Correspondence

922 www.thelancet.com/infection Vol 14 October 2014

Paul Drain and colleagues1 proposed a standard set of criteria to assess the diagnostic accuracy, clinical effect, and costs of point-of-care (POC) tests in low-income countries (LICs). We agree with the authors on the need to improve access to rapid diagnostics in LICs, and we add several factors based on our own research on POC testing for common infections through our work at the

Point-of-care tests: where is the point?A recurrent theme in the Review by Paul Drain and colleagues1 is the dichotomy between point-of-care (POC) tests and their laboratory counterparts, which implies that these tests can be used outside the laboratory. Certainly, rapid diagnostic tests (RDTs) for malaria are an example of a POC test; however, loop-mediated isothermal amplification (LAMP) for malaria has also been touted as a possible POC test.2,3 This discrepancy raises an important question: where is the point of care? For example, GeneXpert (Cepheid, CA, USA) MTB/RIF needs basic lab oratory infrastructure, shifting the POC from a remote area to a peripheral laboratory.4 By contrast, RDTs allow effi cient diagnosis of malaria at the POC, even in remote communities, far away from laboratories or hospitals. Despite the analytical advantage of nucleic acid-based tests like LAMP, basic laboratory infrastructure is needed, meaning that it cannot be used at the same proximity to the POC as RDTs can.

Authors of one review define the setting where POC tests can be used, ranging from home to community, health post, peripheral laboratory, and fi nally hospital.4 Malaria tests are deemed POC tests in four of these fi ve categories. Oddly, this approach seems to turn almost any existing malaria diagnostic test into a POC test, and the POC into a so-called area of care, which is somehow contradictory in itself. The eff ect of this approach is the infl ationary use of the term POC test because there is little, if any, diff erence to a standard laboratory-based test.

Where or what is the POC for malaria patients, and what defines it? At least, tests would need to have some quantifiable degree of suitability for being a POC test? On the Foundation for Innovative New Diagnostics website,5 LAMP is categorised as a “district and sub-district level” test, whereas the term POC is mentioned in the context of RDTs.

These questions are not mun-dane because the term point-of-care could be no longer useful. The term could even be misused in an attempt to capture increasingly com petitive research funding or could misinform implementation strategies in times of tight budgets. In conclusion, and notwithstanding the many useful suggestions, criteria, and definitions provided, we believe that the otherwise highly valuable review by Drain and colleagues should have addressed this POC (point of consideration) more elaborately.We declare no competing interests.

*Thomas Hänscheid, Maria Rebelo, Martin P Grobuscht.hanscheid@medicina.ulisboa.pt

Instituto de Microbiologia, Faculdade de Medicina de Lisboa, P-1649-028 Lisbon, Portugal (TH); Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisbon, Portugal (MR); and Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands (MPG)

1 Drain PK, Noubary F, Freedberg KA, et al. Diagnostic point-of-care tests in resource limited settings. Lancet Infect Dis 2014; 14: 239–49.

2 Cordray MS, Richards-Kortum RR. Emerging nucleic acid-based tests for point- of-care detection of malaria. Am J Trop Med Hyg 2012; 87: 223–30.

3 Abdul-Ghani R, Al-Mekhlafi AM, Karanis P. Loop-mediated isothermal amplifi cation (LAMP) for malarial parasites of humans: would it come to clinical reality as a point-of-care test? Acta Trop 2012; 122: 233–40.

4 Pai NP, Vadnais C, Denkinger C, Engel N, Pai M. Point-of-care testing for infectious diseases: diversity, complexity, and barriers in low- and middle-income countries. PLoS Med 2012; 9: e1001306.

5 Foundation for innovative new diagnostics. About us. http://www.fi nddiagnostics.org/about (accessed Feb 27, 2014).

Mercy Hospital Research Laboratory in Bo, Sierra Leone.

First, POC tests are already available in some LICs for many infections not listed in panel 1 of the Review, including hepatitis B virus2 and typhoid.3 The cost effectiveness of POC tests improves when test kits for locally common infections can be purchased in bulk, and the positive predictive value associated with high incidence and prevalence could improve assessment of the test’s diagnostic accuracy in LIC settings.

Second, we add to the authors’ comments on the scarcity of research on real-world use of POC tests by calling for further comparisons of laboratory-based with community-based and home-based tests. The effectiveness of POC tests in all three settings—the clinic, community, and home–needs further testing and validation. Reports of POC test studies need to describe environmental factors, such as temperature and storage conditions, that might aff ect the test results, and discuss socioeconomic and educational or literacy challenges that could have an eff ect on test results in all of these venues.

Third, clear eligibility criteria should be included for clinicians, patients, and families who might be considering use of POC tests so that these users will know when use of these tests is appropriate. A high number of valid positive results will improve the perceived value of the tests for future POC use. Additionally, test kits designed for community-based or home-based use should include clear instructions on appropriate treatment for those with both a positive or negative test, who might need to consult with a clinician for additional tests. The goal of testing outside of care centres should be to shorten the time to initiation of appropriate treatment, which might need the results of several diff erent tests, especially if a person with an apparent infection or other illness has a negative result for an infectious disease POC test.