Measures of hospital market structure: a review of the alternatives and a proposed approach

Efforts to evaluate the plethora of recent programs adopted by public and private payers to promote hospital price competition critically depend on the availability of measures of local market structure. To gauge the effects of these policies, researchers must be able to delineate hospital market areas and measure the intensity of competition within these markets. This article reviews alternative methods that have been used to define hospital market areas and measure market structure. We propose an empirical patient origin-based method for measuring hospital market structure. The results of sensitivity analyses using data on California hospitals demonstrate the robustness of our measures over a broad range of parameter values.

Projections of HIV infections and AIDS cases to the year 2000

After the recognition of AIDS (acquired immunodeficiency syndrome) in the early 1980s, uncertainty about the present and future dimensions of HIV (human immunodeficiency virus) infection led to the development of many models to estimate current and future numbers of HIV infections and AIDS cases. The Global Programme on AIDS (GPA) of the World Health Organization (WHO) has developed an AIDS projection model which relies on available HIV seroprevalence data and on the annual rate of progression from HIV infection to AIDS for use in areas where reporting of AIDS cases is incomplete, and where scant data are available to quantify biological and human behavioural variables. Virtually all models, including the WHO model, have projected large increases in the number of AIDS cases by the early 1990s. Such short-term projections are considered relatively reliable since most of the new AIDS cases will develop in persons already infected with HIV. Longer-term prediction (10 years or longer) is less reliable because HIV prevalence and future trends are determined by many variables, most of which are still not well understood. WHO has now applied the Delphi method to project HIV prevalence from the year 1988 to mid-2000. This method attempts to improve the quality of the judgements and estimates for relatively uncertain issues by the systematic use of knowledgeable "experts". The mean value of the Delphi projections for HIV prevalence in the year 2000 is between 3 and 4 times the 1988 base estimate of 5.1 million; these projections have been used to obtain annual estimates of adult AIDS cases up to the year 2000. Coordinated HIV/AIDS prevention and control programmes are considered by the Delphi participants to be potentially capable of preventing almost half of the new HIV infections that would otherwise occur between 1988 and the year 2000. However, more than half of the approximately 5 million AIDS cases which are projected for the next decade will occur despite the most rigorous and effective HIV/AIDS prevention efforts since these AIDS cases will develop in persons whose HIV infection was acquired prior to 1989. The Delphi projections of HIV infection and AIDS cases derived from the WHO projection model need to be periodically reviewed and modified as additional data become available. These projections should be viewed as the first of many attempts to develop estimates for planning strategies to combat the HIV/AIDS pandemic in the 1990s.

The global epidemiology and projected short-term demographic impact of AIDS

This paper summarizes the natural history, surveillance, and global patterns of infections with the human immunodeficiency virus (HIV), the etiologic agent of AIDS The focus is primarily on HIV-1 because surveillance of HIV-2, which has recently been recognized as a separate type of the virus, is only just beginning. The natural progress of the disease is described, from acute infection through asymptomatic phase to the clinical illness phase. Available evidence on the speed of progression from infection to AIDS and possible co-factors in that progression are reviewed. The 3 patterns of AIDS which are described characterize the experience of different regions according to the types of transmission ( i.e., homosexual versus heterosexual, contaminated blood, drug use) and demographic characteristics of the affected persons. An epidemiologically based short-term forecasting model for AIDS cases is presented and used to project the demographic impact of AIDS in a hypothetical central African country. In that hypothetical setting, the impact of AIDS is shown to be disproportionately felt in urban areas, where the projected increase in population will decrease by 30% due to AIDS deaths by 1997; the growth rate of the rural population will be only slightly affected. In conclusion, the global prevalence of the disease, and prospects and implications for the future are discussed. Without effective drugs for treatment and no vaccine for prevention of HIV infections, the short-term outlook is not good. HIV/AIDS is expected to be an increasing public-health problem in the next 2 decades.

Transmission of human immunodeficiency virus (HIV) in health-care settings worldwide

Based on the information available, transmission of human immunodeficiency virus (HIV) can and does occur in health-care settings. No cases of such transmission have been reported from an infected health-care worker to a patient. Transmission of HIV from an infected patient to a health-care worker has been documented after parenteral or mucous-membrane exposure to blood. However, this risk is less than 1%, is limited to exposure to blood, and can be further minimized through adherence to routine infection control measures. Patient-to-patient transmission through invasive equipment or through HIV-infected blood, blood products, organs, tissues, or semen also occurs but can be prevented by proper sterilization of instruments and through donor-deferral, donor screening, and heat treatment of Factors VIII or IX to inactivate the HIV. In health-care settings, prevention of HIV transmission requires education of all health-care workers and ancillary staff, provision of necessary equipment, and strict adherence to general infection control practices.

Prospective payments to hospitals: should emergency admissions have higher rates?

