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Utility of absolute lymphocyte count as a surrogate marker of CD4 cell counts: Is it useful?
Amitabh Sagar1, Abhishek Pathak2, Vikas Ambiya3
1Associate Professor, Dept of Internal Medicine, Armed Forces Medical College, Pune 40, India.
Insights
Absolute lymphocyte count (ALC) is not a clinically significant surrogate marker for CD4 lymphocyte counts in HIV management. This study found only a modest correlation, reinforcing the need for accurate CD4 counts.
Area of Science:
- Immunology
- Virology
- Public Health
Background:
- HIV management has evolved significantly, shifting from indirect markers like Absolute Lymphocyte Count (ALC) to CD4 lymphocyte counts and HIV RNA levels.
- Resource disparities necessitate exploring inexpensive surrogate markers for CD4 counts in managing people living with HIV/AIDS (PLHA).
- Previous studies have questioned the validity of ALC as a surrogate for CD4 counts, with calls for further validation.
Purpose of the Study:
- To evaluate the association between Absolute Lymphocyte Count (ALC) and CD4 lymphocyte counts as a potential surrogate marker.
- To determine the clinical significance of ALC as a proxy for CD4 counts in HIV/AIDS patient management.
Main Methods:
- Assessed ALC and CD4 lymphocyte counts from 241 patients at an HIV/AIDS referral center over 13 months.
- Employed Pearson correlation coefficient, coefficient of determination, and standard statistical methods.
Main Results:
- A modest linear correlation was observed between ALC and CD4 lymphocyte counts.
- The correlation was statistically significant but lacked clinical significance for practical application.
- Pearson correlation coefficient and coefficient of determination indicated a weak relationship.
Conclusions:
- Absolute Lymphocyte Count (ALC) should no longer be considered a reliable surrogate marker for CD4 lymphocyte counts.
- The findings suggest that ALC does not possess sufficient clinical significance to replace direct CD4 count monitoring in HIV care.
- Further research may be needed to identify more reliable and cost-effective surrogate markers for CD4 counts in resource-limited settings.
Background:
Human immunodeficiency virus (HIV) management has witnessed paradigm changes over the past decade. In the early era, Absolute lymphocyte counts (ALC) were used as an inexpensive, indirect marker of immunity status. With time, CD4 lymphocyte counts and HIV RNA levels have become a standard of care for follow up of people living with HIV/AIDS (PLHA). Wide disparities between resource rich and poor countries, rekindles the need for an inexpensive surrogate marker for CD4 lymphocyte counts. Multiple studies in the past including one by Sen S et al, in 2011 did not validate ALC as a surrogate marker of CD4 lymphocyte counts and had recommended a similar study at another centre to validate the same.(1) Recently few publications have suggested that ALC may be used as a proxy marker to CD4 lymphocyte counts in resource poor areas.(2) With this backdrop we decided to evaluate the association if any, of ALC as a surrogate marker to CD4 lymphocyte counts.
Methods:
ALC and CD4 lymphocyte counts measurements of 241 patients at our HIV/AIDS referral centre were assessed over a period of 13 months.
Results:
Pearson correlation coefficient, coefficient of determination and standard statistical methods revealed modest linear correlation between ALC and CD4 lymphocyte counts which was statistically significant but did not have clinical significance.
Conclusion:
We recommend that time has come to call curtains down on ALC as a surrogate marker for CD4 lymphocyte count.
