Determinants of nevirapine hypersensitivity and its effect on the association between hepatitis C status and mortality in antiretroviral drug-naive HIV-positive patients

Pharmacogenetics of the cytochromes P450: Selected pharmacological and toxicological aspects

With the availability of detailed genomic data on all 57 human cytochrome P450 genes, it is clear that there is substantial variability in gene product activity with functionally significant polymorphisms reported across almost all isoforms. This article is concerned mainly with 13 P450 isoforms of particular relevance to xenobiotic metabolism. After brief review of the extent of polymorphism in each, the relevance of selected P450 isoforms to both adverse drug reaction and disease susceptibility is considered in detail. Bleeding due to warfarin and other coumarin anticoagulants is considered as an example of a type A reaction with idiosyncratic adverse drug reactions affecting the liver and skin as type B. It is clear that CYP2C9 variants contribute significantly to warfarin dose requirement and also risk of bleeding, with a minor contribution from CYP4F2. In the case of idiosyncratic adverse drug reactions, CYP2B6 variants appear relevant to both liver and skin reactions to several drugs with CYP2C9 variants also relevant to phenytoin-related skin rash. The relevance of P450 genotype to disease susceptibility is also considered but detailed genetic studies now suggest that CYP2A6 is the only P450 relevant to risk of lung cancer with alleles associated with low or absent activity clearly protective against disease. Other cytochrome P450 genotypes are generally not predictors for risk of cancer or other complex disease development.

Genome-wide association study of nevirapine hypersensitivity in a sub-Saharan African HIV-infected population

Background

The antiretroviral nevirapine is associated with hypersensitivity reactions in 6%-10% of patients, including hepatotoxicity, maculopapular exanthema, Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).

Objectives

To undertake a genome-wide association study (GWAS) to identify genetic predisposing factors for the different clinical phenotypes associated with nevirapine hypersensitivity.

Methods

A GWAS was undertaken in a discovery cohort of 151 nevirapine-hypersensitive and 182 tolerant, HIV-infected Malawian adults. Replication of signals was determined in a cohort of 116 cases and 68 controls obtained from Malawi, Uganda and Mozambique. Interaction with ERAP genes was determined in patients positive for HLA-C*04:01 . In silico docking studies were also performed for HLA-C*04:01 .

Results

Fifteen SNPs demonstrated nominal significance ( P  <   1 × 10 -5 ) with one or more of the hypersensitivity phenotypes. The most promising signal was seen in SJS/TEN, where rs5010528 ( HLA-C locus) approached genome-wide significance ( P  <   8.5 × 10 -8 ) and was below HLA -wide significance ( P  <   2.5 × 10 -4 ) in the meta-analysis of discovery and replication cohorts [OR 4.84 (95% CI 2.71-8.61)]. rs5010528 is a strong proxy for HLA-C*04:01 carriage: in silico docking showed that two residues (33 and 123) in the B pocket were the most likely nevirapine interactors. There was no interaction between HLA-C*04:01 and ERAP1 , but there is a potential protective effect with ERAP2 [ P  =   0.019, OR 0.43 (95% CI 0.21-0.87)].

Conclusions

HLA-C*04:01 predisposes to nevirapine-induced SJS/TEN in sub-Saharan Africans, but not to other hypersensitivity phenotypes. This is likely to be mediated via binding to the B pocket of the HLA-C peptide. Whether this risk is modulated by ERAP2 variants requires further study.

Assessment of the nevirapine safety signal using data from the national antiretroviral dispensing database: a retrospective study

BACKGROUND

Clinical trials showed a higher risk of skin- and liver- related adverse reactions when NVP-based antiretroviral therapy (ART) was initiated in female and male patients with baseline CD4 cell counts ≥250 and ≥400, respectively. Some studies reported no difference in risk between the high and low CD4 count groups. Consequently, the use of NVP-based ART in all patients with a CD4 cell count <350, was recommended. In 2011, the Pharmacovigilance Centre detected an increase in reports of grade III and IV reactions. The center was required to determine if there was an increase in NVP-related reactions.

METHODS

Automated dispensing records from January 2008 to November 2011 were accessed from the National Antiretroviral Dispensing Database (NDB). Records of patients who were initiated on NVP-based ART were selected, and records showing a replacement of NVP with protease inhibitor (PI) were identified. The proportions of grade III and IV reactions were calculated per quarter, and Odds Ratios (OR) were calculated, with the confidence interval set at 95 % and a p-value of <0.05.

