PubMed Health⌕ Search

Biomedical subjects

Samuel A Bozzette

Publications and source records attributed to Samuel A Bozzette.

At least 19 recordsLinked to original sources
PubMed2007

Survival curve estimation for informatively coarsened discrete event-time data.

Interval-censored, or more generally, coarsened event-time data arise when study participants are observed at irregular time periods and experience the event of interest in between study observations. Such data are often analysed assuming non-informative censoring, which can produce biased results if the assumption is wrong. This paper extends the standard approach for estimating survivor functions to allow informatively interval-censored data by incorporating various assumptions about the censoring mechanism into the model. We include a Bayesian extension in which final estimates are produced by mixing over a distribution of assumed censoring mechanisms. We illustrate these methods with a natural history study of HIV-infected individuals using assumptions elicited from an AIDS expert.

Bayes Theorem↗
PubMed2006

Transmission patterns of smallpox: systematic review of natural outbreaks in Europe and North America since World War II.

BACKGROUND: Because smallpox (variola major) may be used as a biological weapon, we reviewed outbreaks in post-World War II Europe and North America in order to understand smallpox transmission patterns. METHODS: A systematic review was used to identify papers from the National Library of Medicine, Embase, Biosis, Cochrane Library, Defense Technical Information Center, WorldCat, and reference lists of included publications. Two authors reviewed selected papers for smallpox outbreaks. RESULTS: 51 relevant outbreaks were identified from 1,389 publications. The median for the effective first generation reproduction rate (initial R) was 2 (range 0-38). The majority outbreaks were small (less than 5 cases) and contained within one generation. Outbreaks with few hospitalized patients had low initial R values (median of 1) and were prolonged if not initially recognized (median of 3 generations); outbreaks with mostly hospitalized patients had higher initial R values (median 12) and were shorter (median of 3 generations). Index cases with an atypical presentation of smallpox were less likely to have been diagnosed with smallpox; outbreaks in which the index case was not correctly diagnosed were larger (median of 27.5 cases) and longer (median of 3 generations) compared to outbreaks in which the index case was correctly diagnosed (median of 3 cases and 1 generation). CONCLUSION: Patterns of spread during Smallpox outbreaks varied with circumstances, but early detection and implementation of control measures is a most important influence on the magnitude of outbreaks. The majority of outbreaks studied in Europe and North America were controlled within a few generations if detected early.

Communicable Disease Control↗
PubMed2006

An HIV collaborative in the VHA: do advanced HIT and one-day sessions change the collaborative experience?

BACKGROUND: Many organizations participate in quality collaboratives, yet the return on investment of the associated time and costs is unclear. METHOD: Semistructured interviews, surveys, and direct observation were used to assess experiences, improvement activities, and costs associated with participation in a year-long modified Institute for Healthcare Improvement-style collaborative designed to improve HIV care within the Veterans Health Administration. All nine sites had access to automated patient registries and semi-automated clinical measure reports; five sites also received computerized clinical reminders. Three one-day learning sessions were conducted. RESULTS: Participants reported that burden was small and value high, although many suggested that more time for peer-to peer learning would have been helpful. Teams averaged five quality improvement activities per site and most reported improvements in HIV care processes. The average annual cost per site was dollars 28,000 but costs varied considerably by site. DISCUSSION: Shortened learning sessions and the incorporation of health information technology can reduce some of the costs and burdens associated with collaboratives, yet peer-to-peer interaction and local organizational factors remain important to ensuring perceived effectiveness of collaboratives.

Cooperative Behavior↗
PubMed2005

The effect of socioeconomic status on the survival of people receiving care for HIV infection in the United States.

HIV-infected people with low socioeconomic status (SES) and people who are members of a racial or ethnic minority have been found to receive fewer services, including treatment with Highly Active Antiretroviral Therapy (HAART), than others. We examined whether these groups also have worse survival than others and the degree to which service use and antiretroviral medications explain these disparities in a prospective cohort study of a national probability sample of 2,864 adults receiving HIV care. The independent variables were wealth (net accumulated financial assets), annual income, educational attainment, employment status (currently working or not working), race/ethnicity, insurance status, use of services, and use of medications at baseline. The main outcome variable was death between January 1996 and December 2000. The analysis was descriptive and multivariate adjusted Cox proportional hazards regression analysis of survival. By December 2000, 20% (13% from HIV, 7% non-HIV causes) of the sample had died. Those with no accumulated financial assets had an 89% greater risk of death (RR=1.89, 95% CI=1.15-3.13) and those with less than a high school education had a 53% greater risk of death (RR=1.53, 95% CI=1.15-2.04 ) than their counterparts, after adjusting for sociodemographic and clinical variables only. Further adjusting for use of services and antiretroviral treatment diminished, but did not eliminate, the elevated relative risk of death for those with low SES by three of the four measures. The finding of markedly elevated relative risks of death for those with HIV infection and low SES is of particular concern given the disproportionate rates of HIV infection in these groups. Effective interventions are needed to improve outcomes for low SES groups with HIV infection.

