The sensitivity of conditional choice models for hospital care to estimation technique

Difference in bypass for inpatient care and its determinants between rural and urban residents in China

Background

Bypass for inpatient care is an event of excessive demand. Though primary care facilities provide inpatient care in China, local residents may choose more distant higher-level hospital for inpatient care services. Given the differences in accessibility of hospitals and socioeconomic development between urban and rural areas, this study aims to estimate the rate of bypass for inpatient care and explore the factors predictive of bypass among rural and urban residents in China.

Methods

The rates of bypass for inpatient care were estimated using data from 1352 hospitalized patients, obtained from the 2018 Sixth National Health Service Survey of Hubei, China. Bypass for inpatient care was identified if the patient was hospitalized in a hospital for a certain disease that should be treated at primary care facilities in accordance with government requirement. Anderson’s Behavioral Model of Health Services Use was used as a theoretical framework for determining the factors of bypass. Logistic regression was used to identify the relationship between bypass for inpatient care and predisposing, enabling, and need characteristics for urban and rural residents.

Results

The rate of bypass for inpatient care was 73.8%. This rate for inpatient care (91.3%) in cities is higher than that in rural areas (56.2%). Age were associated with bypass for both rural (OR, 0.982; 95% CI, 0.969–0.995) and urban (OR, 0.947; 95% CI, 0.919–0.976) patients. The patients whose closest healthcare facility was hospitals were more likely to have bypass behavior in rural (OR, 26.091; 95% CI, 7.867–86.537) and urban (OR, 8.323; 95% CI, 2.936–23.591) areas than those living closest to township/community health centers. Signing a family doctor was not helpful for retaining patients at primary care facility. Among rural patients, those with circulatory (OR, 2.378; 95% CI, 1.328–4.258), digestive (OR, 2.317; 95% CI, 1.280–4.192), or skin and bone (OR, 1.758; 95% CI, 1.088–2.840) system diseases were more likely to show bypass behavior than those with respiratory diseases.

Conclusions

Bypass for inpatient care is sizable, and urban residents have a higher bypass rate for inpatient care than rural residents in China. More actionable measures in strengthening and leading patients to primary care are needed. Gradual establishment of a referral system is recommended. Inpatient care for circulatory, digestive, or skin and bone system diseases may be prioritized to be improved at primary care facilities in rural China.

Informed Decision-making for Health Insurance Enrollment: Survey Study

Background

Health insurance enrollment is a difficult financial decision with large health impacts. Challenges such as low health insurance literacy and lack of knowledge about choosing a plan further complicate this decision-making process. Therefore, to support consumers in their choice of a health insurance plan, it is essential to understand how individuals go about making this decision.

Objective

This study aims to understand the sources of information used by individuals to support their employer-provided health insurance enrollment decisions. It seeks to describe how individual descriptive factors lead to choosing a particular type of information source.

Methods

An introduction was presented on health insurance plan selection and the sources of information used to support these decisions from the 1980s to the present. Subsequently, an electronic survey of 151 full-time faculty and staff members was conducted. The survey consisted of four sections: demographics, sources of information, health insurance literacy, and technology acceptance. Descriptive statistics were used to show the demographic characteristics of the 126 eligible respondents and to study the response behaviors in the remaining survey sections. Proportion data analysis was performed using the Cochran-Armitage trend test to understand the strength of the association between our variables and the types of sources used by the respondents.

Results

In terms of demographics, most of the respondents were women (103/126, 81.7%), represented a small household (1-2 persons; 87/126, 69%), and used their insurance 3-12 times a year (52/126, 41.3%). They assessed themselves as having moderate to high health insurance literacy and high acceptance of technology. The most selected and top-ranked sources were Official employer or state websites and Official Human Resources Virtual Benefits Counselor Alex. From our data analysis, we found that the use of official primary sources was constant across age groups and health insurance use groups. Meanwhile, the use of friends or family as a primary source slightly decreased as age and use increased.

Conclusions

In this exploratory study, we identified the main sources of health insurance information among full-time employees from a large state university and found that most of the respondents needed 2-3 sources to gather all the information that they desired. We also studied and identified the relationships between individual factors (such as age, gender, and literacy) and 2 dependent variables on the types of primary sources of information. We encountered several limitations, which will be addressed in future studies.

