Home Print this page Email this page Small font sizeDefault font sizeIncrease font size
Users Online: 1780

 

Home About us Editorial board Search Ahead of print Current issue Archives Submit article Instructions Subscribe Advertise Contacts Login 
     

  Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 55  |  Issue : 5  |  Page : 374-378  

Value of the use of absolute lymphocyte as surrogate for CD4 count in resource poor situations


1 Department of Haematology, Federal Medical Centre, Ido-Ekiti, Nigeria
2 Department of Haematology, University of Ilorin Teaching Hospital, Ilorin, Nigeria
3 Department of Haematology, Olabisi Onabanjo University Teaching Hospital, Sagamu, Nigeria

Date of Web Publication9-Sep-2014

Correspondence Address:
Oluwafemi Johnson Adegbamigbe
Department of Haematology, Federal Medical Centre, PMB 201. Ido-Ekiti
Nigeria
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0300-1652.140324

Rights and Permissions
   Abstract 

Background: The initiation of antiretroviral (ARV) drugs and monitoring of human immunodeficiency virus (HIV) treatment in developing nations such as sub-Sahara Africa is based on the clinical stage and level of CD4 count. Clinical stages can easily be determined using the World Health Organisation (WHO) criteria, this is not so with CD4 count where the right equipment and expertise are not easily available. This lead to various studies being carried out in search of surrogates for CD4 count with use of total lymphocyte count (TLC) being suggested by some studies. Objective: In situation where determination of CD4 cell count is not available or feasible, lymphocyte count is believed to be one alternative method for immunological classification of Acquired Immunodeficiency Syndrome (AIDS). Such assumption may not be true of every population. The objective is, therefore, to examine the correlation between the absolute lymphocyte count and the CD4+ lymphocyte count in HIV positive patients. Materials and Methods: One hundred and sixty-five consecutive HIV positive patients were recruited for the study before the commencement of ARV drugs over a period of 13 months. The haemotological parameters such as the CD4 count was done by flow cytometry using Partec cyflow counter machine made in Germany, with strict adherence to the manufacturer's standard operating procedure. TLC were also determined using Sysmex haematology blood analyser, following the manufacturer's standard operating procedure. Patients were then grouped into CD4 and Total lymphocyte (TLC) categories. These were then compared to determine if there is any correlation as shown in previous studies. Statistical analysis of data was done using Statistical Package for Social Sciences (SPSS) and statistical significance of data was based on P value of less than 0.05. There was significant positive correlation (P value 0.000) between TLC and CD4 count. Results: Majority of the patients with TLC less than 1000/mm [3] had CD4 count <200 cells/μl. Using TLC <1000/mm [3] threshold, there was high sensitivity of 81.8% but low specificity and positive predictive value of 47.5% and 19.4%, respectively, for CD4 count <200 cells/μl. Further assessment using TLC of <1,200/mm [3] for the currently accepted CD4 count cut-off of <350 cells/μl for initiation of antiretroviral drugs, the sensitivity, specificity, positive predictive value were found to be 76.5%, 26.7%, 21.3%, respectively. Conclusions: Considering the low specificity and positive predictive value, it was concluded that the use of TLC of as a surrogate for CD4 count is unreliable. However, where there is no alternative, it could be used with caution bearing in mind its limitations.

Keywords: Antiretroviral (ARV) therapy, CD4 count, predictive values, total lymphocyte count


How to cite this article:
Adegbamigbe OJ, Adewuyi JO, Olatunji PO. Value of the use of absolute lymphocyte as surrogate for CD4 count in resource poor situations. Niger Med J 2014;55:374-8

How to cite this URL:
Adegbamigbe OJ, Adewuyi JO, Olatunji PO. Value of the use of absolute lymphocyte as surrogate for CD4 count in resource poor situations. Niger Med J [serial online] 2014 [cited 2019 Nov 20];55:374-8. Available from: http://www.nigeriamedj.com/text.asp?2014/55/5/374/140324


