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N Galai

Publications and source records attributed to N Galai.

At least 19 recordsLinked to original sources
PubMed2005

Evaluating survival model performance: a graphical approach.

In the last decade, many statistics have been suggested to evaluate the performance of survival models. These statistics evaluate the overall performance of a model ignoring possible variability in performance over time. Using an extension of measures used in binary regression, we propose a graphical method to depict the performance of a survival model over time. The method provides estimates of performance at specific time points and can be used as an informal test for detecting time varying effects of covariates in the Cox model framework. The method is illustrated on real and simulated data using Cox proportional hazard model and rank statistics.

Humans↗
PubMed2005

Increased risk of bloodstream and urinary infections in intensive care unit (ICU) patients compared with patients fitting ICU admission criteria treated in regular wards.

Critically ill patients, eligible for admission into intensive care units (ICUs), are often hospitalized in other wards due to a lack of ICU beds. Differences in morbidity between patients managed in ICUs and elsewhere are unknown, specifically the morbidity related to hospital-acquired infection. Patients fitting ICU admission criteria were identified by screening five entire hospitals on four separate days. Hospital infections within a 30-day follow-up period were compared in ICU patients and in patients on other wards using Kaplan-Meier curves. Residual differences in the patients' case mix between ICUs and other wards were adjusted for utilizing multivariate Cox models. Of 13415 patients screened, 668 were critically ill. The overall infection rates (per 100 patient-days) were 1.2 for bloodstream infection (BSI) and 1.9 for urinary tract infection (UTI). The adjusted hazard ratios in ICU patients compared with patients on regular wards were 3.1 (P<0.001) for BSI and 2.5 (P<0.001) for UTI. This increased risk persisted even after adjusting for the disparity in the number of cultures sent from ICUs compared with ordinary wards. No interdepartmental differences were found in the rates of pneumonia, surgical wound infections and other infections. Minimizing the differences between characteristics of patients hospitalized in ICUs and in other wards, and controlling for the higher frequency of cultures sent from ICUs did not eliminate the increased risk of BSI and UTI associated with admission into ICUs.

Aged↗
PubMed2003

Longitudinal patterns of drug injection behavior in the ALIVE Study cohort,1988-2000: description and determinants.

The objective of this study was to characterize longitudinal patterns of drug injection behavior for individuals and to identify their early determinants. Participants were 1,339 injection drug users recruited into the AIDS Link to Intravenous Experience (ALIVE) Study in Baltimore, Maryland, through community outreach efforts. The study was initiated in 1988, and follow-up continued through 2000, with semiannual visits. Patterns of self-reported drug injection (yes/no) were defined for each participant, based on the number of drug-use transitions. The effect of baseline factors was assessed using multinomial logistic regression models. Over the 12-year study period, four patterns were noted: 29% of participants remained persistent drug injectors, 20% ceased injection, 14% relapsed once, and 37% had multiple transitions. Persistent injectors had the shortest follow-up and the highest mortality. For persons who changed their behavior, 3.4 years elapsed before their first cessation attempt, on average. Factors differentiating the groups included history of incarceration, young age, participation in drug treatment programs, recent overdose, and commercial sex. The observed long-term injection patterns are consistent with the view of drug addiction as a chronic disease. This view emphasizes the need for prolonged efforts to sustain cessation and to prevent adverse health and social outcomes among injection drug users.

Adult↗
PubMed2001

Time to initiating highly active antiretroviral therapy among HIV-infected injection drug users.

