Prognostic Factors of Combined Viral Load and CD4+ Cell Count Responses Under Triple Antiretroviral Therapy, Aquitaine Cohort, 1996–1998

Poor CD4 recovery and risk of subsequent progression to AIDS or death despite viral suppression in a South African cohort

INTRODUCTION

The prognostic role of CD4 response in the first six months of treatment in patients achieving early viral suppression during HIV treatment is unclear.

METHODS

This was a cohort study of HIV-positive adults initiating antiretroviral therapy (ART) between April 2004 and August 2007 who achieved viral suppression (<400 copies/ml) by six months on treatment in South Africa. Immunological response at six months was defined as: (1) absolute CD4 reached (<200 vs. ≥ 200 cells/ml); (2) absolute CD4 reached (0-49, 50-200 and ≥ 200 cells/ml); and (3) CD4 increase from ART initiation (<0, 0-49, 50-199 and ≥ 200 cells/ml). We used Cox regression models to determine the relationship between each definition and both new AIDS-defining condition and death.

RESULTS

A total of 4129 patients were eligible for analysis; 212 (5.1%) of those patients experienced a new AIDS-defining condition and 154 (3.7%) died. Smaller CD4 gains by six months were associated with higher hazards of progression to AIDS (CD4<50 vs. ≥ 200 cells/ml; adjusted hazard ratio (aHR): 2.6; 95% CI: 1.2-2.1) and death (aHR: 2.8; 95% CI: 1.4-5.7). A decrease in CD4 count since ART initiation through six months (aHR: 2.4; 95% CI: 1.2-4.9) and smaller CD4 count gains (0-49 cells/ml; aHR: 2.0; 95% CI: 1.2-3.4 and 50-199 cells/ml; aHR: 1.5; 95% CI: 0.9-2.2) were also associated with greater risk of progression to AIDS compared to an increase of ≥ 200 cells/ml. When we examined mortality differences by gender among this virally suppressed cohort, a higher proportion of males died compared to females, 4.7% versus 3.2%, p=0.01. However, in multivariable analysis, we did not observe any significant differences: aHR: 1.39; 95% CI: 0.98-1.95.

CONCLUSIONS

Patients on ART with poor CD4 recovery early in treatment are at greater risk of progression to new AIDS diagnosis or death despite viral suppression. Approaches to managing this sub-group of patients need further investigation.

Risk of clinical progression among patients with immunological nonresponse despite virological suppression after combination antiretroviral treatment

BACKGROUND

It is unclear whether lack of immunological response despite viral suppression and relatively preserved CD4 T-cell count is associated with increased risk of AIDS or severe non-AIDS events.

METHODS

Patients initiating first combination antiretroviral therapy (cART) were studied from first viral load 80  copies/ml or less up to AIDS, serious non-AIDS events (malignancies, severe infections, acute kidney injury, cardiovascular events, liver decompensation) or death. Follow-up was right censored if viral load was more than 500. Immunological nonresponse (INR) was defined as current CD4 cell count less than 120% pre-cART. A Poisson regression analysis was used to investigate the association between INR and the outcome.

RESULTS

Three thousand, three hundred and seventy-eight patients were followed for a median of 32 months (interquartile range: 15-67). Two hundred and twenty-two events (32 deaths, 39 AIDS-defining events, 48 malignancies, 32 severe infections, 47 acute kidney injuries, 12 cardiovascular events, 12 other nonfatal events) were observed. The rate of clinical events among INR and immunological responders was 4.41 [95% confidence interval (CI) 3.38-5.74] and 1.84 (95% CI 1.58-2.15) per 100 person years of follow-up, respectively, accounting for a crude rate ratio of 2.39 (95% CI 1.77-3.25; P < 0.001). INR remained an independent predictor of clinical progression after adjusting for baseline characteristics, including pre-cART CD4 cell count (adjusted rate ratio 2.93; 95% CI 2.06-4.16, P < 0.001) or current CD4 cell count (adjusted rate ratio 1.94; 95% CI 1.39-2.72, P < 0.001). The association did not vary by pre-cART CD4 cell counts (P for interaction = 0.93)

CONCLUSION

INR are at higher risk of severe clinical events than responders. The association was consistent across different CD4 cell counts at cART initiation and was only partially explained by current CD4 cell count. INR could be a marker of immune system malfunctioning, not completely captured by absolute CD4 cell count.