   Introduction Top


The human immunodeficiency virus (HIV) (causative agent of Acquired Immunodeficiency Syndrome (AIDS)) has been reported to produce a slow but progressive deterioration in the host immune system, leading to infections, neurologic disorders and neoplasms. [1] HIV infection has been found to be commoner among commercial sex workers, and people with other sexually transmitted diseases. [2]

The situation in HIV-infected people involves continuous viral replication and destruction and replacement of CD4+ cells. There is eventual deterioration of the host immune system when the rate of CD4+ T cells destruction by HIV supersedes the rate of replacement. While the CD4+ cell count is used as a measure of HIV disease progression, quantifying the viral load is currently the most direct measurement of the HIV disease process. [3] It has also been used to assess the risk of disease progression and the response to antiretroviral therapy (ART). [4]

Government of Nigeria, as part of its care and support strategies initiated the National Antiretroviral (ARV) Drug Access Programme in 2002. [4] Initiation of ARV drugs is based on CD4 count and World Health Organisation (WHO) clinical stage of the disease. [5] WHO has recommended CD4 count of <350 cells/μl and at least Clinical stage 3 disease for commencement of ARV drugs. [5]

CD4 count, though very important, is still expensive, and needs high expertise, which is obtainable in only few centres in resource poor countries like Nigeria. Thus, there is need for a surrogate test that could correlate closely to the CD4 count. Among the suggested surrogates for CD4 is the use of Serum albumin as surrogate for CD4 count in the study done by Olawumi and Olatunji. [6]

Another suggested surrogate for CD4 count, which is the focus of this study, is the use of total lymphocyte count (TLC) (which is readily available in most centres). Positive correlation has been found between TLC in some studies. [7] This led to suggestions of possible use of TLC as surrogate for CD4 count. Thus, the need arises for studies to confirm the usefulness or not of the use of TLC as surrogate for CD4 count.


   Materials and methods Top


One hundred sixty-five consecutive adult subjects were selected for the study from patients attending University of Ilorin Teaching Hospital, who are being screened for HIV infection.

Patient's consent and approval of Hospital Ethical Review committee were obtained before the study was conducted.

HIV screening was done using the WHO parallel testing algorithm using rapid kits (DETERMINE and UNIGOLD). These were further validated using ELISA kit (GENSCREEN R PLUS HIV Ag-Ab made by BIO-RAD). [8] Western blot or other confirmation testing was not done.

The CD4+ lymphocyte count was done on fresh samples taken by aseptic procedure into Ethylenediaminetetraacetic acid (EDTA) bottles using the Partec Flow cytometry based technique. TLC were also determined using Sysmex haematology blood analyser, with strict adherence to the manufacturer's standard operating procedure.

Statistical analysis of data was done using statistical package for social sciences (SPSS) and statistical significance was based on P-value of less than 0.05. Results were presented in tables and figures where applicable.

Comparisons were made using standard statistical methods in which categorical data was compared by Chi-square and discrete variables by t-test; 95% confidence level was observed. Conclusion and recommendations were based on scientific evidence from the results.


   Results Top


One hundred and sixty-five samples were analysed, 22 (13.3%) had TLC less than 1,000/mm [3] , 74 (44.8%) had TLC between 1,000-2,000/mm [3] , while 69 (41.8%) had TLC >2,000/mm [3] [Table 1].
Table 1: Frequency of total lymphocyte group

Click here to view


Using non-parametric analysis, the mean total lymphocyte count was 2024 ± 988/mm [3] while the mean CD4 count was 270 ± 282 cells/μl. The minimum and maximum counts were 5 and 1599 cells/μl for CD4 count and were 300 and 7,500/mm [3] for TLC.

At TLC less than 1000/mm [3] , 81.8% of these patients had CD4 count less than 200 cells/μl, 13.6% had CD4 count within 200-499 cells/μl and only 4.5% had CD4 count greater than 500 cells/μl.