Adolescent↗
PubMed2005

A national study of the relationship of care site HIV specialization to early adoption of highly active antiretroviral therapy.

BACKGROUND: Little is known about characteristics of organizations that predict early adoption of highly active antiretroviral therapy (HAART) for persons with HIV infection. OBJECTIVES: To describe characteristics of sites where HIV care is provided and to assess site characteristics that predict early adoption of HAART. DESIGN: Cross-sectional analysis of survey data from patients, HIV physicians, and medical directors. PATIENTS AND SETTING: Participants in the HIV Cost and Services Utilization Study, a national probability sample of persons with HIV who received outpatient care in the continental United States during 1996. MAIN OUTCOME MEASURE: Rates of exposure to HAART by December 1996. RESULTS: Nationally, 79% of patients were treated at sites specializing in HIV care (HIV sites). Over 90% of patients were cared for by physicians who were experts in HIV care, either infectious disease specialists (46%) or general medicine experts (45%). Adjusted rates of exposure to HAART by December 1996 varied from 0.02 to 0.79 across sites (mean rate, 0.33). In multivariable models, HIV specialization (odds ratio [OR], 3.6; P < 0.001), total patient volume of more than 20,000 visits a year (OR, 2.1; P < 0.01), and educational level of the zip code in which the site was located (OR, 1.2 for each 10% increase in college education) were associated with higher rates of exposure to HAART. These effects persisted after adjustment for physician HIV expertise. Site effects were more important than physician effects in explaining rates of exposure to HAART. CONCLUSION: In 1996 there were wide variations in rates of HAART use by site of care. Low-volume sites that do not specialize in HIV care should take measures to ensure that HIV expertise is available to their patients.

Adult↗
PubMed2004

The prevalence of antiretroviral drug resistance in the United States.

BACKGROUND: Antiretroviral therapy has dramatically reduced the morbidity and mortality of infection due to HIV. The emergence of drug-resistant virus has limited the usefulness of many drugs. OBJECTIVE: To determine the prevalence of HIV drug resistance in the population of adults receiving care in the United States. DESIGN AND METHODS: HIV drug susceptibility assays were performed on plasma virus from a random sample representative of the 132500 HIV-infected American adults who had received medical care in early 1996 yet were viremic with > 500 copies/ml of HIV RNA in late 1998. A blood sample was obtained from 1797 patients who comprised a representative sample of the 208900 adults receiving urban care for HIV infection in early 1996 who survived to late 1998. The sampling procedure permitted weighting each evaluated patient to reflect demographic and other characteristics of the target population. RESULTS: We estimated that 132500 (63%) of the target population had HIV viremia of > 500 copies/ml. Among viremic patients, an estimated 76% had resistance to one or more antiretroviral drugs. The odds of resistance were significantly higher in patients with a history of antiretroviral drug use, advanced HIV disease, higher plasma HIV viral load and lowest CD4 cell count by self-report. CONCLUSIONS: The frequent selection for drug-resistant virus among viremic patients during the first 3 years of widespread use of potent antiretroviral combination therapy has significant implications for HIV treatment and transmission.

Adolescent↗
PubMed2004

Lipid screening in HIV-infected veterans.

BACKGROUND: Lipid screening is recommended for patients taking protease inhibitors (PIs). METHODS: We examined data from the Veterans Administration Immunology Case Registry to assess lipid screening among HIV-infected veterans who received PIs for at least 6 consecutive months during 1999 and 2001. We estimated crude and adjusted associations between lipid screening and patient characteristics (age, gender, HIV exposure, and race/ethnicity), comorbidities (AIDS, cardiovascular disease, diabetes, hypertension, smoking, and hyperlipidemia), and facility characteristics (urban location, case management, guidelines, and quality improvement programs). RESULTS: Among 4065 patients on PIs, clinicians screened 2395 (59%) for lipids within 6 months of initiating treatment. Adjusting for patient characteristics, comorbidities, facility traits, and clustering, lipid screening was more common among patients who were cared for in urban areas (relative risk [RR] = 1.3, confidence limits: 1.0-1.5), diabetic (RR = 1.2, confidence limits: 1.1-1.3), or previously hyperlipidemic (RR = 1.4, confidence limits: 1.3-1.5) and less common among patients with a history of intravenous drug use (IVDU) (RR = 0.90, confidence limits: 0.79-1.0) or unknown HIV risk (RR = 0.85, confidence limits: 0.75-0.95). CONCLUSIONS: Six in 10 patients taking PIs receive lipid screening within 6 months of PI use. Systemic interventions to improve overall HIV quality of care should also address lipid screening, particularly among patients with unknown or IVDU HIV risk and those cared for in nonurban areas.

