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PubMed1996

Physical medicine and rehabilitation workforce study: the supply of and demand for physiatrists.

OBJECTIVE: Analysis, results, and implications of a supply and demand workforce model for physical medicine and rehabilitation. Explicit issues addressed include: (1) the supply implications of maintaining current (1994-1995) output of physiatrists from residency programs; (2) the implications of continued growth in managed care on the demand for the services of physiatrists; (3) likely future supply and demand conditions; and (4) strategies to adapt to future conditions. DESIGN: A workforce model of the supply and demand for physiatrists was developed. Parameters of the model are estimated using econometric models and by applying the judgments of a consensus panel. The model evaluated several different scenarios regarding managed care growth, competition from other providers and other factors. RESULTS: Based on the analysis, physiatrists will continue to be in excess demand through the year 2000. More aggressive growth in managed care can affect this result. CONCLUSIONS: Based on an overall assessment of supply and demand conditions, and under the assumption that the supply of new entrants each year remains in the range of 1994-1995 levels, demand for physiatrists will continue to exceed supply, on average, through the year 2000. Excess supply has, and will, emerge in selected geographic areas. If the profession is successful in informing the market regarding the advantages of physiatry, the profession can continue to grow without experiencing excess supply, in the aggregate, for the foreseeable future.

Forecasting↗
PubMed2006

Latent class models for utilisation of health care.

This paper explores different approaches to econometric modelling of count measures of health care utilisation, with an emphasis on latent class models. A new model is proposed that combines the features of the two most common approaches: the hurdle model and the finite mixture negative binomial. Additionally, the panel structure of the data is taken into account. The proposed finite mixture hurdle model is shown to fit the data substantially better than the existing models for a particular application to data from the RAND Health Insurance Experiment. The estimation results indicate a higher price effect for low users of health care. It is furthermore found that this results mainly from the difference of the price effects on the probability to visit a doctor, while the price effect on the conditional number of visits does not differ significantly between high and low users.

Health Services↗
PubMed1989

Econometric issues in modeling the costs of AIDS.

The goals of AIDS or HIV econometric modeling efforts are: (i) to evaluate or project the costs-of-illness to the individual and to society; and (ii) to examine the efficiency and cost-effectiveness of medical and social services provided to patients. Most of the standard theoretical and statistical approaches are not applicable because of the scarcity, incompleteness and non-representative nature of available data. This paper discusses specific methodological approaches concerning AIDS and HIV epidemiology, medical cost estimation techniques, evaluation of the cost-effectiveness of social support programs and valuation of human life. The epidemiologic projection approach--a simplified 'back calculation' method--suggests that the number of Americans infected with the AIDS virus in 1987-88 was likely to be between 500,000 and 800,000. This estimate is between 2 and 3 times lower than the U.S. Centers for Disease Control estimates. Methods for estimating both the direct and indirect costs of illness are described.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Forecasting hospital expenditure in Victoria: lessons from Europe and Canada.

This paper specifies an econometric model to forecast State government expenditure on recognised public hospitals in Victoria. The OECD's recent cross-country econometric work exploring factors affecting health spending was instructive. The model found that Victorian Gross State Product, population aged under 4 years, the mix of public and private patients in public hospitals, introduction of casemix funding and funding cuts, the proportion of public beds to total beds in Victoria and technology significantly impacted on expenditure. The model may have application internationally for forecasting health costs, particularly in short and medium-term budgetary cycles.

Adolescent↗
PubMed2003

Using simultaneous equation modeling for defining complex phenotypes.

