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D R Hoover

Publications and source records attributed to D R Hoover.

At least 55 records · Page 3Linked to original sources
PubMed1998

Sustained cognitive decline in HIV infection: relationship to CD4+ cell count, plasma viremia and p24 antigenemia.

To determine the clinical and virological correlates of neuropsychological test performance decline in HIV infection, we measured viral burden in blood in 272 HIV-seropositive men without dementia in the Baltimore arm of the Multicenter AIDS Cohort Study (MACS). These measures were then related to neuropsychological (NP) decline, defined as a decline relative to prior best performance of 2.0 standard deviations or more on one or more neuropsychological tests. A short battery of NP tests (Mini-Screen Battery) was administered to all 272 men. NP test performance decline was identified in 53/272 (19.5%) of participants on the Mini-Screen Battery. Follow-up NP data were available for 204 participants who had undergone the Mini-Screen. The frequency of sustained NP test performance decline was 7.8% for the Mini-Screen Battery. A lower CD4+ cell count was weakly associated with sustained NP test performance decline. After adjustment for CD4+ cell count, hemoglobin, body mass index, and presence of AIDS, none of the viral burden measures (p24 antigenemia, plasma viremia, quantitative culture) correlated with sustained NP test performance decline. We conclude that these measures of blood HIV viral burden are not markers for NP decline, but that a lower CD4+ cell count is.

AIDS Dementia Complex↗
PubMed1998

[Sensitivity and specificity revisited: significance of the terms in analytic and diagnostic language].

Imprecise usage of the terms "sensitivity" and "specificity" produces confusion in the diagnostic use sophisticated laboratory test results. "Analytical sensitivity" represents the smallest amount of substance in a sample that can accurately be measured by an assay. "Analytical specificity refers to the ability of an assay to measure one particular organism or substance, rather than others, in a sample. An assay's analytical sensitivity and analytical specificity are distinct from that assay's clinical diagnostic sensitivity and diagnostic specificity. Diagnostic "sensitivity" is the percentage of persons who have a given disorder who are identified by the assay as positive for the disorder. High analytical sensitivity does not guarantee acceptable diagnostic sensitivity. "Diagnostic sensitivity" is the percentage of persons who do not have a given condition who are identified by the assay as negative for the condition. False-positive reactions occur because of sample contamination and diminish the diagnostic specificity of the assay. The terms "sensitivity" and "specificity" should be used with the requisite adjectives because the "diagnostic" and the "analytical" meanings of these terms are very different.

Diagnosis↗
PubMed1997

The association of herpes simplex virus type 2 (HSV-2), Haemophilus ducreyi, and syphilis with HIV infection in young men in northern Thailand.

To evaluate the association between sexually transmitted diseases that commonly may cause genital ulceration and prevalent and incident HIV infections, we conducted three case control studies in a cohort of 21-year-old male military conscripts in northern Thailand. The men were evaluated at baseline in 1991 and semiannually until their discharge 2 years later. Serologic evidence of infection with herpes simplex virus type 2 (HSV-2), Haemophilus ducreyi, and HIV were more frequent at baseline in 83 men with a history of genital ulcer than in 97 men without such a history. Seropositivity to H. ducreyi (odds ratio [OR] = 3.46), HSV-2 (OR = 3.83), and syphilis (OR = 1.53) were more common in HIV-positive than HIV-negative men. Men (N = 45) who seroconverted to HIV while in the military were more often seropositive for H. ducreyi and HSV-2 before HIV seroconversion and also were more likely to seroconvert to HSV-2 and H. ducreyi during the same interval as their HIV seroconversion compared with men who remained HIV-negative. These data suggest that HSV-2 and H. ducreyi may be both markers for high-risk sexual behavior and risk factors for HIV infection among young men in Thailand.

AIDS-Related Opportunistic Infections↗
PubMed1997

Solar ultraviolet radiation exposure does not appear to exacerbate HIV infection in homosexual men. The Multicenter AIDS Cohort Study.