RESULTS

From 2008 to 2011 a total of 84,741 patients were started on ART. Of these 67,794 were initiated on NVP-containing ART. Of these, 211 females and 79 males were substituted from NVP to a PI. The OR for females was 2.4 (95 % confidence interval [CI] 1.8 - 3.1). For males the OR was 2.4 (OR 2.4; 95 % CI 1.4 - 3.8) which occurred nine months after the change observed in the females. The odds of a NVP-to-PI substitution in females compared to males before the launch of Namibia's 2010 ART guidelines was the same as the odds after the publication of the guidelines (before, OR 1.6; 95 % CI 1.1 - 2.5; after, OR 1.6; 95 % CI 1.2 - 2.2).

CONCLUSIONS

There was an increase in substitutions of NVP with a PI following the increase in the CD4 threshold for initiating NVP-based HAART, meaning that there was an increase in grade III and IV reactions associated with NVP. Therefore the NVP-safety signal was confirmed to be a true signal, which contributed to the Ministry's decision to review the use of NVP.

Initiation of Antiretroviral Therapy in Early Asymptomatic HIV Infection

BACKGROUND

Data from randomized trials are lacking on the benefits and risks of initiating antiretroviral therapy in patients with asymptomatic human immunodeficiency virus (HIV) infection who have a CD4+ count of more than 350 cells per cubic millimeter.

METHODS

We randomly assigned HIV-positive adults who had a CD4+ count of more than 500 cells per cubic millimeter to start antiretroviral therapy immediately (immediate-initiation group) or to defer it until the CD4+ count decreased to 350 cells per cubic millimeter or until the development of the acquired immunodeficiency syndrome (AIDS) or another condition that dictated the use of antiretroviral therapy (deferred-initiation group). The primary composite end point was any serious AIDS-related event, serious non-AIDS-related event, or death from any cause.

RESULTS

A total of 4685 patients were followed for a mean of 3.0 years. At study entry, the median HIV viral load was 12,759 copies per milliliter, and the median CD4+ count was 651 cells per cubic millimeter. On May 15, 2015, on the basis of an interim analysis, the data and safety monitoring board determined that the study question had been answered and recommended that patients in the deferred-initiation group be offered antiretroviral therapy. The primary end point occurred in 42 patients in the immediate-initiation group (1.8%; 0.60 events per 100 person-years), as compared with 96 patients in the deferred-initiation group (4.1%; 1.38 events per 100 person-years), for a hazard ratio of 0.43 (95% confidence interval [CI], 0.30 to 0.62; P<0.001). Hazard ratios for serious AIDS-related and serious non-AIDS-related events were 0.28 (95% CI, 0.15 to 0.50; P<0.001) and 0.61 (95% CI, 0.38 to 0.97; P=0.04), respectively. More than two thirds of the primary end points (68%) occurred in patients with a CD4+ count of more than 500 cells per cubic millimeter. The risks of a grade 4 event were similar in the two groups, as were the risks of unscheduled hospital admissions.

CONCLUSIONS

The initiation of antiretroviral therapy in HIV-positive adults with a CD4+ count of more than 500 cells per cubic millimeter provided net benefits over starting such therapy in patients after the CD4+ count had declined to 350 cells per cubic millimeter. (Funded by the National Institute of Allergy and Infectious Diseases and others; START ClinicalTrials.gov number, NCT00867048.).

Treatment Considerations for Unique Patient Populations With HCV Genotype 1 Infection

OBJECTIVE

To review the literature for the treatment of hepatitis C virus (HCV) genotype 1 in certain populations of patients that require further considerations before therapy initiation.

DATA SOURCES

A systematic electronic literature search using the MEDLINE database was performed using the search terms hepatitis C, chronic hepatitis C, drug therapy, end stage liver disease, liver transplantation, HIV, hepatitis B, African Americans, renal insufficiency, obesity, pregnancy, and pediatrics.

STUDY SELECTION AND DATA EXTRACTION

English language studies from January 1985 to March 2015 were considered. Additional references were identified from ongoing trials obtained from clinicaltrials.gov, conference proceedings, online databases, and citations in relevant review articles.

DATA SELECTION

Direct-acting antivirals are first-line recommendations for the treatment of HCV genotype 1 infection, and these include combinations of sofosbuvir, simeprevir, ledipasvir/sofosbuvir, ombitasvir/paritaprevir/ritonavir plus dasabuvir, and ribarvirin. Historical and clinical data focusing on the treatment of HCV with these agents in the following populations were selected: decompensated cirrhosis, post-liver transplant, HIV, African Americans, obesity, hepatitis B coinfection, renal impairment, pregnancy, and pediatrics.