At TLC between 1,000-2,000/mm [3] range (1-2 × 10 [9] /l), 62.1% had CD4 count less than 200 cells/μl, 28.4% had CD4 count within 200-499 cells/μl, while 9.5% had CD4 count >500.

And at TLC >2000/mm [3] , 42.0% had CD4 <200 cells/μl, 30.4% had CD4 count within 200-499 cells/μl, while 27.5% had CD4 count greater than 500 cells/μl [Table 2].
Table 2: Frequency of total lymphocyte count and CD4 categories

Click here to view


Using CD4 count threshold of <350 cells/μl, showed that at TLC less than 1,200/mm [3] , 26 out of 34 (76.5%) of these patients had CD4 count less than 350 cells/μl, seven (20.5%) had CD4 count between 350-499 cells/μl, while one (3%) had CD4 count greater than 500 cells/μl [Table 3].
Table 3: Relationship between CD4 group and total lymphocyte count using CD4 threshold of <350 cells/ìl

Click here to view


Looking at all the cases that had TLC <2,000/mm [3] , 79 out of 96 (82.2%) had CD4 count <350 cells/μl, nine (9.3%) had CD4 count between 350-499 cells/μl, while eight (8.3%) had CD4 count greater than 500 cells/μl [Table 3].

Linear regression Analysis showed positive correlation between CD4 count and TLC with R-value = 0.08 and P-value of 0.00 [Figure 1].
Figure 1: Linear regression analysis for CD4 count and total lymphocyte count correlation. P value = 0.00

Click here to view


In comparing the sensitivity, specificity and positive predictive value of using TLC of <1,000/mm [3] and <2,000/mm [3] for CD4 count threshold of <200 cells/μ, it was found that using TLC of <1,000/mm [3] as surrogate for CD4 count threshold of <200 cells/μ, has sensitivity of 81.8%, but positive predictive value of 19.4%. However, the use of TLC of <2,000/mm [3] for CD4 count threshold of <200 cells/μ, gave a sensitivity of 66.7% and positive predictive value of 68.8% [Table 4].
Table 4: Sensitivity, specificity, positive and negative predictive value of total lymphocyte count for CD4 count <200cells/ìL

Click here to view


Using the latest recommended CD4 count of <350 cells/μl for initiation of antiretroviral drugs, [4] the sensitivity, specificity, positive and negative predictive value of TLC of <1,200/mm [3] and 2,000/mm [3] for CD4 count threshold of <350 cells/μl, was calculated. It was found that using TLC of <1,200/mm [3] as surrogate for CD4 count threshold of <350 cells/μl, gave a sensitivity of 76.5%, but positive predictive value of 21.3%. However, the use of TLC of <2,000/mm [3] for CD4 count threshold of <350 cells/μ, gave a sensitivity of 82.3% and positive predictive value of 64.8% [Table 5].
Table 5: Sensitivity, specificity, positive and negative predictive value of using total lymphocyte count
for CD4 count threshold of <350cells/ìL


Click here to view



   Discussion Top


In this study, the evaluation of the relationship between TLC and CD4 count, showed a statistically significant positive correlation (P value = 0.02) [Table 2].

It is also of note that a high percentage of patients in this study who had total lymphocyte count <2,000/mm [3] (66.7%) also had CD4 count less than 200 cells/μl [Table 2]. This suggest that most patients with absolute lymphocyte count less than 2000/mm [3] will most likely have CD4 count less than 200 cells/μl. In a similar study by Beck et al., it was found that total lymphocyte count less than 1,250 × 10 [6] /l approximates to CD4 count less than 200. [7]

Linear regression graph showed R square as 0.08, and significance of 0.000 [Figure 1]. This agrees with WHO finding that total lymphocyte count of <1,000/mm [3] correlates with CD4 count of less than 200 cells/μl (WHO Improved clinical staging). This is the basis of WHO recommendation for centre where CD4 count could not be done that HIV patient with TLC of <1,200/mm [3] with at least stage II disease can be started on ARV drugs. [9]

