Optimal Timing of Repeat Multiplex Molecular Testing for Respiratory Viruses.

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Laboratory Medicine

Background:

• Multiplex nucleic acid amplification tests (NAATs) are crucial for diagnosing respiratory viruses.
• Determining optimal timing for repeat testing is challenging, impacting resource allocation and patient care.

Purpose of the Study:

• To analyze repeat multiplex NAAT results for respiratory viruses within 90 days.
• To identify the time window for significant changes in test results.
• To inform laboratory stewardship practices regarding respiratory viral testing.

Main Methods:

• Analysis of 5 years of multiplex NAAT results for 14 respiratory viruses.
• Inclusion of repeat nasopharyngeal specimens tested within 90 days of initial testing.
• Logistic regression to compare odds of result change across different repeat testing intervals.

Main Results:

• 12% of specimens were repeat tests within 90 days; 71% showed no result change.
• Initially positive results remained positive for 11-15 days; negative results generally stayed negative.
• Odds of result change plateaued after 20 days, with significantly lower odds for repeats within 20 days.

Conclusions:

• Repeat multiplex NAATs within 20 days often yield redundant results, increasing costs.
• Evidence supports limiting repeat respiratory viral testing to before 20 days to avoid unnecessary procedures.
• Findings provide a basis for laboratory stewardship to reduce unwarranted respiratory viral testing.