OBJECTIVE: Studies have shown that HIV-infected injection drug users (IDUs) are less likely to receive antiretroviral therapy than non-drug users. We assess factors associated with initiating highly active antiretroviral therapy (HAART) in HIV-infected IDUs. METHODS: A cohort study of IDUs carried out between 1 January 1996 and 30 June 1999 at a community-based study clinic affiliated to the Johns Hopkins University, Baltimore, Maryland. The participants were a total of 528 HIV-infected IDUs eligible for HAART based on CD4+ cell count. The main outcome measure was the time from treatment eligibility to first self-reported HAART use, as defined by the International AIDS Society-USA panel (IAS-USA) guidelines. RESULTS: By 30 June 1999, 58.5% of participants had initiated HAART, most of whom switched from mono- or dual-combination therapy to a HAART regimen. Nearly one-third of treatment-eligible IDUs never received antiretroviral therapy. Cox proportional hazards regression showed that initiating HAART was independently associated with not injecting drugs, methadone treatment among men, having health insurance and a regular source of care, lower CD4+ cell count and a history of antiretroviral therapy. CONCLUSIONS: Self-reported initiation of HAART is steadily increasing among IDUs who are eligible for treatment; however, a large proportion continues to use non-HAART regimens and many remain treatment-naive. Although both groups appear to have lower health care access and utilization, IDUs without a history of antiretroviral therapy use would have more treatment options available to them once they become engaged in HIV care.

Adult↗
PubMed2001

Sex differences in risk factors for hiv seroconversion among injection drug users: a 10-year perspective.

BACKGROUND: Injection drug use directly or indirectly accounts for nearly half the annual human immunodeficiency virus (HIV) infections in the United States. Prospective studies that investigate both sexual and parenteral HIV risks among injection drug users (IDUs) are needed. We studied factors for HIV seroconversion among male and female IDUs in Baltimore, Md. METHODS: The HIV-negative IDUs (1447 male and 427 female) were recruited into a prospective study from 1988 to 1989 or in 1994. Participants underwent semiannual HIV tests and surveys through December 1998. Poisson regression was used to identify risk factors for HIV seroconversion, stratified by sex. Behaviors were treated as time-dependent covariates that varied at each semiannual period. RESULTS: Subjects were primarily African American (91%), and median age at enrollment was 35 years. Incidence of HIV was 3.14 per 100 person years (95% confidence interval, 2.78-3.53) and did not significantly differ by sex. Younger age independently predicted HIV seroconversion for both men and women. Among men, factors that independently predicted HIV seroconversion were the following: less than a high school education, recent needle sharing with multiple partners, daily injection, and shooting-gallery attendance. The incidence of HIV was double for men recently engaging in homosexual activity and cocaine injection. Among women, the incidence of HIV was more than double for those recently reporting sexually transmitted diseases. CONCLUSIONS: The incidence of HIV remained high among IDUs in Baltimore over the past decade. Risk factors for HIV seroconversion differed markedly by sex. Predominant risks among men included needle sharing and homosexual activity; among women, factors consistent with high-risk heterosexual activity were more significant than drug-related risks. Human immunodeficiency virus interventions aimed at IDUs should be sex-specific and incorporate sexual risks.

Adolescent↗
PubMed2001

The prescription pattern of oral nitrates in coronary artery disease. Appropriateness and cost considerations.

OBJECTIVES: To evaluate the prescription patterns of oral nitrates in terms of appropriateness and cost in a community setting. METHODS: A period prevalence, descriptive, applied study. Data including age, gender, type of medication, dosage and cost were extracted from the database of the largest health maintenance organisation (HMO) in Israel. The study population included enrollees over 35 years of age who received oral nitrates at least once during the 12-month study period. RESULTS: Oral nitrates were prescribed for 8007 patients (mean age 72.85+/-9.59 years, male:female ratio 1:1). A total of 52,694 prescriptions were issued for 56,553 medications, of these 88.1% for mononitrates, which constituted 95% of the annual cost for patients and the HMO. The mean prescribed daily dose for the various drugs ranged from 30% less than to 50% more than the recommended dose. Combination therapy with at least two nitrates, which is not the recommended treatment, was given to 5% of the patients. The recommended alternative treatment will alleviate the financial burden for providers and patients. CONCLUSIONS: Improved prescription habits can provide enhanced quality as well as cost savings for patients and providers.