Adolescent↗
PubMed2004

Symptom-based framework for assessing quality of HIV care.

OBJECTIVE: To evaluate HIV quality of care using a symptom-based, patient-centered framework. METHODS: An expert panel developed 13 quality indicators for three common symptoms: cough with fever and/or shortness of breath; severe or persistent diarrhea; and significant weight loss. A nationally representative probability sample of HIV-infected adults was interviewed between 1996 and 1997. PARTICIPANTS: were asked about the presence and severity of HIV symptoms during the preceding 6 months, and care received. Variation in adherence to the indicators was assessed by symptom type and patient characteristics. RESULTS: In all, 2864 (71%) patients completed interviews and 920 reported being at least moderately bothered with one of the three symptoms. Of these, 41, 74, and 65% of patients with a symptom of cough, weight loss, or diarrhea, respectively, reported receiving all indicated care. Performance was better for patients with more severe HIV, measured as a CD4 cell count <50 cells/microliter, compared with those with less severe HIV, measured as CD4 cell count >500 cells/microliter (43% versus 60%; P = 0.02). Uninsured patients had worse performance than Medicare patients (45% versus 62%; P = 0.04), but care did not differ by patient's age, gender, ethnicity, HIV risk factor, providers' HIV patient load, or region. Only CD4 count remained significantly associated with performance in the multivariate analyses. CONCLUSIONS: Symptom-based quality indicators may provide a useful supplement to conventional measures. Patients with HIV reported substantial underuse of services for common, burdensome symptoms. Although adherence to quality indicators was better for patients with more advanced HIV disease, many still received suboptimal care. Vulnerable patient groups generally did not receive worse quality of care, suggesting that symptom-based measures of quality may measure domains that are distinct from those captured by conventional indicators.

Adult↗
PubMed2003

Complementary and alternative medicine use and substitution for conventional therapy by HIV-infected patients.

BACKGROUND: HIV-infected patients commonly use complementary and alternative medicine (CAM), but it is not known how often CAM is used as a complement or as a substitute for conventional HIV therapy. OBJECTIVES: To evaluate the prevalence and factors associated with CAM use with potential for adverse effects and CAM substitution for conventional HIV medication. DESIGN AND PARTICIPANTS: Cross-sectional survey of U.S. national probability sample of HIV-infected patients (2,466 adults) in care from December 1996 to July 1997. MAIN OUTCOME VARIABLES: Any CAM use, CAM use with potential for adverse effects, and use of CAM as a substitute for conventional HIV therapy. Substitution was defined as replacement of some or all conventional HIV medications with CAM. RESULTS: Fifty-three percent of patients had recently used at least one type of CAM. One quarter of patients used CAM with the potential for adverse effects, and one-third had not discussed such use with their health care provider. Patients with a greater desire for medical information and involvement in medical decision making and with a negative attitude toward antiretrovirals were more likely to use CAM. Three percent of patients substituted CAM for conventional HIV therapy. They were more likely to desire involvement in medical decision-making (odds ratio, 1.8; 95% confidence interval, 1.0-3.2) and to have a negative attitude toward antiretrovirals (odds ratio, 7.8; 95% confidence interval, 3.0-19.0). CONCLUSIONS: Physicians should openly ask HIV-infected patients about CAM use to prevent adverse effects and to identify CAM substitution for conventional HIV therapy.

Adolescent↗
PubMed2003

The diverse older HIV-positive population: a national profile of economic circumstances, social support, and quality of life.

