Biomedical subjects

Mark S Roberts

Publications and source records attributed to Mark S Roberts.

At least 37 records · Page 2Linked to original sources

PubMed2004

Procuring organ donors as a health investment: how much should we be willing to spend?

BACKGROUND: This paper examines the benefits and costs that accrue when a cadaveric organ donor is procured. We estimate the cost per quality-adjusted life year (QALY) for donor procurement. Our objective was not only to see whether organ procurement is a "good" health investment, but also to clarify how much it is worth spending to obtain additional donors. METHODS: We calculated the average number of kidney, heart, and liver transplants that a typical cadaveric donor generates. Relying primarily on reviewing the published literature, we estimated for each organ type the average number of QALYs that transplants add and the average medical costs they generate. We multiplied per organ benefits and costs by the number of organs from the typical donor, and summed the results to calculate the cost per QALY from procuring an additional donor. We conducted extensive sensitivity analyses of the assumptions. RESULTS: Our central estimate indicates that the typical donor generates about 13 QALYs at an added medical cost of about $214,000, a cost of approximately $16,000 per QALY. Our high estimate is approximately $57,000. CONCLUSIONS: The implications of these findings depend upon how we choose to value QALYs. Most analysts agree that a figure of $100,000 is reasonable. At this value, the benefit obtained from one added donor would be $1.3 million (13 x $100,000) while the medical costs would be $214,000. The implication is that we should be willing to spend up to $1,086,000 ($1.3 million - $214,000) to obtain one more donor.

Cadaver↗

PubMed2004

Preference-based quality of life measurement in patients with cervical spondylotic myelopathy.

STUDY DESIGN: Prospective cross-sectional observational cohort study. OBJECTIVES: To assess the performance of preference-based quality of life (QOL) instruments in patients with cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA: Generic health status instruments (e.g., SF-36) or disease-specific health status measures (e.g., myelopathy scales) are typically used to measure QOL in patients with CSM; however, these instruments only examine a limited number of domains that contribute to QOL. An alternative is preference-based QOL methods, which integrate all factors contributing to QOL and provide a comprehensive individualized measure of how patients value their current health state. METHODS: We used four preference-based QOL methods to measure QOL in a cohort of 79 patients with CSM: 1) visual analogue scale, 2) standard gamble, 3) time trade-off, and 4) willingness to pay. We measured health status with the SF-36 and with CSM disease-specific scales devised by Nurick, Harsh, Cooper, and the Japanese Orthopedic Association. We used multivariate linear regression techniques to examine the relationships between preference-based QOL, generic health status, CSM disease-specific health status, and patient characteristics. RESULTS: Median preference-based QOL measurements for the CSM cohort were as follows: visual analogue scale, 0.50; standard gamble, 0.79; time trade-off, 0.75, and willingness to pay, $38,256. Preference-based QOL was not well explained by generic health status, CSM disease-specific health status, or patient characteristics, as shown by regression models that were unable to account more than 21% of the variation in preference-based QOL (R < or =0.21). CONCLUSIONS: Preference-based QOL in patients with CSM is poorly correlated with generic health status, CSM disease-specific health status, or patient characteristics. Studies of CSM and other spine diseases should consider incorporating preference-based QOL measures for a fuller evaluation of the impact of spine disease and its treatment on QOL.

Adult↗

PubMed2004

Survival after liver transplantation in the United States: a disease-specific analysis of the UNOS database.

