The Perils of Overly Sensitive Viral Load Testing for Persons With Human Immunodeficiency Virus

Abstract The concept of “undetectable = untransmittable (U = U)” has been revolutionary in both the prevention and treatment of persons with human immunodeficiency virus (HIV). Most studies proving the concept of U = U used an HIV RNA (viral load [VL]) cutoff of 200 copies/mL to define being undetectable. Since then, increasingly sensitive commercial VL assays, sometimes down to a lower limit of detection (LLD) of 20 copies/mL, lead to confusion about the definition of “undetectable” and when someone is truly considered untransmittable. VLs between the LLD and 200 copies/mL have been associated with future virologic failure; however, no data exist to suggest that intervening in those patients leads to any meaningful benefits. In the absence of a demonstrable benefit of reporting such low VLs, we view this practice as harmful. We suggest recommendations for adjusting VL reporting and improving provider counseling, and call for research designs to mitigate the harms of overly sensitive VL testing.


CASE PRESENTATION
A young woman presented to a human immunodeficiency virus (HIV) primary care clinic for the treatment of newly diagnosed HIV infection.She was started on antiretroviral therapy (ART) and was counseled that with time and high adherence, she would achieve an "undetectable" HIV RNA level (viral load [VL]) and would be noninfectious to sexual partners.Over the subsequent 2 years, the patient's VL remained detectable, based on the laboratory's lower limit of detection (LLD) of 20 copies/mL, with measures between 20 and 200 copies/mL and a normal absolute CD4 lymphocyte count.She reported near-perfect adherence, which was confirmed by pharmacy refill records.Her physician explained that a sustained VL of <200 copies/ mL meant that the virus was untransmittable; despite this explanation, she became increasingly frustrated about being unable to achieve an "undetectable" status based on reported laboratory values.She was skeptical about her lack of infectiousness, was dissatisfied with her ART, and was reticent to engage in sexual relationships, which she had avoided since her diagnosis.

THE U = U MOVEMENT
"Undetectable = Untransmittable (U = U)" is the concept that persons with HIV (PWH) with an undetectable VL cannot transmit the virus to sexual partners [1,2].This concept of "treatment as prevention" (TasP) has been endorsed by health authorities across the globe.U = U developed from studies demonstrating a lack of HIV transmission in serodiscordant couples in which the individual with HIV was taking ART.The first study to assess TasP was the HIV Prevention Trials Network Study 052, demonstrating a significant decrease in HIV transmission in patients with early ART initiation [3].
Later observational studies focusing on both same-sex and opposite-sex partners have been essential to the establishment of 200 copies/mL as the lower limit of transmissibility [4].A recent systematic review of the risk of sexual transmission from individuals with low-level viremia found no definitive evidence of HIV transmission when VLs were <600 copies/mL and an incredibly rare occurrence of possible transmissions with VLs between 600 and 1000 copies/mL [4].
Prior to the widespread consensus on U = U and the advent of HIV preexposure prophylaxis, HIV prevention in serodiscordant sexual partners relied upon counseling, frequent HIV testing, and emphasis on reduction of "risky behaviors" [5].These older approaches to prevention were less effective and promoted the idea that sex with PWH was fundamentally more dangerous than with individuals without HIV.The development of TasP and U = U was novel in its understanding of HIV transmissibility, encouraging demand for increased HIV testing and early initiation of treatment [6].Educating patients on U = U is associated with positive health outcomes, including improved perception of sexual and mental Overly-Sensitive HIV Viral Loads • OFID • 1 Open Forum Infectious Diseases health and improved medication adherence [7][8][9].Studies focusing on sexual minority men, a population disproportionately impacted by HIV, showed that PWH feel more comfortable about their HIV diagnosis when counseled in the context of U = U [10].

