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Biomedical subjects

J M Karon

Publications and source records attributed to J M Karon.

At least 37 records · Page 2Linked to original sources
PubMed1995

Prevalence and incidence of vertically acquired HIV infection in the United States.

OBJECTIVE: To estimate human immunodeficiency virus (HIV) type I prevalence among childbearing women, HIV incidence in infants, and the number of children living with HIV infection and acquired immunodeficiency syndrome as a result of transmission from mother to infant (vertical transmission). DESIGN: The national HIV serosurvey of childbearing women was used to estimate the incidence of vertically acquired HIV infection in children born between 1988 and 1993. Data from the national acquired immunodeficiency syndrome case surveillance system and a multicenter pediatric HIV surveillance project were modeled to estimate incidence in children born between 1978 and 1987. SETTING: Surveillance conducted by the Centers for Disease Control and Prevention, Atlanta, Ga, in collaboration with state and local health departments. RESULTS: Approximately 14,920 HIV-infected infants were born in the United States between 1978 and 1993. Of these, an estimated 12,240 children were living at the beginning of 1994; 26% were younger than 2 years, 35% were aged 2 to 4 years, and 39% were aged 5 years or older. Approximately 6530 HIV-infected women gave birth in the United States in 1993, and, based on a 25% vertical transmission rate, an estimated 1630 of their infants were HIV infected. CONCLUSIONS: These results provide a basis for estimating medical and other resource needs for HIV-infected women and their children and for measuring the impact of interventions to reduce vertical transmission of HIV.

AIDS Serodiagnosis↗
PubMed1994

High HIV-1 incidence in young women masked by stable overall seroprevalence among childbearing women in Kinshasa, Zaïre: estimating incidence from serial seroprevalence data.

OBJECTIVE: To describe the dynamics of the HIV-1 epidemic in childbearing women in Kinshasa, Zaïre, by estimating incidence from serial seroprevalence studies. METHODS: In 1986 and 1989, 5937 and 4623 pregnant women, respectively, were screened for HIV-1 in Kinshasa. We estimated age-specific incidence from two seroprevalence surveys by using a birth-year cohort analysis and adjusting for differences in mortality and fertility between HIV-1-infected and uninfected women. Mortality and fertility data were measured in a cohort of women recruited from the survey in 1986 and followed until 1989. RESULTS: While the overall HIV-1 seroprevalence changed little (5.8% in 1986 and 6.5% in 1989; P = 0.17), the prevalence increased in birth-year cohorts of women under 25 years of age in 1989 from 3.2 to 6.2% (P < 0.001), but decreased for women above 25 years of age from 6.9 to 6.7% (P = 0.7). In addition, new HIV infections between 1986 and 1989 were balanced by a higher mortality and lower fertility observed in HIV-infected women. After adjusting for these effects, we estimated an overall 3-year cumulative HIV-1 incidence of 2.8 per 100 uninfected women [95% confidence interval (CI), 1.4-4.2]. The highest incidence, 5.7 per 100 (95% CI, 3.5-8.0), was in women aged 20-24 years in 1989. CONCLUSION: Despite an overall relatively stable HIV-1 prevalence in childbearing women in Kinshasa between 1986 and 1989, approximately 40% of all HIV-1 infections detected in the 1989 survey occurred between 1986 and 1989, and 60% occurred in women under 25 years of age in 1989.

Adult↗
PubMed1994

The seroepidemiology of human immunodeficiency virus in the United States household population: NHANES III, 1988-1991.

