Evaluation of the Nigeria national HIV rapid testing algorithm

Area of Science:

• Public Health
• Infectious Diseases
• Diagnostic Accuracy

Background:

• Accurate Human Immunodeficiency Virus (HIV) diagnosis is critical for initiating care and treatment.
• Changes in HIV prevalence and testing coverage necessitate evaluation of national HIV testing algorithms.
• False positivity in low-prevalence settings can negatively impact clients and healthcare services.

Purpose of the Study:

• To evaluate the performance of Nigeria's national HIV rapid testing algorithm.
• To compare algorithm performance across different HIV prevalence levels in Nigeria's six geopolitical zones.
• To assess the algorithm's accuracy in both field and reference laboratory settings.

Main Methods:

• A dual retrospective and prospective study design was employed.
• Retrospective analysis involved program data from 492,880 routine HIV testing service (HTS) attendees (2017-2019).
• Prospective evaluation used 2,895 field samples tested via the national serial algorithm, re-tested at the National Reference Laboratory (NRL) with supplementary assays (Geenius, multiplex).

Main Results:

• The overall HIV positivity rate was 5.7% (28,319/492,880) retrospectively, with a 1.1% discordant rate between initial tests.
• Prospective testing showed no significant difference between field and NRL results using the national algorithm.
• Agreement with supplementary assays was high: 95.2% (field) and 99.3% (NRL) with Geenius; 96.6% sensitivity/98.2% specificity (field) and 99.2% sensitivity/99.4% specificity (NRL) with multiplex assay.

Conclusions:

• The Nigerian national serial HIV rapid testing algorithm demonstrates good performance across various settings.
• Field performance was slightly lower than NRL performance, indicating a need for quality improvement.
• Targeted training and continuous quality improvement for field testers are recommended to enhance diagnostic accuracy.