Matthew T. McKenna

Estimation of HIV Incidence in the United States

CONTEXT Incidence of human immunodeficiency virus (HIV) in the United States has not been directly measured. New assays that differentiate recent vs long-standing HIV infections allow improved estimation of HIV incidence. OBJECTIVE To estimate HIV incidence in the United States. DESIGN, SETTING, AND PATIENTS Remnant diagnostic serum specimens from patients 13 years or older and newly diagnosed with HIV during 2006 in 22 states were tested with the BED HIV-1 capture enzyme immunoassay to classify infections as recent or long-standing. Information on HIV cases was reported to the Centers for Disease Control and Prevention through June 2007. Incidence of HIV in the 22 states during 2006 was estimated using a statistical approach with adjustment for testing frequency and extrapolated to the United States. Results were corroborated with back-calculation of HIV incidence for 1977-2006 based on HIV diagnoses from 40 states and AIDS incidence from 50 states and the District of Columbia. MAIN OUTCOME MEASURE Estimated HIV incidence. RESULTS An estimated 39,400 persons were diagnosed with HIV in 2006 in the 22 states. Of 6864 diagnostic specimens tested using the BED assay, 2133 (31%) were classified as recent infections. Based on extrapolations from these data, the estimated number of new infections for the United States in 2006 was 56,300 (95% confidence interval [CI], 48,200-64,500); the estimated incidence rate was 22.8 per 100,000 population (95% CI, 19.5-26.1). Forty-five percent of infections were among black individuals and 53% among men who have sex with men. The back-calculation (n = 1.230 million HIV/AIDS cases reported by the end of 2006) yielded an estimate of 55,400 (95% CI, 50,000-60,800) new infections per year for 2003-2006 and indicated that HIV incidence increased in the mid-1990s, then slightly declined after 1999 and has been stable thereafter. CONCLUSIONS This study provides the first direct estimates of HIV incidence in the United States using laboratory technologies previously implemented only in clinic-based settings. New HIV infections in the United States remain concentrated among men who have sex with men and among black individuals.

The epidemiology of tuberculosis among foreign-born persons in the United States, 1986 to 1993

BACKGROUND One third of the worlds population is infected with Mycobacterium tuberculosis, and in the developed countries immigration is a major force that sustains the incidence of tuberculosis. We studied the effects of immigration on the epidemiology of tuberculosis and its recent resurgence in the United States. METHODS We analyzed data from the national tuberculosis reporting system of the Centers for Disease Control and Prevention. Since 1986 reports of tuberculosis have included the patients country of origin. Population estimates for foreign-born persons were derived from special samples from the 1980 and 1990 censuses. RESULTS The proportion of persons reported to have tuberculosis who were foreign-born increased from 21.6 percent (4925 cases) in 1986 to 29.6 percent (7346 cases) in 1993. For the entire eight-year period, most foreign-born patients with tuberculosis were from Latin America (43.9 percent; 21,115 cases) and Southeast Asia (34.6 percent; 16,643 cases). Among foreign-born persons the incidence rate was almost quadruple the rate for native residents of the United States (30.6 vs. 8.1 per 100,000 person-years), and 55 percent of immigrants with tuberculosis had the condition diagnosed in their first five years in the United States. CONCLUSIONS Immigration has had an increasingly important effect on the epidemiology of tuberculosis in the United States. It will be difficult to eliminate tuberculosis without better efforts to prevent and control it among immigrants and greater efforts to control it in the countries from which they come.

