OBJECTIVE: To determine the economic impact on the hospital of a hospitalist program and to develop insights into the relative economic importance of variables such as reductions in mean length of stay and cost, improvements in throughput (patients discharged per unit time), payer methods of reimbursement, and the cost of the hospitalist program. DATA SOURCES: The primary data source was Tufts-New England Medical Center in Boston. Patient demographics, utilization, cost, and revenue data were obtained from the hospital's cost accounting system and medical records. STUDY DESIGN: The hospitalist admitted and managed all patients during a six-week period on the general medical unit of Tufts-New England Medical Center. Reimbursement, cost, length of stay, and throughput outcomes during this period were contrasted with patients admitted to the unit in the same period in the prior year, in the preceding period, and in the following period. PRINCIPAL FINDINGS: The hospitalist group compared with the control group demonstrated: length of stay reduced to 2.19 days from 3.45 days (p<.001); total hospital costs per admission reduced to 1,775 dollars from 2,332 dollars (p<.001); costs per day increased to 811 dollars from 679 dollars (p<.001); no differences for readmission within 30 days of discharge to extended care facilities. The hospital's expected incremental profitability with the hospitalist was -1.44 dollars per admission excluding incremental throughput effects, and it was most sensitive to changes in the ratio of per diem to case rate reimbursement. Incremental throughput with the hospitalist was estimated at 266 patients annually with an associated incremental profitability of 1.3 million dollars. CONCLUSION: Hospital interventions designed to reduce length of stay, such as the hospitalist, should be evaluated in terms of cost, throughput, and reimbursement effects. Excluding throughput effects, the hospitalist program was not economically viable due to the influence of per diem reimbursement. Throughput improvements occasioned by the hospitalist program with high baseline occupancy levels are substantial and tend to favor a hospitalist program. (+info)
A significant limitation to the analytical accuracy and precision of dual-labeled spotted cDNA microarrays is the signal error due to dye bias. Transcript-dependent dye bias may be due to gene-specific differences of incorporation of two distinctly different chemical dyes and the resultant differential hybridization efficiencies of these two chemically different targets for the same probe. Several approaches were used to assess and minimize the effects of dye bias on fluorescent hybridization signals and maximize the experimental design efficiency of a cell culture experiment. Dye bias was measured at the individual transcript level within each batch of simultaneously processed arrays by replicate dual-labeled split-control sample hybridizations and accounted for a significant component of fluorescent signal differences. This transcript-dependent dye bias alone could introduce unacceptably high numbers of both false-positive and false-negative signals. We found that within a given set of concurrently processed hybridizations, the bias is remarkably consistent and therefore measurable and correctable. The additional microarrays and reagents required for paired technical replicate dye-swap corrections commonly performed to control for dye bias could be costly to end users. Incorporating split-control microarrays within a set of concurrently processed hybridizations to specifically measure dye bias can eliminate the need for technical dye swap replicates and reduce microarray and reagent costs while maintaining experimental accuracy and technical precision. These data support a practical and more efficient experimental design to measure and mathematically correct for dye bias. (+info)
Effects of acute mental stress and exercise on T-wave alternans in patients with implantable cardioverter defibrillators and controls.
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BACKGROUND: Malignant cardiac arrhythmias can be triggered by exercise and by mental stress in vulnerable patients. Exercise-induced T-wave alternans (TWA) is an established marker of cardiac electrical instability. However, the effects of acute mental stress on TWA have not been investigated as a vulnerability marker in humans. METHODS AND RESULTS: TWA responses to mental stress (anger recall and mental arithmetic) and bicycle ergometry were evaluated in patients with implantable cardioverter defibrillators (ICDs) and documented coronary artery disease (n=23, age 62.1+/-12.3 years) and controls (n=17, age 54.2+/-12.1 years). TWA was assessed from digitized ECGs by modified moving average analysis. Dual-isotope single photon emission computed tomography was used to assess myocardial ischemia. TWA increased during mental stress and exercise (P values <0.001), and TWA responses were higher in ICD patients than in controls (arithmetic Delta=8.9+/-1.4 versus 4.3+/-2.2 microV, P=0.043; exercise Delta=21.4+/-2.8 versus 13.8+/-3.2 microV, P=0.038). TWA increases with mental stress occurred at substantially lower heart rates (anger recall Delta=9.7+/-7.7 bpm, arithmetic Delta=14.3+/-13.3 bpm) versus exercise (Delta=53.7+/-22.7 bpm; P values <0.001). After adjustment for heart rate increases, mental stress and exercise provoked increased TWA in ICD patients (P values <0.05), but not in controls (P values >0.2). Ejection fraction and stress-induced myocardial ischemia were not associated with TWA. CONCLUSIONS: Mental stress can induce cardiac electrical instability, as assessed via TWA, among patients with arrhythmic vulnerability and occurs at lower heart rates than with exercise. Pathophysiological mechanisms of mental stress-induced arrhythmias may therefore involve central and autonomic nervous system pathways that differ from exercise-induced arrhythmias. (+info)
Research ethics and evidence based medicine.