OBJECTIVE: To determine the effect of sun exposure on HIV progression. DESIGN: Cross-sectional survey nested within a longitudinal cohort study. SETTING: The Multicenter AIDS Cohort Study. PARTICIPANTS: A total of 1155 white HIV-seronegative and 496 white HIV-seropositive homosexual men, of whom 142 seroconverted during the study. MAIN OUTCOME MEASURES: T-helper lymphocyte decline and AIDS. RESULTS: No positive correlation was found between the development of AIDS or loss of T-helper lymphocytes and (i) phenotypic characteristics associated with enhanced ultraviolet radiation (UVR) sensitivity (hair or eye color, skin type), or (ii) reported UVR exposure (sun lamp/tanning bed use, frequency of beach vacations, sunscreen use), or (iii) composite score of UVR sensitivity and exposure history. The composite scores and individual measures of risk were not correlated with rate of T-helper lymphocyte decline (slope) based upon rank correlation (correlation coefficient, 0.04; P = 0.32). In fact, individuals purposefully seeking the sun had slower T-helper lymphocyte declines. Sensitivity to UVR was also not significantly associated with AIDS [odds ratio (OR), 1.11 per unit of higher composite score; 95% confidence interval (CI), 0.66-1.88; P = 0.63]. Among individuals who were HIV-infected at baseline, those who have been purposely seeking sun exposure were less likely to have AIDS (OR, 0.67; 95% CI, 0.39-1.11; P = 0.12). CONCLUSIONS: These data suggest that phenotypic characteristics of high UVR sensitivity and exposure are not highly correlated with decline in T-helper lymphocyte count or with progression to AIDS.

Adult↗
PubMed1997

"Sensitivity" and "specificity" reconsidered: the meaning of these terms in analytical and diagnostic settings.

Imprecise usage of the terms "sensitivity" and "specificity" produces confusion in the diagnostic use of sophisticated laboratory test results. "Analytical sensitivity" represents the smallest amount of substance in a sample that can accurately be measured by an assay. "Analytical specificity" refers to the ability of an assay to measure on particular organism or substance, rather than others, in a sample. An assay's analytical sensitivity and analytical specificity are distinct from that assay's clinical diagnostic sensitivity and diagnostic specificity. "Diagnostic sensitivity" is the percentage of persons who have a given disorder who are identified by the assay as positive for the disorder. High analytical sensitivity does not guarantee acceptable diagnostic sensitivity. "Diagnostic specificity" is the percentage of persons who do not have a given condition who are identified by the assay as negative for the condition. False-positive reactions occur because of sample contamination and diminish the diagnostic specificity of the assay. The terms "sensitivity" and "specificity" should be used with the requisite adjectives because the "diagnostic" and the "analytical" meanings of these terms are very different.

Diagnosis↗
PubMed1997

Prostate size in hypogonadal men treated with a nonscrotal permeation-enhanced testosterone transdermal system.

OBJECTIVES: This study examined the effects of testosterone replacement using a nonscrotal testosterone transdermal (TTD) system on prostate size and prostate-specific antigen (PSA) levels in hypogonadal men. METHODS: As part of an open-label, multicenter study, prostate volume as measured by transrectal ultrasound and PSA were assessed in 29 hypogonadal men during treatment with intramuscular testosterone enanthate (+TE), followed by 8 weeks of androgen withdrawal (-T), and then during 1 year of therapy with Androderm Testosterone Transdermal System, a nonscrotal permeation-enhanced TTD system (+TTD). RESULTS: Mean prostate volume decreased significantly from the +TE period (17 g) compared with the -T period (14 g) (P < 0.001). Prostate volume increased significantly from the -T period compared with the +TTD period (18 g) (P < 0.001). Maximum prostate size, comparable to that measured during +TE (P = 0.125), was reached by month 3 of +TTD therapy; prostate volume did not increase further during the remaining 9 months of +TTD therapy. Prostate volume correlated with age (P < 0.01) during all three periods of observation (+TE: r = 0.69; -T: r = 0.64; and +TTD: r = 0.55). No patient developed symptomatic benign prostatic hyperplasia during the treatment period. PSA levels decreased during androgen withdrawal compared with levels measured during +TE treatment (P < 0.001) and rose with resumption of androgen therapy with TTD (P < 0.006). However, PSA levels during +TTD replacement remained significantly lower (P < 0.001) than during +TE replacement. CONCLUSIONS: Physiologic testosterone replacement in hypogonadal men was achieved using the TTD system. Prostate size during therapy with TTD was comparable to that reported for normal men. In these men treated with TTD, PSA levels were also within the normal range.