Administration, Oral↗
PubMed2001

Sociodemographic and clinical factors associated with low quality of life one year after coronary bypass operations: the Israeli coronary artery bypass study (ISCAB).

OBJECTIVES: We sought to examine the effect of sociodemographic characteristics and perioperative clinical factors 1 year after coronary bypass operations on low health-related quality of life. We also sought to assess the usefulness of an additional single question on overall health for identifying patients with low health-related quality of life. METHODS: This report is part of the Israeli coronary artery bypass study of 1994, in which every patient undergoing isolated coronary bypass grafting in Israel was included. The target population for this report comprised all survivors beyond 1 year who were 45 to 65 years of age. Patients were interviewed before the operations. Self-administered questionnaires regarding health-related quality of life (SF-36) were sent to 1724 patients who were successfully located 1 year postoperatively, and 1270 questionnaires were completed. Low health-related quality of life was defined as the lowest tertile of the distribution of scores for the 2 summary components of the SF-36 and the single question on overall health. Logistic models were constructed for each of the 3 outcomes. RESULTS: Female sex and low socioeconomic background were associated with low health-related quality of life in the logistic models. Other significant factors were symptoms of angina, sleep disturbances, hypertension, high severity of illness scores, hospital readmission, no rehabilitation, and hospitals with high perioperative mortality. Of the 3 study outcomes, the model for the single question on overall health was the most discriminating (C statistic = 0.76 vs 0.70 and 0.70, respectively). CONCLUSIONS: The study identifies patients who would most benefit from posthospitalization community support after bypass operations. Under circumstances of limited resources, these disadvantaged groups should be targeted as a priority. Encouraging participation in existing rehabilitation programs or introducing telephone hotlines could improve health-related quality of life after coronary bypass grafting without large investments.

Aged↗
PubMed2001

Is participation in cardiac rehabilitation programs associated with better quality of life and return to work after coronary artery bypass operations? The Israeli CABG Study.

OBJECTIVE: To explore the putative effect of cardiac rehabilitation programs on the 'health-related quality of life' and 'return to work' in pre-retirement patients one year after coronary artery bypass grafting. METHODS: Of the 2,085 patients aged 45-64 who survived one year after CABG and were Israeli residents, 145 (6.9%) had participated in rehabilitation programs. Of these, 124 (83%) who answered QOL questionnaires were individually matched with 248 controls by gender, age within 5 years, and the time the questionnaire was answered. All patients had full clinical follow-up including a pre-operative interview. The Short Form-36 QOL questionnaire as well as a specific questionnaire were mailed to surviving patients one year after surgery. Study outcomes included the scores on eight scales and two summary components of the SF-36, as well as 'return to work' and 'satisfaction with medical services' from the specific questionnaire. Analysis was done for matched samples. RESULTS: Cardiac rehabilitation participants had significantly higher SF-36 scores in general health, physical functioning, and social functioning. They had borderline significant higher scores in the physical summary component of the SF-36. The specific questionnaire revealed significantly better overall functioning, higher satisfaction with medical care, and higher rate of return to work. While participants in cardiac rehabilitation and their controls were similar in their socio-demographic and clinical profiles, participating patients tended to be more physically active and more fully employed than their controls. CONCLUSIONS: Rehabilitation participants had a self-perception of better HRQOL, most significantly in social functioning. Our findings of more frequent return to work and higher satisfaction with medical care should induce a policy to encourage participation in cardiac rehabilitation programs after CABG.

Case-Control Studies↗
PubMed2000

The natural history of hepatitis C virus infection: host, viral, and environmental factors.

