Provider bias in the selection of non-nucleoside reverse transcriptase inhibitor and protease inhibitor-based highly active antiretroviral therapy and HIV treatment outcomes in observational studies

Comparative Effectiveness of First Antiretroviral Regimens in Clinical Practice Using a Causal Approach

The objective of this study was to estimate the cumulative incidences of failure by months 12 (M12) and 24 (M24) for the most prescribed first-line anti-retroviral regimens (ART). It is retrospective analysis of a prospectively collected database. All patients who initiated their first ART with the most prescribed regimens between 1st January 2004 and 30th June 2013 in 12 large HIV reference centers in France were included. The outcome was treatment failure--defined by any treatment modification for virological or tolerability reasons--and comparisons between regimens were carried out at M12 and M24. Adjusted and weighted methods via the propensity score (PS) were used to compare the effectiveness of the first antiretroviral regimens. Potential confounders of the treatment-outcome association were used to estimate PS with multinomial logistic regression. Overall, 3128 and 2690 patients were included in the M12 and M24 analyses, respectively. Patients received 5 different regimens (ABC/3TC with ATV/r or DRV/r, TDF/FTC with ATV/r, DRV/r, or EFV). Failure was reported in 25% and 42% at M12 and M24, respectively. Patients who received TDF/FTC/EFV had a significantly higher proportion of failure at M12 by comparison with TDF/FTC with DRV/r (reference), but not at M24. Patients in the 3 other groups had a trend toward a higher proportion of failure at M12 although not statistically significant. No difference was found at M24. Using data from a large prospective cohort, we found that boosted atazanavir and darunavir had comparable effectiveness, whatever the associated NRTIs, whereas efavirenz-based regimens were relatively less performing on the short term.

Higher Rates of Viral Suppression with Nonnucleoside Reverse Transcriptase Inhibitors Compared to Single Protease Inhibitors Are Not Explained by Better Adherence

BACKGROUND

Although evidence suggests that antiretroviral (ARV) regimens containing nonnucleoside reverse transcriptase inhibitors (NNRTIs) are superior to single-protease inhibitor (PI)-based regimens at suppressing viral load, it is unclear how much of the improved viral suppression is due to intrinsic drug potency versus higher levels of adherence to simpler regimens. We therefore examined adherence and viral suppression in NNRTI and single-PI regimens in a cohort of largely ARV-experienced participants by using objective measures of adherence.

METHOD

Participants were recruited from the Research on Access to Care in the Homeless (REACH) Cohort and were included in the study if they were on single-PI-based or NNRTI-based highly active antiretroviral therapy (HAART) regimens for at least 3 months prior to study entry. Adherence was measured by unannounced pill counts at the participant's usual place of residence. The primary outcome was suppression of HIV viral RNA to <50 copies/mL.

RESULTS

Among 109 individuals who were followed for a median of 8.7 months, the odds of virologic suppression were approximately 8 times higher (p < .01) for participants on NNRTI-based regimens (n = 53) compared with those using single-PI-based regimens (n = 56) when controlling for adherence, as well as other potential confounders in a multivariable analysis. The only other independent predictors of viral suppression in multivariable modeling were ARV adherence (p < .01), CD4 nadir (p = .02), and continuous months on current regimen prior to the start of adherence monitoring (p < .01). There was no significant difference in adherence by unannounced pill counts in participants receiving NNRTI- versus single-PI-containing regimens.

CONCLUSION

A higher proportion of individuals using NNRTI-based regimens had viral suppression when compared to those taking single-PI-containing regimens, and this association was not confounded by higher levels of adherence. These results suggest that improved viral suppression on NNRTI regimens compared to single-PI regimens is more closely associated with regimen potency than higher levels of adherence.

Comparative effectiveness of initial antiretroviral therapy regimens: ACTG 5095 and 5142 clinical trials relative to ART-CC cohort study

BACKGROUND

The generalizability of antiretroviral therapy (ART) clinical trial efficacy findings to routine care settings is not well studied. We compared the relative effectiveness of initial ART regimens estimated in AIDS Clinical Trial Group (ACTG) randomized controlled trials with that among patients receiving ART at Antiretroviral Therapy Cohort Collaboration (ART-CC) study sites.