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In this paper, the author argues that the requirement to conduct randomised clinical trials to inform policy in cases where one wants to identify a cheaper alternative to known effective but expensive interventions raises an important ethical issue. This situation will eventually arise whenever there are resource constraints, and a policy decision has been made not to fund an intervention on cost effectiveness grounds. It has been thought that this is an issue only in extremely resource poor settings. This paper gives an example from the United Kingdom illustrating that this is also a problem faced by richer countries. (+info)
Control selection strategies in case-control studies of childhood diseases.
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To address concerns regarding the representativeness of controls in case-control studies, two selection strategies were evaluated in a study of childhood leukemia, which commenced in California in 1995. The authors selected two controls per case: one from among children identified by using computerized birth records and located successfully, the other from a roster of friends; both were matched on demographic factors. Sixty-four birth certificate-friend control pairs were enrolled (n = 128). Additionally, 192 "ideal" controls were selected without tracing from the birth records. Data on parental ages, parental education, mother's reproductive history, and birth weight were obtained from the birth certificates of all 320 subjects. For all variables except birth weight, the differences between birth certificate and ideal controls were smaller than those between friend and ideal controls. None of the differences between birth certificate and ideal controls was significant, whereas two factors were significantly different between friend and ideal controls. These findings suggest that friend controls may be less representative than birth certificate controls. Despite difficulty in tracing and a seemingly low participation rate (49.0% for 560 enrolled birth certificate controls), using birth records to recruit controls appears to provide a representative sample of children and an opportunity to assess the representativeness of controls. (+info)
Reference group choice and antibiotic resistance outcomes.
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Two types of cohort studies examining patients infected with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) were contrasted, using different reference groups. Cases were compared to uninfected patients and patients infected with the corresponding, susceptible organism. VRE and MRSA were associated with adverse outcomes. The effect was greater when uninfected control patients were used. (+info)
Cardiac autonomic activity in obstructive sleep apnea: time-dependent and spectral analysis of heart rate variability using 24-hour Holter electrocardiograms.
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To analyze the function of cardiac autonomic regulation in patients with obstructive sleep apnea syndrome (OSAS), we enrolled 36 patients with OSAS and divided them according to the apnea hypopnea index (AHI) into 2 groups: Group I (n=19) had mild OSAS (AHI < 20) and Group II (n=17) had severe OSAS (AHI > or = 20). The findings were compared with those of 24 healthy control subjects who were matched for age, sex, blood pressure, and body mass index. All participants underwent 24-hour Holter monitoring, with continuous time-dependent and spectral analysis of heart rate variability. In addition, we performed arrhythmia analysis. Frequent or repetitive ventricular arrhythmias (> or = 30 premature ventricular beats/hour) were detected in 15 (42%) patients with OSAS and in 6 (25%) members of the control group. In both mild and severe OSAS, SDNN was significantly lower than in controls, and SDANN findings were similar. In mild OSAS, RMSSD values were not significantly lower than in controls, but in severe OSAS they were. The ULF, VLF, LF and LF/HF values of both groups of OSAS patients were significantly higher than those of controls, but their HF values were lower. The mean LF/HF ratio during the same period was significantly higher in Group II than in Group I and the control group. Our results suggest that cardiac autonomic activity may be altered in patients with OSAS throughout a 24-hour period, that this alteration occurs even in the absence of hypertension, heart failure, or other disease states, and that it is linked to the severity of OSAS. (+info)
Some design issues in trials of microbicides for the prevention of HIV infection.
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Trials for the prevention of human immunodeficiency virus (HIV) infection that evaluate microbicides provide significant design challenges. Three of these design issues deserve more careful consideration. The first issue relates to the benefits of using both blinded and unblinded control groups when the placebo regimen may not be inert and when the effectiveness of an intervention heavily depends on behavioral, as well as biological, factors. The second issue relates to the strength of evidence required for regulatory approval for the marketing of drugs and biologics when only a single pivotal phase 3 clinical trial has provided such evidence. The third issue relates to the appropriate next step after the completion of phase 1 trials, as well as the specific merits of conducting phase 2b screening trials that assess the effects on the same clinical efficacy end point that will be the primary end point in a phase 3 trial. The issues considered in microbicide trials for the prevention of HIV infection are also of importance in many other clinical scenarios. (+info)