Vjollca Sadiraj

Risk Factors for 30-Day Hospital Readmission among General Surgery Patients

BACKGROUND Hospital readmission within 30 days of an index hospitalization is receiving increased scrutiny as a marker of poor-quality patient care. This study identifies factors associated with 30-day readmission after general surgery procedures. STUDY DESIGN Using standard National Surgical Quality Improvement Project protocol, preoperative, intraoperative, and postoperative outcomes were collected on patients undergoing inpatient general surgery procedures at a single academic center between 2009 and 2011. Data were merged with our institutional clinical data warehouse to identify unplanned 30-day readmissions. Demographics, comorbidities, type of procedure, postoperative complications, and ICD-9 coding data were reviewed for patients who were readmitted. Univariate and multivariate analysis was used to identify risk factors associated with 30-day readmission. RESULTS One thousand four hundred and forty-two general surgery patients were reviewed. One hundred and sixty-three (11.3%) were readmitted within 30 days of discharge. The most common reasons for readmission were gastrointestinal problem/complication (27.6%), surgical infection (22.1%), and failure to thrive/malnutrition (10.4%). Comorbidities associated with risk of readmission included disseminated cancer, dyspnea, and preoperative open wound (p < 0.05 for all variables). Surgical procedures associated with higher rates of readmission included pancreatectomy, colectomy, and liver resection. Postoperative occurrences leading to increased risk of readmission were blood transfusion, postoperative pulmonary complication, wound complication, sepsis/shock, urinary tract infection, and vascular complications. Multivariable analysis demonstrates that the most significant independent risk factor for readmission is the occurrence of any postoperative complication (odds ratio = 4.20; 95% CI, 2.89-6.13). CONCLUSIONS Risk factors for readmission after general surgery procedures are multifactorial, however, postoperative complications appear to drive readmissions in surgical patients. Taking appropriate steps to minimize postoperative complications will decrease postoperative readmissions.

Small- and Large-Stakes Risk Aversion: Implications of Concavity Calibration for Decision Theory

A growing literature reports the conclusions that: (a) expected utility theory does not provide a plausible theory of risk aversion for both small-stakes and large-stakes gambles; and (b) this decision theory should be replaced with an alternative theory characterized by loss aversion. This paper explains that the arguments in previous literature fail to support these conclusions. Either concavity calibration has no general implication for expected utility theory or it has problematic implications for all decision theories that involve concave transformations (utility or value functions) of positive money payoffs, which makes loss aversion irrelevant to the argument.

Identification of Voters with Interest Groups Improves the Electoral Chances of the Challenger

This short paper investigates the consequences of voters identifying with special interest groups in a spatial model of electoral competition. We show that by effectively coordinating voting behavior, identification with interest groups leads to an increase in the size of the winning set, that is, the set of policy platforms for the challenger that will defeat the incumbent. Consequently, our paper points at a novel process through which interest groups can enhance the electoral chances of a challenger.

Implications of Trust, Fear, and Reciprocity for Modeling Economic Behavior

This paper reports three experiments with triadic or dyadic designs. The experiments include the moonlighting game in which first-mover actions can elicit positively or negatively reciprocal reactions from second movers. First movers can be motivated by trust in positive reciprocity or fear of negative reciprocity, in addition to unconditional other-regarding preferences. Second movers can be motivated by unconditional other-regarding preferences as well as positive or negative reciprocity. The experimental designs include control treatments that discriminate among actions with alternative motivations. Data from our three experiments and a fourth one are used to explore methodological questions, including the effects on behavioral hypothesis tests of within-subjects vs. across-subjects designs, single-blind vs. double-blind payoffs, random vs. dictator first-mover control treatments, and strategy responses vs. sequential play.

On Modeling Voluntary Contributions to Public Goods

This article addresses four “stylized facts†that summarize data from experimental studies of voluntary contributions to the provision of public goods. Theoretical propositions and testable hypotheses for voluntary contributions are derived from two models of social preferences, the inequity aversion model and the egocentric other-regarding preferences model. The authors find that the egocentric other-regarding preferences model with classical regularity properties can better account for the stylized facts than the inequity aversion model with nonclassical properties.

Risky Decisions in the Large and in the Small: Theory and Experiment

Much of the literature on theories of decision making under risk has emphasized differences between theories. One enduring theme has been the attempt to develop a distinction between “normative” and “descriptive” theories of choice. Bernoulli (1738) introduced log utility because expected value theory was alleged to have descriptively incorrect predictions for behavior in St. Petersburg games. Much later, Kahneman and Tversky (1979) introduced prospect theory because of the alleged descriptive failure of expected utility (EU) theory (von Neumann & Morgenstern, 1947).

Asset Integration and Attitudes to Risk: Theory and Evidence

We provide evidence that choices over small-stakes bets are consistent with assumptions of some payoff calibration paradoxes. We then exploit the existence of detailed information on individual wealth of our experimental subjects in Denmark and directly estimate risk attitudes and the degree of asset integration. We discover that behavior is consistent with partial, rather than full, asset integration. The implied risk attitudes from estimating these specifications indicate risk premiums and certainty equivalents that are a priori plausible. This theory and evidence suggest one constructive solution to payoff calibration paradoxes.

Asymmetrically Dominated Choice Problems, the Isolation Hypothesis and Random Incentive Mechanisms

This paper presents an experimental study of the random incentive mechanisms which are a standard procedure in economic and psychological experiments. Random incentive mechanisms have several advantages but are incentive-compatible only if responses to the single tasks are independent. This is true if either the independence axiom of expected utility theory or the isolation hypothesis of prospect theory holds. We present a simple test of this in the context of choice under risk. In the baseline (one task) treatment we observe risk behavior in a given choice problem. We show that by integrating a second, asymmetrically dominated choice problem in a random incentive mechanism risk behavior can be manipulated systematically. This implies that the isolation hypothesis is violated and the random incentive mechanism does not elicit true preferences in our example.

A Computational Electoral Competition Model with Social Clustering and Endogenous Interest Groups as Information Brokers

We extend the basic model of spatial competition in two directions. First, political parties and voters do not have complete information but behave adaptively. Political parties use polls to search for policy platforms that maximize the probability of winning an election and the voting decision of voters is influenced by social interaction. Second, we allow for the emergence of interest groups. These interest groups transmit information about voter preferences to the political parties, and they coordinate voting behavior. We use simulation methods to investigate the convergence properties of this model. We find that the introduction of social dynamics and interest groups increases the separation between parties platforms, prohibits convergence to the center of the distribution of voter preferences, and increases the size of the winning set.

Incentivizing cost-effective reductions in hospital readmission rates

The recent regulatory changes enacted by the Centers for Medicare and Medicaid Services (CMS) have identified hospital readmission rates as a critical healthcare quality metric. This research focuses on the utilization of pay-for-performance (P4P) mechanisms to cost effectively reduce hospital readmission rates and meet the regulatory standards set by CMS. Using the experimental economics laboratory we find that both of the P4P mechanisms researched, bonus and bundled payments, cost-effectively meet the performance criteria set forth by CMS. The bundled payment mechanism generates the largest reduction in patient length of stay (LOS) without altering the probability of readmission. Combined these results indicate that utilizing P4P mechanisms incentivizes cost effective reductions in hospital readmission rates.