METHODS

Treatment-naive HIV-infected patients initiating identical ART regimens in ACTG trials (A5095 and A5142) and at 15 ART-CC cohort study sites were included. Virological failure (HIV-1 RNA >200 copies/mL) at 24 and 48 weeks, incident AIDS-defining events and mortality were measured according to study design (ART-CC cohort vs. ACTG trial) and stratified by third drug [abacavir (ABC), efavirenz (EFV), and lopinavir/r (LPV/r)]. We used logistic regression to estimate and compare odds ratios (OR) for virological failure between different regimens and study designs, and used Cox models to estimate and compare hazard ratios for AIDS and death.

RESULTS

Compared with patients receiving ABC, those receiving EFV had roughly half the odds of 24-week virologic failure (>200 copies/mL) in both ACTG 5095 (OR = 0.53, 95% confidence interval: 0.36 to 0.79) and ART-CC (0.46, 0.37 to 0.57). Virologic superiority of EFV (vs. ABC) seemed comparable in ART-CC and ACTG 5095 (ratio of ORs 0.86, 95% confidence interval: 0.54 to 1.35). Odds ratios for 48-week virologic failure, comparing EFV with LPV/r, were also comparable in ACTG 5142 and ART-CC (ratio of ORs: 0.87, 0.45 to 1.69).

CONCLUSIONS

Between ART regimen virologic efficacy of third drugs ABC, EFV, and LPV/r observed in the ACTG 5095 and 5142 trials seem generalizable to the routine care setting of ART-CC clinical cohorts.

Risk of resistance to highly active antiretroviral therapy among HIV-positive injecting drug users: a meta-analysis

Although highly active antiretroviral therapy (HAART) is an effective treatment for HIV, many physicians withhold this treatment from HIV-positive injecting drug users (IDUs) because of fears of non-adherence and consequent development of antiretroviral resistance. Little is known, however, about whether the rates of resistance differ between IDUs and non-IDUs. We did a meta-analysis of studies that compared antiretroviral resistance rates in IDUs (current or previous) with those in HIV-positive patients infected by other routes and who had never injected drugs. We used a random-effects model to investigate overall resistance rates and resistance to individual drug classes. Of 181 potential studies, 27 were eligible for review. We were able to extract data from 14 studies, but two were excluded because of a very small sample size of IDUs or data being available only from a secondary analysis. Thus we included 12 studies in the meta-analysis, involving 9055 patients, of which 2054 (23%) were IDUs. The risk of development of antiretroviral resistance did not differ significantly between IDU and non-IDU (odds ratio 1.04, 95% CI 0.74-1.45, p=0.84). Rates of loss to follow-up and virological failure were similar in IDU and non-IDU samples. Existing evidence does not support the common practice of withholding antiretroviral therapy from HIV-positive IDU on the basis of an elevated risk of antiretroviral resistance. Therapeutic guidelines should consider reassessment of this issue.

Does short-term virologic failure translate to clinical events in antiretroviral-naïve patients initiating antiretroviral therapy in clinical practice?

OBJECTIVE

To determine whether differences in short-term virologic failure among commonly used antiretroviral therapy (ART) regimens translate to differences in clinical events in antiretroviral-naïve patients initiating ART.

DESIGN

Observational cohort study of patients initiating ART between January 2000 and December 2005.

SETTING

The Antiretroviral Therapy Cohort Collaboration (ART-CC) is a collaboration of 15 HIV cohort studies from Canada, Europe, and the United States.

STUDY PARTICIPANTS

A total of 13 546 antiretroviral-naïve HIV-positive patients initiating ART with efavirenz, nevirapine, lopinavir/ritonavir, nelfinavir, or abacavir as third drugs in combination with a zidovudine and lamivudine nucleoside reverse transcriptase inhibitor backbone.