CONCLUSION

Depending on the population studied, clinicians must consider differences in efficacy outcomes, potential drug interactions, and adverse effects that patients may experience.

CYP2B6 c.983T>C polymorphism is associated with nevirapine hypersensitivity in Malawian and Ugandan HIV populations

Background

Nevirapine, an NNRTI used in HIV treatment, can cause hypersensitivity reactions in 6%–10% of patients. In the most serious cases (1.3%) this can manifest as Stevens–Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN).

Methods

DNA samples were obtained and analysed from a total of 209 adult patients with nevirapine hypersensitivity (57 from a prospective cohort and 152 routine clinic patients) and compared with 463 control patients on nevirapine without any hypersensitivity. The case group included 70 patients with SJS/TEN. All individuals were genotyped for two SNPs in the CYP2B6 gene [c.516G>T (CYP2B6*9) and c.983T>C (CYP2B6*18)] using the TaqMan real-time genotyping platform. The replication cohort comprised 29 controls and 55 nevirapine hypersensitive patients, including 8 SJS/TEN cases.

Results

An association between the CYP2B6 c.983T>C polymorphism and nevirapine-induced SJS/TEN was observed. In the SJS/TEN group, 30% of individuals possessed at least one c.983T>C versus 16% in the tolerant group [P = 0.006; OR (95% CI) 2.24 (1.27–3.94)]. This association was not significant in the replication cohort [P = 0.075; OR (95% CI) 4.33 (0.80–23.57)]. Combined analysis resulted in an OR of 2.52 (95% CI 1.48–4.20; P = 0.0005) for the association of c.983T>C with SJS/TEN. No association was observed for c.983T>C with other hypersensitivity phenotypes and for CYP2B6 c.516G>T with any hypersensitivity phenotypes.

Conclusions

Our data show an association between the c.983T>C polymorphism and nevirapine-induced SJS/TEN. CYP2B6 c.983T>C has a frequency of 5%–10% in a variety of African populations, but is not observed in Caucasians, thus representing an ethnic-specific predisposing factor.

Antiretroviral therapy for prevention is a combination strategy

In the past several years, the debate of "treatment vs prevention" has shifted with the introduction of the concept of "treatment as prevention," (TasP), stemming from a series of compelling observational, ecological, and modeling studies as well as HPTN 052, a randomized clinical trial, demonstrating that use of ART is associated with a decrease in HIV transmission. In addition to TasP being viewed as 1 intervention in a combination strategy for HIV Prevention, TasP is, in and of itself, a combination of multiple interventions that need to be implemented with high coverage in order to achieve its potential impact.

Association of human leukocyte antigen alleles and nevirapine hypersensitivity in a Malawian HIV-infected population

Human leukocyte antigen genotyping of 272 Malawian HIV patients receiving nevirapine-containing regimens (of whom 117 had nevirapine hypersensitivity) has shown that HLA-C*04:01 increases the risk of Stevens-Johnson syndrome/toxic epidermal necrolysis, with an odds ratio of 5.17 (95% confidence interval, 2.39–11.18).

Background. The nonnucleoside reverse transcriptase inhibitor nevirapine is the cornerstone of treatment for human immunodeficiency virus (HIV) in many sub-Saharan African countries. However, nevirapine is associated with a 6%–10% risk of developing a hypersensitivity reaction, with different phenotypes, including the blistering conditions Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Our aim was to identify predictive human leukocyte antigen (HLA) markers that are associated with nevirapine hypersensitivity.

Methods. We identified 117 HIV-infected Malawian adults with nevirapine hypersensitivity (15 drug-induced liver injury [DILI], 33 SJS/TEN, 20 hypersensitivity syndrome, and 46 nevirapine-induced rash plus 3 with both DILI and SJS phenotype) and 155 age-, sex- and ethnicity-matched nevirapine-exposed controls. HLA typing for 5 loci (A, B, C, DRB1, and DQB1) was undertaken using a sequence-based high-resolution protocol. Logistic regression analysis included CD4⁺ cell count as a covariate.

Results. HLA-C*04:01 was found to markedly increase the risk for SJS (odds ratio [OR] = 17.52; 95% confidence interval, 3.31–92.80) and all hypersensitivity phenotypes (OR = 2.64; 95% CI, 1.13–6.18) when compared to the baseline rare allele group in a binary logistic regression model. The OR for absolute risk of SJS/TEN associated with carriage of HLA-C*04:01 was 5.17 (95% CI, 2.39–11.18). Positive predictive value was 2.6% and negative predictive value was 99.2%. In addition, a number of alleles within the HLA-DQB1 loci protected against nevirapine-induced hypersensitivity phenotypes.