The relationship between ankle brachial index, other atherosclerotic disease, diabetes, smoking and mortality in older men and women

The goal of this study is to investigate the relationship between peripheral arterial disease and mortality in a large patient population and assess the effects of other atherosclerotic diseases, diabetes and smoking on this relationship. All patients, 50 years or older and with no history of lower extremity surgery, evaluated for lower extremity arterial disease in a university hospital peripheral vascular laboratory over a 13-year period (1977-1989) were included in the study (n = 1930). Arterial disease was assessed by measurement of the resting ankle brachial index (ABI) in these patients. The ABI was calculated by dividing the systolic pressure in the tibial arteries by the pressure in the brachial artery. Analyses of the data by use of multivariate statistical techniques and by stratification of the patient population by co-morbid condition indicate that ABI is a robust and independent predictor of all-cause mortality in both men (relative risk (RR) = 1.6, 95% confidence interval (CI) 1.3, 2.0) and women (RR = 1.9, 95% CI 1.4, 2.4). The relative risks are essentially unchanged after exclusion of all patients with clinical history of cardiovascular disease or diabetes. Similarly, a low ABI is an important risk factor for mortality among patients with a history of stroke, angina or diabetes; men and women with a history of smoking and women who are non-smokers. Therefore, the measurement of ABI, a simple, objective, non-invasive technique which can be used in the physicians office, may be useful for early identification of patients at high risk for morbidity and mortality.

Epidemiology of Human Immunodeficiency Virus in the United States

SUMMARY The human immunodeficiency virus (HIV) epidemic emerged in the early 1980s with HIV infection as a highly lethal disease among men who have sex with men and among frequent recipients of blood product transfusions. Advances in the treatment of HIV infection have resulted in a fundamental shift in its epidemiology, to a potentially chronic and manageable condition. However, challenges in the prevention of this infection remain. In particular, increasing evidence suggests that transmission of drug-resistant virus is becoming more common and that the epidemic is having a profound impact on morbidity and mortality in ethnic and racial minority subgroups in the United States. New population-based data collection systems designed to describe trends in behaviors associated with HIV transmission and better methods for measuring the true incidence of transmission will better elucidate the characteristics of HIV infection in the United States and inform future public health policies.

Completeness and timeliness of tuberculosis case reporting. A multistate study.

BACKGROUND Tuberculosis (TB) control activities are contingent on the timely identification and reporting of cases to public health authorities to ensure complete assessment and appropriate treatment of contacts and identification of secondary cases. We report the results of a multistate evaluation of completeness and timeliness of reporting of TB cases in the United States during 1993 and 1994. METHODS To determine completeness of TB reporting, laboratory log books, death certificates, hospital discharge, Medicaid databases, and pharmacy databases were reviewed in seven states to identify possible unreported cases. Timeliness of TB reporting was calculated using the number of days between date of TB diagnosis and date of report to the local or state health department. Cases reported >7 days after diagnosis were considered to have delayed reporting. RESULTS Of 2711 cases identified through review of secondary data sources, 14 (0.5%) were previously unreported to public health. The largest yield of unreported cases was identified through review of laboratory records; 13 of the 14 unreported cases were identified, of which eight were found only through this method. Timeliness of reporting varied between sites from a median of 7 days to a median of 38 days. The number of cases with delayed reporting varied from 5% to 53% between sites. Factors associated with delayed reporting included infectiousness, type of provider, diagnosing provider, and reporting source. CONCLUSIONS Through a review of several different secondary data sources, few unreported TB cases were detected; however, timeliness of reporting was poor among the reported cases.

Monitoring the incidence of HIV infection in the United States

The Centers for Disease Control and Prevention maintains a national surveillance system that provides data about the HIV/AIDS epidemic for program planning and resource allocation. Until recently, incidence of HIV infection (i.e., the number of individuals recently infected with HIV) has not been directly measured. New serologic testing methods make it possible to distinguish between recent and long-standing HIV-1 infection on a population level. This article describes the new National HIV Incidence Surveillance System.

The Status of National HIV Case Surveillance, United States 2006

Since the height of HIV incidence in the mid-1980s, advances in treatment have delayed progression of HIV infection. As a result, surveillance of AIDS cases alone is no longer sufficient to monitor the current status of the HIV epidemic. At the national level, new HIV diagnoses and progression of these cases to AIDS are used to describe the epidemic. The capacity to monitor the national HIV epidemic has consistently improved over the last several years. An increasing number of states report diagnosed HIV cases to the national surveillance system, allowing data from this system to better represent the national picture. Monitoring the national HIV epidemic depends on a nationwide system using standardized methods of data collection, and establishing such a comprehensive system remains one of the highest priorities for national HIV case surveillance.