OVERLY SENSITIVE VIRAL LOAD TESTING CHALLENGES
The definition of an undetectable VL has evolved over the years as clinical laboratory detection of HIV has advanced.Increasingly sensitive VL testing will inevitably lead to more PWH being labeled as "detectable," when defined as "above the LLD of the assay" or even when the VL is below the LLD but still present and reported as detectable.Many commercial laboratories now detect as few as 20 viral copies/mL depending on which polymerase chain reaction (PCR) assay is used (Table 1).For patients, seeing a detectable VL reported but being told they are untransmittable sows confusion and may challenge beliefs in the otherwise clear U = U message, as it did in this patient case.
Persistent HIV RNA level ≥200 copies/mL, and especially >500 copies/mL, has been associated with evidence of viral evolution and accumulation of drug resistance mutations [11,12].Patients who have a persistent HIV RNA level ≥200 copies/mL are considered to be experiencing virologic failure.The goal of ART is to suppress HIV replication as much as possible to a level below which drug resistance mutations cannot emerge.To date, there are no clear data indicating that a VL between the LLD and 200 copies/mL is clinically relevant in portending negative outcomes such as CD4 T-cell decline, cardiovascular disease, malignancy, or immunologic conditions associated with HIV infection.The main identified risk of low-level viremia (LLV, variably defined as 20-200 copies/mL on ≥2 occasions) is an association with future virologic failure [13,14].It is also important to consider that VL assays lose precision at lower values of HIV RNA, potentially contributing to the observation of values that are continuously above the LLD [15,16].Yet it has not been established that identification of LLV or virological blips (single instances of detectable VLs <200 copies/mL) lead to actions that successfully prevent future virologic failure.Although LLV is associated with future virologic failure, in absolute terms, most virologic failures (>70%) actually occur among those without preceding LLV [13,17].
Because VLs deemed detectable but <200 copies/mL have not demonstrated meaningful clinical implications, and have the potential to cause confusion and mistrust among patients and providers alike, we consider reporting these values to be a harmful medical practice with a negative public health message.

NEXT STEPS FOR VIRAL LOAD REPORTING
The simplest approach to mitigating the harms of overly sensitive VL reporting lies in innovations in clinical laboratory reporting and electronic health record (EHR) display of results to patients and providers (Figure 1).One possibility is for laboratories and EHRs to continue reporting quantitative VLs with the addition of interpretation of the potential for sexual transmission.Physicians would know a patient's exact VL, but patients would have the benefit of a laboratory interpretation of "no risk of sexual transmission" if a VL is <200 copies/ mL.Alternatively, all VLs <200 copies/ mL could be automatically reported as undetectable, with the precise value hidden but available to providers to disclose with further explanation if needed.This change would also allow for consistency in reporting between different laboratory assays and between different institutions.
Providers should adjust patient education and counseling to preempt confusion about U = U and detectable VLs  <200 copies/mL.One approach is to spend extra time ensuring that the term undetectable is equated specifically to a VL <200 copies/mL rather than looking for the words "not detected" or a "<" symbol in laboratory results.Another option is to focus on the number 200 as being an important number to remember for PWH to understand the status of their HIV.Patients can be counseled that "our goal for treatment is a VL less than 200 and CD4 count above 200."Finally, we call for further research into the value of patient and provider awareness of VL values between the LLD and 200 copies/mL.Studies facilitated through the EHR could randomize patients to having quantitative values between the LLD and 200 copies/mL displayed in their results compared to having all values <200 copies/mL hidden and reported only as "undetectable" or "<200."The outcomes of interest would be to investigate if either approach is associated with a lower incidence of virologic failure and differences in quality of life or perceived health status.Additionally, studies evaluating adherence support programs might evaluate if the magnitude of benefit is higher for preventing virologic failure among those with LLV compared to those who have VLs less than the LLD.

CONCLUSIONS
The establishment of U = U and the evidence showing near-zero risk of sexual transmission even with LLV has been transformative and empowering for PWH.It also provides an opportunity to destigmatize PWH and promote adherence to ART through dissemination of this positive public health message.Testing and reporting of VL values between the LLD and 200 copies/mL have the potential to sow confusion and further stigma in the absence of evidence that this information is clinically useful or actionable.We advocate for alternative approaches to reporting VL values, suggest adjusting patient counseling to clarify the definition of undetectable, and call for pragmatic research to determine the value-or harm-of highly precise VL reporting.

Notes
Author contributions.M. G. R. and A. S. were both third-year medical students at the time of drafting this manuscript.They conceptualized the article and performed writing of the original draft and writing-reviewing and editing of the final article.D. P. S. and A. E. R. helped conceptualize the article and edited the manuscript drafts.
Patient consent.The case presented above is a fictitious case; therefore, no patient consent is required.
Potential conflicts of interest.The authors: No reported conflicts of interest.