Effect of age on immunological response in the first year of antiretroviral therapy in HIV-1-infected adults in West Africa

OBJECTIVE

To assess the effect of aging on the immunological response to antiretroviral therapy (ART) in the West African context.

METHODS

The change in CD4 T-cell count was analysed according to age at the time of ART initiation among HIV-infected patients enrolled in the International epidemiological Database to Evaluate AIDS (IeDEA) Collaboration in the West African region. CD4 gain over 12 months of ART was estimated using linear mixed models. Models were adjusted for baseline CD4 cell count, sex, baseline clinical stage, calendar period and ART regimen.

RESULTS

The total number of patients included was 24,107, contributing for 50,893 measures of CD4 cell count in the first year of ART. The baseline median CD4 cell count was 144 cells/μl [interquartile range (IQR) 61-235]; median CD4 cell count reached 310 cells/μl (IQR 204-443) after 1 year of ART. The median age at treatment initiation was 36.3 years (10th-90th percentiles = 26.5-50.1). In adjusted analysis, the mean CD4 gain was significantly higher in younger patients (P < 0.0001). At 12 months, patients below 30 years recovered an additional 22 cells/μl on average [95% confidence interval (CI) 2-43] compared to patients at least 50 years.

CONCLUSION

Among HIV-infected adults in West Africa, the immunological response after 12 months of ART was significantly poorer in elderly patients. As the population of treated patients is likely to get older, the impact of this age effect on immunological response to ART may increase over time.

Immune reconstitution under antiretroviral therapy: the new challenge in HIV-1 infection

Although highly active antiretroviral therapy has enabled constant progress in reducing HIV-1 replication, in some patients who are "aviremic" during treatment, the problem of insufficient immune restoration remains, and this exposes them to the risk of immune deficiency-associated pathologies. Various mechanisms may combine and account for this impaired immunologic response to treatment. A first possible mechanism is immune activation, which may be because of residual HIV production, microbial translocation, co-infections, immunosenescence, or lymphopenia per se. A second mechanism is ongoing HIV replication. Finally, deficient thymus output, sex, and genetic polymorphism influencing apoptosis may impair immune reconstitution. In this review we will discuss the tools at our disposal to identify the various mechanisms at work in a given patient and the specific therapeutic strategies we could propose based on this etiologic diagnosis.

A CD4+ cell count <200 cells per cubic millimeter at 2 years after initiation of combination antiretroviral therapy is associated with increased mortality in HIV-infected individuals with viral suppression

OBJECTIVE

To determine the long-term impact of immunologic discordance (viral load <50 copies/mL and CD4+ count <=200 cells/mm3) in antiretroviral-naive patients initiating combination antiretroviral therapy (cART).

METHODS

Our analysis included antiretroviral-naive individuals from a population-based Canadian Observational Cohort that initiated cART after January 1, 2000, and achieved virologic suppression. Multivariable Cox proportional hazards regression was used to examine the association between 1-year and 2-year immunologic discordance and time to death from all-causes. Correlates of immunologic discordance were assessed with logistic regression.