Healthcare-Seeking Behavior among Chinese Older Adults: Patterns and Predictive Factors

This study aimed to investigate the patterns and predictive factors of healthcare-seeking behavior among older Chinese adults. A sample of 10,914 participants aged ≥60 years from the 2011, 2013 and 2015 China Health and Retirement Longitudinal Study (CHARLS) was included. The bivariate analyses and Heckman selection model was used to identify predictors of healthcare-seeking behavior. Results shows that the utilization rate of outpatient services increased from 21.61% in 2011 to 32.41% in 2015, and that of inpatient services increased from 12.44% to 17.68%. In 2015, 71.93% and 92.18% chose public medical institutions for outpatient and inpatient services, 57.63% and 17.00% chose primary medical institutions. The individuals who were female, were younger, lived in urban, central or western regions, had medical insurance, had poor self-rated health and exhibited activity of daily living (ADL) impairment were more inclined to outpatient and inpatient services. Transportation, medical expenses, the out-of-pocket ratio and the urgency of the disease were associated with provider selection. The universal medical insurance schemes improved health service utilization for the elderly population but had little impact on the choice of medical institutions. The older adults preferred public institutions to private institutions, preferred primary institutions for outpatient care, and higher-level hospitals for hospitalization.

Impacts of Geographic Distance on Peritoneal Dialysis Utilization: Refining Models of Treatment Selection

OBJECTIVE

To examine the relationship between distance to dialysis provider and patient selection of dialysis modality, informed by the absolute distance from a patient's home and relative distance of alternative modalities.

DATA SOURCES

U.S. Renal Data System.

STUDY DESIGN

About 70,131 patients initiating chronic dialysis and 4,795 dialysis facilities in 2006. The primary outcome was patient utilization of peritoneal dialysis (PD). Independent variables included absolute distance between patients' home and the nearest hemodialysis (HD) facility, relative distance between patients' home and nearest PD versus nearest HD facilities, and their interaction. Logistic regression was used to model distance on PD use, controlling for patient and market characteristics.

PRINCIPAL FINDINGS

Nine percent of incident dialysis patients used PD in 2006. There was a positive, nonlinear relationship between absolute distance to HD services and PD use (p < .0001), with the magnitude of the effect increasing at greater distances. In terms of relative distance, odds of PD use increased if a PD facility was closer or the same distance as the nearest HD facility (p = .006). Interaction of distance measures to dialysis facilities was not significant.

CONCLUSIONS

Analyses of patient choice between alternative treatments should model distance to reflect all relevant dimensions of geographic access to treatment options.

Spatial access to residential care resources in Beijing, China

BACKGROUND

As the population is ageing rapidly in Beijing, the residential care sector is in a fast expansion process with the support of the municipal government. Understanding spatial accessibility to residential care resources by older people supports the need for rational allocation of care resources in future planning.

METHODS

Based on population data and data on residential care resources, this study uses two Geographic Information System (GIS) based methods--shortest path analysis and a two-step floating catchment area (2SFCA) method to analyse spatial accessibility to residential care resources.

RESULTS

Spatial accessibility varies as the methods and considered factors change. When only time distance is considered, residential care resources are more accessible in the central city than in suburban and exurban areas. If care resources are considered in addition to time distance, spatial accessibility is relatively poor in the central city compared to the northeast to southeast side of the suburban and exurban areas. The resources in the northwest to southwest side of the city are the least accessible, even though several hotspots of residential care resources are located in these areas.

CONCLUSIONS

For policy making, it may require combining various methods for a comprehensive analysis. The methods used in this study provide tools for identifying underserved areas in order to improve equity in access to and efficiency in allocation of residential care resources in future planning.

Channeling consumers to preferred providers and the impact of status quo bias: does type of provider matter?

CONTEXT

To effectively bargain about the price and quality of health services, health insurers need to successfully channel their enrollees. Little is known about consumer sensitivity to different channeling incentives. In particular, the impact of status quo bias, which is expected to differ between different provider types, can play a large role in insurers' channeling ability.

OBJECTIVE

To examine consumer sensitivity to channeling strategies and to analyze the impact of status quo bias for different provider types.

DATA SOURCES/STUDY DESIGN

With a large-scale discrete choice experiment, we investigate the impact of channeling incentives on choices for pharmacies and general practitioners (GPs). Survey data were obtained among a representative Dutch household panel (n = 2,500).

PRINCIPAL FINDINGS

Negative financial incentives have a two to three times larger impact on provider choice than positive ones. Positive financial incentives have a relatively small impact on GP choice, while the impact of qualitative incentives is relatively large. Status quo bias has a large impact on provider choice, which is more prominent in the case of GPs than in the case of pharmacies.

