Procedures for estimating growth rates in thoracic aortic aneurysms

Thoracic aortic aneurysms (TAAs) are potentially lethal medical conditions often requiring surgical intervention. Reliable information on TAA growth rates and associated risk factors is important for managing this challenging patient population. Unfortunately, a number of studies have employed questionable statistical methods, leading to biased and imprecise estimates. The present study describes these statistical problems in existing studies and delineates procedures for obtaining more reliable results. Using data from the Yale Center for Thoracic Aortic Disease, the study compares TAA growth rate estimates using conventional methods versus the recommended approach of instrumental variables (IV) estimation. The IV approach is designed to mitigate problems of measurement errors inherent in existing estimates of TAA growth. The results demonstrate that IV estimation yields more robust and precise estimates of TAA growth rates and risk factors for TAA growth. For example, the conventional approach yields TAA growth rates that fluctuate substantially-from 0.12 cm/yr to 0.90 cm/yr-depending on (1) the minimum serial follow-up period for patient inclusion in the study and (2) how subjects with negative measured growth rates are handled. In contrast, growth rate estimates using the IV approach are much more robust, ranging from 0.12 to 0.13 cm/yr. The 95% confidence intervals of estimated TAA growth are much more compact using the IV approach as well. We conclude that the IV estimation procedure yields more reliable estimates of TAA growth than does the conventional approach.

Health care utilization and costs in a Medicare population by fall status

OBJECTIVES

The economic impact of trauma in older persons is a matter of increasing concern to public health practitioners and planners, yet it is an issue that has not been widely studied. Available evidence does suggest, however, that falls are the costliest category of injury among older persons.

METHODS

This study used data from the Health Care Financing Administration and the Connecticut Long-Term Care Registry to isolate the effects of fall severity on hospital, nursing home, home health, and emergency room costs. Multivariate and logistic regression methods were used to control for the influence of a number of clinical and demographic factors believed to be independently related to health care costs. Health care costs of fallers were tracked for 1 year after the fall. The cost experience of this cohort was compared with nonfallers during the same time period.

RESULTS

The results provide strong evidence that falls are associated with increased health care costs, and that this relation increases monotonically with the frequency and severity of falls. Incurring one or more injurious falls was associated with increased annual hospital costs of $11,042 (1996), nursing home costs of $5,325, and total health care costs of $19,440. Incurring two or more noninjurious falls increased costs substantially as well.

CONCLUSIONS

The health care costs of falls are pervasive and substantial, and they increase with fall frequency and severity.

The economic returns to hospital admitting privileges

Legal suits contesting the denial or termination of hospital staff privileges are the most common antitrust cases involving medical markets. There is, however, very little evidence about the economic implications for the physicians of having staff privileges. Using a nationally representative sample of self-employed physicians from 1992, this article presents estimates of the effects of hospital admitting privileges on physician earnings. The results indicate that for nonprimary care specialists with few admitting privileges, gaining an additional privilege increase earnings. This effect diminishes as the number of admitting privileges increases, however, and there are no economic gains beyond having three to four admitting privileges. Among primary care physicians, we detect no statistically significant effect of hospital admitting privileges on earnings. With the growing emphasis on managed care, physicians are being scrutinized both in terms of the quality of care they deliver and their impact on the economic performance of hospitals and managed care organizations. This suggests that the frequency of lawsuits involving the denial or rescission of medical staff privileges may assume even greater importance.

Penetrating ulcer of the thoracic aorta: what is it? How do we recognize it? How do we manage it?

BACKGROUND

Although classic type A and B aortic dissections have been well described, less is known about the natural history of penetrating atherosclerotic ulcers of the thoracic aorta. This study differentiates penetrating ulcer from aortic dissection, determines the clinical features and natural history of these ulcers, and establishes appropriate correlates regarding optimal treatment.

METHODS

A retrospective review of patient records and imaging studies was conducted with 198 patients with initial diagnoses of aortic dissection (86 type A, 112 type B) at our institution from 1985 to 1997.