Systematic variation in patient resource use can be a significant problem for a system based on diagnosis-related groups (DRG's) if this variation is not evenly distributed across hospitals. If certain hospitals routinely treat patients who require more services than average under DRG's, the long-run financial viability of these hospitals will be threatened. In this study, the authors examine whether patients who are admitted on an emergency or urgent basis represent an identifiable group of patients whose costs are systematically higher than those of electively admitted patients, controlling for DRG. Alternative approaches for incorporating admission status into a DRG payment system are developed and tested.

Rupture of the left ventricular free wall during acute myocardial infarction: analysis of 138 necropsy patients and comparison with 50 necropsy patients with acute myocardial infarction without rupture

Clinical and necropsy findings in 138 patients (69 men and 69 women) with rupture of the left ventricular (LV) free wall during acute myocardial infarction (AMI) (rupture group) were compared with 50 patients who died during their first AMI without rupture (nonrupture group). The frequency of systemic hypertension (55 vs 52%), angina pectoris (13 vs 22%) and congestive heart failure (0 vs 0%) before the fatal AMI was similar for both rupture and nonrupture groups. Mean heart weights for men (479 vs 526 g) and women (399 vs 432 g) with and without rupture also were insignificantly different. LV scar before the infarct that ruptured was present in 18 patients (13%); previous necropsy studies of fatal AMI without rupture have indicated that 50% have LV scars. The rupture group had a significantly more frequent (p less than 0.01) lateral wall location of the infarct (12 vs 2%). The number of 3 major (right, left anterior descending and left circumflex) epicardial coronary arteries narrowed at some point greater than 75% in cross-sectional area by atherosclerotic plaque was significantly lower (p less than 0.01) in the rupture group (39 vs 58%). The percent of these 3 arteries totally occluded or nearly so (greater than 95% in cross-sectional area) by plaque also was significantly less (p less than 0.001) in the rupture group (24 of 198 arteries [12%] vs 38 of 144 arteries [26%]). Analysis of each 5-mm long segment of these arteries in each group disclosed that the rupture group had significantly less narrowing than the nonrupture group. Of the 3,287 five-mm segments of artery examined in the rupture group (66 patients), 512 (15%) were narrowed greater than 75% in cross-sectional area by plaque; in contrast, of the 1,848 five-mm segments in the nonrupture group (38 patients), 508 (28%) were narrowed to this degree by plaque (p less than 0.0001). Thus, rupture of the LV free wall primarily is a complication of the first AMI and is associated with considerably less amounts of coronary narrowing than fatal AMI without rupture.

Human immunodeficiency virus infection among employees in an African hospital

To define the prevalence and course of human immunodeficiency virus (HIV) infection, we examined prospectively a cohort of 2002 adult hospital workers in Kinshasa, Zaire. From 1984 to 1986 the prevalence of HIV infection increased from 6.4 percent to 8.7 percent. Over the two years there was a cumulative incidence of new HIV infection of 3.2 percent. The prevalence was higher among women (16.9 percent) and men (9.3 percent) under the age of 30 than among women (9.0 percent) and men (6.2 percent) over 30. Prevalence rates were similar among physicians (5.6 percent), laboratory workers (2.9 percent), and clerical workers (7.9 percent), but they were higher among female nurses (11.4 percent) and manual workers (11.8 percent). Despite marked differences in the intensity of nosocomial exposure, female nurses had similar infection rates on the female internal medicine ward (9.9 percent), in pediatrics (10.8 percent), and in the delivery room (10.7 percent). The attributable risk of HIV infection from a transfusion was 5.9 percent. Neither medical injections nor scarification was a risk factor for HIV infection. Of the 101 seropositive asymptomatic employees in the 1984 survey, 16 percent had AIDS-related complex, 3 percent had AIDS, and 12 percent had died of AIDS by 1986. Previous studies have revealed a seroprevalence of 8.4 percent among women attending an antenatal clinic near the hospital in 1984 and 1986, and of 5.8 percent (in 1984) and 6.5 percent (in 1986) among men donating blood at the hospital's blood bank. We conclude that there is a continuing high prevalence of HIV infection among hospital workers in Kinshasa, Zaire, which appears to be representative of that in the community and not nosocomial.

