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2.  Risk Factors for Tuberculosis After Highly Active Antiretroviral Therapy Initiation in the United States and Canada: Implications for Tuberculosis Screening 
The Journal of Infectious Diseases  2011;204(6):893-901.
Background. Screening for tuberculosis prior to highly active antiretroviral therapy (HAART) initiation is not routinely performed in low-incidence settings. Identifying factors associated with developing tuberculosis after HAART initiation could focus screening efforts.
Methods. Sixteen cohorts in the United States and Canada contributed data on persons infected with human immunodeficiency virus (HIV) who initiated HAART December 1995–August 2009. Parametric survival models identified factors associated with tuberculosis occurrence.
Results. Of 37845 persons in the study, 145 were diagnosed with tuberculosis after HAART initiation. Tuberculosis risk was highest in the first 3 months of HAART (20 cases; 215 cases per 100000 person-years; 95% confidence interval [CI]: 131–333 per 100000 person-years). In a multivariate Weibull proportional hazards model, baseline CD4+ lymphocyte count <200, black race, other nonwhite race, Hispanic ethnicity, and history of injection drug use were independently associated with tuberculosis risk. In addition, in a piece-wise Weibull model, increased baseline HIV-1 RNA was associated with increased tuberculosis risk in the first 3 months; male sex tended to be associated with increased risk.
Conclusions. Screening for active tuberculosis prior to HAART initiation should be targeted to persons with baseline CD4 <200 lymphocytes/mm3 or increased HIV-1 RNA, persons of nonwhite race or Hispanic ethnicity, history of injection drug use, and possibly male sex.
doi:10.1093/infdis/jir421
PMCID: PMC3156918  PMID: 21849286
3.  Late Presentation for HIV Care in the United States and Canada 
Background:
Initiatives to improve early detection and access to HIV services have increased over time. We assessed the immune status of patients at initial presentation for HIV care from 1997-2007 in 13 US and Canadian clinical cohorts.
Methods:
We analyzed data from 44,491 HIV-infected patients enrolled in the North American – AIDS Cohort Collaboration on Research and Design. We identified first presentation for HIV care as the time of first CD4+ T-lymphocyte (CD4) measurement and excluded patients who prior to this date had HIV RNA measurements, evidence of antiretroviral exposure, or a history of AIDS-defining illness. Trends in mean CD4 count (measured as cells/mm3) and 95% confidence intervals ([,]) were determined using linear regression adjusted for age, gender, race/ethnicity, HIV transmission risk and cohort.
Results:
Median age at first presentation for HIV care increased over time (range 40-43 years, p<0.01), while the proportion of patients with injection drug use HIV transmission risk decreased (26% to 14%, p<0.01) and heterosexual transmission risk increased (16% to 23%, p<0.01). Median CD4 at presentation increased from 256 (IQR: 96-455) to 317 (IQR: 135-517) in 1997 to 2007 (p<0.01). The proportion with a CD4 count ≥350 at first presentation also increased from 1997 to 2007 (38% to 46%, p=<0.01). The estimated adjusted mean CD4 count increased at a rate of 6 [5, 7] per year.
Conclusion:
CD4 count at first presentation for HIV care has increased annually over the past 11 years, but has remained <350 cells/mm3, suggesting the urgent need for earlier HIV diagnosis and treatment.
doi:10.1086/652650
PMCID: PMC2862849  PMID: 20415573
CD4 Lymphocyte Count; Delivery of Health Care / statistics & numerical data; HIV Infections / therapy; United States; Canada
4.  CD4 count at presentation for HIV care in the United States and Canada: Are those over 50 years more likely to have a delayed presentation? 
We assessed CD4 count at initial presentation for HIV care among ≥50-year-olds from 1997-2007 in 13 US and Canadian clinical cohorts and compared to <50-year-olds. 44,491 HIV-infected individuals in the North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD) were included in our study. Trends in mean CD4 count (measured as cells/mm3) and 95% confidence intervals ([,]) were determined using linear regression stratified by age category and adjusted for gender, race/ethnicity, HIV transmission risk and cohort. From 1997-2007, the proportion of individuals presenting for HIV care who were ≥50-years-old increased from 17% to 27% (p-value < 0.01). The median CD4 count among ≥50 year-olds was consistently lower than younger adults. The interaction of age group and calendar year was significant (p-value <0.01) with both age groups experiencing modest annual improvements over time (< 50-year-olds: 5 [4 , 6] cells/mm3; ≥50-year-olds: 7 [5 , 9] cells/mm3), after adjusting for sex, race/ethnicity, HIV transmission risk group and cohort; however, increases in the two groups were similar after 2000. A greater proportion of older individuals had an AIDS-defining diagnosis at, or within three months prior to, first presentation for HIV care compared to younger individuals (13% vs. 10%, respectively). Due to the increasing proportion, consistently lower CD4 counts, and more advanced HIV disease in adults ≥50-year-old at first presentation for HIV care, renewed HIV testing efforts are needed.