CONCLUSION

The large impact of the status quo bias makes channeling consumers away from their current providers a daunting task, particularly in the case of GPs.

Why do general practitioners abandon the local hospital? An analysis of referral decisions related to elective treatment

AIM

The right to choose a hospital was granted to Norwegian elective patients through the Patients' Rights Act of 2001. The Act assumes that hospital choice will be executed by patients and general practitioners (GPs) at the point of referral. This study examined the probability of referring patients away from the nearest hospitals for three common elective diagnoses: hip replacement, knee surgery, and back pain treatment.

METHODS

Data describing referral rates and individual characteristics with the GP were collected by a self-administered questionnaire to Norwegian GPs in 2004 and 2006. These were combined with data on interactions between the GP and the local hospital from a database describing the hospital's internal organisation, variables describing needs (demand) at local government level from Statistics Norway, variables describing waiting times from the Norwegian Patient Register, and variables describing travelling distances to the nearest hospital and hospital characteristics. The probability of referring patients away from the nearest hospital was analysed using a cross-section regression model with fixed effects for region, years, and hospital type.

RESULTS

GPs were on average more reluctant to send patients away for hip surgery and back pain than they were for knee surgery. Formal coordinative mechanisms between the hospitals and the GPs - meeting places and arenas for information exchange - significantly reduced the likelihood of referring patients away from the local hospital. Long waiting times and long distances to the local hospital also increased the probability of abandoning the local hospital.

CONCLUSION

Hospital managers could attract elective patients by developing arenas for communication and collaboration with local GPs.

Assessing hospital competition when prices don't matter to patients: the use of time-elasticities

Health care reforms in several European countries provide health insurers with incentives and tools to become prudent purchasers of health care. The potential success of this strategy crucially depends on insurers' bargaining leverage vis-à-vis health care providers. An important determinant of insurers' bargaining power is the willingness of consumers to consider alternative providers. In this paper we examine to what extent consumers are willing to switch hospitals when they are fully covered for hospital services, which is typical for many European countries. Since prices do not matter to these patients, we estimate time-elasticities to assess hospital substitutability. Using data from a large Dutch health insurer on non-emergency neurosurgical outpatient hospital visits in 2003, we estimate a conditional logit model of patient hospital choice taking both patient heterogeneity and hospital characteristics into account. We use the parameter estimates to simulate the demand effect of an artificial increase in travel time by 10% for every patient, holding all other hospital attributes constant. Overall, the resulting point estimates of hospitals' time-elasticities are fairly high, although variation is substantial (-2.6 to -1.4). Sensitivity tests reveal that these estimates are very robust and differ significantly across individual hospitals. This implies that all hospitals in our study sample have at least one close substitute which is an important precondition for effective hospital competition.

Determinants of hospital choice of rural hospital patients: the impact of networks, service scopes, and market competition

Among 10,384 rural Colorado female patients who received MDC 14 (obstetric services) from 2000 to 2003, 6,615 (63.7%) were admitted to their local rural hospitals; 1,654 (15.9%) were admitted to other rural hospitals; and 2,115 (20.4%) traveled to urban hospitals for inpatient services. This study is to examine how network participation, service scopes, and market competition influences rural women's choice of hospital for their obstetric care. A conditional logistic regression analysis was used. The network participation (p < 0.01), the number of services offered (p < 0.05), and the hospital market competition had a positive and significant relationship with patients' choice to receive obstetric care. That is, rural patients prefer to receive care from a hospital that participates in a network, that provides more number of services, and that has a greater market share (i.e., a lower level of market competition) in their locality. Rural hospitals could actively increase their competitiveness and market share by increasing the number of health care services provided and seeking to network with other hospitals.

Steering patients to safer hospitals? The effect of a tiered hospital network on hospital admissions

OBJECTIVE

To determine if a tiered hospital benefit and safety incentive shifted the distribution of admissions toward safer hospitals.

DATA SOURCES/STUDY SETTING

A large manufacturing company instituted the hospital safety incentive (HSI) for union employees. The HSI gave union patients a financial incentive to choose hospitals that met the Leapfrog Group's three patient safety "leaps." The analysis merges data from four sources: claims and enrollment data from the company, the American Hospital Association, the AHRQ HCUP-SID, and a state Office of the Insurance Commissioner.

STUDY DESIGN

Changes in hospital admissions' patterns for union and nonunion employees using a difference-in-difference design. We estimate the probability of choosing a specific hospital from a set of available alternatives using conditional logistic regression.