Administration, Cutaneous↗
PubMed1997

Early levels of CD4, neopterin, and beta 2-microglobulin indicate future disease progression.

Reduced CD4 T cell level and increased serum neopterin and beta 2-microglobulin levels, which reflect immunological activation and dysregulation, are three important markers of HIV disease. The aim in this study is to delineate more clearly the relation of activation to future CD4 values and disease progression. By analyzing a cohort of 198 seroconverters from the Multicenter AIDS Cohort Study with 9 years' follow-up, the dynamic changes and levels of these three markers and their interrelationships are explored. We observed that the levels of markers in the first year after seroconversion have a much stronger impact on the progression of the disease than the preseroconversion marker levels. The actual change during the year after seroconversion is not as important as the final level reached during that year. The early levels of markers after seroconversion appear to be good indicators of the subsequent course of disease as defined by CD4 level and slightly better than the quantitative changes following seroconversion or the changes in the period 1 to 2.5 years after seroconversion. To investigate the variation between subjects, the 198 seroconverters were stratified into three approximately equal-sized groups in 12 ways based on their pre- and postseroconversion levels and changes in the three markers. The group with the highest CD4 level within a year after seroconversion maintains the highest CD4 level 8 years after seroconversion. The group with the lowest level of neopterin or beta 2-microglobulin in this period has much higher future CD4 counts than the other two groups. The level of markers during the first year after seroconversion has a high predictive power for AIDS onset. Substantial differences in the hazards of AIDS are found between the groups with the highest and lowest CD4 count, neopterin, and beta 2-microglobulin following seroconversion. The three markers are generally correlated throughout the postseroconversion period but can provide distinct information. High current levels of neopterin or beta 2-microglobulin tend to be associated with low future CD4 count, while current levels of CD4 count have less association with future neopterin and beta 2-microglobulin levels.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Effect of treatment with zidovudine on subsequent incidence of Kaposi's sarcoma.

Despite much investigation of zidovudine, little has been reported regarding its effect on the development of most individual AIDS-defining illnesses, including Kaposi's sarcoma (KS). We used observational data from the Multicenter AIDS Cohort Study (MACS) to estimate the effect of zidovudine use on the subsequent incidence of KS. To do this, we examined and adjusted for predictors of zidovudine use. CD4 lymphocyte counts, the development of HIV-related symptoms and AIDS, and changes in these factors were important predictors of zidovudine use. We used these associations to control for confounding by these and other factors with the G-estimation approach. We found no evidence that zidovudine use affected the time to KS in the MACS; the point estimate (95% confidence interval [CI]) for increase in time to KS was zero (-28%-68%). The relative risk was 1.0 (95% CI, 0.54-1.84). Randomized trials suggest that zidovudine may prevent KS. We discuss possible explanations for differences between results.

AIDS-Related Opportunistic Infections↗
PubMed1997

The influence of drug use patterns on the rate of CD4+ lymphocyte decline among HIV-1-infected injecting drug users.