BACKGROUND: Interactions between multiple biological phenotypes are difficult to model. Simultaneous equation modelling (SEM), as used in econometric modelling, may prove an effective tool for this problem. Generalized linear models were used to derive the structural equations defining the interactions between cholesterol, glucose, triglycerides and high-density lipoprotein cholesterol (HDL-C). These structural equations were then applied, using SEM, to Cohort 2 data (replicates 1-100) to estimate the phenotypic structure underlying the simulation. The goal was to determine if this empiric method of deriving structural equations for use in SEM was able to recover the simulation model better than generalized linear models. RESULTS: First, the underlying structural equations were estimated using generalized linear model techniques, which found strong a relationship between glucose, triglycerides and HDL-C. Using these structural equations, I used SEM to evaluate these relationships jointly. I found that a combination of the empiric structural equations and the SEM method was better at recovering the underlying simulated relationship between biologic measures than generalized linear modelling. CONCLUSION: The empiric SEM procedure presented here estimated different relationships between dependent variables than generalized linear modelling. The SEM procedure using empirically developed structural equations was able to recover the underlying simulation relationship partially and thus holds promise as a technique for complex phenotype analysis. Robust methods for determining the structural equations must be developed for application of SEM to population data.

Cardiovascular Diseases↗
PubMed2002

The estimation of a preference-based measure of health from the SF-36.

This paper reports on the findings of a study to derive a preference-based measure of health from the SF-36 for use in economic evaluation. The SF-36 was revised into a six-dimensional health state classification called the SF-6D. A sample of 249 states defined by the SF-6D have been valued by a representative sample of 611 members of the UK general population, using standard gamble. Models are estimated for predicting health state valuations for all 18,000 states defined by the SF-6D. The econometric modelling had to cope with the hierarchical nature of the data and its skewed distribution. The recommended models have produced significant coefficients for levels of the SF-6D, which are robust across model specification. However, there are concerns with some inconsistent estimates and over prediction of the value of the poorest health states. These problems must be weighed against the rich descriptive ability of the SF-6D, and the potential application of these models to existing and future SF-36 data set.

Activities of Daily Living↗
PubMed2004

Using simulation-based inference with panel data in health economics.

Panel datasets provide a rich source of information for health economists, offering the scope to control for individual heterogeneity and to model the dynamics of individual behaviour. However the qualitative or categorical measures of outcome often used in health economics create special problems for estimating econometric models. Allowing a flexible specification of the autocorrelation induced by individual heterogeneity leads to models involving higher order integrals that cannot be handled by conventional numerical methods. The dramatic growth in computing power over recent years has been accompanied by the development of simulation-based estimators that solve this problem. This review uses binary choice models to show what can be done with conventional methods and how the range of models can be expanded by using simulation methods. Practical applications of the methods are illustrated using data on health from the British Household Panel Survey (BHPS).

Bayes Theorem↗
PubMed2006

Does the profit motive make Jack nimble? Ownership form and the evolution of the US hospital industry.

We examine the evolving structure of the US hospital industry since 1970, focusing on how ownership form influences entry and exit behavior. We develop theoretical predictions based on the model of Lakdawalla and Philipson, in which for-profit and not-for-profit hospitals differ regarding their objectives and costs of capital. The model predicts for-profits would be quicker to enter and exit than not-for-profits in response to changing market conditions. We test this hypothesis using data for all US hospitals from 1984 to 2000. Examining annual and regional entry and exit rates, for-profit hospitals consistently have higher entry and exit rates than not-for-profits. Econometric modeling of entry and exit rates yields similar patterns. Estimates of an ordered probit model of entry indicate that entry is more responsive to demand changes for for-profit than not-for-profit hospitals. Estimates of a discrete hazard model for exit similarly indicate that negative demand shifts increase the probability of exit more for for-profits than not-for-profits. Finally, membership in a hospital chain significantly decreases the probability of exit for for-profits, but not not-for-profits.

Efficiency, Organizational↗
PubMedDate not supplied

SSI eligibility and participation among the oldest old: evidence from the AHEAD.