Our goal was to describe disease-specific survival and the clinical variables that predict survival in a large national cohort of adult liver transplant recipients. Data on 17,044 adult patients who received an initial orthotopic liver transplant between 1990 and 1996 with follow-up through 1999 was obtained from the United Network for Organ Sharing (UNOS). Disease-specific Kaplan-Meier survival plots and Cox Proportional Hazards models were estimated, and differences in the clinical characteristics of patients at the time of transplantation by disease were examined. Overall posttransplant survival currently exceeds 85% in the first year and is approaching 75% at 5 years. Unadjusted Kaplan-Meier survival is improved for recipients who are younger, female, and in better clinical condition. Survival is a function of disease and level of illness: cancer, fulminant liver failure, alcoholic liver disease, and the hepatitidies have the poorest prognosis, while primary billiary cirrohsis and sclerosing cholangitis have the best. Recipients who were outpatients before transplantation have longer survival than those transplanted from the hospital or intensive care unit. Although the model for end-stage liver disease (MELD) score was designed to predict pretransplant survival, patients with higher MELD scores have poorer posttransplant survival, but the MELD score is less predictive than the specific disease. Differences in disease-specific survival are partially explained by differences in disease severity at the time of transplantation. In conclusion, Disease-specific survival models indicate that there remains tremendous variability in survival as a function of underlying liver disease. However, a significant portion of the difference in survival between diseases arises from differences in clinical characteristics at the time of transplantation.

Adolescent↗

PubMed2004

Health status versus utilities of patients with end-stage liver disease.

BACKGROUND: Health-related quality of life (HRQL) in patients with end-stage liver disease (ESLD) can be evaluated using either health-status questionnaires or utility assessment techniques. The two approaches have never been compared in terms of the values they assign to health prior to liver transplantation. STUDY DESIGN: We assessed health status of patients with ESLD using validated disease-specific instruments covering multiple domains (measures of disease, psychological status, personal function, social/role function, and general health perception). We also elicited utilities using formal approaches (standard gamble [SG] and time tradeoff [TTO]) and a simpler alternative (visual analog scale [VAS]). PATIENTS: Outpatients and inpatients at a single center prior to liver transplantation (n = 78). PRINCIPAL FINDINGS: Health status was generally poor (median physical symptoms score on a 0-1 [worst to best] scale, 0.33; psychological symptoms, 0; happiness, 0.50; personal function, 0; social/role function, 0.40; and general health perception, 0.40). The median VAS score was 0.50. The median TTO was 0.79, indicating that half of the patients in our sample chose healthier life in return for a 21% shorter life expectancy. The median SG score was 0.50, indicating that half of the patients were willing to take up to a 50% risk of death in exchange for perfect health. CONCLUSIONS: Both health status measures and utility assessments indicate that HRQL is compromised in patients awaiting liver transplantation. Despite the overall consistency between the two approaches, however, health status measures do not serve as reasonable proxies for utilities. For formal economic evaluations such as cost effectiveness analyses, only direct measures of utility can be used to quantify health states.

Adult↗

PubMed2004

Economics of nerve block pain management after anterior cruciate ligament reconstruction: potential hospital cost savings via associated postanesthesia care unit bypass and same-day discharge.

BACKGROUND: Anterior cruciate ligament reconstruction is a complex outpatient surgical procedure often associated with pain. Traditionally, the procedure is performed under general anesthesia and often requires the use of the PACU. Refractory pain and/or nausea/vomiting occasionally leads to an unplanned hospital admission. In this study, the authors examine the associations of nerve block analgesia for these patients and its associated reductions in PACU use, hospital admission, and hospital costs. METHODS: This was an observational, nonrandomized study in which existing data regarding patients' day-of-surgery outcomes were merged with hospital cost data. We reviewed a consecutive sample of 948 men and women who were in good health and underwent anterior cruciate ligament reconstruction in an outpatient surgery unit between July 1995 and June 1999. RESULTS: The use of nerve block analgesia was associated with reduced PACU admissions to 18% and decreased unplanned hospital admission rates from 17% to 4%. Multivariate linear regression analysis showed that patients bypassing the PACU had an associated hospital cost reduction of 12% (P = 0.0001), whereas patients who needed hospital admission had an associated hospital cost increase of 11% (P = 0.0003). CONCLUSIONS: The use of nerve blocks for acute pain management in patients undergoing anterior cruciate ligament reconstruction is associated with PACU bypass and reliable same-day discharge. Although the cost savings for this one procedure are unlikely to generate sufficient cost savings via staffing reductions, extrapolating these results to a large volume of all types of invasive outpatient orthopedic procedures may have the potential to create significant hospital cost savings.

