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BASIC SCIENCE: CONCISE COMMUNICATIONS

Simple markers for initiating antiretroviral therapy among HIV-infected Ethiopians

Mekonnen, Yareda; Dukers, Nicole HTMa,b; Sanders, Eduarda; Dorigo, Wendeliena; Wolday, Dawita; Schaap, Aba; Geskus, Ronald Bb; Coutinho, Roel Aa,b; Fontanet, Arnauda,b,c

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Abstract

Introduction

Decisions to initiate highly active antiretroviral therapy (HAART) treatment are generally based on the level of CD4 T-cell counts and HIV RNA load [1], which measuring unfortunately requires equipment beyond the capacity of most laboratories in the developing world. Recently, the World Health Organization (WHO) developed guidelines for initiating treatment which do not require such sophisticated measurements [2]. In Haiti, simple criteria such as clinical conditions and standard blood cell counts have been proposed and successfully used, proving that treatment is possible with limited laboratory back-up [3]. However, it is unknown whether some patients needing treatment were missed by the criteria or whether other patients were over-treated.

In the present study we evaluated the use of simple criteria for initiating treatment by comparing the timing of treatment under guidelines using sophisticated laboratory analyses and guidelines using simple laboratory analyses (including haemoglobin level and lymphocyte counts) in hypothetical cases based on a cohort study of factory workers in Ethiopia.

Patients and methods

Study participants and clinical examination

Data were used through August 2001 from an ongoing cohort started in 1997, encompassing a factory in Akaki and in Wonji, towns respectively 15 km south and 110 km southeast of Addis Ababa. Participants were regularly seen every 6 months at the study clinic and between visits, if general care was needed [4,5]. Clinical information was obtained through a medical examination focussing on the conditions included in the WHO staging system [6]. Most diagnoses were presumptive, as access to laboratory investigations was limited. Acid-fast bacilli sputum smears, chest X-ray, and lymph node biopsies were used to investigate suspected tuberculosis cases. Ethical clearance for the study was given by both institutional (EHNRI) and national ethical clearance committees.

Laboratory analysis

HIV-1 screening was performed by HIVSPOT (Genelabs Diagnostics, Singapore) and ELISA (Vironostika HIV Uni-Form II, Organon Teknika, Boxtel, the Netherlands). All positive or discrepant results were confirmed by a Western Blot Assay (HIV BLOT 2.2, Genelabs Diagnostics). The absolute number of leucocytes per microliter of whole blood was obtained using a Coulter counter T540 (Coulter Electronics, Miami Lakes, Florida, USA). Lymphocyte subsets were determined by flow cytometry using a FACScan (Becton Dickinson, San Jose, California, USA). Viral load in plasma was assessed using the Nuclisens assay (Organon, Teknika) which has a detection level of 80 HIV RNA copies/ml.

Statistical analysis

Guidelines for initiating therapy in developed countries are based on the identification of medium-term (3–4 years) predictors of AIDS development [1,7]. Using AIDS as an endpoint in analysis would have been impractical, as very few patients were diagnosed with AIDS during the follow-up of the cohort study. In fact, due to the poor local medical infrastructure and reluctance to reveal AIDS, most such patients developing AIDS died within a few days or weeks without being seen by our study personnel. The cause of death was therefore investigated through retrospective interviews of patients’ family members and hospital physicians using a standardized questionnaire. As all HIV-infected patients died of conditions presumably related to HIV infection (of the total of 35 deaths recorded, 16 were attributable to tuberculosis, 10 to wasting syndrome, four to pneumonia, one to meningitis, and four to unknown causes), we used ‘death’ as our endpoint for the analysis of predictors of HIV infection progression.