RESULTS

Of the 198 patients, 15 (7.6%) were found to have a penetrating aortic ulcer on re-review of computed tomographic scans, magnetic resonance images, angiograms, echocardiograms, intraoperative findings, or pathology reports. Two ulcers (13.3%) were located in the ascending aorta; the other 13 (86.7%) were in the descending aorta. In comparison with those with type A or B aortic dissection, patients with penetrating ulcer were older (mean age 76.6 years, p = 0.018); had larger aortic diameters (mean diameter 6.5 cm); had ulcers primarily in the descending aorta (13 of 15 patients, 86.7%); and more often had ulcers associated with a prior diagnosed or managed AAA (6 of 15 patients, 40.0%; p = 0.0001). Risk for aortic rupture was higher among patients with penetrating ulcers (40.0%) than patients with type A (7.0%) or type B (3.6%) aortic dissection (p = 0.0001).

CONCLUSIONS

Accurate recognition and differentiation of penetrating ulcers from classic aortic dissection at initial presentation is critical for optimal treatment of these patients. For penetrating ulcer, the prognosis may be more serious than with classic type A or B aortic dissection. Surgical management is advocated for penetrating ulcers in the ascending aorta and for penetrating ulcers in the descending aorta that exhibit early clinical or radiologic signs of deterioration.

Linking the health utilities index to National Medical Expenditure Survey data

Measures of health-related quality of life (HR-QOL) are becoming increasingly important in assessing the effects of chronic illness and healthcare interventions designed to treat them. Obtaining measures of HR-QOL for a nationally representative sample of individuals would enhance understanding of health status in the US, and promote further study of the economic causes and effects of health status. This study reports on our efforts to link a prominent HR-QOL scale, the Health Utilities Index Mark I (HUI), to the National Medical Expenditure Survey (NMES). Six distinct algorithms were constructed for linking the HUI to NMES. These alternative linkage algorithms yielded HUI measures that were highly intercorrelated (p = 93 to 99%). Multivariate regression analyses performed to predict variations in HR-QOL revealed that the HUI exhibited good predictive validity--the HUI demonstrated lower quality of life for a variety of chronic illnesses, and wealthier individuals and better educated individuals had a higher quality of life. In contrast to some previous HR-QOL research, the present analysis demonstrates that: (i) cancer is negatively and significantly related to quality of life; and (ii) smoking is negatively and significantly related to quality of life. Overall, the results suggest that the HUI linkages to NMES provide reliable and valid measures of quality of life. As such, items from the NMES can be grouped and linked in such a way as to obtain health state utility values. These values should be of use to those who wish to understand the global health of the US population for policy-making efforts.

Clinical value of acute rest technetium-99m tetrofosmin tomographic myocardial perfusion imaging in patients with acute chest pain and nondiagnostic electrocardiograms

OBJECTIVES

We sought to evaluate the clinical use and cost-analysis of acute rest technetium-99m (Tc-99m) tetrofosmin single-photon emission computed tomographic (SPECT) myocardial perfusion imaging in patients with chest pain and a normal electrocardiogram (ECG).

BACKGROUND

Current approaches used in emergency departments (EDs) for treating patients presenting with chest pain and a nondiagnostic ECG result in poor resource utilization.

METHODS

Three hundred fifty-seven patients presenting to six centers with symptoms suggestive of myocardial ischemia and a nondiagnostic ECG underwent Tc-99m tetrofosmin SPECT during or within 6 h of symptoms. Follow-up evaluation was performed during the hospital period and 30 days after discharge. All entry ECGs, SPECT images and cardiac events were reviewed in blinded manner and were not available to the admitting physicians.

RESULTS

By consensus interpretation, 204 images (57%) were normal, and 153 were abnormal (43%). Of 20 patients (6%) with an acute myocardial infarction (MI) during the hospital period, 18 had abnormal images (sensitivity 90%), whereas only 2 had normal images (negative predictive value 99%). Multiple logistic regression analysis demonstrated abnormal SPECT imaging to be the best predictor of MI and significantly better than clinical data. Using a normal SPECT image as a criterion not to admit patients would result in a 57% reduction in hospital admissions, with a mean cost savings per patient of $4,258.