Adult↗

PubMed2004

Simulation and critical care modeling.

PURPOSE OF REVIEW: Decisions made in critical care are often complicated, requiring an in-depth understanding of the relations between complex diseases, available interventions, and patients with a wide range of characteristics. Standard modeling techniques such as decision trees and statistical modeling have difficulty in capturing these interactions as the complexity of the problem increases. RECENT FINDINGS: Recent models in the literature suggest that simulation modeling techniques such as Markov modeling, Monte Carlo simulation, and discrete-event simulation are useful tools for analyzing complex systems in critical care. These simulation techniques are reviewed briefly, and examples from the literature are presented to demonstrate their usefulness in understanding real problems in critical care. SUMMARY: Simulation models provide useful tools for organizing and analyzing the interactions between therapies, tradeoffs, and outcomes.

Computer Simulation↗

PubMed2003

Optimizing management and financial performance of the teaching ambulatory care clinic.

OBJECTIVE: To examine how to optimize teaching ambulatory care clinics performance with regard to access to care, access to teaching, and financial viability. DESIGN: Optimization analysis using computer simulation. METHODS: A discrete-event simulation model of the teaching ambulatory clinic setting was developed. This method captures flow time, waiting time, competition for resources, and the interdependency of events, providing insight into system dynamics. Sensitivity analyses were performed on staffing levels, room availability, patient characteristics such as "new" versus "established" status, and clinical complexity and pertinent probabilities. MAIN RESULTS: In the base-case, 4 trainees:preceptor, patient flow time (registration to check out) was 148 minutes (SD 5), wait time was 20.6 minutes (SD 4.4), the wait for precepting was 6.2 minutes (SD 1.2), and average daily net clinic income was $1,413. Utilization rates were preceptors (59%), trainees (61%), medical assistants (64%), and room (68%). Flow time and the wait times remained relatively constant for strategies with trainee:preceptor ratios <4:1 but increased with number of trainees steadily thereafter. Maximum revenue occurred with 3 preceptors and 5 trainees per preceptor. The model was relatively insensitive to the proportion of patients presenting who were new, and relatively sensitive to average evaluation and management (E/M) level. Flow and wait times rose on average by 0.05 minutes and 0.01 minutes per percent new patient, respectively. For each increase in average E/M level, flow time increased 8.4 minutes, wait time 1.2 minutes, wait for precepting 0.8 minutes, and net income increased by $490. CONCLUSION: Teaching ambulatory care clinics appear to operate optimally, minimizing flow time and waiting time while maximizing revenue, with trainee-to-preceptor ratios between 3 and 7 to 1.

Ambulatory Care↗

PubMed2003

Quality of life assessment with the medical outcomes study short form-36 among patients with cervical spondylotic myelopathy.

OBJECTIVE: Cervical spondylotic myelopathy (CSM) is a chronic degenerative condition of the cervical spine that produces narrowing of the spinal canal and disruption of spinal cord function. We used Medical Outcomes Study Short Form-36 (SF-36), a generic quality of life outcome-assessment instrument, to assess the quality of life among patients with CSM. METHODS: A cohort of 88 Veterans Administration neurosurgery clinic patients with CSM underwent structured interviews for collection of data on demographic features, symptoms, operations, and comorbid diseases. Patients also completed the SF-36. Symptoms and examination findings were used to assign each patient scores on the Nurick, Cooper, and Harsh myelopathy scales and a Western modification of the Japanese Orthopaedic Association scale. SF-36 scores were compared with age-adjusted Veterans Administration population normative values by using Student's t test with unequal variances. Cuzick's nonparametric test for trend was used to explore the relationship between the SF-36 physical component summary scores and the myelopathy scale scores. RESULTS: Patients with CSM exhibited decreased quality of life in all eight SF-36 domains, as well as with the physical and mental component summary scores, compared with Veterans Administration population normative values (for all, P </= 0.003). Lower physical component summary scores were associated with worse myelopathy scores on the Nurick scale (P < 0.001), Cooper leg subscale (P = 0.012), and Harsh scale (P < 0.001). CONCLUSION: Patients with CSM exhibit decreased quality of life in all health domains assessed with the SF-36, a generic health outcome-measurement instrument. The impairments of patients with CSM extend beyond the motor, sensory, and bladder dysfunctions recorded with myelopathy scales, into the realms of emotional and mental health.