To provide an estimate of the seroprevalence of human immunodeficiency virus (HIV) in a representative sample of the U.S. household population, serum samples from participants in the third National Health and Nutrition Examination Survey (NHANES III) were tested for HIV antibody. The testing was performed anonymously on 5,430 individuals 18-59 years old from phase 1 of NHANES III conducted from 1988 to 1991. Twenty-nine individuals were HIV positive. The total weighted prevalence was 0.39%. The population estimate of infected individuals was 547,000, with a 95% confidence interval of 299,000-1,020,000 infected persons. Black participants were four times more likely to be HIV positive than white/other individuals and three times more likely than Mexican Americans. Men were three times more likely to be infected than women. Higher nonresponse to the survey and to phlebotomy was observed in young white men; therefore these data provide a conservative estimate of HIV infection in the general household population. This estimate does not include individuals who do not live in households and who may be at higher risk of infection, such as persons in penal institutions, the homeless, or certain hospitalized patients.

Adult↗
PubMed1993

Trends in HIV prevalence among disadvantaged youth. Survey results from a national job training program, 1988 through 1992.

OBJECTIVE: To describe trends in the prevalence of human immunodeficiency virus (HIV) among socially and educationally disadvantaged US youth. DESIGN: Analysis of demographic and geographic trends of HIV infection among Job Corps students from January 1988 through December 1992. SETTING: The Job Corps is a national training program for disadvantaged and out-of-school youth. POPULATION SCREENED: Youths aged 16 to 21 years who entered the Job Corps residential training centers during the survey period. MAIN OUTCOME MEASURE: Trends in prevalence of HIV infection among Job Corps students stratified by sex, age, race, and region of the country. RESULTS: Of the 269,956 Job Corps students screened, 812 (0.3%) tested positive for the antibody to HIV type 1. Seroprevalence of HIV for young men decreased from 3.6 per 1000 in 1988 to 2.2 per 1000 in 1992 (chi 2 test for trend, P < .001). Seroprevalence for young women increased from 2.1 per 1000 in 1988 to 4.2 per 1000 in 1990 (P = .001), with seroprevalence remaining stable from 1990 through 1992. The decreasing trends in HIV prevalence among men and increasing trends among women were primarily due to changes in seroprevalence in African-American students. CONCLUSIONS: The overall prevalence of HIV infection of three per 1000 is high, given the youth of Job Corps students. The significant rise in HIV rates among female Job Corps students provides evidence of the increasing risk of infection for socioeconomically disadvantaged young women. Reasons for the declining trend in HIV prevalence among male Job Corps students are not clear. Efforts to prevent the spread of HIV infection among adolescents must focus on the group that is hardest to reach--out-of-school and impoverished youth.

Adolescent↗
PubMed1993

Effect of routine use of therapy in slowing the clinical course of human immunodeficiency virus (HIV) infection in a population-based cohort.

Clinical trials have shown that the prophylactic use of zidovudine and aerosolized pentamidine (or other antibiotics used as prophylaxis against Pneumocystis carinii pneumonia) in acquired immunodeficiency syndrome (AIDS)-free human immunodeficiency virus (HIV)-infected persons delays the development of AIDS, but the effectiveness of such therapy in general use in the population still remains largely undocumented. To help answer this question, the authors estimate the effectiveness of this therapy in a population-based cohort of HIV-infected homosexual and bisexual men in San Francisco. The authors use a continuous-time Markov process to model the decline of CD4+ T-lymphocytes (T4-cells) measured in cells/microliter in HIV-infected persons. The model partitions the HIV (type 1) infection period into six progressive T4-cell count intervals (stages), followed by a seventh stage: AIDS diagnosis. The authors use maximum likelihood methods to fit the model to the observed transitions for 428 HIV-infected men during June 1984 to March 1991, from the San Francisco Men's Health Study. Since zidovudine was not widely used before 1988, the model has a component that controls for calendar time-related biases. The fitted model provides statistical estimates and confidence intervals for measuring therapy effectiveness. The authors estimate that prophylactic therapy reduces the progression rate from stage 4 (T4-cell count, 350-499) to stage 5 (T4-cell count, 200-349) by a factor of 0.26 (95% confidence interval (CI) -0.22 to 0.55); from stage 5 to stage 6 (T4-cell count < 200) by a factor of 0.33 (95% CI 0.04-0.54); and from stage 6 to 7 (AIDS) by a factor of 0.62 (95% CI 0.47-0.73). In addition, therapy started by an HIV-infected person in stage 4 is estimated to reduce the risk of developing AIDS by a factor of 0.83 (95% CI 0.46-0.94) at 6 months and 0.68 (95% CI 0.35-0.89) at 24 months after entering stage 4. Therapy started by HIV-infected persons in more advanced stages is estimated to reduce the risk of developing AIDS by factors ranging from 0.70 (95% CI 0.39-0.90), early in stage 5, to 0.28 (95% CI 0.14-0.45), late in stage 6. Thus, the prophylactic use of zidovudine and pentamidine in routine medical care has a strong, consistent, and significant effect in slowing the clinical course of HIV infection in a population-based cohort.