In this study, it was found that using absolute lymphocyte count threshold of <1,000/mm [3] for CD4 count <200 cells/μl, gave a sensitivity of 81.8%, with positive predictive value of 19.4%. Increasing the absolute lymphocyte count threshold to <2,000/mm [3] for CD4 count <200 cells/μl gave the sensitivity of 61.5% and positive predictive value to 68.8% [Table 4]. It may be inferred that using absolute lymphocyte count threshold of <2,000/mm [3] for CD4 count <200 cells/μl l will be a more reliable predictor in view of the higher sensitivity and positive predictive value.

Similar study was done by Brites and colleagues to evaluate the absolute lymphocyte count as a substitute for CD4 count in the follow-up of patients under HAART in Brazilian patients. [10] Using the absolute lymphocyte count threshold of 1,000 cells/mm [3] , they found a positive predictive value (PPV) of 70.2% for CD4 count <200 cells/μl. Increasing the absolute lymphocyte count to 2,000/mm [3] , was found to increase the sensitivity to 96.7% but decreases the positive predictive value to 26.7% (unlike the better positive predictive value found when TLC was increased to 2,000/mm [3] in this study). They concluded that using higher limit of absolute lymphocyte count (such as 2,000 cells/mm [3] ) for estimation of CD4 <200 cells/μl, would save the use of CD4 tests in only one-third of patients. [10] This study was, however, conducted on patients already on HAART.

Study by S. P. Blatt and colleague found that the likelihood ratio of the TLC in predicting absolute CD4 count <200 cells/μl increased from 2.4 (95% confidence interval) for all TLC <2,000/mm [3] to 33.2 (95% confidence interval) for all TLC less than 1,000/mm [3] . [11] The specificity for this prediction was found to increase from 57% to 97% over this range. They concluded that TLC between 1,000/mm [3] and 2,000/mm [3] appears to be useful predictor of significant immunosuppressant as measured by a CD4+ T cells less than 200 cells/μl in HIV infected persons. [11] This agrees with the finding in this study where a large percentage of patients with TLC <2,000/mm [3] has CD4 count of <200 cells/μl [Table 2].

However, using the latest accepted CD4 count of <350 cells/μl for initiation of ARV drugs, [4] the sensitivity, specificity, positive and negative predictive value of using TLC of <1,200/mm [3] and 2,000/mm [3] for CD4 count threshold of <350 cells/μl, were respectively 76.5%, 26.5%, 21.3%, 81% for TLC <1,200/mm [3] and 82.3%, 37.7%, 64.8%, 60.5 for TLC 2,000/mm [3] [Table 5].

Comparing the sensitivity, specificity, positive predictive value of using total lymphocyte count as surrogate for CD4 count of <200cells/μl and <350 cells/μl, it was observed that though both values showed a relatively high sensitivity value, the specificity and positive predictive values were low.

This agreed with the findings by Deresse and Eskindir [12] where they also recorded low specificity for the use of TLC as a surrogate for CD4 count. They however submitted that TLC as surrogate for CD4 count in resource poor situations can still be used with the understanding of its low sensitivity and specificity.

It was found that out of 122 patients that had CD4 count <350 cells/μl, only 26 (21.3%) had TLC <1,200/mm [3] [Table 3]. Thus, using TLC <1,200/mm [3] in the absence of CD4 count would have excluded 78.7% of patients that should have been on ARV drugs based on CD4 count <350 cells/μl. This corroborates similar findings by Akinola et al., [13] where they also concluded that TLC is not a reliable predictor of CD4 cell count in HIV-infected individuals.


   Conclusion Top


From this study, it was found that there was statistical positive correlation between TLC and CD4 count, which is consistent with findings in other studies. [13]

That, based on the low specificity and positive predictive value as recorded in this study and some other studies, the use of TLC as a surrogate for CD4 count is unreliable.