Activities of Daily Living↗

PubMed2003

Creatinine production, nutrition, and glomerular filtration rate estimation.

This study examined the validity and clinical implications of the assumption of the Modification of Diet in Renal Disease Study (MDRD) formula that age, gender, race, and BUN account for creatinine production (CP). The relationships of MDRD GFR, CP, and nutrition were examined in 1074 Dialysis Morbidity and Mortality Study Wave II patients with reported measured creatinine clearances at initiation of dialysis. Age, gender, race, BUN, and serum creatinine (Scr) were used to calculate MDRD GFR. The measured 24-h urinary creatinine was used to estimate CP. In linear regression, Scr positively correlated with CP independent of age, gender, race, and BUN. Compared with the highest CP quartile, the lowest CP quartile had lower creatinine clearance (5.8 +/- 2.9 versus 11.3 +/- 3.4 ml/min, P <.01) despite lower Scr (5.8 +/- 2.6 versus 8.6 +/- 3.1 mg%, P <.01). There was an excellent correlation between the reciprocal of Scr and the MDRD GFR (r = 0.90). As a result, the MDRD GFR was higher in the lowest CP quartile (10.9 +/- 4.6 versus 7.6 +/- 2.4 ml/min, P <.01). Malnutrition (48% versus 26%, P <.01) was more common in the lowest CP quartile. Each 5-ml/min increase in MDRD GFR was associated with 21% higher odds of malnutrition (P = 0.046) in a multivariable logistic regression, which was abolished by controlling for CP. The fundamental assumption of the MDRD formula is invalid in patients with advanced renal failure, and the use of this formula in these patients might introduce biases.

Adult↗

PubMed2003

Impact of timing of initiation of dialysis on mortality.

Previous studies showed that sicker patients were initiated on dialysis at higher GFR as estimated by the Modification of Diet in Renal Disease (MDRD) formula. It was previously shown that patients with low creatinine production were malnourished and had low serum creatinine levels and creatinine clearances (CrCl) but high MDRD GFR at initiation of dialysis. Therefore, a propensity score approach was used to examine the associations of MDRD GFR and measured CrCl at the initiation of dialysis with subsequent mortality. Baseline data and outcomes were obtained from the Dialysis Morbidity Mortality Study Wave II. Propensity scores for early initiation derived by logistic regression were used in Cox models to examine mortality. Each 5-ml/min increase in MDRD GFR at initiation of dialysis in the entire cohort was associated with increased hazard of death in multivariable Cox model (hazard ratio [HR] 1.14; P = 0.002). In the subgroup of patients with reported CrCl, higher MDRD GFR was associated with increased risk of death (for each 5-ml/min increase, HR 1.27; P < 0.001) but not CrCl (for each 5-ml/min increase, HR 0.98; P = 0.81). These divergent results might reflect erroneous GFR estimation by the MDRD formula. Furthermore, these data do not support earlier initiation of dialysis. Therefore, for patients without clinical indications for initiation of dialysis, the appropriate GFR level for initiation of dialysis is unknown.

Adult↗

PubMed2003

Cost-effectiveness of inhaled nitric oxide in the treatment of neonatal respiratory failure in the United States.