AIDS-Related Opportunistic Infections↗
PubMed1993

An analysis of AIDS incidence data by clustering trends.

AIDS incidence trends vary greatly among geographic areas in the United States. We define clusters of areas within which AIDS incidence trends are similar, as areas within a cluster may have similar human immunodeficiency virus epidemic patterns and thus may lead to similar prevention/intervention strategies. Methods of exploratory data analysis are used to define such clusters from reported quarterly AIDS incidence to December 1990 (adjusted for estimated reporting delays) in homosexual and bisexual men not using intravenous drugs in 39 metropolitan statistical areas (MSAs) in the United States. After smoothing AIDS incidence in each MSA, we define groups from cluster analysis based on a measure of similarity between pairs of MSAs. A log-linear model gives estimates of the scale factors and the common trend for the MSAs in each group. Alternative metrics and simulated data suggest that the clustering is fairly robust to variations in AIDS incidence data. The resulting clusters separate MSAs with different trends, for example, MSAs in which AIDS incidence shows signs of reaching a plateau are separated from MSAs in which incidence continues to increase rapidly.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Projections of the number of persons diagnosed with AIDS and the number of immunosuppressed HIV-infected persons--United States, 1992-1994.

This report presents projections of the number of persons who will initially be diagnosed with a condition included in the 1987 surveillance definition for acquired immunodeficiency syndrome (AIDS) in the United States during the period 1992-1994. The report also presents estimates and projections of the prevalence of persons infected with the human immunodeficiency virus (HIV) who have CD4+ T-lymphocyte (T-cell) counts < 200/microL and who have not been diagnosed with a condition listed in the 1987 AIDS surveillance definition. These estimates and projections are used to predict the effect of expanding the AIDS surveillance definition to include all HIV-infected persons with a CD4+ T-cell count < 200/microL. Approximately 58,000 persons were diagnosed with AIDS in the United States during 1991. During the period 1992-1994, the number of persons newly diagnosed with AIDS is expected to increase by at most a few percent annually, with approximately 60,000-70,000 persons diagnosed per year. Although AIDS diagnoses among homosexual and bisexual men and among injecting drug users are projected to reach a plateau during this period, the number of AIDS diagnoses among persons whose HIV infection is attributed to heterosexual transmission of HIV is likely to continue to increase through 1994. The number of living persons who have been diagnosed with AIDS is expected to increase from approximately 90,000 in January 1992 to approximately 120,000 in January 1995. There is, however, considerable uncertainty in these projections. For example, the plausible range for the number of persons initially diagnosed with AIDS in 1994 is 43,000-93,000. CDC estimates that, as of January 1992, 115,000-170,000 U.S. residents had severe immunosuppression (a CD4+ T-cell count < 200 cells/microL without a diagnosis of AIDS in an HIV-infected person). Only about 50,000 of these persons were receiving medical care for HIV-related conditions and were known to have a CD4+ T-cell count < 200 cells/microL. The number of persons with severe immunosuppression is expected to increase to 130,000-205,000 by January 1995, with the actual number more likely to be in the lower half of this range than the upper half. The expanded AIDS surveillance definition, which includes severe immunosuppression, is predicted to result in an increase of approximately 75% in the number of persons reported during 1993, but an increase of < 20% in 1994 compared with the number of persons who would have been reported had the definition not been changed.(ABSTRACT TRUNCATED AT 400 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1992

Changes in AIDS incidence trends in the United States.