CONCLUSIONS

Abnormal rest Tc-99m tetrofosmin SPECT imaging accurately predicts acute MI in patients with symptoms and a nondiagnostic ECG, whereas a normal study is associated with a very low cardiac event rate. The use of acute rest SPECT imaging in the ED can substantially and safely reduce the number of unnecessary hospital admissions.

Variations in compliance among hypertensive patients by drug class: implications for health care costs

Health care decision-makers require more information on differences in compliance rates associated with alternative classes of antihypertensive drugs and the implications of these differences for health care utilization and costs. We examined medical claims data from the Pennsylvania Medicaid Management Information System to investigate compliance rates for four major antihypertensive drug classes (angiotensin-converting enzyme [ACE] inhibitors, beta-blockers, calcium antagonists, and diuretics) and the health care costs associated with noncompliance. Multivariate analysis was used to relate antihypertensive drug class with compliance and variations in compliance with health care costs. The highest estimated rates of compliance were associated with ACE inhibitors and calcium antagonists, and these rates were significantly greater than with beta-blockers and diuretics. Moreover, poor compliance was associated with higher health care costs. Efforts to increase compliance with antihypertensive drug therapy are needed to improve patient outcomes and reduce health care costs.

Cost-effectiveness of antidepressant treatment reassessed

BACKGROUND

A recent simulation concluded that the serotonin-specific reuptake inhibitor (SSRI) paroxetine was more cost-effective than the tricyclic antidepressant (TCA) imipramine, despite substantially higher medication acquisition costs.

METHOD

We replicated the previous model and revised key assumptions which drove the results. The revised model was subjected to sensitivity analysis.

RESULTS

Most scenarios in the revised model showed that the TCA is equally or more cost-effective than the SSRI. Model revision producing these results were changes in assumptions about switched treatment success rates, treatment length and initial treatment success. The revised model appears sensitive to drug acquisition and delivery costs and costs of treatment failure.

CONCLUSIONS

Based on the model, a policy of using TCAs as first-choice antidepressant treatment, with SSRIs reserved for those patients not doing well initially, appears more cost-effective than the reverse sequence. Given limitations in current knowledge about key parameters to include in a simulation model, large prospective random-assignment cost-effectiveness studies are needed.

What is the appropriate size criterion for resection of thoracic aortic aneurysms?

Although many articles have described techniques for resection of thoracic aortic aneurysms, limited information on the natural history of this disorder is available to aid in defining criteria for surgical intervention. Data on 230 patients with thoracic aortic aneurysms treated at Yale University School of Medicine from 1985 to 1996 were analyzed. This computerized database included 714 imaging studies (magnetic resonance imaging, computed tomography, echocardiography). Mean size of the thoracic aorta in these patients at initial presentation was 5.2 cm (range 3.5 to 10 cm). The mean growth rate was 0.12 cm/yr. Overall survivals at 1 and 5 years were 85% and 64%, respectively. Patients having aortic dissection had lower survival (83% 1 year; 46% 5 year) than the cohort without dissection (89% 1 year; 71% 5 year). One hundred thirty-six patients underwent surgery for their thoracic aortic aneurysms. For elective operations, the mortality was 9.0%; for emergency operations, 21.7%. Median size at time of rupture or dissection was 6.0 cm for ascending aneurysms and 7.2 cm for descending aneurysms. The incidence of dissection or rupture increased with aneurysm size. Multivariable regression analysis to isolate risk factors for acute dissection or rupture revealed that size larger than 6.0 cm increased the probability by 32.1 percentage points for ascending aneurysms (p = 0.005). For descending aneurysms, this probability increased by 43.0 percentage points at a size greater than 7.0 cm (p = 0.006). If the median size at the time of dissection or rupture were used as the intervention criterion, half of the patients would suffer a devastating complication before the operation. Accordingly, a criterion lower than the median is appropriate. We recommend 5.5 cm as an acceptable size for elective resection of ascending aortic aneurysms, because resection can be performed with relatively low mortality. For aneurysms of the descending aorta, in which perioperative complications are greater and the median size at the time of complications is larger, we recommend intervention at 6.5 cm.