RESULTS

Immunologic discordance was observed in 19.9% (404 of 2028) and 10.2% (176 of 1721) of individuals at 1 and 2 years after cART initiation, respectively. Two-year immunologic discordance was associated with an increased risk of death [adjusted hazard ratio = 2.69; 95% confidence interval (CI): 1.26 to 5.78]. One-year immunologic discordance was not associated with death (adjusted hazard ratio = 1.12; 95% CI: 0.54 to 2.30). Two-year immunologic discordance was associated with older age (aOR per decade = 1.23; 95% CI: 1.03 to 1.48), male gender (aOR = 1.86; 95% CI: 1.09 to 3.16), injection drug use (aOR = 2.75; 95% CI: 1.81 to 4.17), and lower baseline CD4+ count (aOR per 100 cells = 0.24; 95% CI: 0.19 to 0.31) and viral load (aOR per log10 copies/mL = 0.46; 95% CI: 0.33 to 0.65).

CONCLUSIONS

Immunologic discordance after 2 years of cART in antiretroviral-naive individuals was significantly associated with an increased risk of mortality.

Effect of baseline CD4 cell counts on the clinical significance of short-term immunologic response to antiretroviral therapy in individuals with virologic suppression

BACKGROUND

Achieving virologic suppression is a clear therapeutic goal for patients receiving combination antiretroviral therapy (cART). However, the effects of immunologic responses, whether measured as CD4 count changes from baseline or CD4 counts at follow-up, in patients with virologic suppression, have not been clearly established.

METHODS

Treatment-naive individuals aged > or =16 years, who initiated cART between 1998 and 2005 in participating cohorts of the ART Cohort Collaboration and achieved viral load < or =400 copies per milliliter 6 months after cART initiation, were included. We used Cox models to examine associations of CD4 change from baseline to 6 months, and absolute CD4 counts at 6 months, with subsequent rates of mortality and AIDS. Analyses were stratified by baseline CD4 count.

RESULTS

Among 23,679 eligible participants, the median increase in CD4 count at 6 months, and the implications of these increases for subsequent mortality and AIDS, varied with baseline CD4 count. Mortality hazard ratios for increases of 0-50 cells per microliter, compared with >100 cells per microliter, were 1.87 (95% confidence interval: 1.28 to 2.73), 1.60 (1.13 to 2.28), 0.98 (0.58 to 1.65) and 1.24 (0.70 to 2.18) in participants with baseline CD4 cell count <50, 50-199, 200-349 and > or =350 cells per microliter, respectively. In contrast, hazard ratios for mortality or AIDS associated with absolute CD4 cell counts at 6 months were similar across all but the highest baseline CD4 cell count strata.

CONCLUSION

It is not possible to derive thresholds for change in CD4 count that define an adequate immunologic response in individuals receiving cART. Absolute CD4 counts at 6 months are a more useful measure of immunologic response and subsequent prognosis.

Response to combination antiretroviral therapy: variation by age

OBJECTIVE

To provide information on responses to combination antiretroviral therapy in children, adolescents and older HIV-infected persons.

DESIGN AND SETTING

Multicohort collaboration of 33 European cohorts.

SUBJECTS

: Forty-nine thousand nine hundred and twenty-one antiretroviral-naive individuals starting combination antiretroviral therapy from 1998 to 2006.

OUTCOME MEASURES

Time from combination antiretroviral therapy initiation to HIV RNA less than 50 copies/ml (virological response), CD4 increase of more than 100 cells/microl (immunological response) and new AIDS/death were analysed using survival methods. Ten age strata were chosen: less than 2, 2-5, 6-12, 13-17, 18-29, 30-39 (reference group), 40-49, 50-54, 55-59 and 60 years or older; those aged 6 years or more were included in multivariable analyses.

RESULTS

The four youngest age groups had 223, 184, 219 and 201 individuals and the three oldest age groups had 2693, 1656 and 1613 individuals. Precombination antiretroviral therapy CD4 cell counts were highest in young children and declined with age. By 12 months, 53.7% (95% confidence interval: 53.2-54.1%) and 59.2% (58.7-59.6%) had experienced a virological and immunological response. The probability of virological response was lower in those aged 6-12 (adjusted hazard ratio: 0.87) and 13-17 (0.78) years, but was higher in those aged 50-54 (1.24), 55-59 (1.24) and at least 60 (1.18) years. The probability of immunological response was higher in children and younger adults and reduced in those 60 years or older. Those aged 55-59 and 60 years or older had poorer clinical outcomes after adjusting for the latest CD4 cell count.