PRINCIPAL FINDINGS

Patients affiliated with the engineers' union and admitted for a medical diagnosis were 2.92 times more likely to select a hospital designated as safer in the postperiod than in the preperiod, while salaried nonunion (SNU) patients (not subject to the financial incentive) were 0.64 times as likely to choose a compliant hospital in the post- versus preperiod. The difference-in-difference estimate, which is based on the predictions of the conditional logit model, is 0.20. However, the machinists' union was also exposed to the incentive and they were no more likely to choose a safer hospital than the SNU patients. The incentive did not have an effect on patients admitted for a surgical diagnosis, regardless of union status. All patients were averse to travel time, but those union patients selecting an incentive hospital were less averse to travel time.

CONCLUSIONS

Patient price incentives and quality/safety information may influence hospital selection decisions, particularly for medical admissions, though the optimal incentive level for financial return to the plan sponsor is not clear.

Payer type and the returns to bypass surgery: evidence from hospital entry behavior

In this paper, we estimate the returns associated with the provision of coronary artery bypass graft (CABG) surgery, by payer type (Medicare, HMO, etc.). Because reliable measures of prices and treatment costs are often unobserved, we seek to infer returns from hospital entry behavior. We estimate a model of patient flows for CABG patients that provides inputs for an entry model. We find that FFS provides a high return throughout the study period. Medicare, which had been generous in the early 1980s, now provides a return that is close to zero. Medicaid appears to reimburse less than average variable costs. HMOs essentially pay at average variable costs, though the return varies inversely with competition.

The impact of health plan report cards on managed care enrollment

How does the release of health plan performance ratings influence employee health plan choice? A natural experiment at General Motors (GM) Corporation provides valuable evidence on this question. During the 1997 open enrollment period, GM disseminated a health plan report card for the first time. By comparing 1996 and 1997 enrollment patterns, our analysis estimates the impact of the report card information while accounting for fixed, unobserved plan traits. Results indicate that employees are less likely to enroll in plans requiring relatively high out-of-pocket contributions. Results with respect to report card ratings suggest that individuals avoid health plans with many below average ratings.

Provider choice and utility loss due to selective contracting in rural and urban areas

An econometric model estimated the disutility of traveling long distances for depression treatment, and simulations calculated the utility loss associated with selective contracting in rural and urban areas. A representative sample of depression patients (n = 106) and all practicing providers (n = 3,710) in Arkansas were identified and the distances between them were calculated. Using discrete choice analysis, patient preferences for provider type and travel distance were estimated. Simulations calculated the utility loss associated with alternative scenarios of selective contracting. Provider type and distance were significant predictors of provider choice. To equate the utility loss associated with selective contracting in rural and urban areas, a slightly higher proportion of rural physicians and a substantially higher proportion of rural mental health specialists must be contracted. To avoid further reductions in geographic access, managed care organizations should contract with a higher proportion of rural providers than urban providers.

Selection of a cardiac surgery provider in the managed care era

OBJECTIVE

Many health planners promote the use of competition to contain cost and improve quality of care. Using a standard econometric model, we examined the evidence for "value-based" cardiac surgery provider selection in eastern Massachusetts, where there is significant competition and managed care penetration.

METHODS

McFadden's conditional logit model was used to study cardiac surgery provider selection among 6952 patients and eight metropolitan Boston hospitals in 1997. Hospital predictor variables included beds, cardiac surgery case volume, objective clinical and financial performance, reputation (percent out-of-state referrals, cardiac residency program), distance from patient's home to hospital, and historical referral patterns. Subgroup analyses were performed for each major payer category.

RESULTS

Distance from patient's home to hospital (odds ratio 0.90; P =.000) and the historical referral pattern from each patient's hometown (z = 45.305; P =.000) were important predictors in all models. A cardiac surgery residency enhanced the probability of selection (odds ratio 5.25; P =.000), as did percent out-of-state referrals (odds ratio 1.10; P =.001). Higher mortality rates were associated with decreased probability of selection (odds ratio 0.51; P =.027), but higher length of stay was paradoxically associated with greater probability (odds ratio 1.72; P =.000). Total hospital costs were irrelevant (odds ratio 1.00; P =.179). When analyzed by payer subgroup, Medicare patients appeared to select hospitals with both low mortality (odds ratio 0.43; P =.176) and short length of stay (odds ratio 0.76; P =.213), although the results did not achieve statistical significance. The commercial managed care subgroup exhibited the least "value-based" behavior. The odds ratio for length of stay was the highest of any group (odds ratio = 2.589; P =.000) and there was a subset of hospitals for which higher mortality was actually associated with greater likelihood of selection.