The cost-effectiveness of a multifactorial targeted prevention program for falls among community elderly persons

OBJECTIVES

Falls and fall injuries are common-potentially preventable-causes of morbidity, functional decline, and increased health-care use among elderly persons. The current analyses, performed on data obtained as part of a randomized controlled trial conducted within a health maintenance organization, describe the costs of a multifactorial, targeted prevention program for falls, present total net health-care costs, estimate the cost per fall prevented, and describe acute fall-related health-care costs.

METHODS

The 301 participants were at least 70 years of age and possessed at least one of eight targeted risk factors for falling. The 153 participants randomized to the targeted intervention (TI) group received a combination of medication adjustment, behavioral recommendations, and exercises as determined by their baseline assessment. The 148 participants randomized to the usual care (UC) group received a series of home visits by a social work student.

RESULTS

The mean intervention cost per TI participant was $925 (range $588 to $1,346). Total mean health-care costs were approximately $2,000 less in the TI than UC group, whereas median costs were approximately $1,100 higher in the TI than UC group. The TI strategy was unequivocally cost effective when mean costs were used because the intervention was associated with both lowered total health-care costs and fewer total and medical care falls. In sensitivity analyses, the cost-effectiveness of the TI strategy appeared robust to widely differing assumptions about total health-care costs (25th to 75th percentile of the actual distribution) and intervention costs (minimum to maximum costs). In subgroup analyses, the TI strategy showed its strongest effect among individuals at high risk of falling, defined as possession of at least four of the eight targeted risk factors.

CONCLUSIONS

Consideration should be given toward incorporating and reimbursing the cost of fall-prevention programs within the usual health care of community-living elderly persons, particularly for those persons at high risk for falling.

Is the target income hypothesis an economic heresy?

This study is the first to relate physician-specific measures of target and actual income to pricing decisions. We find that a higher ratio of target to actual income leads to a significant price increase among self-employed, fee-for-service primary care physicians, with an elasticity of approximately 0.3, but not among self-employed primary care physicians who are not paid on a fee-for-service basis. Thus we find evidence of target income pricing when, as in the case of fee-for-service practices, physicians stand to gain financially from their pricing decisions. Although the target income hypothesis (TIH) has been criticized for lacking firm grounding in economic theory, this article argues that the notion of targets has a long history in economic theory and pricing to achieve a target is not new. Moreover, a variety of economic explanations render such behavior consistent with profit maximizing objectives.

Labour productivity effects of prescribed medicines for chronically ill workers

Previous work on the labour productivity effects of chronic illness has not separated the effects of chronic illnesses from the effects of prescription medications taken to alleviate these conditions. Using nationally representative observational data, this study estimates the pure effect of chronic illness, and the marginal effect of prescription medicines, on labour productivity. As Americans continue to scrutinize health care expenditures, such estimates will play an increasing role in determining the allocation of resources for medical treatments. Estimates are presented of the costs and benefits to employers of covering prescription medications for workers aged 18-64 years afflicted with specific chronic illnesses. The effects of prescription medicines on hourly wages and days lost from work are examined for four major chronic illnesses: hypertension, heart disease, non-insulin dependent (type II) diabetes and depression. The net benefits to employers from having workers take prescription medicines for their chronic illnesses are substantial. Assuming average compliance rates are achieved, net benefits to employers in 1987 amounted to $286 per hypertensive employee, $633 per employee with heart disease; $822 per depressed employee, and $1475 per type II diabetic employee under medication from a physician. These estimated benefits accrue because prescription medications substantially lower absenteeism among chronically ill workers.

Nutrient intake of nursing-home residents receiving pureed foods or a regular diet

OBJECTIVE

To evaluate (1) the nutrient content of menus planned for regular consistency meals and pureed meals in a long-term care facility and (2) to assess nutrient intakes of women consuming these meals.

DESIGN

A descriptive survey.

SETTING

A nursing home facility in central Pennsylvania.

PARTICIPANTS

Fifty-one female nursing home residents were chosen randomly. Thirty-one received a regular diet and 20 received a pureed diet.