Several clinical and laboratory markers were evaluated: (i) symptomatic HIV infection, defined as stage 3 and 4 of the WHO staging system for HIV infection and disease [6]; (ii) low body mass index (BMI), defined as BMI < 18.5 kg/m2 according to the United Nations FAO criteria [8]; (iii) anaemia, defined as haemoglobin < 13.4 g/dl for males and 11.9 g/dl for females in Akaki at 2100 meters of altitude, < 13.0 g/dl for males and < 11.5 g/dl for females in Wonji at 1500 meters of altitude, according to the definition of anaemia of the Centres for Disease Control [9]; (iv) lymphocyte counts < 1500 × 106/l, according to standard medical textbooks definition for lymphopenia [10]; (v) CD4 cell counts, with two cut-off points tested, < 200 × 106/l and < 350 × 106/l; and (vi) plasma HIV RNA load, with two cut-off points tested, ≥ 10 000 and ≥ 55 000 copies/ml.

Participants were considered lost to follow-up after missing two consecutive visits plus 1 month. For individual cases lacking data for all markers at intake, the analysis starts at the first follow-up visit for which all data are present; for seroconverters, the analysis starts at the seroconversion visit.

The scarcity of resources in the developing world may justify the delay of treatment initiation and urge the use of short-term rather than medium-term predictors of death for initiating therapy. The median duration between two visits was 196 days, so ‘short-term’ approximates 6 months. Using time-dependent Cox proportional hazards analysis, all markers were introduced in the first model and were then deleted using a backward selection procedure to retain only markers with significant P values (< 0.05) in the final model (`best’ model). The same procedure was repeated excluding the sophisticated markers (CD4 cell counts and plasma viral load) from the initial set of markers available (`simple markers’ model).

Antiretroviral treatment guidelines were then elaborated based on the predictors of death identified in the ‘simple markers’ models. It was postulated that participants should be treated when at least one predictor was present. The DHHS guideline requests that treatment is initiated when at least one prognostic marker is present (HIV-related conditions or CD4 cell counts < 350 × 106/l or viral load ≥ 55 000 copies/ml), and this was the rule adopted in this study. The WHO guidelines for resource-limited settings vary according to the availability of CD4 cell counts [2]. The guidelines in which CD4 cell counts are available stipulate that patients are treated if subjects have either clinical AIDS, or CD4 cell counts < 200 × 106/l. The guidelines in which CD4 cell counts are not available suggest treating subjects if they have clinical AIDS, or WHO stage II conditions or higher and lymphocyte counts < 1200 × 106/l. The various treatment guidelines were then hypothetically applied to the cohort participants, and compared by looking at the following indicators: (i) number of cohort participants who would have died without receiving treatment; (ii) number of participants who would have been treated under the proposed guideline; (iii) median CD4 cell counts at the time of hypothetical treatment initiation; (iv) proportion of patients with CD4 cell counts < 200 × 106/l at the time of treatment initiation; (v) median viral load at the time of treatment initiation; (vi) proportion of patients with viral load ≥ 55 000 copies/ml at the time of treatment initiation.

Results

Between 26 February 1997 and 31 August 2001, a total of 1666 individuals joined the cohort, among which 156 (9.4%) were HIV-positive at intake. During follow-up, 18 seroconversions for HIV antibodies occurred and 35 deaths were recorded among HIV positive persons.

Excluding participants with incomplete data (n = 19) and deaths (n = 4) occurring after participants became lost to follow-up, we were left with 155 HIV-positive participants, including 27 deaths for the analysis of prognostic markers of mortality. Of these 155 participants, 106 (68.4%) were male and the median age was 33 years at study enrolment. At entry, 16.1% of participants had symptomatic HIV infection, 20.0% had low BMI, 20.6% were anaemic, 38.1% had lymphopaenia, 23.2% had CD4 cell counts < 200 × 106/l and 51.6% had a viral load of > 10 000 copies/ml.

Table 1 shows that all markers were significantly associated with an increased risk of death in univariate analyses. While anaemia and lymphocyte count < 1500 × 106/l were not significant predictors anymore in models that included CD4 cell counts and viral load, they became independently significant after exclusion of the latter two.

Table 1
Table 1:
Univariate and multivariate hazard ratios (HR) of death according to different time-dependent Cox proportional hazards models for the ENARP HIV-positive cohort (n = 155), 1997–2001.