CONCLUSION

Better virological responses but poorer immunological responses in older individuals, together with low precombination antiretroviral therapy CD4 cell counts, may place this group at increased clinical risk. The poorer virological responses in children may increase the likelihood of emergence of resistance.

Clinical outcome of HIV-infected antiretroviral-naive patients with discordant immunologic and virologic responses to highly active antiretroviral therapy

BACKGROUND

The prognostic significance of a response to highly active antiretroviral therapy (HAART) that is immunologically and virologically discordant is not well understood.

METHODS

Four hundred four antiretroviral-naive patients initiating HAART at an urban HIV outpatient clinic in 1995 to 2004 were analyzed. The association of treatment responses at 3 to 9 months after HAART initiation with time to development of an opportunistic infection (OI) or death was determined using Cox proportional hazards modeling. Logistic regression modeling was used to examine the association between discordant responses and patient characteristics.

RESULTS

Of 404 patients, 70.5% experienced favorable concordant responses (CD4 cell count [CD4]+/viral load [VL]+: increase in CD4 count of >or=50 cells/microL and achievement of undetectable plasma HIV RNA level), 15.8% an immunologic response only (CD4+/VL(-)), 8.7% a virologic response only (CD4(-)/VL+), and 5.0% a concordant unfavorable response (CD4(-)/VL(-)). Both types of discordant responses (CD4+/VL(-) and CD4(-)/VL+), nonresponse (CD4(-)/VL(-)), and baseline CD4 cell count were significantly associated with earlier development of an OI or death (relative hazard [RH] = 2.81, 95% confidence interval [CI]: 1.31 to 3.97; RH = 4.83, 95% CI: 2.10 to 11.12; and RH = 0.93, 95% CI: 0.88 to 0.99, respectively). CD4+/VL(-) and CD4(-)/VL(-) were associated with nonwhite race in multivariate logistic regression models (adjusted OR = 2.83, 95% CI: 1.46 to 5.47 and adjusted OR = 6.50, 95% CI: 1.65 to 25.69, respectively).

CONCLUSION

Discordant immunologic and virologic responses at 3 to 9 months after HAART initiation play important roles in predicting long-term clinical outcomes in treatment-naive patients.

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.

Discordant immunologic and virologic responses to highly active antiretroviral therapy are associated with increased mortality and poor adherence to therapy

OBJECTIVE

To examine the independent association of discordant virologic and immunologic responses to highly active antiretroviral therapy (HAART) with mortality.

METHODS

A population-based study of 1527 treatment-naive individuals initiating HAART used Cox proportional hazards modeling to determine the independent association of treatment response at 3 to 9 months with nonaccidental mortality. Logistic regression was used to examine associations with discordant responses.

RESULTS

Viral load (VL)/CD4 discordant responses were seen in 235 (15.4%) of subjects, and VL/CD4 responses were seen in 179 (11.7%) of subjects. In adjusted Cox regression models, discordant responses were found to be independently associated with an increased risk of mortality (VL/CD4: relative hazard [RH] = 1.87, 95% confidence interval [CI]: 1.15 to 3.04; VL/CD4: RH = 2.47, 95% CI: 1.54 to 3.95). VL/CD4 discordance was found to be associated with increasing age, baseline HIV RNA load <100,000 copies/mL, baseline CD4 counts <50 cells/muL, the use of lamivudine (3TC)/zidovudine (ZDV), and poor adherence to therapy. VL/CD4 discordance was associated with younger age; injection drug use; baseline HIV RNA load >100,000 copies/mL; the use of 3TC/ZDV, didanosine (ddI)/3TC, or ddI/stavudine; and poor adherence to therapy.

CONCLUSION

Discordant responses are independently associated with an increased risk of mortality and are, in turn, associated with poor adherence to therapy.