OBJECTIVE: Two recent randomized controlled trials (RCTs) reported that inhaled nitric oxide (iNO) decreased the incidence of extracorporeal membrane oxygenation (ECMO) or death in term and near-term newborns with hypoxic respiratory failure. Our objective was to estimate the cost-effectiveness ratio of iNO in this population. METHODS: We studied 1000 simulation cohorts (n = 483 for each cohort) of term/near-term newborns with hypoxemic respiratory failure. We conducted our study following US Public Health Service Panel on Cost-Effectiveness in Health and Medicine guidelines, adopting the US societal perspective. We constructed a decision tree reflecting iNO use, subsequent ECMO use, death, and long-term neurologic and respiratory morbidity in survivors, as determined from the combined outcomes of the 2 RCTs (n = 483). We estimated costs on the basis of length-of-stay data for the initial episode of care from 1 of the RCTs, unit costs from administrative data sets, and current pricing for iNO. We ran a Monte Carlo simulation to generate estimates of differences in costs and effects at 1 year, along with the stochastic uncertainty around these estimates. We expressed effects as quality-adjusted survival, assuming quality of life = 1 with no comorbidity, 0.7 with 1 comorbidity, and 0.49 (0.7 x 0.7) with 2 comorbidities. We constructed a base case, in which iNO was initiated at tertiary care ECMO centers (mimicking the RCTs) and a Public Health Service Panel on Cost-effectiveness in Health and Medicine reference case, in which iNO was initiated at the local hospital before transfer (mimicking real-world practice). We exposed our assumptions to a sensitivity analysis. RESULTS: Direct application of the trial results (base case) suggested that iNO was both more effective and cheaper (cost savings of 1880 dollars per case despite acquisition costs of 5150 dollars, predominantly as a result of decreased need for ECMO), with 84.6% probability that the cost-effectiveness ratio was better than 100,000 dollars per quality-adjusted life-year. Under the reference case, iNO was also more effective (though slightly less so) and was even cheaper (cost savings of 4400 dollars per case), with 71.6% probability that iNO was cheaper and more effective and 91.6% probability that the cost effectiveness ratio was better than 100,000 dollars per quality-adjusted life-year. Sensitivity analyses showed these estimates to be sensitive to patient selection and the price of iNO but insensitive to assumptions regarding quality of life. CONCLUSIONS: From a US societal perspective, iNO has a favorable cost-effectiveness profile when initiated either at ECMO centers or at local hospitals in term/near-term neonates with hypoxemic respiratory failure.

Cost-Benefit Analysis↗

PubMed2002

Cost-effectiveness of newer treatment strategies for influenza.

PURPOSE: Recent advances in the diagnosis and treatment of influenza, such as rapid testing and neuraminidase inhibitor therapy, are available, but their place in clinical practice and their cost-effectiveness have not been determined. MATERIALS AND METHODS: To estimate the cost-effectiveness of these newer interventions, we used a decision model that compared several influenza management strategies: no testing or treatment, amantadine or rimantadine treatment without testing, testing then amantadine or rimantadine treatment, neuraminidase inhibitor treatment without testing, or testing then neuraminidase inhibitor treatment. Antiviral therapy began within 48 hours in febrile patients with characteristic symptoms of influenza. We assumed that antiviral treatment did not change rates of influenza complication or mortality, and chose parameter values in the baseline analysis to bias slightly against antiviral treatment and toward testing strategies. RESULTS: In the baseline analysis, testing strategies are more expensive and less effective than treatment strategies. Amantadine costs $9.06 per illness day avoided or $11.60 per quality-adjusted day gained. Compared with amantadine, zanamivir costs $198 per illness day avoided or $185 per quality-adjusted day gained, whereas oseltamivir costs $252 per illness day avoided or $235 per quality-adjusted day gained. In elderly patients who require reduced dosage, rimantadine costs $128 per quality-adjusted day gained compared with amantadine. In younger patients, amantadine is favored if the likelihood of influenza A is >67%; otherwise, neuraminidase inhibitors are favored. Testing strategies are more costly and less effective when the influenza probability is >30%. No testing or treatment is favored if the influenza probability is <32% and the influenza utility is >0.77. In elderly patients, amantadine is favored over rimantadine if the utility of medication side effects is >0.94. CONCLUSIONS: Antiviral treatment of influenza without rapid testing is reasonable economically in febrile patients with typical symptoms during influenza season. The choice of antiviral agent depends on age, the likelihood of influenza A, and the willingness to pay per quality-adjusted day gained.