MEASUREMENTS

Demographic and health variables were collected from medical records. Nutrient variables were calculated for regular and pureed consistency meals, as served. Nutrient intake data for each woman were based on seven consecutive days of food intake and nutrient supplement use.

MAIN RESULTS

Energy and nutrient values for regular diet menus (i.e., food served) were higher than for pureed menus, but both had values exceeding recommended allowances for most nutrients. Average energy and nutrient intakes were similar for both groups of women (t test, P < 0.05). Data showed that many women in both groups had lower than the recommended intakes of iron, zinc, calcium, and Vitamin D.

CONCLUSIONS

Both regular and pureed consistency diets provided to residents met current recommended allowances. Diet consistency did not affect nutrient intakes. Intakes were adequate overall; however, a low intake of the same nutrients generally occurred in both groups.

The costs and effects of switching calcium channel blockers: evidence from Medicaid claims data

This study used Medicaid claims data from Pennsylvania to examine the costs and effects of changing calcium channel blocker therapies. Specifically, we compared Procardia XL with Adalat CC. They are the only once-daily-dosed, extended-release forms of nifedipine available. These drugs were interesting to compare for several reasons. First, because the frequency of treatment regimens has been shown to be the most important determinant of long-term compliance with calcium channel blocker medications, it was desirable to compare drugs having identical dosing regimens. Second, switching from one to the other should be quite feasible in most patients. Third, Adalat CC is priced (ie, average wholesale price) less than Procardia XL. The results indicate that prescription prices were lower when patients were switched from Procardia XL to Adalat CC, with no apparent effects on blood pressure control, the incidence of adverse drug reactions, or nonprescription health care costs. The potential savings to Medicaid from switching patients from Procardia XL to Adalat CC appears to be large, more than $2.5 million annually for Procardia XL-treated Medicaid patients in the state of Pennsylvania. Our study also demonstrates that large retrospective databases can be used to evaluate economic and clinical outcomes for specific therapy alternatives. Such evaluations are increasingly relevant to third-party payers, health maintenance organizations, and other parties involved in managed care.

Treatment of bancroftian filariasis in Recife, Brazil: a two-year comparative study of the efficacy of single treatments with ivermectin or diethylcarbamazine

The effectiveness of single oral doses of ivermectin (200 or 400 micrograms/kg) and diethylcarbamazine (DEC, 6 mg/kg), preceded 4 d earlier by either placebo or very small doses of these drugs, was compared, over a 2-year period, in a double-blind trial in 67 microfilaraemic Brazilian men with bancroftian filariasis. Regimens containing ivermectin alone decreased the number of microfilariae significantly faster and more effectively for the first month after treatment than regimens containing DEC alone, but the latter were significantly more effective throughout the second year after treatment (1.7-8.2% of pretreatment levels with DEC vs. 12.6-30.8% with ivermectin during that period); the higher ivermectin dose showed a tendency towards more effectiveness than the lower dose. Most effective was the combination of ivermectin (20 micrograms/kg) followed 4 d later by DEC (6 mg/kg), with reduction of microfilaraemia to 2.4% of pretreatment levels at 2 years. Adverse reactions were well tolerated with all regimens, the reactions being significantly more generalized (i.e., fever) following ivermectin and localized (i.e., scrotal inflammatory nodules around dying adult worms) following DEC. Further trials of single-dose combination therapy vs. single high doses of ivermectin or DEC should determine the ideal regimen for treatment and control of bancroftian filariasis.

Physician labor supply: do income effects matter?

This paper estimates a model of physician labor supply, focusing on the impacts of wage and non-wage income. We find evidence of significant income effects. For male physicians, the income effect of a wage change on labor supply is negative, with an elasticity of -0.26. The pure substitution effect of a wage change increases labor supply: a 1% increase in wages leads to a 0.49% increase in labor supply, controlling for income effects. The results also suggest that the labor supply decisions of females are more responsive to variations in their earnings than are those of males.