The proportion of elderly SSI recipients aged 70 or older has been growing in recent years, perhaps because of rising life expectancies overall and a higher incidence of poverty among the oldest old. In 1999, 84 percent of all elderly SSI recipients were 70 or older. This article examines Supplemental Security Income (SSI) eligibility and participation among the oldest old. The analysis was based on 1993 data from the Study of Assets and Health Dynamics Among the Oldest Old that were used to build a detailed SSI eligibility model to identify individuals who meet the federal criteria for SSI income and resource eligibility. The participation rate among those eligible for federal SSI benefits is 53.9 percent, which is generally consistent with the findings of other studies. Furthermore, eligible participants would receive a significantly higher federal SSI benefit than eligible nonparticipants. Correspondingly, eligible participants have significantly lower incomes and assets than eligible nonparticipants. An econometric model is used to estimate the influence of various demographic, financial, and health care use characteristics on the probability of SSI participation among eligible individuals and couples. The model corrects for measurement error in calculated benefits and for misclassifying someone as ineligible. The empirical results show that the effect of higher SSI benefits on the probability of participation is substantial--a $100 increase in benefits would increase the probability of participating for an average eligible unit by 15 percentage points. Many of the demographic, financial, and health care use variables also are important predictors of SSI participation among the oldest old. The eligibility and participation models are also used to simulate the effect of increasing the SSI unearned income disregard from $20 to $125. Those made eligible by this policy change would receive a very low federal SSI benefit on average, suggesting that they are on the margin of eligibility under the original program rules. The simulated participation rate is 48.8 percent--5 percentage points lower than under the original program rules--reflecting the low benefit that new eligibles would receive. Only 36 percent of those made eligible by the new program rules are predicted to participate. These SSI eligibility and participation models are potentially useful tools for policy analysis. It is fairly straightforward to use these models to change a feature of SSI eligibility, reestimate the group of eligible individuals and couples, and predict participation among those who are eligible under the simulated program rules. New eligibles can be compared with those eligible under original program rules. New participants can be compared with old participants. Although these models focus only on individuals aged 70 or older, this type of analysis can be helpful in estimating the potential distributional effects of proposed SSI policy changes.

Aged↗
PubMed1999

The gatekeeper model is inefficient for the delivery of dermatologic services.

BACKGROUND: Gatekeeper-paradigm managed care systems may discourage the use of dermatologists in the management of skin conditions by limiting direct access. This may limit the quality of care patients with skin disorders receive and may be an inefficient use of medical resources. OBJECTIVE: The purpose of this study was to determine the likelihood that patients with dermatologic conditions who see a primary care provider will be referred to a dermatologist. METHODS: Data on the disposition of outpatient visits to primary care physicians for one and only one dermatologic diagnosis were obtained from the 1990-1994 National Ambulatory Medical Care Survey. These data were used in an econometric model to estimate the likelihood of referral to a dermatologist for an episode of care. RESULTS: Of all visits for a single dermatologic diagnosis, 39% were to primary care physicians. The disposition of referral was more common for these dermatology-related visits than for all office visits to primary care physicians (5.8% vs 4.5%, P < .001). The most frequent diagnoses associated with referral were common dermatologic problems, not rare disorders. The number of visits per episode of care was highly dependent on the assumptions of the analysis, resulting in estimate ranges for referral rates per episode between 6.8% and 18.5% for pediatricians, 8.2% and 23% for family and general practitioners, and 16.6% and 46.5% for internists. CONCLUSION: The relative difficulty for primary care providers of managing skin problems is reflected by their frequent need to refer patients with common skin problems and by the greater likelihood of referral for skin disorders than for other medical conditions. The high rates of referral per episode of care supports the cost-effectiveness of direct access to dermatologists.

Costs and Cost Analysis↗
PubMed2006

Surviving the perfect storm: an RVU-based model to evaluate the continuing impact of MMA on the practice of oncology.