HIV infection and associated risk factors in female prostitutes in Kinshasa, Zaire

In Africa, female prostitutes represent a high risk group for HIV infection. In Kinshasa, Zaire, 101 (27%) out of 377 prostitutes were seropositive to HIV by ELISA and Western blot determination. Seropositivity was significantly associated with the number of lifetime partners with a median number of 600 partners, four seropositives and 338 for seronegative individuals (P = 0.02). Seropositivity was also significantly associated with a history of taking oral medications for the prevention of sexually transmitted diseases and/or pregnancy (odds ratio = 2.21, confidence interval = 1.2-4.2), and with the introduction of any product into the vagina for hygiene or other purposes (odds ratio = 2.3, confidence interval = 1.1-4.7). In addition, among 85 prostitutes reporting condom use by their sexual partners during the previous year, the use of condoms by 50% or more of partners was associated with a reduced risk of HIV seropositivity (P = 0.046). An increased risk of HIV seropositivity was not associated with fellatio, anal intercourse, or with any type of kissing. Twenty-nine per cent of prostitutes reported at least one symptom suggestive of HIV infection, and seropositivity was associated with weight loss, either with or without chronic diarrhea or pruritic dermatitis. These data confirm that African prostitutes are at high risk for HIV infection and that the number of lifetime sexual partners, and factors which interfere with the integrity of the vaginal or cervical mucosa, may be associated with an increased risk of HIV infection acquired through heterosexual contact.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired ventricular septal defect during acute myocardial infarction: analysis of 38 unoperated necropsy patients and comparison with 50 unoperated necropsy patients without rupture

Thirty-eight patients (24 men and 14 women) with an acquired ventricular septal defect during acute myocardial infarction (AMI) (rupture group) were studied and their clinical and necropsy findings were compared with 50 patients who died during their first AMI without rupture (nonrupture group). The frequency of systemic hypertension (54 vs 52%), angina pectoris (28 vs 22%) and congestive heart failure (5 vs 0%) before the fatal AMI was similar for both rupture and nonrupture groups. Mean heart weights for men (498 vs 526 g) and women (397 vs 432 g) with and without septal rupture also were insignificantly different. Whereas previous studies of fatal AMI cases have shown that 50% of cases of fatal AMI without rupture have left ventricular scars, only 4 (10%) of the rupture cases had a left ventricular scar before the infarct that ruptured. The rupture group had a significantly more frequent (p less than 0.01) posterior location of the infarcts (74 vs 40%) and, therefore, a higher frequency of associated right ventricular infarcts 50 vs 18%). The number of 3 major (right, left anterior descending and left circumflex) epicardial coronary arteries narrowed at some point greater than 75% in cross-sectional area of atherosclerotic plaque was the same in both groups. The percent of these 3 arteries totally occluded or nearly so (greater than 95% in cross-sectional area) by plaque was significantly less (p less than 0.001) in the rupture group compared with the nonrupture group (9 of 99 arteries [9%] vs 38 of 144 arteries [26%]).(ABSTRACT TRUNCATED AT 400 WORDS)

Parotid swelling during human immunodeficiency virus infection

In Europe and in the United States, bilateral parotid gland swelling has been observed as a sign of human immunodeficiency virus (HIV) infection in children, but it has not been associated with HIV infection in adults. We observed a chronic parotid gland swelling in nine HIV-seropositive patients during a nine-month period in Kinshasa, Zaire. Parotid gland enlargement was bilateral in seven patients (78%), slightly painful in seven patients (78%), and painless in two patients (22%). No evidence of inflammation was observed around Stensen's duct. One of the two patients in whom a parotid gland biopsy was performed had a malignant lymphoma of the large-cell, histiocytic type. In the other patient, the parotid gland showed normal morphology with minor inflammation. Among 284 adults and 40 children with symptomatic HIV infection, chronic parotid gland enlargement was observed in none of the patients. However, two (0.7%) of the adults presented with an acute pyogenic parotitis. Further studies are needed to determine whether parotid gland enlargement is associated with HIV infection.

AIDS: an international perspective

The acquired immunodeficiency syndrome (AIDS) and infection with the human immunodeficiency virus type 1 (HIV-1) constitute a worldwide public health problem. Whereas in Europe and in most of the Americas transmission of HIV-1 has occurred predominantly among homosexual men and intravenous drug abusers, in Africa a distinct epidemiologic pattern has emerged that indicates that HIV-1 infection is mainly heterosexually acquired. Heterosexual transmission appears to be increasing in some parts of Latin America and the Caribbean, and possibly in the United States. In addition to HIV-1, at least one other human retrovirus, namely HIV-2, has been implicated as a cause of AIDS in Africa and Europe. Factors that influence heterosexual transmission of HIV-1 include genital ulcerations, early or late stages of HIV-1 infection in the index case, and possibly oral contraception and immune activation. The rate of perinatal transmission is enhanced when the mother's illness is more advanced. AIDS and HIV-1 infection may have a significant impact not only on public health, but also on the demography and socioeconomic conditions of some developing countries. Programs for the prevention and control of AIDS should be an immediate priority in all countries.