Facilitating care delivery redesign using measures of unit culture and work characteristics

Work culture has a compelling effect on work redesign efforts. Because culture can either inhibit or promote innovation, it needs to be examined and understood. To achieve this understanding in a community hospital setting, the authors used measures of unit culture and work characteristics. The data analysis revealed cultural patterns specific to each patient care unit. Nursing staff members are using this information to effect change in their care delivery model.

Ivermectin treatment of bancroftian filariasis in Recife, Brazil

To determine the effectiveness of single oral dosages of ivermectin ranging between 20 and 200 micrograms/kg and to make detailed observations of both the kinetics of parasite killing and the adverse reactions induced by treatment, the present double-blind study on ivermectin treatment of lymphatic filariasis caused by Wuchereria bancrofti was undertaken with 43 microfilaremic patients in Recife, Brazil. Follow-up at one year indicated equivalent efficacy for the 20-, 100-, and 200-micrograms/kg drug dosages in reducing microfilaremia to geometric means of 13-25% of pretreatment levels. Adverse clinical reactions (predominantly fever, headache, weakness, and myalgia) occurred to some degree in almost all patients but generally lasted only 24-48 hr and were easily managed symptomatically. Adverse reactions were significantly milder in those receiving the lowest (20 micrograms/kg) ivermectin dose, and they were significantly correlated with individuals' pretreatment microfilaremia levels in all groups. Posttreatment eosinophilia was a regular feature of the response to treatment, with the magnitude and kinetics also proportional to pretreatment microfilarial levels. Transient pulmonary function abnormalities (16 of 42, 38%), liver enzyme elevations (10 of 43, 23%), and hematuria (9 of 42, 22%) developed posttreatment, but all cleared without significant complications. The results indicate that W. bancrofti from Brazil is similar to strains of the parasites studied elsewhere in susceptibility to ivermectin, that the drug's systemic adverse reactions are essentially those resulting from parasite clearance, and that the intensity of these reactions can be significantly reduced by using the low (20 micrograms/kg) dose of ivermectin. This detailed dose-finding study provides information necessary for developing optimal regimens to treat bancroftian filariasis with ivermectin either alone or in combination with other medications.

Physician uncertainty and the art of persuasion

Incomplete information is a chronic feature of medica markets. Much attention has focused on information asymmetries between physicians and their patients. In contrast, physician uncertainty has received far less attention. This is a significant omission. Physician uncertainty may be an even more important reason than consumer uncertainty for the high cost of health care. This paper reviews and evaluates major approaches for managing physician uncertainty. We argue that quantitative approaches alone, such as scientific advancement and the application of decision analysis to clinical reasoning, are insufficient for dealing with uncertainty. Qualitative approaches, such as forging consensus through expert panels, and teaching physicians to accept and cope with uncertainty, will play a valuable role in promoting more effective clinical decision-making under conditions of uncertainty. The current tensions between those who would eradicate physician uncertainty through quantitative approaches and those who favor qualitative methods has parallels in many other fields, including economics and mathematics. These tensions are unfortunate, since the most promising initiative to promote better clinical decision-making will likely need to draw upon both approaches. The recent initiative to implement medical practice guidelines is one example of a broad-based approach to improve clinical decision-making. Guidelines draw upon available scientific evidence, but typically involve consensus-building as well. They seek to persuade and educate physicians about appropriate treatments, without mandating changes in physician treatment patterns. Given the persistent uncertainties physicians will undoubtedly confront regarding appropriate clinical decision-making, this flexible approach may be the best way to mitigate market failures resulting from inappropriate clinical decisions.(ABSTRACT TRUNCATED AT 250 WORDS)

[Beclomethasone dipropionate, in high dose, in the treatment of patients with chronic persistent asthma]