CONTEXT: Hepatitis C virus (HCV) infection may resolve (viral clearance), persist without complications, or cause end-stage liver disease (ESLD). The frequency and determinants of these outcomes are poorly understood. OBJECTIVE: To assess the incidence and determinants of viral clearance and ESLD among persons who acquired HCV infection from injection drug use. DESIGN AND SETTING: Community-based prospective cohort study with enrollment in 1988-1989 and a median follow-up of 8.8 years. SUBJECTS: A total of 1667 persons aged 17 years or older with a history of injection drug use and an HCV antibody-positive test result during follow-up. MAIN OUTCOME MEASURES: Viral clearance was assessed in a subset of 919 patients and defined as failure to detect HCV RNA in at least 2 consecutive samples collected 5 or more months apart. End-stage liver disease was assessed at semiannual visits and by review of medical records and death certificates and defined by the presence of ascites, esophageal varices, or hepatic encephalopathy, or when ESLD was stated as a cause of death. RESULTS: Viral clearance was observed in 90 persons who were compared with 722 with persistent viremia, while the viremia of 107 was not resolved. Viral clearance occurred more often in nonblacks (adjusted odds ratio [OR], 5.15; 95% confidence interval [CI], 2.60-10.17) and those not infected with human immunodeficiency virus (HIV) (adjusted OR, 2.19; 95% CI, 1.26-3.47). Forty cases of ESLD were observed throughout follow-up (incidence, 3.1 per 1000 person-years). In a multivariate model, risk of ESLD was higher for persons aged 38 years or older at enrollment (adjusted relative incidence, 3.67; 95% CI, 1.96-6.88) and who reported ingestion of more than 260 g of alcohol per week (adjusted relative incidence, 3.60; 95% CI, 1.73-7.52). Of 210 patients without ESLD randomly selected for biopsy, only 2 had cirrhosis. CONCLUSIONS: Our results indicate that although HCV infection can be self-limited or associated with ESLD, the majority of adults have persistent viremia without clinically demonstrable liver disease. Further research is needed to explain the less frequent clearance of HCV infection among black persons and to improve utilization of treatment for those infected in the context of injection drug use. JAMA. 2000;284:450-456

Adult↗
PubMed2000

Sequential logistic models for 30 days mortality after CABG: pre-operative, intra-operative and post-operative experience--The Israeli CABG study (ISCAB). Three models for early mortality after CABG.

OBJECTIVES: The goal of this paper was to examine the added effect of operative and post-operative variables on 30 days mortality, in addition to patients' case-mix factors. SETTING AND DESIGN: A prospective study of 4835 patients, 95% of all Israeli patients who underwent coronary artery bypass grafting (CABG) in 1994. Information related to risk of death was collected at admission to hospital (preceding the operation), at time of the operation and in the immediate post-operative period. Deaths were independently ascertained. METHOD: Data collectors followed every patient from admission to discharge. Sequential logistic models were constructed for the 'case-mix', 'operative' and the 'post-operative' periods in chronological order. Each model incorporated and adjusted for the risk estimated at the previous point in time, by forcing individual risk scores. RESULTS: Significant pre-operative risk factors for 30 days mortality, in the case-mix model included mainly severity of illness characteristics, such as, left ventricular dysfunction and emergency admission, (c-statistic 78.8%). Model 2 (the 'operation' model) included in addition to the case-mix score, excessive duration of the operation per graft, bleeding, etc. (c-statistic 85.3%). The post-operative model showed the added effect of the post-operative factors such as low haemoglobin, additional surgery, and excessive time on respirator, (c-statistic 92.4%). CONCLUSIONS: The sequential analysis was an efficient method for updating patients' risk over time, where the number of events was small, relative to the number of risk factors. The addition of peri-operative factors increased significantly the predictive power of the model, adding clinical insights to the role of the hospital experience on 30 days mortality.

Adult↗
PubMed2000

Determinants of the quantity of hepatitis C virus RNA.