Conclusions. Our study has identified HLA-C*04:01 carriage as a risk factor for nevirapine-induced SJS/TEN in a Malawian HIV cohort. Validation of these findings in a larger cohort of patients and mechanistic investigation of the pathogenesis are required.

Pharmacological and clinical evidence of nevirapine immediate- and extended-release formulations

We reviewed the current information available on nevirapine immediate- and extended-release formulations and its role in single-dose and combination antiretroviral therapy. Nevirapine was approved in 1996 and was the first non-nucleoside reverse-transcriptase inhibitor available for the treatment of HIV-1 infection. Nevirapine has demonstrated good efficacy and a well-characterized safety profile. A major drawback is the low genetic barrier, allowing the emergence of resistance in the presence of single mutations in the reverse-transcriptase gene. This shortcoming is particularly relevant when nevirapine is administered in a single dose to prevent mother-to-child transmission of HIV-1 infection, compromising the efficacy of future non-nucleoside reverse transcriptase-inhibitor regimens. Studies published recently have probed the noninferiority of nevirapine compared to ritonavir-boosted atazanavir with both tenofovir disoproxil fumarate and emtricitabine in antiretroviral treatment-naïve patients. In 2011, a new formulation of nevirapine (nevirapine extended release) that allowed once-daily dosing was approved by the Food and Drug Administration and by the European Medicines Agency. VERxVe, a study comparing nevirapine extended release with nevirapine immediate release in antiretroviral treatment-naïve patients, and TRANxITION, a study carried out in antiretroviral treatment-experienced patients who switched therapy from nevirapine immediate release to nevirapine extended release, provided data on the noninferiority of the new formulation of nevirapine compared with nevirapine immediate release in terms of efficacy and safety. Nevirapine extended release will further increase the durability and persistence of nevirapine-containing antiretroviral therapy, allowing once-daily dosing regimens.

Prevalence and predictors of kaposi sarcoma herpes virus seropositivity: a cross-sectional analysis of HIV-infected adults initiating ART in Johannesburg, South Africa

Background

Kaposi sarcoma (KS) is the most common AIDS-defining tumour in HIV-infected individuals in Africa. Kaposi sarcoma herpes virus (KSHV) infection precedes development of KS. KSHV co-infection may be associated with worse outcomes in HIV disease and elevated KSHV viral load may be an early marker for advanced HIV disease among untreated patients. We examined the prevalence of KSHV among adults initiating antiretroviral therapy (ART) and compared immunological, demographic and clinical factors between patients seropositive and seronegative for KSHV.

Results

We analyzed cross-sectional data collected from 404 HIV-infected treatment-naïve adults initiating ART at the Themba Lethu Clinic, Johannesburg, South Africa between November 2008 and March 2009. Subjects were screened at ART initiation for antibodies to KSHV lytic K8.1 and latent Orf73 antigens. Seropositivity to KSHV was defined as positive to either lytic KSHV K8.1 or latent KSHV Orf73 antibodies. KSHV viremia was determined by quantitative PCR and CD3, 4 and 8 lymphocyte counts were determined with flow cytometry. Of the 404 participants, 193 (48%) tested positive for KSHV at ART initiation; with 76 (39%) reactive to lytic K8.1, 35 (18%) to latent Orf73 and 82 (42%) to both. One individual presented with clinical KS at ART initiation. The KSHV infected group was similar to those without KSHV in terms of age, race, gender, ethnicity, smoking and alcohol use. KSHV infected individuals presented with slightly higher median CD3 (817 vs. 726 cells/mm³) and CD4 (90 vs. 80 cells/mm³) counts than KSHV negative subjects. We found no associations between KSHV seropositivity and body mass index, tuberculosis status, WHO stage, HIV RNA levels, full blood count or liver function tests at initiation. Those with detectable KSHV viremia (n = 19), however, appeared to present with signs of more advanced HIV disease including anemia and WHO stage 3 or 4 defining conditions compared to those in whom the virus was undetectable.

Conclusions

We demonstrate a high prevalence of KSHV among HIV-infected adults initiating ART in a large urban public-sector HIV clinic. KSHV viremia but not KSHV seropositivity may be associated with markers of advanced HIV disease.