Table 2 compares treatment guidelines based on the previous models and international guidelines. Both WHO guidelines (i.e., with and without CD4 cell counts available) resulted in the lowest numbers of treated patients during the course of the study (65 and 67 treated patients). However, with both guidelines, several patients would have died before reaching a treatment indication (five and 11, respectively). The two remaining guidelines (DHHS guidelines and simple markers guidelines) gave similar results in terms of number of patients to be treated and the laboratory markers values present at the time of treatment initiation: 135 (87%) of all 155 participants would have had the same management under both guidelines, i.e., would have been treated (n = 114, 74%) or not treated (n = 21, 14%). Of those treated under both guidelines 91 (80%) would have started treatment at the same time. Of the 13 patients who would have started treatment under the DHHS guideline but not under the simple markers guidelines, none would have had CD4 cell counts < 200 × 106/l at the time of treatment initiation. During follow-up, two of these 13 patients had CD4 cell counts dropping below 200 × 106/l (123 × 106 and 156 × 106/l at the last visit) while no simple predictor was present. Finally, all seven patients who would have started treatment under the simple markers guidelines, but not under the DHHS guidelines, would have had CD4 counts < 500 × 106/l.

Table 2
Table 2:
Evaluation indicators of different treatment guidelines for the ENARP HIV-positive cohort (n = 155), 1997–2001.

Discussion

The timing of HAART would have been very similar had patients been treated using the international guidelines recommended by the DHHS or the guidelines based on the simple predictors of death identified in this study. It seems reasonable, therefore, to suggest that simple markers be used to initiate HAART in areas lacking a sophisticated laboratory or to identify patients for referral to locations that have such laboratories. Before generalization, however, such findings would require validation using other datasets obtained in similar settings.

One may argue that such similarity in timing and number of treatments contradicts our initial intention of delaying treatment in resource-poor settings because of scarcity of drugs. Indeed, under the simple markers guidelines, up to 78% of the cohort participants would have been treated including 58% from cohort intake. This number may seem exaggerated for a population known to be healthy enough to work in a factory. However, our simulation shows that postponing treatment would have resulted in having subjects dying without ever meeting a treatment indication during their regular follow-up visits. In this regard, the WHO guidelines without CD4 cell counts would have not performed well in our setting, with 41% of the patients who died doing so without being treated. If one is ready to accept death of a few patients in order to minimize the number of treatments provided, a modification of our simple markers guidelines, dropping anaemia as a criterion for initiating treatment, would have performed reasonably well in our setting. Indeed, only two patients would have died without being treated, while only 52% patients would have been treated over the course of the study period (detailed data not shown). One explanation for the large number of patients that would be treated under the DHHS guidelines might be the generally low CD4 cell counts found among Ethiopians, compared to people elsewhere in the world [5,11].

While simple markers performed well compared to established laboratory markers in deciding on treatment initiation, we do not know how well they would perform in monitoring a patient's improvement following initiation of therapy. Drugs likely to induce anaemia, such as zidovudine [1], would obviously preclude the use of haemoglobin for monitoring patient's recovery under therapy.

In conclusion, we have identified simple markers for initiating anti-retroviral therapy among HIV-infected individuals in a suburb of Addis Ababa, Ethiopia. We hope that the development of such tools will facilitate the introduction of antiretroviral drugs in resource-poor countries, where they are needed most.

Acknowledgments

We thank L. D. Phillips for editing an earlier version of this manuscript.

Sponsorship: The Ethio-Netherlands AIDS Research Project (ENARP) is a collaborative effort of the Ethiopian Health and Nutrition Research Institute (EHNRI), Addis Ababa, the Municipal Health Service, Amsterdam, the Department of Human Retrovirology of the Academic Medical Centre (University of Amsterdam) and the Central Laboratory of the Netherlands Red Cross Blood Transfusion Service. ENARP is financially supported by the Dutch Ministry for Development Co-operation and the Ethiopian Ministry of Health.

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Keywords:

antiretroviral therapy; HIV; Africa; prognosis markers; cohort study

© 2003 Lippincott Williams & Wilkins, Inc.