Estimating the current prevalence of human immunodeficiency virus (HIV) and projecting the future incidence of AIDS require that trends in incidence be analyzed and interpreted. We analyzed AIDS incidence trends in the United States by exposure category and selected demographic factors. In 1987, the trend in United States AIDS incidence changed as growth in the number of cases diagnosed per quarter began to decline. The slowing in growth is due in large part to a plateau in quarterly incidence in men who have sex with men in the New York City, San Francisco, and Los Angeles metropolitan statistical areas (MSAs), and in injecting drug users in the New York City MSA and New Jersey. Incidence has also reached a plateau in both adult/adolescent and pediatric blood and blood product recipients. Quarterly U.S. AIDS incidence was roughly constant during 1990, but appears to have increased to a higher level during the first half of 1991. The variation in incidence trends among subgroups suggests that several factors have affected the trend in total incidence and that the burden of severe symptomatic HIV disease may be shifting.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Using provisional diagnoses in monitoring a clinical trial.

In clinical trials there is delay between the occurrence of an event and the recording of that event as an end point in the trial data base. Delays are especially likely if events are reviewed carefully to determine whether diagnostic criteria for end points are satisfied. As a result, the value of a statistic used to evaluate efficacy during a trial may differ from the value of that statistic based on the true end point status of all events which have already occurred. Simulating the process causing delays can be useful in evaluating interim efficacy data by providing a quantitative estimate of the uncertainty in a monitoring statistic. These ideas are illustrated using data from the Lipid Research Clinics Coronary Primary Prevention Trial.

Adult↗
PubMed1991

A simulation model of AIDS in San Francisco: II. Simulations, therapy, and sensitivity analysis.

The HIV and AIDS incidences each year for homosexual men in San Francisco are estimated from data. A computer simulation model for HIV transmission dynamics and progression to AIDS is used to reconstruct the HIV epidemic. Using some a priori parameter estimates, simulations are found that give good fits to the incidence data. In the stimulations the populations is divided into risk groups whose sexual activities are found to be strongly connected. There is saturation in the high-risk group, but changes in sexual behavior are more important in obtaining adequate fits. The simulation modeling yields useful parameter estimates, but the remaining uncertainty in parameter values implies that the simulation forecasts are also uncertain. Changes in HIV incidence lead to changes in AIDS incidence about 6-10 years later. Simulation models with and without zidovudine treatment both fit the incidence data; thus the effects of therapy on AIDS incidence are unclear. The fits of the simulation model are most sensitive to the yearly migration rate, the number of stages in the progression to AIDS, and the average number of new sexual partners per month; thus better estimates of these parameters would be desirable.

Acquired Immunodeficiency Syndrome↗
PubMed1991

The geographic and ethnic diversity of AIDS incidence trends in homosexual/bisexual men in the United States.

We examined geographic and racial/ethnic variation in acquired immune deficiency syndrome (AIDS) incidence in homosexual and bisexual men (i.e., men who report sex with men: MSWM) not using i.v. drugs in the United States. The AIDS incidence in these men has continued to increase in the United States. Incidence increased much less rapidly after 1986 in the three metropolitan statistical areas (MSAs) with the most cases, New York City, Los Angeles, and San Francisco, and may have reached a plateau in these areas. This change in incidence occurred in non-Hispanic black and Hispanic MSWM as well as in non-Hispanic whites in these MSAs, but earlier in whites. There have been similar changes in incidence (but later in time) in all other MSAs with a population of at least 1,000,000 combined, with more tendency toward a plateau in whites than in non-whites. In contrast, incidence increased linearly through 1989 in MSAs with a population less than 1,000,000 and in rural areas, with no change in trend after 1986. Changes in human immunodeficiency virus (HIV) infection incidence before 1985, better therapy and medical care, and migration all contributed to these changes in incidence, as may have changes in reporting. Continued HIV seroconversions among MSWM show that efforts to prevent HIV infection must be continued in all areas of the United States.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Black-white differences in exercise blood pressure. The Lipid Research Clinics Program Prevalence Study.