Hypersensitivity reactions to HIV therapy

Many drugs used for the treatment of HIV disease (including the associated opportunistic infections) can cause drug hypersensitivity reactions, which vary in severity, clinical manifestations and frequency. These reactions are not only seen with the older compounds, but also with the newer more recently introduced drugs. The pathogenesis is unclear in most cases, but there is increasing evidence to support that many of these are mediated through a combination of immunologic and genetic factors through the major histocompatibility complex (MHC). Genetic predisposition to the occurrence of these allergic reactions has been shown for some of the drugs, notably abacavir hypersensitivity which is strongly associated with the class I MHC allele, HLA-B*5701. Testing before the prescription of abacavir has been shown to be of clinical utility, has resulted in a change in the drug label, is now recommended in clinical guidelines and is practiced in most Western countries. For most other drugs, however, there are no good methods of prevention, and clinical monitoring with appropriate (usually supportive and symptomatic) treatment is required. There is a need to undertake further research in this area to increase our understanding of the mechanisms, which may lead to better preventive strategies through the development of predictive genetic biomarkers or through guiding the design of drugs less likely to cause these types of adverse drug reactions.

Nevirapine-associated toxicity in clinical practice in Buenos Aires, Argentina

OBJECTIVES

to determine the incidence and risk factors for nevirapine (NVP)-associated toxicity in a cohort of HIV-infected people in Buenos Aires, Argentina.

DESIGN

retrospective study.

METHODS

HIV-infected adults who received NVP-based highly active antiretroviral therapy (HAART) at least for 2 weeks between May 1997 and March 2008 were included in this study. We analyzed patients' age, gender, HIV transmission route, HIV disease stage, pregnancy, alcohol intake, adverse events, coinfection with hepatitis B or C virus, time until toxicity, and withdrawal rates.

RESULTS

a total of 1110 patients (631 men) were included. Rash was the most frequently observed adverse event; it was more frequent in women. The incidence of severe rash and hepatotoxicity was similar in women and men. Female sex was the only variable significantly associated with mild-to-moderate rash. High CD4 count, pregnancy, and chronic hepatitis were not associated with NVP-related toxicity. An undetectable viral load at the time of starting NVP treatment resulted in a lower risk of NVP-related rash.

Italian consensus statement on paediatric HIV infection

The objective of this document is to identify and reinforce current recommendations concerning the management of HIV infection in infants and children in the context of good resource availability. All recommendations were graded according to the strength and quality of the evidence and were voted on by the 57 participants attending the first Italian Consensus on Paediatric HIV, held in Siracusa in 2008. Paediatricians and HIV/AIDS care specialists were requested to agree on different statements summarizing key issues in the management of paediatric HIV. The comprehensive approach on preventing mother-to-child transmission (PMTCT) has clearly reduced the number of children acquiring the infection in Italy. Although further reduction of MTCT should be attempted, efforts to personalize intervention to specific cases are now required in order to optimise the treatment and care of HIV-infected children. The prompt initiation of treatment and careful selection of first-line regimen, taking into consideration potency and tolerance, remain central. In addition, opportunistic infection prevention, adherence to treatment, and long-term psychosocial consequences are becoming increasingly relevant in the era of effective antiretroviral combination therapies (ART). The increasing proportion of infected children achieving adulthood highlights the need for multidisciplinary strategies to facilitate transition to adult care and maintain strategies specific to perinatally acquired HIV infection.

Meta-analysis: increased mortality associated with hepatitis C in HIV-infected persons is unrelated to HIV disease progression

BACKGROUND

It is unclear whether coinfection with hepatitis C virus (HCV) increases mortality in patients with human immunodeficiency virus (HIV) infection during the era of highly active antiretroviral therapy (HAART). With use of a meta-analysis, we estimated the effect of HCV infection on HIV disease progression and overall mortality in the pre-HAART and HAART eras.

METHOD

The PubMed and EMBASE databases were searched for studies published through 30 April 2008. Additional studies were identified from cited references. Studies reporting disease progression or mortality among HCV-HIV coinfected patients were selected. Cross-sectional studies, studies without HCV-negative control subjects, and studies involving children and/or patients who had undergone liver transplantation were excluded. Two authors reviewed articles and extracted data on the demographic characteristics of study populations and risk estimates. Meta-regression was used to explore heterogeneity.

RESULTS

Ten studies from the pre-HAART era and 27 studies from the HAART era were selected. In the pre-HAART era, the risk ratio for overall mortality among patients with HCV-HIV coinfection, compared with that among patients with HIV infection alone, was 0.68 (95% confidence interval [CI], 0.53-0.87). In the HAART era, the risk ratio was 1.12 (95% CI, 0.82-1.51) for AIDS-defining events and 1.35 (95% CI, 1.11-1.63) for overall mortality among coinfected patients, compared with that among patients with HIV monoinfection.