The Resource-Based Relative Value Scale (RBRVS) system instituted by Centers for Medicare and Medicaid Services has lead to the implementation of a new financial analysis paradigm based on relative value units (RVUs). RVU-based financial tools have great potential to allow in-depth analysis of all components of the cancer care delivery system. Because all medical oncology practices must become conversant in RVU terminology and methodology, RVU-based financial tools will allow standardization and benchmarking for intra- and interpractice comparisons. Understanding this approach is essential for sound business management. The emotional and financial pressures facing the medical oncologist in private practice are enormous, with no real relief in sight. The complexity of managing the business of private practice oncology rivals that of managing the complexity of cancer care. With anticipated reductions in total net revenue per clinical treatment protocol per course of care, funds available for providers and their practices will be severely reduced. Only those practices with superlative RVU-based cost and revenue accounting systems will be able to prospectively and efficiently manage their businesses. Clearly, management of the Oncology Practice Econometric Model (OPEM) expense RVU or similar RVU-based data will be required for survival. The purpose of this article is to explore an RVU-based model to analyze the professional, infusion, and therapeutic components of contemporary cancer care.

Accounting↗
PubMed1982

A model of the demand for medical and health services in Peninsular Malaysia.

This paper provides an empirical analysis of the determinants of the demand for medical services in Peninsular Malaysia. After elaborating a theoretical model of household demand for medical care in Section II an econometric model is specified and estimated in Sections III, IV, and V. The results indicate that total medical demand, as measured by the absolute volume of outpatient and inpatient consumption, is highly inelastic to the cash price and to the cost in time of utilization. Total medical demand is also inelastic with respect to income. Yet consumers are clearly responsive to the relative prices of alternative sources of medical care. Consumers are also sensitive to the way in which the time of utilization is spent, with high travel and treatment time causing reduced demand for services.

Costs and Cost Analysis↗
PubMed1998

Much ado about two: reconsidering retransformation and the two-part model in health econometrics.

In health economics applications involving outcomes (y) and covariates (x), it is often the case that the central inferential problems of interest involve E[y/x] and its associated partial effects or elasticities. Many such outcomes have two fundamental statistical properties: y > or = 0; and the outcome y = 0 is observed with sufficient frequency that the zeros cannot be ignored econometrically. This paper (1) describes circumstances where the standard two-part model with homoskedastic retransformation will fail to provide consistent inferences about important policy parameters; and (2) demonstrates some alternative approaches that are likely to prove helpful in applications.

Data Interpretation, Statistical↗
PubMed1998

Alcohol and all-cause mortality in Europe 1982-1990: a pooled cross-section time-series analysis.

AIM: To test the relationship between alcohol consumption and all-cause mortality. DESIGN DATA: Yearly mortality rates and per capita consumption from 25 European countries between 1982 and 1990. STATISTICAL MODELS: This paper employs time-series cross-sectional data to model the relationships between alcohol consumption and all-cause mortality. The data are derived from 25 European countries in the 1980s. The statistical analyses controlling cross-sectional correlation and timewise autoregression were used to implement the econometric modelling. FINDINGS: Increases (decreases) in the per capita consumption of 1 litre of pure alcohol were associated with increases (decreases) of 1.3% in all-cause mortality rates. The beverage-specific analyses indicated a significant relationship between consumption of beer and all-cause mortality only. CONCLUSION: The data show that per capita alcohol consumption, according to reported levels in Europe, is related to all-cause mortality and is thus of relevance to public health.

Alcohol Drinking↗
PubMed2004

Physicians' perceptions towards the impact of and willingness to pay for clinical computerization in Hong Kong.