Acetamides↗

PubMed2002

Validity and reliability of the Short Form-36 in cervical spondylotic myelopathy.

OBJECT: Validity (the extent to which a test measures what it is intended to measure) and reliability (the stability and reproducibility of measures of the same concept over time or across methods of gathering data) are important characteristics of any outcomes instrument. Generic outcomes instruments are designed for use in any population; however, their validity and reliability in particular diseases should be verified to ensure their appropriateness for use in that disease. In this study the authors assessed the validity and reliability of the Medical Outcomes Study Short Form-36 (SF-36), a generic outcomes instrument, in a population of patients with cervical spondylotic myelopathy (CSM). METHODS: The SF-36 was administered to a cohort of patients with CSM on an outpatient basis. Symptom-related data derived from a structured interview and physical examination findings were used to classify cases according to the myelopathy scales of Nurick, Cooper, Harsh, and a Western modification of the Japanese Orthopaedic Association (JOA). Construct validity was assessed by determining whether SF-36 scores varied in accordance with predefined hypotheses relating to the myelopathy scores by using the Cuzick nonparametric test for trend. The reliability of the SF-36 scores was assessed using Cronbach alpha. Eighty-eight patients with CSM completed the SF-36 and interview. Construct validity was demonstrated by confirming the hypothesized relationship between SF-36 scales and the myelopathy scales of Nurick (p < or = 0.003), Cooper leg subscale (p < or = 0.012, except the general health perceptions domain [p = 0.091]), Harsh (p < or = 0.016), and the motor component of the modified JOA (p < or = 0.006). Reliability was demonstrated for all eight SF-36 domain scales and the physical component and mental component summary scales, in which Cronbach alpha satisfied the Nunnally criterion of 0.7. CONCLUSIONS: The SF-36 provides valid and reliable data on patients with CSM.

Activities of Daily Living↗

PubMedDate not supplied

Long-term HIV/AIDS survival estimation in the highly active antiretroviral therapy era.

BACKGROUND: Highly active antiretroviral therapy (HAART) prolongs short-term survival in patients with HIV/AIDS. HAART has only been available since 1996; thus, no long-term survival data are available. Computer simulation models extrapolating short-term survival data can provide estimates of long-term survival. These survival estimates may assist patients and clinicians in HAART treatment planning. The authors construct a computer simulation model based on observational data to estimate long-term survival in a cohort of HIV/AIDS patients undergoing treatment with HAART. METHODS: The authors use data from the Collaboration in HIV Outcomes Research-US (CHORUS) observational cohort (N = 4791), the published literature, and US Life Tables to specify a computer simulation model of expected survival accounting for baseline CD4 cell count, progressive HAART treatment failure, progressive risk of HAART on treatment mortality, and age-associated mortality. Time to treatment failure for each of three rounds of HAART and risk of mortality on-treatment were estimated using parametric survival models with censoring of follow-up fit to CHORUS data. Off-treatment survival after HAART failure was estimated from the pre-HAART literature. Age-associated mortality was taken from US Life Tables. RESULTS: Median projected survivals stratified by baseline CD4 cell count subgroups were CD4 > 200 cells/mm3, 15.4 years; CD4 < or = 200 cells/mm3, 8.5 years; and CD4 < or = 50 cells/mm3, 5.5 years. These values are 4 to 6 years longer than pre-HAART cohorts. The sensitivity analyses showed that the model survival predictions were most sensitive to the treatment failure rate, the on-treatment mortality rate, and the number of treatment rounds. CONCLUSIONS: Computer simulation modeling of long-term survival of patients with HIV/AIDS on HAART--accounting for differential treatment failure and death rates stratified by CD4 cell count and age-associated mortality--suggests a relatively consistent 4- to 6-year survival benefit over pre-HAART therapies.

