CD4+ T-lymphocytes natural decrease in HAART-naïve HIV-infected adults in Abidjan

Joint models for longitudinal and time-to-event data: a review of reporting quality with a view to meta-analysis

BACKGROUND

Joint models for longitudinal and time-to-event data are commonly used to simultaneously analyse correlated data in single study cases. Synthesis of evidence from multiple studies using meta-analysis is a natural next step but its feasibility depends heavily on the standard of reporting of joint models in the medical literature. During this review we aim to assess the current standard of reporting of joint models applied in the literature, and to determine whether current reporting standards would allow or hinder future aggregate data meta-analyses of model results.

METHODS

We undertook a literature review of non-methodological studies that involved joint modelling of longitudinal and time-to-event medical data. Study characteristics were extracted and an assessment of whether separate meta-analyses for longitudinal, time-to-event and association parameters were possible was made.

RESULTS

The 65 studies identified used a wide range of joint modelling methods in a selection of software. Identified studies concerned a variety of disease areas. The majority of studies reported adequate information to conduct a meta-analysis (67.7% for longitudinal parameter aggregate data meta-analysis, 69.2% for time-to-event parameter aggregate data meta-analysis, 76.9% for association parameter aggregate data meta-analysis). In some cases model structure was difficult to ascertain from the published reports.

CONCLUSIONS

Whilst extraction of sufficient information to permit meta-analyses was possible in a majority of cases, the standard of reporting of joint models should be maintained and improved. Recommendations for future practice include clear statement of model structure, of values of estimated parameters, of software used and of statistical methods applied.

Implementation and Operational Research: Cost-Effectiveness of Antiretroviral Therapy and Isoniazid Prophylaxis to Reduce Tuberculosis and Death in People Living With HIV in Botswana

OBJECTIVE

In Botswana, a 36-month course of isoniazid treatment of latent tuberculosis (TB) infection [isoniazid preventive therapy (IPT)] was superior to 6-month IPT in reducing TB and death in persons living with HIV (PLHIV), having positive tuberculin skin tests (TSTs) but not in those with negative TST. We examined the cost-effectiveness of IPT in Botswana, where antiretroviral therapy (ART) is widely available.

DESIGN

Using a decision-analytic model, we determined the incremental cost-effectiveness of strategies for reducing TB and death in 10,000 PLHIV over 36 months.

METHODS

IPT for 6 months and provision of ART if CD4 lymphocyte count <250 cells per microliter (2011 Botswana policy) was compared with 6 alternative strategies that varied the use of IPT, TST, and ART for CD4 count thresholds, including CD4 <350 and <500 cells per microliter.

RESULTS

Botswana policy, 2011 was dominated by most other strategies. IPT of 36 months for TST-positive PLHIV with ART for CD4 <250 cells per microliter resulted in 120 fewer TB cases for an additional cost of $1612 per case averted and resulted in 80 fewer deaths for an additional $2418 per death averted compared with provision of 6-month IPT to TST-positive PLHIV who received ART for CD4 <250 cells per microliter, the next most effective strategy. Alternative strategies offered lower incremental effectiveness at higher cost. These findings remained consistent in sensitivity analyses.

CONCLUSIONS

A strategy of treating PLHIV who have positive TST with 36-month IPT is more cost effective for reducing both TB and death compared with providing IPT without a TST, providing only 6-month IPT, or expanding ART eligibility without IPT.

CD4-specific mortality rates among HIV-infected adults with high CD4 counts and no antiretroviral treatment in West Africa

BACKGROUND

CD4-specific rates of mortality in sub-Saharan African adults with high CD4 counts have rarely been estimated. This estimation is useful to the when to start antiretroviral treatment (ART) debate.

METHODS

We pooled data from National Agency for Research on AIDS and Viral Hepatitis (ANRS)-funded research cohorts or associated partners in West Africa. All HIV-infected adults (≥18 years) with available follow-up time off ART were eligible. We used a joint model to estimate CD4 count evolution. We estimated CD4-specific rates of mortality, loss-to-follow-up (LTFU) and ART initiation by dividing the number of first event by the follow-up time off ART within each CD4 category.

RESULTS

Between 1996 and 2009, 2588 adults (80% women) from 5 cohorts in Cote d'Ivoire and Burkina Faso were followed off ART during 6862 person-years. In the 201-350, 351-500, 501-650, and >650 cells per cubic millimeter CD4 categories, mortality rates were: 3.0, 1.5, 0.4, 0.2 per 100 person-years; LTFU rates: 6.0, 4.6, 6.1, 6.0 per 100 person-years; and ART initiation rates: 18.1, 2.7, 0.5, 0.5 per 100 person-years, respectively. All estimates varied across cohorts; mortality rates were higher when rates of LFTU and ART initiation were lower; LTFU rates were 2-40 times higher than mortality rates.

CONCLUSIONS

Among untreated West African adults with high CD4 counts, mortality and LTFU rates were substantial. Even when data are collected under research conditions, informative censoring due to ART initiation and LTFU could lead to significantly underestimate mortality figures.