BACKGROUND AND OBJECTIVES: We evaluated factors associated with physicians' perceptions towards the effects of computers on health care and on current levels of computerization in their practice. We also performed a contingent valuation to quantify physicians' perceived benefits from computerization in a hypothetical ambulatory, solo clinic. METHODS: We surveyed 949 representative physicians in Hong Kong by post. Factor analysis was performed to summarize similar items into categories. Multivariable log-linear regression models were employed to assess the relationships between different factor scores and the number of functions computerized. We elicited their willingness-to-pay (WTP) for three defined computer systems using contingent valuation techniques. WTP values were estimated using econometric modeling by both, parametric and geometric methods. Sociodemographic, attitudinal, and practice-related predictors of WTP were estimated through regression analyses. RESULTS: Factor analysis revealed a three-factor solution which explained 53% of total variance. The overall mean score (mean = 3.51 +/- 0.45) showed a generally positive attitude towards the effects of computers on health care. Respondents with a higher level of computer knowledge had significantly higher mean overall (P = 0.002) and factor scores for all three factors (P < 0.01). Higher factor scores on the effects of computers on patient care and clinicians (P = 0.006) and on the health system (P = 0.032) were associated with a higher number of functions computerized. The parametric median WTP values for computerizing administrative, clinical, and both sets of functions were HK dollars 21205 (US dollars 2719), HK dollars 34231 (US dollars 4389), and HK dollars 45720 (US dollars 5862), respectively, which were lower than the estimates obtained from demand curves using the geometric method [HK dollars 43286 (US dollars 5549), HK dollars 59570 (US dollars 7637), and HK dollars 84623 (US dollars 10849), respectively]. Doctors with higher incomes were willing to pay more to computerize the clinic, with strong dose-response gradients demonstrated. Those who worked in corporate settings were also more likely to accept higher WTP values. CONCLUSIONS: Our findings confirm that better knowledge about computers is contributory to a more positive attitude towards the effects of computers on health care, which is in turn significantly associated with higher levels of actual computerization in clinical practice. WTP values represent the likelihood, in monetary terms, of translating doctors' perceived benefits from computerization into investment action.

Adult↗
PubMed1997

Monitoring patients with diabetes mellitus: an application of the probit model using managed care claims data.

The primary objective of this study was to estimate the likelihood of the use of either a glycosylated hemoglobin (HbA1c) test or an eye examination, or both, among a cohort of patients diagnosed with diabetes mellitus. A secondary objective was to provide a step-by-step discussion of the applicability of an econometric model to managed care organizations. The study used medical and pharmacy claims data from a managed care organization for the calendar year 1995. A probit regression model was specified to estimate the probability of occurrence for either an HbA1c test or an eye examination among patients with insulin-dependent, non-insulin dependent, or atypical/unclassified diabetes. Data were available only for patients under 65 years of age due to data truncation for patients covered by Medicare, resulting in a study sample size of 6,841. Results indicate that age, presence of hypertension, hyperlipidemia, multiple cardiovascular comorbidities, ophthalmic disease, and combinations of multiple commonly observed comorbidities were positively correlated with the probability of either HbA1c testing or eye examination. Gender and the type of benefit plan were not statistically significant as predictors of disease monitoring. A total of 1,860 patients with diabetes mellitus were predicted by the model to have undergone one of the two monitoring procedures; but in actuality, these patients were not monitored in 1995. They could be considered as high-risk patients who were not getting recommended monitoring. The probit model shows a predictive power of 64.48%.

Adult↗
PubMed2003

A critique of the World Health Organisation's evaluation of health system performance.

The World Health Organisation's (WHO) approach to the measurement of health system efficiency is briefly described. Four arguments are then presented. First, equity of finance should not be a criterion for the evaluation of a health system and, more generally, the same objectives and importance weights should not be imposed upon all countries. Secondly, the numerical value of the importance weights do not reflect their true importance in the country rankings. Thirdly, the model for combining the different objectives into a single index of system performance is problematical and alternative models are shown to alter system rankings. The WHO statistical analysis is replicated and used to support the fourth argument which is that, contrary to the author's assertion, their methods cannot separate true inefficiency from random error. The procedure is also subject to omitted variable bias. The econometric model for all countries has very poor predictive power for the subset of OECD countries and it is outperformed by two simpler algorithms. Country rankings based upon the model are correspondingly unreliable. It is concluded that, despite these problems, the study is a landmark in the evolution of system evaluation, but one which requires significant revision.

Delivery of Health Care↗