MAIN OUTCOME MEASURES

Short-term (24-week) virologic failure (>500 copies/ml) and clinical events within 2 years of ART initiation (incident AIDS-defining event, death, and a composite measure of these two outcomes).

RESULTS

Compared with efavirenz as initial third drug, short-term virologic failure was more common with all other third drugs evaluated; nevirapine (adjusted odds ratio = 1.87, 95% confidence interval (CI) = 1.58-2.22), lopinavir/ritonavir (1.32, 95% CI = 1.12-1.57), nelfinavir (3.20, 95% CI = 2.74-3.74), and abacavir (2.13, 95% CI = 1.82-2.50). However, the rate of clinical events within 2 years of ART initiation appeared higher only with nevirapine (adjusted hazard ratio for composite outcome measure 1.27, 95% CI = 1.04-1.56) and abacavir (1.22, 95% CI = 1.00-1.48).

CONCLUSION

Among antiretroviral-naïve patients initiating therapy, between-ART regimen, differences in short-term virologic failure do not necessarily translate to differences in clinical outcomes. Our results should be interpreted with caution because of the possibility of residual confounding by indication.

Superior virological response to boosted protease inhibitor-based highly active antiretroviral therapy in an observational treatment programme

BACKGROUND

The use of boosted protease inhibitor (PI)-based antiretroviral therapy has become increasingly recommended in international HIV treatment consensus guidelines based on the results of randomized clinical trials. However, the impact of this new treatment strategy has not yet been evaluated in community-treated cohorts.

METHODS

We evaluated baseline characteristics and plasma HIV RNA responses to unboosted and boosted PI-based highly active antiretroviral therapy (HAART) among antiretroviral-naïve HIV-infected patients in British Columbia, Canada who initiated HAART between August 1997 and September 2003 and who were followed until September 2004. We evaluated time to HIV-1 RNA suppression (<500 HIV-1 RNA copies/mL) and HIV-1 RNA rebound (>or=500 copies/mL), while stratifying patients into those that received boosted and unboosted PI-based HAART as the initial regimen, using Kaplan-Meier methods and Cox proportional hazards regression.

RESULTS

During the study period, 682 patients initiated therapy with unboosted PI and 320 individuals initiated HAART with a boosted PI. Those who initiated therapy with a boosted PI were more likely to have a CD4 cell count <200 cells/muL and to have a plasma HIV RNA>100 000 copies/mL, and to have AIDS at baseline (all P<0.001). However, when we examined virological response rates, those who initiated HAART with a boosted PI achieved more rapid virological suppression [relative hazard 1.26, 95% confidence interval (CI) 1.06-1.51, P=0.010].

CONCLUSIONS

Patients prescribed boosted PIs achieved superior virological response rates despite baseline factors that have been associated with inferior virological responses to HAART. Despite the inherent limitations of observational studies which require this study be interpreted with caution, these findings support the use of boosted PIs for initial HAART therapy.

Regimen-dependent variations in adherence to therapy and virological suppression in patients initiating protease inhibitor-based highly active antiretroviral therapy

OBJECTIVE

To examine differences among four protease inhibitor (PI)-based drug regimens in adherence to therapy and rate of achievement of virological suppression in a cohort of antiretroviral-naive patients initiating highly active antiretroviral therapy (HAART).