doi:10.1186/1742-6405-7-45
PMCID: PMC3022663  PMID: 21159161
5.  Trends in Multidrug Treatment Failure and Subsequent Mortality among Antiretroviral Therapy–Experienced Patients with HIV Infection in North America 
Background
Although combination antiretroviral therapy continues to evolve, with potentially more effective options emerging each year, the ability of therapy to prevent multiple regimen failure and mortality in clinical practice remains poorly defined.
Methods
Sixteen cohorts representing over 60 sites contributed data on all individuals who initiated combination antiretroviral therapy. We identified those individuals who experienced virologic failure (defined as a human immunodeficiency virus [HIV] RNA level >1000 copies/mL), received modified therapy, and subsequently had a second episode of virologic failure. Multivariate Cox regression was used to assess factors associated with time to second regimen failure and the time to death after the onset of second regimen failure.
Results
Of the 42,790 individuals who received therapy, 7159 experienced a second virologic failure. The risk of second virologic failure decreased from 1996 (56 cases per 100 person-years) through 2005 (16 cases per 100 person-years; P < .001). The cumulative mortality after onset of second virologic failure was 26% at 5 years and decreased over time. A history of AIDS, a lower CD4+ T cell count, and a higher plasma HIV RNA level were each independently associated with mortality. Similar trends were observed when analysis was limited to the subset of previously treatment-naive patients
Conclusions
Although the rates of multiple regimen failure have decreased dramatically over the past decade, mortality rates for those who have experienced failure of at least 2 regimens have remained high. Plasma HIV RNA levels, CD4+ T cell counts at time of treatment failure, and a history of AIDS remain independent risk factors for death, which emphasizes that these factors remain important targets for those in need of more-aggressive therapeutic interventions.
doi:10.1086/644768
PMCID: PMC2871149  PMID: 19845473
6.  Effect of Early versus Deferred Antiretroviral Therapy for HIV on Survival 
The New England journal of medicine  2009;360(18):1815-1826.
Background
The optimal time for the initiation of antiretroviral therapy for asymptomatic patients with human immunodeficiency virus (HIV) infection is uncertain.
Methods
We conducted two parallel analyses involving a total of 17,517 asymptomatic patients with HIV infection in the United States and Canada who received medical care during the period from 1996 through 2005. None of the patients had undergone previous antiretroviral therapy. In each group, we stratified the patients according to the CD4+ count (351 to 500 cells per cubic millimeter or >500 cells per cubic millimeter) at the initiation of antiretroviral therapy. In each group, we compared the relative risk of death for patients who initiated therapy when the CD4+ count was above each of the two thresholds of interest (early-therapy group) with that of patients who deferred therapy until the CD4+ count fell below these thresholds (deferred-therapy group).
Results
In the first analysis, which involved 8362 patients, 2084 (25%) initiated therapy at a CD4+ count of 351 to 500 cells per cubic millimeter, and 6278 (75%) deferred therapy. After adjustment for calendar year, cohort of patients, and demographic and clinical characteristics, among patients in the deferred-therapy group there was an increase in the risk of death of 69%, as compared with that in the early-therapy group (relative risk in the deferred-therapy group, 1.69; 95% confidence interval [CI], 1.26 to 2.26; P<0.001). In the second analysis involving 9155 patients, 2220 (24%) initiated therapy at a CD4+ count of more than 500 cells per cubic millimeter and 6935 (76%) deferred therapy. Among patients in the deferred-therapy group, there was an increase in the risk of death of 94% (relative risk, 1.94; 95% CI, 1.37 to 2.79; P<0.001).
Conclusions
The early initiation of antiretroviral therapy before the CD4+ count fell below two prespecified thresholds significantly improved survival, as compared with deferred therapy.
doi:10.1056/NEJMoa0807252
PMCID: PMC2854555  PMID: 19339714

Results 1-6 (6)