OBJECTIVES: To assess the relationship between various injecting drug use patterns and the rate of CD4+ lymphocyte decline in HIV-1-infected injecting drug users in Baltimore, Maryland, USA. METHODS: A cohort of 605 HIV-1-infected injecting drug users was recruited between 1988 and early 1989 in East Baltimore using extensive community outreach techniques. The participants were interviewed semi-annually to collect information on drug use practices. The outcome measure of interest was the rate of CD4+ lymphocyte decline between pairs of CD4+ lymphocyte counts. A mixed model was used to evaluate the relationship between the change in CD4+ lymphocyte count per month and previous CD4+ lymphocyte count and various drug use variables. RESULTS: The 605 HIV-infected injecting drug users had a median initial CD4+ lymphocyte count of 513 cells x 10(6)/l. Using 3209 paired observations, the mean change in CD4+ lymphocyte count was -3.2 cells x 10(6)/l per month. The rate of decline was higher in those with a higher level of CD4+ lymphocytes (P < 0.01) and length of drug use (P < 0.01), but did not vary by injection frequency or injection intensity of specific drug types. Although animal studies have suggested that the pattern of drug administration (continuous versus intermittent) and episodes of withdrawal or overdose might impact the rate of CD4+ lymphocyte decline, this was not observed in the present study. CONCLUSION: Patterns of injecting drug use, based on self-report, were not associated with the rate of decline in CD4+ lymphocytes.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Helper T-lymphocyte count. TRAx CD4 test kit versus conventional flow cytometry.

BACKGROUND: We evaluated a newly developed enzyme-linked immunosorbent assay system for measuring helper T-lymphocyte count. METHODS: Data from 111 human immunodeficiency virus-infected injection drug users in a cohort study were analyzed by flow cytometry and independent duplicate runs of the TRAx enzyme-linked immunosorbent assay. RESULTS: The mean helper T-cell counts were 470, 480, and 506 per microliter by flow cytometry and TRAx runs 1 and 2, respectively. The correlation coefficients for TRAx runs 1 and 2 with the flow cytometry results as the dependent variable were .93 and .91, respectively. A cross-tabulation of the enzyme-linked immunosorbent assay helper T-lymphocyte counts with flow cytometry counts showed agreement of 71% and 76% when the flow count was between 201 and 500, and 88% and 90% when it was greater than 500 cells per microliter. In those samples with 200 or fewer helper T cells, agreement was 73% and 41% for each TRAx run. CONCLUSIONS: The TRAx enzyme-linked immunosorbent assay system is an acceptable method for measuring helper T-lymphocyte count, but should be recalibrated for better performance at helper T-cell counts below 200 per microliter.

CD4 Lymphocyte Count↗
PubMed1996

Changes in sexual behavior and a decline in HIV infection among young men in Thailand.

BACKGROUND: In Thailand the epidemic of human immunodeficiency virus (HIV) infection is of recent origin. Because of the high seroprevalence of HIV among sex workers, the Ministry of Public Health began a program in 1990 and 1991 to promote the use of condoms during commercial sex. We evaluated the effect of this and other programs to prevent HIV infection in Thailand. METHODS: Using direct interviews, we studied five cohorts of 21-year-old men from northern Thailand who were conscripted into the army by a lottery in 1991, 1993, and 1995. In all, 4311 men were tested for HIV antibodies by enzyme-linked immunosorbent assay, with confirmation by Western blot assay. RESULTS: In the 1991 and 1993 cohorts, the prevalence of HIV infection was 10.4 to 12.5 percent. In 1995, it fell to 6.7 percent (P < 0.001). The seroprevalence was only 0.7 percent among men who did not have sexual relations with a sex worker before 1992. Over the study period, the proportion of men who reported having sexual relations with a sex worker fell from 81.4 percent to 63.8 percent (P < 0.001). From 1991 to 1995, the men's reported use of condoms during the most recent sexual contacts with sex workers increased from 61.0 percent to 92.5 percent (P < 0.001); and in 1995, 15.2 percent of men had a history of a sexually transmitted disease, as compared with 42.2 percent in 1991 (P < 0.001). CONCLUSIONS: Public health programs in Thailand have led to substantial changes in sexual behavior among young men, especially an increased use of condoms, and the rate of new HIV infections has declined.