CONCLUSIONS

HCV coinfection did not increase mortality among patients with HIV infection before the introduction of HAART. In contrast, in the HAART era, HCV coinfection, compared with HIV infection alone, increases the risk of mortality, but not the risk of AIDS-defining events. Future studies should determine whether successful treatment of HCV infection could reduce this excess risk of mortality in coinfected patients.

Role of the CD4 count in HIV management

As a result of successful antiretroviral treatment over the last 20 years, HIV has become more of a chronic disease for practitioners to manage, requiring careful, but routine, clinical monitoring. Laboratory markers, such as the HIV-1 RNA viral load and CD4 cell count, are regularly used for patient management in addition to predicting disease progression and/or treatment outcomes. The HIV viral load is considered to be the gold standard for evaluating treatment success, although it is often limited by the cost. Furthermore, in certain cases, there is a mismatch between an undetectable viral load (<50 copies/ml) and the absence of immune reconstitution, which can be confusing to both the treatment provider and patient. In this review, the utility of the CD4 count as a predictor for HIV disease progression in patients not on therapy is evaluated, as well as a method for monitoring a patient’s response to therapy. Its use in predicting immune reconstitution in patients initiating antiretrovirals is also identified. We hope to aid the clinician by examining the most recent literature and discussing the added value of the CD4 count in the management of a person with HIV infection.

Risk factors for treatment-limiting toxicities in patients starting nevirapine-containing antiretroviral therapy

BACKGROUND

This collaboration of seven observational clinical cohorts investigated risk factors for treatment-limiting toxicities in both antiretroviral-naive and experienced patients starting nevirapine-based combination antiretroviral therapy (NVPc).

METHODS

Patients starting NVPc after 1 January 1998 were included. CD4 cell count at starting NVPc was classified as high (>400/microl/>250/microl for men/women, respectively) or low. Cox models were used to investigate risk factors for discontinuations due to hypersensitivity reactions (HSR, n = 6547) and discontinuation of NVPc due to treatment-limiting toxicities and/or patient/physician choice (TOXPC, n = 10,186). Patients were classified according to prior antiretroviral treatment experience and CD4 cell count/viral load at start NVPc. Models were stratified by cohort and adjusted for age, sex, nadir CD4 cell count, calendar year of starting NVPc and mode of transmission.

RESULTS

Median time from starting NVPc to TOXPC and HSR were 162 days [interquartile range (IQR) 31-737] and 30 days (IQR 17-60), respectively. In adjusted Cox analyses, compared to naive patients with a low CD4 cell count, treatment-experienced patients with high CD4 cell count and viral load more than 400 had a significantly increased risk for HSR [hazard ratio 1.45, confidence interval (CI) 1.03-2.03] and TOXPC within 18 weeks (hazard ratio 1.34, CI 1.08-1.67). In contrast, treatment-experienced patients with high CD4 cell count and viral load less than 400 had no increased risk for HSR 1.10 (0.82-1.46) or TOXPC within 18 weeks (hazard ratio 0.94, CI 0.78-1.13).

CONCLUSION

Our results suggest it may be relatively well tolerated to initiate NVPc in antiretroviral-experienced patients with high CD4 cell counts provided there is no detectable viremia.

Impact of housing on the survival of persons with AIDS

BACKGROUND

Homeless persons with HIV/AIDS have greater morbidity and mortality, more hospitalizations, less use of antiretroviral therapy, and worse medication adherence than HIV-infected persons who are stably housed. We examined the effect of homelessness on the mortality of persons with AIDS and measured the effect of supportive housing on AIDS survival.

METHODS

The San Francisco AIDS registry was used to identify homeless and housed persons who were diagnosed with AIDS between 1996 and 2006. The registry was computer-matched with a housing database of homeless persons who received housing after their AIDS diagnosis. The Kaplan-Meier product limit method was used to compare survival between persons who were homeless at AIDS diagnosis and those who were housed. Proportional hazards models were used to estimate the independent effects of homelessness and supportive housing on survival after AIDS diagnosis.

RESULTS

Of the 6,558 AIDS cases, 9.8% were homeless at diagnosis. Sixty-seven percent of the persons who were homeless survived five years compared with 81% of those who were housed (p < 0.0001). Homelessness increased the risk of death (adjusted relative hazard [RH] 1.20; 95% confidence limits [CL] 1.03, 1.41). Homeless persons with AIDS who obtained supportive housing had a lower risk of death than those who did not (adjusted RH 0.20; 95% CL 0.05, 0.81).