METHODS

Participants were antiretroviral-naive and were first dispensed combination therapy containing two nucleosides and a ritonavir (RTV)-boosted PI, or unboosted nelfinavir, between 1 January 2000 and 30 September 2003. Logistic regression analysis was used to examine associations between the prescribed PI and other baseline factors associated with being >90% adherent to therapy and then to determine the associations of prescribed drug regimen, adherence to therapy and baseline variables with the odds of achieving two consecutive viral loads of <500 HIV-1 RNA copies/mL. RESULTS A total of 385 subjects were available for analysis. Lopinavir (LPV)/RTV was prescribed for 168 patients (42% of total); 86 (22%) received indinavir (IDV)/RTV; 91 (24%) received nelfinavir (NFV) and 40 (10%) received saquinavir (SQV)/RTV. SQV/RTV-based HAART was associated with reduced adherence to therapy [odds ratio (OR)=0.40; 95% confidence interval (CI) 0.19-0.83]. In multivariate models, IDV/RTV (OR=0.45; 95% CI 0.22-0.92), SQV/RTV (OR=0.18; 95% CI 0.07-0.43) and NFV were associated with reduced odds of achieving virological suppression within 1 year in comparison to LPV/RTV-based therapy. For patients receiving NFV, adjusting for adherence (OR=0.73; 95% CI 0.36-1.47) rendered this association nonsignificant.

CONCLUSION

Patients prescribed IDV/RTV, NFV or SQV/RTV were less likely to achieve virological suppression on their first regimen compared with patients prescribed LPV/RTV. Reduced adherence to these therapies only partly explained these observed differences.

Discordant Responses to Potent Antiretroviral Treatment in Previously Naive HIV-1-Infected Adults Initiating Treatment in Resource-Constrained Countries

OBJECTIVES

To assess the frequency of and risk factors for discordant responses at 6 months on highly active antiretroviral therapy (HAART) in previously treatment-naive HIV patients from resource-limited countries.

METHODS

The Antiretroviral Therapy in Low-Income Countries Collaboration is a network of clinics providing care and treatment to HIV-infected patients in Africa, Latin America, and Asia. Patients who initiated therapy between 1996 and 2004, were aged 16 years or older, and had a baseline CD4 cell count were included in this analysis. Responses were defined based on plasma viral load (PVL) and CD4 cell count at 6 months as complete virologic and immunologic (VR(+)IR(+)), virologic only (VR(+)IR(-)), immunologic only (VR(-)IR(+)), and nonresponse (VR(-)IR(-)). Multinomial logistic regression was used to assess the association between therapy responses and clinical and demographic variables.

RESULTS

Of the 3111 patients eligible for analysis, 1914 had available information at 6 months of therapy: 1074 (56.1%) were VR(+)IR(+), 364 (19.0%) were VR(+)IR(-), 283 (14.8%) were (VR(-)IR(+)), and 193 (10.1%) were VR(-)IR(-). OF THE 3111 patients eligible for analysis, 1914 had available information at 6 months of therapy: 1074 (56.1%) were VRIR, 364 (19.0%) were VRIR, 283 (14.8%) were (VRIR), and 193 (10.1%) were VRIR. Compared with complete responders, virologic-only responders were older, had a higher baseline CD4 cell count, had a lower baseline PVL, and were more likely to have received a nonstandard HAART regimen; immunologic-only responders were younger, had a lower baseline CD4 cell count, had a higher baseline PVL, and were more likely to have received a protease inhibitor-based regimen.

CONCLUSIONS

The frequency of and risk factors for discordant responses were comparable to those observed in developed countries. Longer follow-up is needed to assess the long-term impact of discordant responses on mortality in these resource-limited settings.

Continued improvement in survival among HIV-infected individuals with newer forms of highly active antiretroviral therapy

OBJECTIVE

To characterize the temporal changes in mortality and life expectancy among HIV-positive individuals initiating antiretroviral therapy in British Columbia, Canada, from 1993 to 2004.

METHODS

This analysis was restricted to 2238 antiretroviral-naive HIV-positive individuals who started antiretroviral therapy between January 1993 and September 2004. The primary analysis endpoint was all-cause mortality stratified by four time periods: 1993-1995, 1996-1998, 1999-2001, and 2002-2004. Cox proportional hazard models, with associated 95% confidence intervals (CI), were used to estimate the hazard of death. Abridged life tables were constructed to compare life expectancies at the age of 20 years.