CONCLUSIONS

The observable determinants of cardiac surgery provider selection are related to hospital reputation, historical referral patterns, and patient proximity, not objective clinical or cost performance. The paradoxic behavior of commercial managed care probably results from unobserved choice factors that are not primarily based on objective provider performance.

Modeling cross-border care in the EU using a principal-agent framework

Cross-border care is likely to become a major issue among EU countries because patients have the option of obtaining treatment abroad under Community Regulations 1408/71. This paper develops a model formalizing both the patient's decision to apply for cross-border care and the authorizing physician's decision to admit a patient to the program. The patient is assumed to maximize expected utility, which depends on the quality of care and the length of waiting in the home country and the host country, respectively. Not all patients qualifying for the EU program present themselves to the authorizing physician because of the transaction cost involved. The physician in her turn shapes effective demand for authorization through her rate of refusal, which constitutes information to potential applicants about the probability of obtaining treatment abroad. The authorizing physician thus acts as an agent serving two principals, her patient and her national government, trading off the perceived utility loss of patients who are rejected against her commitment to domestic health policy. The model may be used to explain existing patient flows between EU countries.

Hospital choice of Medicare beneficiaries in a rural market: why not the closest?

As part of a larger study of hospital choice, the travel patterns of more than 12,000 Medicare beneficiaries residing in three overlapping rural areas were examined. During 1986 these Medicare beneficiaries were admitted to one of 53 hospitals in an area that encompassed parts of Minnesota, North Dakota, and South Dakota. Information on ZIP code of residence, closest hospital, and hospital of admission were used to analyze hospital choices of the Medicare rural elderly residing in this area. To summarize their travel patterns, the admitting hospital was categorized based on whether it was urban or rural, its size and whether or not it was the closest facility. Findings indicated that 60 percent of these rural Medicare beneficiaries used hospital services at their closest rural hospital, regardless of its size. However, 79 percent of those whose closest hospital was larger than 75 beds used it, while only 54 percent of those whose closest rural hospital was fewer than 75 beds obtained services there. Overall, 30 percent of those residing in this rural market area went to an urban hospital. These patterns appeared to reflect an evaluation by the physician and/or individual of the relative attractiveness of the local hospital versus alternatives available, as well as the individual's characteristics. Travel patterns varied by the beneficiary's age as well as his or her relative complexity of illness, as measured by a Disease Staging methodology. Findings have implications for the provision and financing of hospital services in rural areas.

Health maintenance organization penetration and the practice location choices of new physicians: a study of large metropolitan areas in the United States

OBJECTIVES

The rapid growth of health maintenance organizations is reshaping the practice opportunities available to physicians. The practice location decisions of new physicians provide a sensitive bellwether of these changes. This study assessed the effect of health maintenance organization penetration on practice location for physicians completing graduate medical education (GME).

METHODS

Conditional logit regression analysis was used to determine the effect of health maintenance organization penetration on practice location, controlling for other market characteristics. Subjects were physicians who finished GME between 1989 and 1994 and who located in one of the 98 US metropolitan areas with more than 500,000 population. The outcome measure was the particular metropolitan area chosen by each new physician.

RESULTS

Early in the study period, new generalists were significantly more likely to locate in metropolitan areas with high health maintenance organization penetration than in low penetration areas, whereas new specialists' practice location choices were not associated with health maintenance organization penetration. The likelihood of choosing a high penetration relative to a low penetration area declined with time, however, for both generalists and specialists. Consequently, by the end of the study period, health maintenance organization penetration had a weak but significant negative effect on practice location for generalists and a strong negative influence on practice location for specialists.

CONCLUSIONS

New generalists who completed graduate medical education between 1989 and 1994 were more likely than new specialists to locate in market areas with high health maintenance organization penetration; however, the proportions of both generalists and specialists who chose high penetration areas decreased during the study period. This finding may reflect reduced practice opportunities in high penetration areas relative to low penetration areas as health maintenance organizations' systems for controlling utilization began to yield results. Alternatively, new physicians may have become more hesitant to accept available positions in high penetration areas.