CD4 decline in seroconverter and seroprevalent individuals in the precombination of antiretroviral therapy era

BACKGROUND

Studies based on seroconverters have increased our understanding of HIV disease. It is not clear, however, whether their disease progression differs from that of the general HIV population, given their reasons for presenting for testing.

METHODS

Using linear mixed models we compared CD4 decline rates for a seroconverter (CASCADE) and seroprevalent group (Concorde trial) with time origin being dates of seroconversion and randomization, respectively. Follow-up was censored at the earlier of last alive date and 1 January 1996. Analyses were adjusted for risk group, age and sex. To explore the role of symptomatic seroconversion we further categorized seroconverters into two groups: with and without an HIV test interval below 30 days as proxy.

RESULTS

The 7226 seroconverter and 1746 seroprevalent eligible individuals were mainly men (78 and 85%, respectively) infected through sex between men (52 and 63%) with mean [95% confidence interval (CI)] baseline CD4 cell count of 610 (602, 619) and 492 (479, 505) cells/μl, respectively. There was no evidence that rate of CD4 decline differs between the two groups even after adjusting for potential confounders (P = 0.67). Estimated loss in the year after reaching an arbitrary threshold of 400 cells/μl was 67 (95% CI 65, 69) and 67 (64, 69) cells/μl in the seroconverter and seroprevalent group, respectively. Whereas seroconverters with test interval below 30 days (n = 310) experienced faster decline, there was no difference in rates between other seroconverters and seroprevalent individuals (P = 0.87).

CONCLUSIONS

These data suggest that estimates of HIV progression derived from seroconverters are likely to hold more generally for the HIV-infected population.

Comparison of early CD4 T-cell count in HIV-1 seroconverters in Côte d'Ivoire and France: the ANRS PRIMO-CI and SEROCO cohorts

OBJECTIVE

We compared CD4+ decline among untreated HIV-1-infected seroconverters living in Côte d'Ivoire (CI) and in France.

METHODS

HIV-1-infected adults were enrolled in the ANRS1220 PRIMO-CI (CI, 1997-2006) and ANRSCO2 SEROCO (France, 1988-1995) cohorts. CD4+ count and percentage declines were estimated from enrollment until 24 months of seroconversion by linear random-effect models adjusted for time since seroconversion, age, gender, cell-associated HIV DNA, HIV RNA, and country.

RESULTS

Overall 521 seroconverters (CI 148, 62% men; France 373, 77% men) were enrolled after a median of 7.6 months since seroconversion. Median follow-up duration was 12.7 months. Median age was 28 years. Median baseline CD4+ count was 472 and 560 cells per cubic millimeter, respectively. Median baseline HIV RNA was 4.4 and 4.0 log10 copies per milliliter and median HIV DNA was 3.0 and 2.8 log10 copies per 10(6) peripheral blood mononuclear cells, respectively. In adjusted models, CD4+ count and percentage at baseline were lower in CI than in France (P < 0.01), and the difference did not vary during follow-up (P = 0.55). Low HIV RNA and low HIV DNA at baseline were associated with higher CD4+ count at baseline.

CONCLUSIONS

CD4+ count and percentage were lower in CI than in France. These differences were already observed during early infection and remained similar after adjustment.

Micronutrient supplementation has limited effects on intestinal infectious disease and mortality in a Zambian population of mixed HIV status: a cluster randomized trial

BACKGROUND

Diarrheal disease remains a major contributor to morbidity and mortality in Africa, but host defense against intestinal infection is poorly understood and may depend on nutritional status.

OBJECTIVE

To test the hypothesis that defense against intestinal infection depends on micronutrient status, we undertook a randomized controlled trial of multiple micronutrient supplementation in a population where there is borderline micronutrient deficiency.

DESIGN

All consenting adults (> or =18 y) living in a carefully defined sector of Misisi, Lusaka, Zambia, were included in a cluster-randomized (by household), double-blind, placebo-controlled trial with a midpoint crossover. There were no exclusion criteria. Participants were given a daily tablet containing 15 micronutrients at just above the recommended nutrient intake or placebo. The primary endpoint was the incidence of diarrhea; secondary endpoints were severe episodes of diarrhea, respiratory infection, nutritional status, CD4 count, and mortality.

RESULTS

Five hundred participants were recruited and followed up for 3.3 y (10,846 person-months). The primary endpoint, incidence of diarrhea (1.4 episodes/y per person), did not differ with treatment allocation. However, severe episodes of diarrhea were reduced in the supplementation group (odds ratio: 0.50; 95% CI: 0.26, 0.92; P = 0.017). Mortality was reduced in HIV-positive participants from 12 with placebo to 4 with supplementation (P = 0.029 by log-rank test), but this was not due to changes in CD4 count or nutritional status.

CONCLUSION

Micronutrient supplementation with this formulation resulted in only modest reductions in severe diarrhea and reduced mortality in HIV-positive participants. The trial was registered as ISRCTN31173864.