Herpes zoster in African patients: a clinical predictor of human immunodeficiency virus infection

A recent episode or a history of herpes zoster was found in 30 (11%) of 284 patients hospitalized with human immunodeficiency virus (HIV) infection at Mama Yemo Hospital, Kinshasa, Zaire. Of 146 African patients with a history of herpes zoster who were referred to us by physicians at the Mama Yemo Hospital, 133 (91%) were HIV seropositive. The clinical characteristics of the herpes zoster episodes did not differ between HIV-seropositive and -seronegative individuals, except that 23% of the HIV-seropositive patients experienced recurrences compared with none of the HIV-seronegative patients (P = .05). No patient developed a generalized herpes zoster eruption, and only patients with ophthalmic zoster developed related complications. Patients who experienced severe pain during their herpes zoster attack lost more weight than did those who had only minor pain (P = .0003).

The association between malaria, blood transfusions, and HIV seropositivity in a pediatric population in Kinshasa, Zaire

Since Plasmodium falciparum malaria is a frequent cause of anemia among African children, and blood transfusions, unscreened for human immunodeficiency virus (HIV) antibody, are used frequently in the treatment of children with severe malaria, the relationships between malaria, transfusions, and HIV seropositivity were investigated in a pediatric population in Kinshasa, Zaire. In a cross-sectional survey of 167 hospitalized children, 112 (67%) had malaria, 78 (47%) had received transfusions during the current hospitalization, and 21 (13%) were HIV seropositive. Ten of the 11 seropositive malaria patients had received transfusions during the current hospitalization; pretransfusion specimens were available for four of these children and were seronegative. Of all blood transfusions, 87% were administered to malaria patients, and there was a strong dose-response association between transfusions and HIV seropositivity. A review of 1000 emergency ward records demonstrated that 69% of transfusions were administered to malaria patients, and 97% of children who received transfusions had pretransfusion hematocrits of 0.25 or less (less than or equal to 25%). The treatment of malaria with blood transfusions is an important factor in the exposure of Kinshasa children to HIV infection.

AIDS--A global perspective

Images

AIDS--A global perspective. Global epidemiology

A total of 62,811 cases of the acquired immunodeficiency syndrome (AIDS) have been reported to the World Health Organization from throughout the world. Extensive epidemiologic studies have shown that human immunodeficiency virus (HIV) infections are transmitted by three routes: sexual, parenteral and perinatal. Three geographic patterns of transmission have been defined. In pattern I, transmission occurs predominantly among homosexual and bisexual men and urban intravenous drug abusers; transmission via blood products has been controlled; the male:female sex ratio is 10:1 or more; population HIV seroprevalence is low, and perinatal transmission is uncommon (for instance, United States, western Europe). In pattern II, transmission is predominantly heterosexual and perinatal; transmission via blood products exists but is being reduced; unsterile needles and other skin-piercing instruments cause some parenteral transmission (magnitude not known); the male:female sex ratio is 1:1, and population seroprevalence often exceeds 1% (central Africa, Haiti). In pattern III, AIDS cases are just being documented and are generally due to sexual exposure abroad or imported blood products (Middle East, Asia).

The World Health Organization's global strategy for the prevention and control of AIDS

The magnitude of the human immunodeficiency virus (HIV) pandemic and its broad impact have been seriously underestimated and underappreciated. The Special Programme on AIDS (acquired immunodeficiency syndrome) of the World Health Organization (WHO) was created on February 1, 1987, as the architect and keystone of the global AIDS plan. The Special Programme on AIDS has designed the global strategy, has raised sufficient funds to begin implementing the strategy and, for this effort, has marshalled the support of every nation in the world. AIDS affects both the developing and the industrialized worlds; therefore, every country will need a national AIDS program. This is vital not only for national interests but also because ultimately AIDS cannot be stopped in any one country unless it is stopped in all countries. National AIDS programs are being rapidly established throughout the world with the technical and financial support of WHO's Special Programme on AIDS. At the global level, the Special Programme is responsible for strategic leadership, developing consensus, coordinating scientific research, exchanging information, assuring technical cooperation and mobilizing and coordinating resources. National AIDS committees have already been established in more than 150 countries and, by the end of 1988, the Special Programme will support every country in the world that requests collaboration.

Plague meningitis--a retrospective analysis of cases reported in the United States, 1970-1979

Meningitis caused by Yersinia pestis developed in 6 (6%) of a total of 105 patients with plague reported to the Centers for Disease Control from 1970 to 1979. Five of the six cases occurred in children aged 10 to 15 years. All six patients received antibiotic therapy before meningitis developed, which appeared between the 9th and 14th days after the onset of acute illness in five of the six patients. There were no neurologic sequelae. The antigenic and biochemical profiles of the Y pestis strains isolated from cerebrospinal fluid in the meningitis cases did not differ from those of the Y pestis strains obtained from blood and bubo aspirates in the other 99 patients, and neither did in vitro studies suggest antibiotic resistance. While plague meningitis is an uncommon complication of acute plague infection, physicians in the western United States should be aware that it may develop as much as 14 days after antibiotic therapy for the acute plague infection has been initiated.