Consumer health plan choice: current knowledge and future directions

A keystone of the competitive strategy in health insurance markets is the assumption that "consumers" can make informed choices based on the costs and quality of competing health plans, and that selection effects are not large. However, little is known about how individuals use information other than price in the decision making process. This review summarizes the state of knowledge about how individuals make choices among health plans and outlines an agenda for future research. We find that the existing literature on health plan choice is no longer sufficient given the widespread growth and acceptance of managed care, and the increased proportion of consumers' income now going toward the purchase of health plans. Instead, today's environment of health plan choice requires better understanding of how plan attributes other than price influence plan choice, how other variables such as health status interact with plan attributes in the decision making process, and how specific populations differ from one another in terms of the sensitivity of their health plan choices to these different types of variables.

Specialized service offerings and patients' choice of hospital: the case of cardiac catheterization

Patients' choice of hospital is modeled as a function of their expectation of needing a specialized service (option demand). The estimation tests whether cardiac patients' choice of hospital responds to changes over time in the availability of a specialized cardiac service. Results suggest that availability of cardiac catheterization has a strong, significant effect on the choice of hospital, even after controlling for other quality characteristics. However, the effect appears confined to those patients whose diagnosis indicates some probability of needing the service. Patients with no 'option demand' do not appear to use specialized services as a signal of quality.

Correlation of travel time on roads versus straight line distance

Studies of hospital demand and choice of hospital have used straight line distance from a patient's home to hospitals as a measure of geographic access, but there is the potential for bias if straight line distance does not accurately reflect travel time. Travel times for unimpeded travel between major intersections in upstate New York were compared with distances between these points. The correlation between distance and travel time was 0.987 for all observations and 0.826 for distances less than 15 miles. These very high correlations indicate that straight line distance is a reasonable proxy for travel time in most hospital demand or choice models, especially those with large numbers of hospitals. The authors' outlier analyses show some exceptions, however, so this relationship may not hold for studies focusing on specific hospitals, very small numbers of hospitals, or studies in dense urban areas with high congestion and reliance on surface streets.

Hospital choice models: a review and assessment of their utility for policy impact analysis

The changing competitive hospital environment and recent greater availability of patient origin data have stimulated an increased research interest in factors influencing the reason patients are admitted to one hospital over another. Hospital marketers and managed care planners seek information for attracting patients and for negotiating hospital provider networks, respectively. Hospital choice models can help regulators make better informed assessments of the welfare implications of proposed mergers or closures. The literature shows the development of increasingly sophisticated models and techniques for analysis of hospital choice. Recent studies have also related the findings to health policy issues. This review summarizes the historical developments and the cumulative knowledge gained about hospital choice to date, identifies some key issues in need of greater attention, and assesses the potential strengths and limitations of contemporary choice models for making policy impact assessments.

The effect of distance to VA facilities on the choice and level of utilization of VA outpatient services

The 1987 survey of Veterans is used to explain the effects of distance to VA facilities on the choice and level of utilization of VA outpatient services by U.S. veterans. A two part discrete/continuous model is used to separate two elements of the decision to seek outpatient services from federally operated VA facilities. First, a discrete choice is made to seek care from the VA. Second, a continuous choice is made to seek a particular level of utilization. Distance is found to affect the initial discrete choice significantly for measured distances up to 60 miles at a decreasing rate. Once some VA outpatient contact is made, distance is a major factor only for the elderly in determining the amount of utilization. Disturbingly, elderly veteran users living more than 30-40 miles from the nearest VA are expected to make fewer visits in a year than younger veterans.

Border crossing for hospital care and its implications for the use of statewide data

A major concern of researchers using state data sets for population-based analyses and market share studies in the health care sector is the potential bias caused by 'border crossing'--patients receiving care out of state. By using the Health Care Financing Administration (HCFA) discharge abstract files for 1987 and 1988, we found that 'border crossing' is not a serious problem for the two large states we examined. Only 4.4% of New York patients and 2.15% of California patients received care out of state. At the county and zip code level, 'border crossing' is more frequent but tends to be concentrated in areas adjacent to other states. Even excluding all zips with more than 10% of patients crossing the 'border' results in a small loss of patients (2.2% for New York and 1.0% for California).

The impact of physician characteristics in conditional choice models for hospital care

Recent research has investigated the determinants of the specific hospitals to which patients are admitted. Data limitations have led researchers to examine the effects of patient and hospital characteristics while ignoring the role of physician characteristics. In this study we analyze the effects of all three sets of factors on hospital choice in the greater Phoenix area during 1989. Our results suggest that physician characteristics are strong determinants of hospital choice, accounting for much of the explained variation. Differences in hospital quality and cost, on the other hand, exert significant effects on hospital choice but explain relatively little variation.