RESULTS

Product limit estimates of the cumulative mortality rate at 12 months after therapy initiation decreased from 15.8% (+/- 1.6%) in 1993-1995 to 6.1% (+/- 1.1%) in 2002-2004. Life expectancy at the age of 20 years has increased from 9.1 years (+/- 2.3 years) in 1993-1995 to 23.6 years (+/- 4.4 years) in 2002-2004. Subjects in 1993-1995 were more likely to die than those who started therapy in 2002-2004 (hazard ratio 2.78; 95% CI 1.92-3.85). Patients who initiated dual therapy or therapies containing three or more antiretroviral drugs were, respectively, 1.49 (95% CI 1.23-1.82) and 2.56 (95% CI 2.13-3.13) times less likely to die than those who started on monotherapy.

CONCLUSION

A significant and progressive decrease in mortality and increase in life expectancy were observed over the 12-year study period. The increase in life expectancy and decrease in mortality were directly associated with the use of modern forms of HAART.

Lopinavir/Ritonavir or Efavirenz plus two Nucleoside Analogues as First-Line Antiretroviral Therapy: A Non-Randomized Comparison

Background

Although efavirenz (EFV) and lopinavir/ritonavir (LPV/r) are both recommended antiretroviral agents for combination therapy in drug-naive HIV-infected patients, no randomized comparison of their efficacy and tolerability is available yet. A multi-cohort prospective observational comparative study was performed.

Methods

Efficacy was examined comparing time to virological failure, CD4 recovery and clinical progression. Tolerability was examined comparing time to treatment discontinuation for any reason and for toxicity and time to liver enzymes or lipid alterations. Survival analysis was conducted by an intent-to-treat principle using the Kaplan–Meier method, and standard and weighted Cox regression models.

Results

A total of 674 antiretroviral-naive patients starting a two nucleoside reverse transcriptase inhibitor regimen plus either EFV ( n=481) or LPV/r ( n=193) were examined. At baseline, patients starting LPV/r had higher HIV RNA and lower CD4+ T-cell counts. There was no difference in the adjusted hazards of virological failure (LPV/r versus EFV relative hazard [RH] 1.16, 95% confidence intervals [CI]: 0.58–2.32, P=0.67), CD4 recovery (RH=0.93, 95% CI: 0.66–1.30, P=0.66), clinical progression (RH=1.64, 95% CI: 0.70–3.84, P=0.25), drug discontinuation for toxicity (RH=0.92, 95% CI: 0.51–1.64, P=0.76) and for any reason, and rates of liver enzyme and total/low density lipoprotein (LDL) cholesterol elevation. In contrast, the rate of triglycerides elevations (>1 NCEP Adult Treatment Panel III category increase) was higher in the LPV/r group (RH=1.69, 95% CI: 1.14–2.50; P=0.01). Models weighted for the inverse of conditional probability of receiving either drug applied to the efficacy endpoints yielded similar results. CD4 recovery with both drugs was also similar in the lowest CD4 strata.

Conclusions

Our analysis suggests similar efficacy and tolerability for EFV- or LPV/r-based first-line antiretroviral regimens. LPV/r was associated with higher rates of hypertriglyceridaemia.

The nonnucleoside reverse transcriptase inhibitors efavirenz and nevirapine in the treatment of HIV

Clinical trial data and real-world experience have shown the nonnucleoside reverse transcriptase inhibitors (NNRTIs) to be an important class of agents for the treatment of HIV. Given their long plasma half-lives, in vitro and in vivo potency against HIV, low pill burdens, and ability to be safely combined with other commonly used medications, the NNRTIs nevirapine and efavirenz are widely used in combination antiretroviral therapies. Observational, retrospective cohort studies among antiretroviral treatment (ART)-naive patients have suggested that efavirenz may be superior to nevirapine in terms of efficacy. Recently, data from the 2NN study, a large, multicenter, multinational, prospective, randomized, head-to-head trial comparing efavirenz and nevirapine, have been reported. The results from this study indicate that ART-naive patients achieved good antiviral response after 48 weeks of treatment with nucleoside reverse transcriptase inhibitors (NRTIs) combined with either efavirenz or nevirapine (viral load >50 copies/mL: efavirenz, 70%; nevirapine bid, 65.4%; nevirapine qd, 70%). Even though central nervous system disturbances occurred more frequently among efavirenz-treated patients and nonclinically significant transaminitis occurred more frequently among nevirapine-treated patients, these adverse events were not statistically significant or mutually exclusive. Given the results of the 2NN study, the selection of one agent or the other for use in clinical practice will depend more upon patient-specific factors than expected differences in antiviral responses.