The objectives of this study were to provide a national profile of socioeconomic circumstances of the middle-aged and older population living with HIV and to evaluate variations in social support and quality of life (QOL) across age and socioeconomic subgroups, controlling for indicators of disease progression. The design used was a cross-sectional analysis of nationally representative interview data on HIV-infected individuals collected in the HIV Cost and Services Utilization Study. Multiple measures of social support and QOL were used. Bivariate comparisons of outcomes across categories of age and exposure category were performed; multivariate analyses to isolate the effect of older age on outcomes within exposure categories were performed, controlling for socioeconomic and clinical co-variates. Study results indicate that older gay men with HIV/AIDS are a predominantly white population and more likely to have health insurance than their younger counterparts; 38% were employed and 48% reported incomes of more than $25,000. Older injection drug users (IDUs) with HIV/AIDS are a predominantly black population with a particularly high concentration of disadvantages; only 11% were employed and 74% reported incomes of less than $10,000. Older IDUs reported especially low levels of physical functioning and emotional support in comparison with their younger counterparts, whereas older gay men did not significantly differ from younger gay men in these respects. The authors conclude that characteristics and care needs of the older HIV-positive population are very diverse and vary sharply by exposure route. Interventions need to be tailored to the needs of these distinct subpopulations, with an emphasis on development of supportive care interventions for older IDUs.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Differences in symptom expression in older HIV-positive patients: The Veterans Aging Cohort 3 Site Study and HIV Cost and Service Utilization Study experience.

Symptom recognition is critical for patient care but has been little studied in older HIV-infected individuals. The authors examined differences in symptom expression between younger (younger than age 50 years) and older (older than age 50 years) HIV-infected individuals. The authors analyzed data from two cross-sectional studies of HIV-infected individuals: 2864 individuals from the HIV Cost and Service Utilization Study (HCSUS) and 881 individuals from the Veterans Aging Cohort 3 Site Study (VACS 3). The authors compared the prevalence of eight symptoms common to both studies and 10 symptoms examined only in the VACS 3 population, stratified by age and race. Disease severity was assessed by CD4 count and 18 HIV-related diseases reported. Multivariate logistic regression models were used to account for demographics and severity differences. VACS 3 versus HCSUS participants were more likely nonwhite and older. In unadjusted comparisons, older nonwhites were less likely to report experiencing symptoms than younger whites. They reported the fewest total number of symptoms and the fewest individual symptoms common to both studies (headache, fever, nausea/vomiting, and diarrhea) or in the VACS 3 only (dizziness, sleeping difficulty, fatigue, rashes, bloating, and myalgias/arthalgias). Multivariate regression estimates suggest older age predicts a greater likelihood of reporting peripheral neuropathy, weight loss, or hair loss, but a lower likelihood of reporting headaches, depressed mood, white oral patches, or diarrhea. Nonwhites appeared less likely to report symptoms. Age is a determinant of reporting certain symptoms in HIV disease but may be masked or accentuated by other factors such as race.

Adult↗
PubMed2003

Cardiovascular and cerebrovascular events in patients treated for human immunodeficiency virus infection.

BACKGROUND: Metabolic abnormalities associated with human immunodeficiency virus (HIV) infection, including dysglycemia and hyperlipidemia, are increasingly prevalent, and there is concern about the possibility of an association with accelerated cardiovascular and cerebrovascular disease. METHODS: We conducted a retrospective study of the risk of cardiovascular and cerebrovascular disease among the 36,766 patients who received care for HIV infection at Veterans Affairs facilities between January 1993 and June 2001. RESULTS: For antiretroviral therapy, 70.2 percent of the patients received nucleoside analogues, 41.6 percent received protease inhibitors, and 25.6 percent received nonnucleoside reverse-transcriptase inhibitors for a median of 17 months, 16 months, and 9 months, respectively. Approximately 1000 patients received combination therapy with a protease inhibitor for at least 48 months, and approximately 1000 patients received combination therapy with a nonnucleoside reverse-transcriptase inhibitor for at least 24 months. Between 1995 and 2001, the rate of admissions for cardiovascular or cerebrovascular disease decreased from 1.7 to 0.9 per 100 patient-years, and the rate of death from any cause decreased from 21.3 to 5.0 deaths per 100 patient-years. Patient-level regression analyses indicated that there was no relation between the use of nucleoside analogues, protease inhibitors, or nonnucleoside reverse-transcriptase inhibitors and the hazard of cardiovascular or cerebrovascular events, but the use of antiretroviral drugs was associated with a decreased hazard of death from any cause. CONCLUSIONS: Use of newer therapies for HIV was associated with a large benefit in terms of mortality that was not diminished by any increase in the rate of cardiovascular or cerebrovascular events or related mortality. Fear of accelerated vascular disease need not compromise antiretroviral therapy over the short term. However, prolonged survival among HIV infected patients means that longer-term observation and analysis are required.

Adult↗
PubMed2003

Physician specialization and antiretroviral therapy for HIV.