The efficacy of inhaled beclomethasone dipropionate (BDP) was examined in 8 patients with chronic persistent asthma, uncontrolled by inhaled bronchodilators and oral theophylline. Beclomethasone was administered at a dose of 1500 mcg a day, using a metered dose inhaler containing 250 mcg of BDP per dose. The medication was administered twice daily, three 250 mcg puffs at 8 A.M. and three at 8 P.M. The patients were assessed by means of clinical examination, diary records and daily Peak Flow Rate (PFR) measurement made at home. The therapeutic responses were measured over an 8-wk period. The clinical score (0-4) improved significantly (3.25 +/- 0.71 before and 0.75 +/- 0.89 after [p < 0.001]), and the peak flow rate rose from baseline mean value of 48.0% +/- 11.9 (predicted value) to 78.8% +/- 16.7% with significant improvement (p < 0.01). Of the total of 8 patients, 5 achieved complete control of symptoms and normal values of PFR, 1 remained with sporadic wheezing but with significant improvement of PFR and 2, despite the clinical efficacy in symptom relief, persisted without significant improvement on PFR values. Transitory hoarseness occurred in 1 patient. No other side-effects were observed.

Supply and demand factors in the determination of Medicare expenditures

This article presents multivariate estimates of the effects of supply-side factors (e.g., provider reimbursement) and demand-side factors (e.g., beneficiary ability to pay) on state-level expenditures per enrollee in Medicare Part A and Part B. The results indicate that a 1 percent increase in elderly income significantly increases the propensity to use Medicare Part B services, resulting in a 0.45 percent increase in Part B expenditures per enrollee. By contrast, patients' ability to pay has a much weaker effect on Part A expenditures. Changes in provider reimbursement also exert a substantial effect on expenditures. A 1 percent rise in the Medicare Prevailing Charge Index raises Medicare Part B expenditures by 0.43 percent. Collectively, the findings of this study suggest that both limits on Medicare reimbursement to providers and increased beneficiary liability have substantial effects on Medicare costs. Whatever the merits of arguments for or against such controls, the responsiveness of Medicare expenditures to equal percentage changes in supply and demand factors appears to be of a similar order of magnitude.

Physician referrals and the medical market place

Factors determining the extent to which physicians obtain new patients through referrals are examined. A more thorough understanding of physician referral patterns can help to explain how competitive forces function in this market and how physician characteristics and credentials affect individual performance. Referral networks promote entry by young physicians into both primary and nonprimary care medical markets. Nevertheless, there are marked differences in referral patterns between primary care and nonprimary care providers. For instance, referrals are directly related to the degree of market competition and board-certification status among primary care physicians but not among nonprimary care specialists. Membership in a group practice is related to significantly more referral activity among nonprimary care physicians but not among primary care providers. No significant differences were found in referral patterns by physician sex. Although foreign medical graduates (FMGs) receive proportionately fewer referrals than do U.S. medical graduates, the differences are not large. While earlier research suggests that the returns to board certification are higher for female physicians, the present study finds little evidence that board certification is particularly helpful to either female physicians or to FMGs in terms of obtaining patients on referral.

Who cares for uninsured persons? A study of physicians and their patients who lack health insurance

Physician involvement with uninsured patients is a topic of increasing policy interest. In the past, data limitations have hindered analysis of factors influencing physician contact with uninsured patients. This article attempts to bridge this gap in the health services research literature. Using a nationally representative sample of nonfederal patient care physicians, the study revealed marked variations in physician involvement with uninsured patients by specialty class, employment status, and other practice characteristics. Pediatricians and general practitioners had roughly comparable involvement with uninsured patients, while internists and surgeons were significantly less involved. Self-employed physicians generally participated less in caring for uninsured patients than did employed physicians. While definitive evidence that people without coverage face serious access problems is not provided, such a conclusion is certainly consistent with the results of this study. Indeed, the proportion of the average physician's patients who are uninsured is substantially below current estimates of the proportion of the general population that is uninsured.

Physician contact with and attitudes toward HIV-seropositive patients. Results from a national survey

The growing population of HIV-seropositives raises serious concerns about who will provide medical care to this group. This article presents the first national estimates of physician involvement in, and attitudes toward, the treatment of HIV-seropositive patients. Nearly 50% of the nonfederal patient care physicians in our nationally representative sample have treated at least one HIV patient, with an average of 6.7 such patients being treated per physician. Perceived responsibility to treat HIV-seropositive patients is uniformly strong across such physician and practice characteristics as specialty, years of experience, and practice type. However, there are pronounced differences in actual physician involvement along these dimensions.