To test the hypothesis that person-to-person variability in blood levels of hepatitis C virus (HCV) RNA can be explained, the quantity of HCV RNA was assessed in 969 persons who acquired HCV infection in the context of injection drug use. Serum HCV RNA levels ranged from 200,000 to >120 million equivalents/mL (the linear range of the assay). The median log10 HCV RNA level was 0.46 higher in 468 human immunodeficiency virus (HIV)-positive persons than in 501 HIV-negative persons (P<.001). In addition, among HIV-negative persons, lower HCV RNA levels were independently associated with younger age (P<.001), ongoing hepatitis B infection (P=.005), and the absence of needle sharing (P=.02). However, >90% of the person-to-person HCV RNA level variability was not explained by these sociodemographic, environmental, and virologic factors. Additional research is necessary to ascertain what determines the level of HCV RNA in blood.

Adult↗
PubMed2000

Chronic immune activation associated with intestinal helminth infections results in impaired signal transduction and anergy.

Helminthic parasites cause widespread, persistent infections in humans. The immigration of Ethiopians to Israel (a group denoted here by "Eth."), many of them infested with helminths and in a chronic immune-activation state, enabled us to investigate the effects of such immune activation on immune responses. We studied the immune profile and immune functions of 190 Eth. and Israeli non-Eth. (Isr.) highly, partially, or non-immune-activated individuals. Immune cells from highly immune-activated individuals were defective in several signaling responses, all of which were restored gradually following anti-helminthic treatment. These cells showed poor transmembrane signaling, as seen by the phosphorylation of various tyrosine kinases and of the MAPK kinases, ERK1/2 and p38; deficient degradation of phosphorylated IkappaBalpha; increased expression of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), which appears to block proliferative responses in these cells; decreased beta-chemokine secretion by CD8(+) cells after stimulation; and reduced proliferation to recall antigen stimulation. Highly immune-activated individuals also showed decreased delayed-type skin hypersensitivity responses to recall antigen before deworming. These findings support the notion that chronic helminthic infections cause persistent immune activation that results in hyporesponsiveness and anergy. Such impaired immune functions may diminish the capacity of these individuals to cope with infections and to generate cellular protective immunity after vaccination.

Abatacept↗
PubMed1999

HIV incidence among repeat HIV testers with sexually transmitted diseases in Italy. STD Surveillance Working Group.

OBJECTIVES: To provide data on the incidence of HIV infection among repeat testers with sexually transmitted diseases (STD) in Italy. DESIGN: Retrospective longitudinal study. METHODS: Study participants, enrolled by 47 STD centres throughout Italy, included individuals with a newly diagnosed STD who were tested for HIV at the time of the STD diagnosis and who had a previous documented HIV-negative test. 'Seroconverters' were defined as those individuals who tested HIV-positive at the time of the STD diagnosis. The cumulative and the annual incidence of HIV in this population were estimated. RESULTS: Of 1950 patients, 47 were seroconverters, with an incidence rate of 1.7 per 100 person-years (PY) (95% confidence interval, 1.2-2.2). HIV incidence was higher among males than among females (2.5 versus 0.6 per 100 PY). The highest incidence rate was found among homosexual injecting drug users (IDU) (13.8 per 100 PY), whereas the lowest rate was observed among heterosexual non-IDU (0.4 per 100 PY). The annual incidence decreased from 1.8 per 100 PY in 1989 to 0.9 per 100 PY in 1996. CONCLUSIONS: Our results show that new HIV infections have occurred among STD patients in Italy since 1988, although a clear decrease in incidence has occurred since 1989. However, the rate of seroconversion appears to be alarmingly high in some high-risk groups. These findings suggest that there is a need for continued monitoring of new HIV infections among STD patients, and these individuals may represent a useful sentinel population for a better understanding of the HIV epidemic.

Cohort Studies↗
PubMed1999

Direct comparison of time to AIDS and infectious disease death between HIV seroconverter injection drug users in Italy and the United States: results from the ALIVE and ISS studies. AIDS Link to Intravenous Experiences. Italian Seroconversion Study.

