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[Correlation and concordance of three HIV viral load techniques available in Colombia]
Patricia Olaya1, Carlos A DíazGranados
1Centro de Análisis Molecular, Bogotá, D.C., Colombia. patolaya@etb.net.co
Insights
Three Human Immunodeficiency Virus (HIV) quantitation technologies show high correlation and concordance. However, observed variability necessitates using the same HIV testing method for serial patient monitoring to ensure accurate clinical decisions.
Area of Science:
- Virology
- Clinical Diagnostics
- Public Health
Background:
- Accurate Human Immunodeficiency Virus (HIV) viral load quantitation is crucial for patient management and treatment monitoring.
- Colombia has several commercially available HIV testing technologies, but their comparative performance in the local context is not well-established.
Purpose of the Study:
- To evaluate and compare the performance of three distinct Human Immunodeficiency Virus (HIV) quantitation technologies available in Colombia.
- Assess the correlation and concordance among different HIV viral load assays.
Main Methods:
- Convenience sampling of HIV-positive patient specimens from various regions in Colombia.
- Quantitation of HIV viral load using three methods: Versant bDNA 3.0 (Bayer), LCx HIV (Abbott), and Amplicor Monitor v1.5 (Roche).
- Statistical analysis including linear regression for correlation and kappa statistics for concordance, alongside discordance analysis at clinical cut-off points.
Main Results:
- All three HIV quantitation techniques demonstrated high correlation (R2 > 0.97) and substantial concordance (kappa > 0.7).
- Despite high correlation, considerable discordance was observed at clinically significant cut-off points (8.8%-15.6%) and for differences exceeding 0.5 logs (19.6%-36.3%).
Conclusions:
- The evaluated Human Immunodeficiency Virus (HIV) viral load quantitation technologies are generally adequate, exhibiting strong correlation and concordance.
- Due to observed variability, it is recommended to consistently use the same HIV testing methodology for serial measurements in clinical decision-making to avoid misinterpretation of results.
Objective:
To compare the performance of three available technologies for Human Immunodeficiency Virus quantitation in Colombia.
Methods:
Samples from different areas of the Country were selected by convenience and underwent Human Immunodeficiency Virus quantitation using three methods: Versant bDNA 3.0 (Bayer), LCx HIV (Abbott) and Amplicor Monitor v1.5 (Roche). All samples were processed at the Centro de Análisis Molecular in Bogotá, Colombia. Results obtained with the three techniques were compared using linear regression. Additionally, the concordance between techniques was assessed calculating the unweighted kappa, the frequency of discordance according to cut-off points of clinical importance, and the frequency of differences exceeding 0.5 logs.
Results:
The correlation between techniques was highly significant, with an R2 higher than 0.97. The concordance was substantial, with unweighted kappas above 0.7. Nevertheless, the frequency of discordance for cut-off points of clinical importance and the frequency of differences exceeding 0.5 logs were considerable (8.8%-15.6% and 19.6%-36.3% respectively).
Conclusion:
The three technologies for quantitation of viral load are adequate with high levels of correlation and concordance. However, because of the observed variability we recommend comparing a reading from one technique with another reading from the same technique when incorporating the results into clinical decision making.