Initiating Highly Active Antiretroviral Therapy and Continuity of HIV Care: The Impact of Incarceration and Prison Release on Adherence and HIV Treatment Outcomes

Objective

To examine the effect of incarceration within 12 months of initiating highly active antiretroviral therapy (HAART) on non-adherence and HIV-1 RNA suppression.

Methods

We compared the adherence and virological outcomes among participants in a population-based HIV/AIDS Drug Treatment Program in British Columbia, Canada, by history of incarceration in a provincial prison. Participants who were HIV-infected, naive to HAART and who were prescribed treatment between 1 July 1997 and 1 March 2002 were eligible for this study. Logistic regression was used to determine the factors associated with non-adherence and Cox proportional hazards modelling was used to determine the factors associated with HIV-1 RNA suppression adjusting for age, gender, history of drug use, baseline HIV-1 RNA, baseline CD4 cell count, type of antiretroviral regimen [two nucleosides + protease inhibitor (PI) vs two nucleosides + non-nucleoside reverse transcriptase inhibitor (NNRTI)], physician's HIV-related experience for each subject and adherence as measured by pharmacy refill compliance.

Results

There were 1746 subjects (101 incarcerated/ 1645 non-incarcerated) who started antiretroviral therapy between 1 July 1997 and 1 March 2002. Of those incarcerated, 50 initiated HAART while in prison and 27 subjects were released but returned to prison in the follow-up period. Subjects received antiretroviral therapy while incarcerated for a median number of 4 months [interquartile range (IQR): 2–10]. Multiple logistic regression results showed that a history of incarceration within 12 months of initiating HAART independently increased the odds of non-adherence [adjusted odds ratio (AOR): 2.40; 95% confidence interval (95% CI): 1.54–3.75]. A history of injected drug use was also associated with non-adherence (AOR: 1.49; 95% CI: 1.17–1.90). The following factors were negatively associated with non-adherence: older age (AOR: 0.81; 95% CI: 0.72–0.91), male sex (AOR: 0.50; 95% CI: 0.38–0.65) and higher physician HIV-related experience (AOR: 0.97; 95% CI: 0.96–0.98). In addition, a history of incarceration within 12 months of initiating HAART reduced the odds of achieving HIV-1 RNA suppression [adjusted hazards ratio (AHR): 0.68; 95% CI: 0.51–0.89]. Other factors negatively associated with viral suppression included a history of drug injection (AHR: 0.79; 95% CI: 0.69–0.91), two nucleosides + PI vs two nucleosides + NNRTI (AHR: 0.77; 95% CI: 0.69–0.87), higher baseline HIV-1 RNA (AHR: 0.66; 95% CI: 0.62–0.70). Higher adherence was positively associated with viral suppression (AHR: 1.38; 95% CI: 1.34–1.42). Among the 101 subjects who were incarcerated in the first year of starting HAART, the time spent in jail was positively associated with HIV-1 RNA suppression (HR: 1.06; 95% CI: 1.02–1.10).

Conclusion

HIV-infected subjects with a history of incarceration within 12 months of initiating HAART have higher odds of non-adherence and, consequently, lower probability of achieving HIV-1 RNA suppression. The longer their sentence, however, the higher the probability of virological suppression. The British Columbian provincial prison system provided a structured setting for HAART but subjects are unable to continue this level of adherence upon release. Strategies to ensure continuation of HIV/AIDS care for HIV-infected individuals leaving the criminal justice system must be a public health priority.