CONCLUSION

Supportive housing ameliorates the negative effect of homelessness on survival with AIDS.

Early treatment of HIV: implications for resource-limited settings

PURPOSE OF REVIEW

We review the current literature supporting adoption of higher CD4 thresholds for initiation of antiretroviral treatment and survey progress in adoption of early treatment policies in resource-limited settings. We highlight some of the challenges and opportunities implementation of early treatment will bring.

RECENT FINDINGS

The initial success of combination antiretroviral treatment resulted in the recommendation to treat early all individuals with HIV. However, the gradual realization that antiretroviral treatment was associated with toxicity led to a more tempered approach. Recent cohort studies and some clinical trials have shown that delaying treatment is associated with increased morbidity and mortality.

SUMMARY

Early treatment is routinely practiced in developed countries. Now, early treatment is being adopted as a strategy in many resource-limited settings. The implications of this policy shift are not known, but we predict early treatment will have important consequences for the health system, the individual, and the community. Whereas these consequences will bring significant challenges, the increased numbers of HIV-infected individuals on treatment will result in many new opportunities - antiretroviral treatment will become less expensive, systems to deliver chronic care will be strengthened, and the policy shift will focus greater attention on pregnant women and children. Finally, some authors postulate that early treatment may impact HIV transmission.

Long-term follow-up of nevirapine-treated patients in a single-centre cohort

OBJECTIVES

We reviewed the safety and efficacy of nevirapine (NVP)-based therapy in all patients initiating NVP-containing combined antiretroviral therapy [cART (>or=3 drugs)] in our clinic since 1994.

METHODS

Patient characteristics and laboratory values from the start of the NVP-based cART regimen to the last available follow-up or to NVP discontinuation were retrieved from an observational database.

RESULTS

Five hundred and seventy-three patients were treated with NVP-based cART for a median of 18.4 (range 0.1-128.8) months. The 1-year cumulative estimated probability of discontinuing NVP-containing regimens for toxicity was 0.203. Only 1.9% developed a grade 3 alanine aminotransferase (ALT) elevation. Significant increases in high-density lipoprotein cholesterol were observed up to month 12 except in treatment-naïve patients, where the increase was limited to 3 months. Discontinuation because of cutaneous reaction was predicted independently by female gender [Hazard Ratio (HR) 3.21, P<0.001] and Centers for Disease Control class C (HR 0.50, P=0.012). Discontinuation because of liver toxicity was predicted independently by anti-hepatitis C virus positivity (HR 3.84, P<0.001). In patients starting NVP-containing cART with undetectable viral loads, the 5-year estimated probability of viral load >400 HIV-1 RNA copies/mL was 0.34.

CONCLUSIONS

Long-term follow-up with an NVP-containing cART showed a low rate of discontinuation caused by liver toxicity and the maintenance of virological suppression in patients switched with undetectable viral loads.

Validity and comparison of two measures of days supply in Medicaid claims data

BACKGROUND

In claims-based pharmacoepidemiologic and health services research studies of chronic medications, days supply can be determined using either an observed measure or a measure calculated from quantity dispensed and dosing directions. The two measures should yield the same duration, but if not, the preferred method is unknown.

OBJECTIVES

We aimed to determine whether the observed or calculated measure of days supply more closely approximated the actual refill interval.

METHODS

Using California Medicaid data from 1998 to 2001, we identified all prescriptions followed by > or = 1 refill for nevirapine and abacavir tablets. For each record, we calculated the difference between the days supply and the refill interval for each method. In a subgroup analysis, we compared the measures only in records where the methods were discordant.

RESULTS

Of 29 646 records, in 27 230 (92.5%) the measures were identical. The difference between the days supply and the refill interval was identical for each measure with a median difference of 4 days (range 0-1142 days), p = 0.5 for the difference between them. In the discordant subset, the median difference for the observed measure was 10 days (range 0-1053 days) and for the calculated measure it was 12 days (range 0-1023 days), p = 0.003 for the difference between them.

CONCLUSIONS

In California Medicaid, observed and calculated measures of days supply generally provided identical data which closely approximated the refill interval. In the few discordant records, the observed measure was slightly more accurate. These findings suggest that both variables provide valid data for temporal relations between anti-retroviral prescriptions and events.

Effect of early versus deferred antiretroviral therapy for HIV on survival

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.