Importance of perspective in economic analyses of cancer screening decisions

As the fifth, and final, report in this Lancet series on health economics, we discuss how economic analyses in public health, with cancer screening as the example, differ depending on the perspective taken. We identify nine different, but related, decision makers at various levels, from the individual patient to society as a whole, and discuss how their different viewpoints affect their ultimate decisions. Central to our discussion is the identification of seven distinct components of perspective, each potentially important in the screening decision. In many fields of healthcare, decisions about the use of resources, such as time, wealth, or energy, are made by weighing up the positive and negative consequences of the alternatives under consideration and are thus based on an economic analysis of the situation (although sometimes this process is subconscious). For simplicity, we restrict our report to the effect of perspective on cancer screening decisions and show how the costs (negative consequences) and benefits (positive consequences) vary depending on the decision maker.

Variation in average costs among federally sponsored state-organized cancer detection programs: Economies of scale?

Background Societal cost-effectiveness analysis and its variants help decision makers achieve an efficient allocation of resources across the set of all possible health interventions. Sometimes, however, decision makers are focused instead on the efficient allocation of resources within a particular intervention program that has already been implemented. This is especially true when the intervention is being delivered at several different sites. An analysis of average cost across program sites may help program officials to maximize the health benefits that can be achieved with limited resources. In this article, the authors present such an analysis, with special attention paid to the possible existence and implications of economies of scale. Methods Focusing on federally sponsored, state-organized cancer detection programs, the authors modeled 19 state programs as productive processes and examined their average costs over a 2- to 5-year period of operation. They considered 3 alternative definitions of output: women served, screens performed, and conditions detected. Average federal costs and average total costs were estimated for each grant period. Multivariate regression analysis was used to help explain the variation in average costs. Results The average cost estimates were distributed in a skewed pattern with the majority of observations falling close to the median and substantially below the mean. For all measures considered, average cost decreased as output expanded. This inverse relationship between average cost and output level persisted even after controlling for the effects of other predictors, suggesting the possible existence of economies of scale. Discussion The potential existence of economies of scale calls into question the assumption of a constant average cost frequently made in economic analyses of proposed public health programs. It also implies that a) differences in output level should be taken into account when comparing operating efficiency across program sites; b) conclusions from societal cost-effectiveness analyses may depend on the level of output at which the programs are evaluated; c) cost projections could be inaccurate if they do not take into account the decrease in average cost that occurs as output expands; and d) gains might be possible if similar programs with limited output potential are integrated, perhaps through cost sharing.

Assessing the burden of disease among an employed population: implications for employer-sponsored prevention programs.

Learning ObjectivesList the components of the DALY (disability-adjusted life year) and explain how DALYs are estimated.Recall the disease states that are the most frequent causes of DALYs and note any differences related to gender or employment status (hourly or salaried).Discuss the risk factors underlying the leading causes of DALYs and how they might be modified. Escalating healthcare costs have led employers to identify ways to assess the actual burden of disease among their employees. One such measure is the use of disability-adjusted life-years (DALYs). DALYs were calculated for the General Motors (GM) population for 1994 through 1998 using data from GM’s Mortality Registry, published life tables, and age- and sex-specific disease incidence and disability data from the U.S. Burden of Disease Study. Chronic diseases accounted for 45% (245,844 of 540,450) of total DALYs lost. Ischemic heart disease, stroke, lung cancer, and chronic obstructive pulmonary disease led the list for both men and women and accounted for 39% and 31%, respectively, of the top 10 DALYs lost. Disease burden among employees could be reduced through targeted interventions aimed at the risk factors associated with the leading causes of DALYs.