That in areas where there are no alternative, or the alternatives (as suggested by Didier et al.) [15] are not affordable; it could be used with caution as expressed by Deresse and Eskindir, [12] bearing in mind its low PPV.

 
   References Top

1.Nigeria Bulletin of Epidemiology. AIDS in Nigeria 1992;2:6.  Back to cited text no. 1
    
2.Boaz AO. The 'sexogenic' viruses. AIDS and other sexually transmitted diseases. Library and Publications Committee, University of Ilorin, Nigeria 2003;52-5.  Back to cited text no. 2
    
3.Richard NM, Cotran RS. Diseases of Immunity. In: Contran RS, Kumar V, Collins T, editors. Pathologic Basis of Disease. 6 th ed. Philaldelphia: WB Saunders Company 1999;236-50.  Back to cited text no. 3
    
4.Federal Ministry of Health. Guidelines for the use of antiretroviral drugs in Nigeria 2007:10-9.  Back to cited text no. 4
    
5.Federal Ministry of Health. Guidelines for the use of antiretroviral drugs in Nigeria 2007:23-34.  Back to cited text no. 5
    
6.Olawumi HO, Olatunji PO. The value of serum albumin in pretreatment assessment and monitoring of therapy in HIV/AIDS patients. HIV Med 2006;7:351-5.  Back to cited text no. 6
    
7.Beck EJ, Kupek, EJ, Gomples MM, Pinching AJ. Correlation between total and CD4 lymphocyte counts in HIV infection: Not making the good an enemy of the not so perfect. Int J STD AIDS 1996;7:422-8.  Back to cited text no. 7
    
8.BIO-RAD. GENSCREEN® PLUS HIV Ag-Ab screening kit for the detection of HIV infection in human serum/plasma by Enzyme immunoassay (ELISA):3-12.  Back to cited text no. 8
    
9.Federal Ministry of Health, Nigeria. Guidelines for the use of antiretroviral (ARV) drugs in Nigeria 2005:18-22.  Back to cited text no. 9
    
10.Brites CR, Angelo AL, Dias C, Torres AJ, Ramos AM, Lima M, et al. Evaluating the absolute lymphocyte count as a substitute for CD4 count in the follow-up of AIDS patients under HAART. Braz J Infect Dis 2007;11:466-70.  Back to cited text no. 10
    
11.Blatt SP, Lucey CR, Butzin CA, Hendrix CW Lucey DR. Total lymphocyte count as a predictor of absolute CD4+ count and CD4+ percentage in HIV-infected persons. JAMA 1993;269:622-6.  Back to cited text no. 11
    
12.Daka D, Loha E. Relationship between total lymphocyte count (TLC) and CD4 count among peoples living with HIV, Southern Ethiopia: A retrospective evaluation. AIDS Res Ther 2008;5:26.  Back to cited text no. 12
    
13.Akinola NO, Olasode O, Adediran IA, Onayemi O, Murainah A, Irinoye O, et al. The search for a predictor of CD4 cell count continues: Total lymphocyte count is not a substitute for CD4 cell count in the management of HIV-infected individuals in a resource-limited setting. Clin Infect Dis 2004;39:579-81.  Back to cited text no. 13
    
14.Technical and operational recommendation to achieve 3 by 5. UNAIDS/WHO publication Geneva; 2004.  Back to cited text no. 14
    
15.Didier JM, Kazatchkine MD, Demouchy C, Moat C, Diagbouga S, Sepulveda C, et al. Comparative assessment of five alternative methods for CD4+ T-lymphocyte enumeration for implementation in developing countries. J Acquir Immune Defic Syndr 2001;26:193-5.  Back to cited text no. 15
    


    Figures

  [Figure 1]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

Top
  
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
    Abstract
   Introduction
    Materials and me...
   Results
   Discussion
   Conclusion
    References
    Article Figures
    Article Tables

 Article Access Statistics
    Viewed2148    
    Printed44    
    Emailed0    
    PDF Downloaded148    
    Comments [Add]    

Recommend this journal