After exclusion of persons on blood pressure medication or with prevalent cardiovascular disease, we studied 83 black and 2,548 white men and 113 black and 1,519 white women 20-69 years old from the Lipid Research Clinics population sample who had performed a standardized treadmill exercise test. Resting systolic and diastolic blood pressures were similar in black and white men, but the diastolic pressure was significantly higher in black than in white women (81.4 vs 77.4 mm Hg). Body weight was higher in black than in white women, and reported physical activity was higher in black than in white men. The proportion of smokers was somewhat higher in blacks than in whites. During the treadmill exercise test with a modified Bruce protocol, mean systolic blood pressure at stage 2 was 174 mm Hg in black men and 166 mm Hg in white men (p less than 0.02), but stage 2 blood pressures did not differ between black and white women (153 and 152 mm Hg, respectively). Even after adjustments were made for levels of baseline characteristics (age, weight, resting systolic blood pressure, smoking, low density lipoprotein cholesterol, physical activity, and alcohol intake), black men responded with a 7-mm Hg higher systolic blood pressure during exercise than white men (p less than 0.01). Another new finding was a highly significant positive association between stage 2 systolic blood pressure and low density lipoprotein cholesterol in men. The findings suggest a higher systemic vascular resistance during exercise in the selected sample of black men, which is consistent with the higher incidence of hypertension in black men.

Adult↗
PubMed1990

The increasing frequency of heterosexually acquired AIDS in the United States, 1983-88.

Of 88,510 cases of acquired immunodeficiency syndrome (AIDS) reported in adults in the United States from 1983 through 1988, the percentage attributed to reported heterosexual contact with persons known to be infected or at increased risk of infection with human immunodeficiency virus (HIV) has increased steadily from 0.9 percent in the first quarter of 1983 to 4.0 percent in the fourth quarter of 1988, from 0.1 (in 1983) to 1.4 percent (in 1988) among men, and from 13 (in 1983) to 28 percent (in 1988) among women. Among women, the cumulative incidence of AIDS attributable to heterosexual contact per million population is over 11 times greater for Blacks and Hispanics than for Whites. Among men, this incidence is over 10 times greater for Blacks and four times greater for Hispanics than for Whites. The pattern of distribution of heterosexually acquired AIDS parallels the distribution of other heterosexually transmitted diseases, which are also more frequent in Black and Hispanic inner-city populations. Drug use, exchange of sex for drugs or money, and early onset of sexual activity in adolescents are increasingly associated with heterosexually transmitted infections and are likely to be very important in heterosexual transmission of HIV in inner-city US populations.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Impact of the 1987 revision of the case definition of acquired immune deficiency syndrome in the United States.

To measure the impact of the 1987 expansion of the definition of acquired immune deficiency syndrome on the number and characteristics of cases in the United States, we reviewed the 28,920 cases diagnosed since the revision and reported through 1988. The proportion meeting only new criteria was 28% overall, with a range of 0 to 82% in different states and territories. This proportion was 26% in the last quarter of 1987 and increased to 31% in the last quarter of 1988. It was higher in heterosexual intravenous drug abusers (IVDAs) (43%) and lower in homosexual male non-IVDAs (21%) than in other groups. The new criteria, but not earlier (pre-1985) criteria, generally require a positive test for human immunodeficiency virus (HIV) infection; however, use of HIV testing varies among states, as demonstrated by differences in the percentage of pre-1985-criteria cases with a reported HIV test (39 to greater than 95%). The revision has changed the distribution of characteristics of cases (e.g., heterosexual IVDAs composed 18% of cases meeting old criteria, 35% of cases meeting only new criteria, and 23% of all cases). Interpretation of trends in both the number and characteristics of cases should take into account the variable impact of the revision on reporting.