The therapeutic implications of timely linkage and early retention in HIV care

Following HIV diagnosis, linkage to outpatient treatment, antiretroviral initiation, and longitudinal retention in care represent the foundation for successful treatment. While prior studies have evaluated these processes in isolation, a systematic evaluation of successive steps in the same cohort of patients has not yet been performed. To ensure optimal long-term outcomes, a better understanding of the interplay of these processes is needed. Therefore, a retrospective cohort study of patients initiating outpatient care at the University of Alabama at Birmingham 1917 HIV=AIDS Clinic between January 2000 and December 2005 was undertaken. Multivariable models determined factors associated with: late diagnosis=linkage to care (initial CD4 < 350 cells=mm3), timely antiretroviral initiation, and retention across the first two years of care. Delayed linkage was observed in two-thirds of the overall sample (n = 567) and was associated with older age (odds ratio [OR] = 1.31 per 10 years; 95%confidence interval [CI] = 1.06-1.62) and African American race (OR = 2.45; 95% CI = 1.60-3.74). Attending all clinic visits (hazard ratio [HR] = 6.45; 95% CI = 4.47-9.31) and lower initial CD4 counts led to earlier antiretroviral initiation. Worse retention in the first 2 years was associated with younger age (OR = 0.68 per 10 years;95% CI = 0.56-0.83), higher baseline CD4 count, and substance abuse (OR = 1.78; 95% CI = 1.16-2.73). Interventions to improve timely HIV diagnosis and linkage to care should focus on older patients and African Americans while efforts to improve retention should address younger patients, those with higher baseline CD4 counts, and substance abuse. Missed clinic visits represent an important obstacle to the timely initiation of antiretroviral therapy. These data inform development of interventions to improve linkage and retention in HIV care, an emerging area of growing importance.

Hepatitis infection in the treatment of opioid dependence and abuse

Many new and existing cases of viral hepatitis infections are related to injection drug use. Transmission of these infections can result directly from the use of injection equipment that is contaminated with blood containing the hepatitis B or C virus or through sexual contact with an infected individual. In the latter case, drug use can indirectly contribute to hepatitis transmission through the dis-inhibited at-risk behavior, that is, unprotected sex with an infected partner. Individuals who inject drugs are at-risk for infection from different hepatitis viruses, hepatitis A, B, or C. Those with chronic hepatitis B virus infection also face additional risk should they become co-infected with hepatitis D virus. Protection from the transmission of hepatitis viruses A and B is best achieved by vaccination. For those with a history of or who currently inject drugs, the medical management of viral hepatitis infection comprising screening, testing, counseling and providing care and treatment is evolving. Components of the medical management of hepatitis infection, for persons considering, initiating, or receiving pharmacologic therapy for opioid addiction include: testing for hepatitis B and C infections; education and counseling regarding at-risk behavior and hepatitis transmission, acute and chronic hepatitis infection, liver disease and its care and treatment; vaccination against hepatitis A and B infection; and integrative primary care as part of the comprehensive treatment approach for recovery from opioid abuse and dependence. In addition, participation in a peer support group as part of integrated medical care enhances treatment outcomes. Liver disease is highly prevalent in patient populations seeking recovery from opioid addiction or who are currently receiving pharmacotherapy for opioid addiction. Pharmacotherapy for opioid addiction is not a contraindication to evaluation, care, or treatment of liver disease due to hepatitis virus infection. Successful pharmacotherapy for opioid addiction stabilizes patients and improves patient compliance to care and treatment regimens as well as promotes good patient outcomes. Implementation and integration of effective hepatitis prevention programs, care programs, and treatment regimens in concert with the pharmacological therapy of opioid addiction can reduce the public health burdens of hepatitis and injection drug use.

Pharmacogenetic information derived from analysis of HLA alleles

A large amount of pharmacogenetic information has, in particular, accumulated on the association between human leukocyte antigen (HLA) alleles and hypersensitivity to certain drugs. Prospective HLA typing has dramatically reduced the risk of abacavir hypersensitivity because of its strong association with HLA-B*5701. Significant predisposition to nevirapine hypersensitivity has been reported in Caucasian Australians harboring HLA-DRB1*0101 with high CD4+ T-cell counts, and Sardinians and Japanese harboring HLA-Cw8. A strong association between carbamazepine hypersensitivity and HLA-B*1502 has been reported in Han Chinese. Most Han Chinese individuals with allopurinol-induced severe cutaneous adverse reactions are positive for HLA-B*5801. HLA typing can stratify risk of hypersensitivity to certain drugs and allow personalized treatment, although the patients should be monitored closely even if they are negative for HLA alleles associated with hypersensitivity.