OBJECTIVE: To compare the rate of HIV disease progression in a sample of polydrug injectors (AIDS Link to Intravenous Experiences [ALIVE] study) with that in a sample of predominantly opiate injectors (Italian Seroconversion Study [ISS]). DESIGN: Prospective cohort studies of HIV-positive individuals whose date of seroconversion (SC) is known with a good degree of precision. The ALIVE study involves a community-based cohort of injection drug users (IDU) in the United States and the ISS reports on a clinic-based cohort of seroconverters in Italy with different exposure modalities to HIV. METHODS: Data from the two cohorts were combined. The date of SC was estimated as the midpoint in time between the last negative and the first positive HIV test. Time-to-event (i.e., AIDS or death from an infectious disease) statistical methods were used. Relative hazards (RH) of progression to event were adjusted by age at SC, gender, and year of SC. RESULTS: Of the 1003 IDUs (251 from ALIVE and 752 from ISS), 226 progressed to AIDS, and 146 died after AIDS or from an infectious disease; of these, 10 were without an AIDS diagnosis. The two groups of IDUs differed in terms of age at SC (median, 35 years for ALIVE and 25 years for ISS), proportion of women (24% versus 31%), race (7.6% versus 100% white), and year of seroconversion (i.e., ISS participants seroconverted, on average, earlier than ALIVE participants). Although the univariate analysis suggested possible differences for progression to AIDS, or to death from infectious disease between cohorts, multivariate analyses that adjusted for age showed no significant differences by cohort, gender, race, or time of seroconversion. The median time to AIDS for 25-year-old persons was 12.3 years for ALIVE and 11.8 years for ISS; for 35-year-old persons, it was 8.5 and 8.2 years, respectively. These estimates were similar to those for non-IDUs observed in the ISS and to those from large cohort of homosexual men. CONCLUSION: Our results confirm the importance of accounting for age when considering the incubation period for HIV infection. Despite differences in drug use characteristics, the similar median times to AIDS, for each age, between the two cohorts of IDUs and between the IDUs and the non-IDUs suggest a negligible effect of injection drug use on HIV progression.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Prediction of readmissions after CABG using detailed follow-up data: the Israeli CABG Study (ISCAB)

OBJECTIVE: To use detailed pre-discharge follow-up data to predict readmissions within 3 months after Coronary Artery Bypass Grafting (CABG). SETTINGS AND DESIGN: A prospective nationwide study (ISCAB) of 4,835 patients undergoing isolated CABG in Israel in 1994. Survivors of the initial hospitalization were candidates for the readmission study. METHODS: Patient information was prospectively collected from preoperative interviews and hospital follow-up. Readmissions' data were obtained from the National Hospital Admission Registry. Logistic and multinomial models were constructed for total and cause-specific readmissions, respectively. RESULTS: Of CABG survivors, 1,094 (24.1%) were rehospitalized within 3 months of the original surgery. Significant multivariate predictors of total readmissions included the following: preoperative co-morbidities; operative factors; immediate post-operative complications and socio-demographic characteristics as well as provider characteristics. However, the logistic model had low predictive power (c-statistic = 0.65). The heterogeneous reasons for readmissions were classified into specific serious cardiac diagnoses (19.0%), other cardiac reasons (35.4%), specific infections at the site of the operation (10.2%), other infections (7.3%), and various other reasons (23.0%). The multinomial model for cause-specific readmissions caused by either serious cardiac reasons or wound infection had a higher predictive value (c-statistics of 0.75, 0.72, respectively). CONCLUSIONS: Total readmissions after CABG in Israel were difficult to predict, even with an extensive pre-discharge follow-up data. We propose that reasons for readmission vary from true emergencies to nonspecific causes, with the latter related to a lack of support services in the community. We suggest that cause-specific rehospitalizations could be a better outcome for evaluating quality of care.

Aged↗