AIDS Serodiagnosis↗
PubMed1989

Detection of aberrations in the occurrence of notifiable diseases surveillance data.

The detection of unusual patterns in the occurrence of diseases and other health events presents an important challenge to public health surveillance. This paper discusses three analytic methods for identifying aberrations in underlying distributions. The methods are illustrated on selected infectious diseases included in the National Notifiable Diseases Surveillance System of the Centers for Disease Control. Results suggest the utility of such an analytic approach. Further work will determine the sensitivity of such methods to variations in the occurrence of disease. These methods are useful for evaluating and monitoring public health surveillance data.

Centers for Disease Control and Prevention, U.S.↗
PubMed1988

The projected incidence of AIDS and estimated prevalence of HIV infection in the United States.

Planning for health and social services and for prevention programs requires predicting the number of AIDS cases likely to be diagnosed during the next several years and estimating the prevalence of HIV infection. Extrapolating from recent AIDS incidence data, we estimate that 365,000 AIDS cases will be diagnosed in the United States through 1992 (68% prediction interval, 205,000 to 440,000). Both recent HIV seroprevalence surveys and historical AIDS incidence are consistent with the U.S. Public Health Service estimate that 1.0 to 1.5 million persons in the United States are now infected with human immunodeficiency virus (HIV). Although current estimates of future AIDS cases and of current prevalence of HIV infection are somewhat uncertain, better statistical estimation procedures are being developed, and current surveys will provide additional data on HIV prevalence in the United States within the next several years.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Predictive value of the exercise tolerance test for mortality in North American men: the Lipid Research Clinics Mortality Follow-up Study.

More than 3600 white men, from 30 to 79 years old and without a history of myocardial infarction, underwent submaximal treadmill exercise tolerance tests as part of their baseline evaluation for the Lipid Research Clinics Mortality Follow-up Study. The exercise test was conducted according to a common protocol and coded centrally; depression of the ST segment by at least 1 mm (visual coding) and/or 10 microV-sec (ST integral, computer coding) signified a positive test. Concurrent measurements of age, blood pressure, history of cigarette smoking, and plasma levels of lipids, lipoproteins, and glucose, as well as other coronary risk factors, were obtained. Cumulative mortality from cardiovascular disease was 11.9% (22/185) over 8.1 years mean follow-up among men with a positive exercise test vs 1.2% (36/2993) over 8.6 years mean follow-up among men with a negative test. Three-quarters (43) of these deaths were due to coronary heart disease. The relative risk for cardiovascular mortality associated with a positive exercise test was 9.3 before and 4.6 after age adjustment. Cardiovascular mortality rates were especially elevated (relative risk 15.6 before and 5.1 after age adjustment) among the 82 men whose exercise tests were adjusted "strongly" positive based on degree and timing of the ischemic electrocardiographic response. A positive exercise test was also moderately associated with noncardiovascular mortality; the relative risk for all-cause mortality was 7.2 before and 3.4 after age adjustment. The relative risk for cardiovascular mortality associated with a positive exercise test was not appreciably altered by covariance adjustment for known coronary risk factors other than age. A positive exercise test was a stronger predictor of cardiovascular death than were high plasma levels of low-density lipoprotein cholesterol, low plasma levels of high-density lipoprotein cholesterol, smoking, hyperglycemia, or hypertension. Its impact on risk of cardiovascular death was equivalent to that of a 17.4 year increment in age.

Adult↗