An improved comorbidity summary score for measuring disease burden and predicting mortality with applications to two national cohorts

Abstract

Research involving administrative healthcare data to study patient outcomes requires the investigator to account for the patient’s disease burden in order to reduce the potential for biased results. Here we develop a comorbidity summary score based on variable importance measures derived from several statistical and machine learning methods and show it has superior predictive performance to the Elixhauser and Charlson indices when used to predict 1-year, 5-year, and 10-year mortality. We used two large Veterans Administration cohorts to develop and validate the summary score and compared predictive performance using the area under ROC curve (AUC) and the Brier score.     

Seasonal Adjustment of Time Series Using One-Sided Filters

This article presents a model-based signal extraction seasonal adjustment procedure to extract estimates of the independent unobserved seasonal and nonseasonal components from an observed time series. The decomposition yields a one-sided filter that is optimal for adjusting the most recent observation under the assumption of using only the past observed series. Some advantages of this procedure are that no forecasts are required for implementation and there are no problems of revision of estimates or questions of concurrent adjustment. Comparisons are made with existing procedures using two-sided filters.     

On risk aversion,classical demand theory,and KM preferences

Building on Kihlstrom and Mirman (Journal of Economic Theory, 8(3), 361–388, 1974)’s formulation of risk aversion in the case of multidimensional utility functions, we study the effect of risk aversion on optimal behavior in a general consumer’s maximization problem under uncertainty. We completely characterize the relationship between changes in risk aversion and classical demand theory. We show that the effect of risk aversion on optimal behavior depends on the income and substitution effects. Moreover, the effect of risk aversion is determined not by the riskiness of the risky good, but rather the riskiness of the utility gamble associated with each decision.     

Simple Efficient Contracts in Complex Environments

This paper studies a general model of holdup in a setting encompassing the models of Segal (1999) and Che and Hausch (1999) among others. It is shown that if renegotiation is modeled as an infinite‐horizon noncooperative bargaining game, then, with a simple initial contract, an efficient equilibrium will generally exist. The contract is robust in the sense that it does not depend on fine details of the model. The contract gives authority to one party to set the terms of trade and gives the other party a nonexpiring option to trade at these terms. The difference from standard results arises because the initial contract ensures that the renegotiation game has multiple equilibria; the multiplicity of continuation equilibria can be used to enforce efficient investment.     

A grounded theory research approach to building and testing TQM theory in operations management

Total quality management (TQM) has continued to develop as a strategic business improvement approach in organisations and within the Operations Management literature. Strategic TQM is a dynamic phenomenon, reflecting the complexity and technology development in the business environment. Therefore, this conception of TQM has led to significant challenges with regards to developing suitable models and research methodology where traditional, and normative research data, includes survey responses associated with deductive theory and testing. Such data, and its use, is often premised on cause and effect rationality and fails to supply deep rich data to address meanings, phenomena and complex socio-political events, which is a feature of strategic TQM.     

Sexual behavior of clients with street prostitutes in Camden,NJ

This paper describes the sexual behaviors of 101 male clients with female street prostitutes. An earlier study (Freund, Leonard, & Lee, 1989) was limited to sexual behaviors of street prostitutes themselves. Interviews were given by 62% of the clients approached. The clients were mature men (mean = 39.8 years), long‐term residents of Camden, NJ (mean = 19.2 years), and currently or previously married (78/101). Racial composition was similar to the general population of the area, 65% white, 33% black, 2% Asian. Clients reported a mean of 5.3 years of using prostitution, with 81% having been clients of Camden prostitutes for more than a year. Most were regular (or repeat) clients; 93% monthly or more frequently, and 63% weekly or more frequently. About one‐half (55%) reported sex with the same prostitute or same small group of prostitutes. The primary meeting place was the street (78/101) and 43% of the sexual encounters took place in the clients' cars. Ejaculation into the vagina was most frequently reported (43/101), followed by ejaculation into the mouth (39/101) Reports of condom use were substantial; 72% for vaginal and 33% for oral intercourse (mean = 58% of encounters).