated with decreased ICU admission. Increasing tertile of visits (OR 1.5 (1.2-1.8)) was associated with 30-day readmission. Frailty and prior-year healthcare visits were associated with 30-day readmission among influenza-positive participants. Neuraminidase inhibitors were associated with decreased LOS among vaccinated participants with influenza A (HR 1.6 (1.0-2.4)). Overall, frailty and lack of prior-year healthcare visits were predictors of disease severity. Neuraminidase inhibitors were associated with reduced severity among vaccine recipients.
Subject(s)
Influenza, Human/epidemiology , Respiratory Tract Infections/epidemiology , Acute Disease , Adolescent , Adult , Aged , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/therapeutic use , Female , Frailty , Health Status , Humans , Influenza Vaccines/administration & dosage , Inpatients , Intensive Care Units/statistics & numerical data , Interviews as Topic , Length of Stay/statistics & numerical data , Male , Michigan/epidemiology , Middle Aged , Morbidity , Nasopharynx/virology , Neuraminidase/antagonists & inhibitors , Patient Readmission/statistics & numerical data , Risk Factors , Severity of Illness Index , Young AdultABSTRACT
An understanding of the mechanisms which control solids formation can provide information on the characteristics of the solids which are formed. The nature of the solids formed in turn impacts on dewatering behaviour. The 'upstream' solids formation determines a set of suspension characteristics: solids concentration, particle size distribution, solution ionic strength and electrostatic surface potential. These characteristics together define the suspension's rheological properties. However, the complicated interdependence of these has precluded the prediction of suspension rheology from such a fundamental description of suspension characteristics. Recent shear yield stress models, applied in this study to compressive yield, significantly reduce the empiricism required for the description of compressive rheology. Suspension compressibility and permeability uniquely define the dewatering behaviour, described in terms of settling, filtration and mechanical expression. These modes of dewatering may be described in terms of the same fundamental suspension mechanics model. In this way, it is possible to link dynamically the processes of solids formation and dewatering of the resultant suspension. This, ultimately, opens the door to improved operability of these processes. In part I of this paper we introduced an integrated system model for solids formation and dewatering. This model was demonstrated for the upstream processes using experimental data. In this current paper models of colloidal interactions and dewatering are presented and compared to experimental results from batch filtration tests. A novel approach to predicting suspension compressibility and permeability using a single test configuration is presented and tested.
Subject(s)
Biophysics/methods , Colloids/chemistry , Water/chemistry , Electrolytes/chemistry , Filtration , Hydrogen-Ion Concentration , Hydroxides/chemistry , Ions , Models, Statistical , Rheology , Static Electricity , Time FactorsABSTRACT
An understanding of the mechanisms which control solids formation can provide information on the characteristics of the solids which are formed. These characteristics will in turn impact on dewatering behaviour. In this paper a model for solids formation is proposed. The first part of the model considers the hydrodynamics in the precipitation vessel, from which a reactant mixing model is developed. Spatially variant solution conditions are quantified (dynamically) using an equilibrium speciation model. These calculations are performed in conjunction with an adsorption model, accounting for equilibria involving adsorbed species. The kinetics of solids formation, including nucleation, growth and aggregation, are described empirically using spatially variant supersaturation profiles. These, together with moment transformations of the solids population balance, describe the evolution of particle sizes throughout the precipitation process. Precipitation of nickel hydroxide is explored experimentally, and models developed are fitted to the results. Comments are offered on the impact of simplifications required for computational reasons, and assumptions required due to lack of information, on the accuracy of the model. In part II of this paper, the use of model outputs in predicting filtration behaviour is explored.