Adult↗
PubMed1996

Seroconversion to antibodies against Kaposi's sarcoma-associated herpesvirus-related latent nuclear antigens before the development of Kaposi's sarcoma.

BACKGROUND: If Kaposi's sarcoma-associated herpesvirus (KSHV) is the cause of Kaposi's sarcoma, serologic evidence of infection should be present in patients before the disease develops. METHODS: Using an immunoblot assay for two latent nuclear antigens of KSHV, we tested serum samples from homosexual male patients with the acquired immunodeficiency syndrome (AIDS) with and without Kaposi's sarcoma (HIV-infected men with hemophilia), HIV-seronegative blood donors, and HIV-seronegative patients with high titers of antibodies against Epstein-Barr virus (EBV). Serial serum samples obtained from patients with Kaposi's sarcoma before the diagnosis of the disease were tested for evidence of seroconversion. RESULTS: Of 40 patients with Kaposi's sarcoma, 32 (80 percent) were positive for antibodies against KSHV antigens by the immunoblot assay, as compared with only 7 of 40 homosexual men (18 percent) without Kaposi's sarcoma immediately before the onset of AIDS. Of 122 blood donors, 22 EBV-infected patients, and 20 HIV-infected men with hemophilia, none were seropositive. When studied by the immunoblot assay over a period of 13 to 103 months, 21 of the 40 patients with Kaposi's sarcoma (52 percent) seroconverted 6 to 75 months before the clinical appearance of Kaposi's sarcoma. The median duration of antibody seropositivity for KSHV-related latent nuclear antigens before the diagnosis of Kaposi's sarcoma was 33 months. CONCLUSIONS: In most patients with kaposi's sarcoma and AIDS, seroconversion to positivity for antibodies against KSHV-related nuclear antigens occurs before the clinical appearance of Kaposi's sarcoma. This supports the hypothesis that Kaposi's sarcoma results from infection with KSHV.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Extension of the life table to repeating and changing events.

Estimation of cumulative and adjusted occurrence of life events and measures over time is often important in settings where study subjects have incomplete or different follow-up periods. Well-known methods to do this, such as the life table and age adjustment, exist for binary nonrecurrent events (i.e., death). However, a general approach to evaluate recurrent life events (e.g., repeated infections), life events with different durations (e.g., hospitalization days), costs, or changing life measures (e.g., body weight) is not available. This paper develops the "Life-Event Table," an analog of the life table that can analyze occurrence of diverse types of events and measures when the observation periods of subjects are incomplete and different. This method, based on a central limit theorem for incomplete multivariate data, obtains point estimates and variances for cumulative incidence, age-adjusted expectation, and other quantities. Simple hypotheses tests and comparisons are possible with this approach. Three applications are presented. The Life-Event Table may facilitate use of currently available robust multivariate analysis methods. Further research into other multivariate methods that take advantage of this Life-Event Table's specific covariance/variance structure may be warranted.

AIDS-Related Opportunistic Infections↗
PubMed1996

Survival in HIV-infected patients who have received zidovudine: comparison of combination therapy with sequential monotherapy and continued zidovudine monotherapy. Multicenter AIDS Cohort Study Group.