BACKGROUND: Since the introduction of the first protease inhibitor in January 1996, there has been a dramatic change in the treatment of persons infected with HIV. The changing nature of HIV care has important implications for the types of physicians that can best care for patients with HIV infection. OBJECTIVE: To assess the association of specialty training and experience in the care of HIV disease with the adoption and use of highly active antiretroviral (ARV) therapy (HAART). DESIGN: Observational cohort study of patients under care for HIV infection and their physicians. PATIENTS AND SETTING: This analysis used data collected from a national probability sample of noninstitutionalized persons with HIV infection participating in the HIV Costs and Service Utilization Study and their primary physicians. We analyzed 1,820 patients being cared for by 374 physicians. MEASUREMENTS: Rates of HAART use at 12 months and 18 months after the approval of the first protease inhibitor. RESULTS: Forty percent of the physicians were formally trained in infectious diseases (ID), 38% were general medicine physicians with self-reported expertise in the care of HIV, and 22% were general medicine physicians without self-reported expertise in the care of HIV. The majority of physicians (69%) reported a current HIV caseload of 50 patients or more. In multivariable models controlling for patient characteristics, there were no differences between generalist experts and ID physicians in rates of HAART use in December 1996. When compared to ID physicians, however, patients being treated by non-expert general medicine physicians were less likely to be on HAART (odds ratio [OR], 0.32; 95% confidence interval [95% CI], 0.17 to 0.61). Patients being treated by low-volume physicians were also much less likely to be on HAART therapy than those treated by high-volume physicians (OR, 0.26; 95% CI, 0.14 to 0.48). These findings were attenuated by June 1997, suggesting that over time, the broader physician community successfully adopted HAART therapy. This finding is consistent with prior research on the diffusion of innovations. CONCLUSIONS: Similar proportions of patients treated by expert generalists and ID specialists were on appropriate HAART therapy by December 1996 and July 1997. Patients treated by non-expert generalists, most of whom were the lowest-volume physicians, were much less likely to be on appropriate ARV therapy in the earlier time period. Our findings demonstrate that expert generalists who develop specialized expertise are able to provide care of quality comparable to that of specialists.

Adult↗
PubMed2003

Underdiagnosis of depression in HIV: who are we missing?

OBJECTIVE: To determine the sociodemographic and service delivery correlates of depression underdiagnosis in HIV. DESIGN: Cross-sectional survey. PATIENTS/PARTICIPANTS: National probability sample of HIV-infected persons in care in the contiguous United States who have available medical record data. MEASUREMENTS AND MAIN RESULTS: We interviewed patients using the Composite International Diagnostic Interview (CIDI) survey from the Mental Health Supplement. Patients also provided information regarding demographics, socioeconomic status, and HIV disease severity. We extracted patient medical record data between July 1995 and December 1997, and we defined depression underdiagnosis as a diagnosis of major depressive disorder based on the CIDI and no recorded depression diagnosis by their principal health care provider in their medical records between July 1995 and December 1997. Of the 1140 HIV Cost and Services Utilization Study patients with medical record data who completed the CIDI, 448 (37%) had CIDI-defined major depression, and of these, 203 (45%) did not have a diagnosis of depression documented in their medical record. Multiple logistic regression analysis revealed that patients who had less than a high school education (P <.05) were less likely to have their depression documented in the medical record compared to those with at least a college education. Patients with Medicare insurance coverage compared to those with private health insurance (P <.01) and those with >or=3 outpatient visits (P <.05) compared to <3 visits were less likely to have their depression diagnosis missed by providers. CONCLUSIONS: Our results suggest that providers should be more attentive to diagnosing comorbid depression in HIV-infected patients.

Adolescent↗
PubMed2003

Insurance status of HIV-infected adults in the post-HAART era: evidence from the United States.

In the United States, universal public insurance is only available for the elderly. But unlike most other major diseases, HIV/AIDS predominantly affects the nonelderly. The result is that insurance availability and public programme participation are linked to disease progression in a complicated way. This paper uses data from a unique, nationally representative sample of HIV-infected adults receiving medical care, to describe the relationship between disease progression and insurance coverage in the United States. We find that public insurance is the predominant source of coverage for those in care for HIV, and that coverage increases as disease progresses. Those with public coverage have substantial work experience and earnings capacity, but do not work. This suggests that reforms allowing HIV positive (+) patients to maintain public coverage while returning to work could increase employment and earnings significantly. More speculatively, it suggests that the United States system for financing health care is not well-equipped to deal with epidemics that afflict a population in its prime work years.

Adult↗