Adult↗

PubMedDate not supplied

"Perfect health" versus "disease free": the impact of anchor point choice on the measurement of preferences and the calculation of disease-specific disutilities.

BACKGROUND: During preference testing, some investigators use "perfect health" as the upper anchor point of their measurement scale ("Q scale"), whereas others use "disease free" ("q scale"), which can confound the interpretation and comparison of study results. METHODS: We measured current health preferences among 74 patients with cervical spondylotic myelopathy (CSM) on both the Q and q scales using the visual analogue scale (VAS), standard gamble (SG), time tradeoff (TTO), and willingness to pay (WTP). RESULTS: There were significant differences in mean Q and q scale values for the VAS, SG, and WTP (for all, P < 0.011); there were no significant differences for mean TTO values (P = 0.592). CSM accounted for 63% to 82% of total disutility, whereas other comorbidities accounted for 28% to 37%. CONCLUSIONS: Preferences for CSM differ when measured on the Q and q scales. Caution should be used when comparing and interpreting health values measured on scales with different upper anchors.

Adult↗

PubMedDate not supplied

Positive association between current health and health values for hypothetical disease states.

BACKGROUND: Valuations of hypothetical health state scenarios can be affected by participant characteristics. METHODS: The authors interviewed 108 veterans using the visual analogue scale (VAS), standard gamble (SG), time tradeoff (TTO), and willingness to pay (WTP) to measure health values for 1) current health and 2) 3 hypothetical health states portrayed in written scenarios describing cervical spondylotic myelopathy (CSM), a degenerative spine condition. They used bivariate rank order and multivariate regression analyses to assess the relationship between CSM values, participants' characteristics, and participants' current health values. RESULTS: Participants were predominantly male (89.8%) and Caucasian (75.9%), with a median age of 58.3 years and a median annual income of $15,000. Median values for current health were VAS, 0.75; SG, 0.80; TTO, 0.80; and WTP, $25,000. In the multivariate analysis, higher CSM values were associated with better current health as measured with the SG, TTO, and WTP (for all, P < 0.001); there was no association with VAS values (P = 0.157). CONCLUSIONS: Health values for CSM are positively associated with the current health of the study population.

Cost of Illness↗

PubMedDate not supplied

A clinically based discrete-event simulation of end-stage liver disease and the organ allocation process.

BACKGROUND: The optimal allocation of scarce donor livers is a contentious health care issue requiring careful analysis. The objective of this article was to design a biologically based discrete-event simulation to test proposed changes in allocation policies. METHODS: The authors used data from multiple sources to simulate end-stage liver disease and the complex allocation system. To validate the model, they compared simulation output with historical data. RESULTS: Simulation outcomes were within 1% to 2% of actual results for measures such as new candidates, donated livers, and transplants by year. The model overestimated the yearly size of the waiting list by 5% in the last year of the simulation and the total number of pretransplant deaths by 10%. CONCLUSION: The authors created a discrete-event simulation model that represents the biology of end-stage liver disease and the health care organization of transplantation in the United States.

Adolescent↗

PubMedDate not supplied

A methodological framework for optimally reorganizing liver transplant regions.

BACKGROUND: The United States is divided currently into 11 transplant regions, which vary in area and number of organ procurement organizations (OPOs). Region size affects organ travel time and organ viability at transplant. PURPOSE: To develop a methodologic framework for determining optimal configurations of regions maximizing transplant allocation efficiency and geographic parity. METHODS: An integer program was designed to maximize a weighted combination of 2 objectives: 1) intraregional transplants, 2) geographic parity-maximizing the lowest intraregional transplant rate across all OPOs. Two classes of functions relating liver travel time to liver viability were also examined as part of the sensitivity analyses. RESULTS: Preliminary results indicate that reorganizing regions, while constraining their number to 11, resulted in up to 17 additional transplants/year depending on the travel-viability function; when not constrained, it resulted in up to 18/year of increase. CONCLUSION: Our analysis indicates that liver transplantation may benefit through region reorganization. The analytic method developed here should be applicable to other organs and sets of organs.

Humans↗