BACKGROUND: Among patients who begin receiving zidovudine during intermediate-stage human immunodeficiency virus (HIV) infection, it is unclear whether changing to combination therapy (adding didanosine or zalcitabine) or sequential monotherapy (changing to didanosine or zalcitabine) significantly improves survival. OBJECTIVE: To determine, among patients who began receiving zidovudine during intermediate-stage HIV infection, the differential effects of changing to combination therapy (zidovudine with didanosine or zalcitabine) or sequential monotherapy (with didanosine or zalcitabine) or continuing zidovudine monotherapy. PATIENTS: 1077 HIV-seropositive men in the Multicenter AIDS (acquired immunodeficiency syndrome) Cohort Study who began receiving zidovudine before an AIDS-defining illness developed. SETTING: University-affiliated clinics in Baltimore, Chicago, Los Angeles, and Pittsburgh. DESIGN: Longitudinal cohort study, Treatment groups and important prognostic variables were modeled as time-dependent covariates in Cox proportional hazards models. MEASUREMENTS: Progression to AIDS and death. RESULTS: Compared with patients receiving continued zidovudine monotherapy, patients receiving combination therapy had a 45% improvement in survival (relative risk, 0.55 [95% Cl, 0.41 to 0.74; P < 0.001]) and patients who changed to sequential monotherapy had a 32% improvement in survival (relative risk, 0.68 [Cl, 0.52 to 0.89; P = 0.005]). In the landmark analyses, the median prolongation of survival associated with changing therapy was, at best, 3 to 6 months. Survival curves converged at 3.5 years for the 50 cells/mm3 disease-stage landmark, at 4.4 years for the 100 cells/mm3 landmark and at 4.9 years for the 150 cells/mm3 landmark. Mortality within these periods was 100%, regardless of treatment group or landmark. CONCLUSIONS: For patients who began receiving zidovudine during intermediate-stage disease, changing to either combination therapy or sequential monotherapy was associated with a statistically significant survival benefit compared with continuation of zidovudine monotherapy. The absolute increase in survival was modest, however, and long-term survival remained poor. Simultaneous time-dependent adjustment for changes in therapy and in important prognostic variables is necessary to derive relatively unbiased estimates of treatment effects in observational studies of HIV infection.

Antiviral Agents↗
PubMed1996

Survivor treatment selection bias in observational studies: examples from the AIDS literature.

Unlike patients in a randomized, clinical trial, patients in an observational study choose if and when to begin treatment. Patients who live longer have more opportunities to select treatment; those who die earlier may be untreated by default. These facts are the essence of an often overlooked bias, termed "survivor treatment selection bias," which can erroneously lead to the conclusion that an ineffective treatment prolongs survival. Unfortunately, misanalysis of survivor treatment selection bias has been prevalent in the recent literature on the acquired immunodeficiency syndrome. Approaches to mitigating this bias involve complex statistical models. At a minimum, initiation of therapy should be treated as a time-dependent covariate in a proportional hazards model. Investigators and readers should be on the alert for survivor treatment selection bias and should be cautious when interpreting the results of observational treatment studies.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Projecting disease when death is likely.

Projection disease incidence, prevalence, and net morbidity is often needed when individuals are likely to die, either disease free or after the disease has developed. Examples of this include remission of cancer or heart disease in elderly people who can die from these or other causes and occurrence of a particular acquired immune deficiency syndrome illness in human immunodeficiency virus type 1 (HIV-1) disease. Death is not an ancillary event but, rather, indicates either and end to disease morbidity or an end to risk to ever develop the disease. Thus, time to disease survival analyses that censor disease-free individuals at death can produce misleading results. The paper describes several useful quantifications of disease and death for this setting. A paradigm that utilizes Kaplan-Meier functions to estimate these quantities is introduced. The approach anchors on a four-stage disease/death model: stage A, living without disease; stage B, dead without ever developing disease; stage C, developed the disease and living; and stage D, dead after developing the disease. An application is made to projecting cytomegalovirus disease in a cohort of HIV-1-infected users of zidovudine and Pneumocystis prophylaxis from the Multicenter AIDS Cohort Study (MACS) during 1989-1993. At 3 years after a CD4+ count below 100/microliters, a man had an 18.7%, 46.3%, 5.3% or 29.9% chance, respectively, to be in stage A, B, C, or D. This man, on average, had 0.28 years of cytomegalovirus morbidity during these 3 years.

AIDS-Related Opportunistic Infections↗