Direct-to-consumer testing – benefits for consumers, people with disease and public health

Introduction

A direct-to-consumer (DTC) test can be defined as any in-vitro diagnostic (IVD) test or, more broadly, any medical test using an IVD or medical device, that is marketed directly to consumers without involvement of a health care provider (HCP). Expanding the definition beyond IVD tests and including medical devices is useful for three reasons: 1. The opportunities and challenges are very similar in both cases. 2. Some medical devices such as continuous glucose monitoring (CGM) systems are classified as medical devices; however, they measure a substance, like IVD tests. 3. Many medical devices have been used successfully for diagnostic measurements in the form of DTC tests for a very long time. DTC tests can either mean that people obtain the test or device and perform the test by themselves (self-testing) or obtain a kit for collecting a sample (blood, throat swab, etc.) and send the sample to a qualified laboratory (self-sampling). The latter is typical for genetic testing. Classical examples of DTC are listed in Table 1.

In many cases, it is preferable that diagnostic testing is initiated and controlled by HCP to assure appropriate indication, execution, quality control, and interpretation of the test results. Unnecessary DTC testing should be avoided. Whether a test is a DTC test also depends on the county or market in which it is used: While in countries with sufficient healthcare resources many diagnostic tests are typically performed by HCP, in countries with limited resources, access to HCP is often limited and DTC testing is a means to expand access to healthcare.

While laboratory professionals often look critically at DTC tests and focus on challenges and problems associated with them, it is worthwhile to take a complementary perspective and ask what their benefits are. Their sheer existence and the demand from customers to perform DTC tests make it obvious that they fulfill a multitude of customer needs. There are many valid reasons why people want DTC tests (Table 2) that can be classified as follows (with many DTC tests falling into more than one category).

Making rapid decisions

Examples are: SARS-CoV-2 antigen test, hormone test identifying fertile days (ovulation predictor kit), alcohol test, INR test, glucose self-monitoring for insulin dosing, taking the temperature.

The COVID-19 pandemic is a good example for the successful use of DTC tests. It has been demonstrated that the vast majority of people are able to correctly perform rapid antigen tests (lateral flow tests) to determine whether they are positive for SARS-CoV-2 [1]. Without this testing, much tighter preventive restrictions regarding mobility and access would have been required and many people with disease would have been identified later or too late. While government and health authorities have defined rules as to when testing is mandatory, many people used SARS-CoV-2 antigen tests on their own initiative to protect themselves and others. Management of the pandemic would have been much more difficult without the availability of these tests.

Women who plan to become pregnant have a vested interest to know their fertile days in order to increase the likelihood of success. The World Health Organization (WHO) recommends that home-based ovulation predictor kits (OPK) should be made available as an additional approach to fertility management for individuals attempting to become pregnant [2]. In addition, women who don’t want or cannot use contraceptive means and want to avoid pregnancy also benefit from this DTC test.

Drunk driving has a high death toll in many countries. While recommendations on drinking and driving exist and no drinking would certainly be the optimal solution, many people use inexact rules of thumb to estimate their blood alcohol concentration. Alcohol rapid tests based on breathing air alcohol content provide a better decision criterion. In France, restaurants, clubs and stores selling alcohol are required by law to provide alcohol rapid tests for sale [3, 4].

INR tests for people on anticoagulating medications such as marcumar or warfarin have been successful for a long time. Randomized controlled trials demonstrate that people adjusting their dose by self-management based on INR self-test results showed significant reduction of thromboembolic events and all-cause mortality [5].

Taking the temperature to decide upon self-treatment vs. seeking professional help is an experience that virtually everyone has had.

For glucose monitoring in insulin-dependent diabetes see separate section below.

Monitoring chronic conditions between HCP visits

Examples are: glucose monitoring, blood pressure monitoring.

Typically, people with chronic disease see their treating healthcare provider a few times per year. Fixed intervals between visits are typically recommended. However, the medical condition might improve or worsen between visits. In addition, diagnostic measurements obtained during visits might not be representative for the course or state of the disease. Technologies such as self-monitoring of blood glucose (SMBG) or blood pressure support HCP to get a more comprehensive picture of the state of disease. However, self-monitoring of blood pressure seems to have little impact on medication adherence [6].

SMBG using capillary blood samples is beneficial not only for people with insulin-dependent diabetes (see below) but also non-insulin dependent diabetes [7], provided it is done in the form of ‘structured testing’, e.g. a 7-point profile on 3 consecutive days or in similar ways, between HCP visits. Structured testing reduces hemoglobin A_1c [8], most likely since HCP provided with structured testing data perform more therapy changes [9]. International guidelines recommend structured testing [10] and variants such as the concept of ‘testing in pairs’ (before/after meals or exercise) which provides feedback to people with disease on how lifestyle changes can improve glucose control. Apps that provide easy to understand graphic representation of the data and statistics and allow upload of the data to the cloud for easy sharing with HCP are an integrated part of many SMBG systems.

Saving time and travel and reducing HCP visits

Examples are: INR test, SARS-CoV-2 antigen test.

People with disease that are typically summoned for INR testing in clinics every 2–4 weeks can avoid time, travel and associated cost by performing DTC tests with satisfactory concordance of the results to results obtained by HCP with the same test or with a laboratory analyzer [11].

Instead of queuing up for SARS-CoV-2 antigen tests (during the pandemic often free of charge), people often prefer self-paid DTC tests (as long as no official certificate is required) which can be performed 24/7.

Screening for disease when no symptoms are present

Examples are: occult blood, cholesterol, triglycerides, SARS-CoV2 antigen test.

The purpose is not to replace HCP visits but to detect conditions early. DTC testing and HCP visits can complement each other.

Maintaining privacy

Examples are: pregnancy test, HIV test, HPV test, certain genetic tests.

Women often are interested to know about being pregnant earlier than anybody else in order to prepare for potential difficulties or conflicts. People being HIV positive might fear stigma or social pressure and need time to reflect the next steps to be taken. Self-testing is highly valued, especially among individuals who were not open about their sexual behaviors with men [12, 13]. A meta-analysis of randomized controlled trials showed that HIV self-testing increased the uptake of HIV testing by 1.43 times compared to standard of care, increased the mean number of HIV tests by 2.34 during follow-up, doubled the detection of new HIV infections among those tested, and reported higher repeat testing as compared to the control arm [14]. In 2016, the WHO recommended HIV self-testing (HIVST) as a safe, accurate and effective way to reach people who may not test otherwise and as an empowering and innovative strategy and an additional testing approach to attain the United Nations treatment targets [15].

An example of self-sampling are HPV tests. HPV self-sampling has also been shown to increase uptake of cervical cancer screening in systematic reviews and meta-analyses as well as being highly acceptable by users [16, 17]. Most women preferred home-based self-sampling vs. sampling at a clinic, quoting as reasons privacy and less embarrassment or anxiety [18].

Similar privacy aspects apply to people who want to find out about certain genetic conditions.

Glucose self-monitoring in insulin-dependent diabetes as an example for successful DTC tests

During the 1980s, the concept of SMBG with test strips for home use became standard of care in particular for people with type 1 diabetes to improve glycemic control [19]. Insulin regimes have become more flexible over time, developing from fixed insulin combinations twice or three times daily to multiple daily injections, trying to better mimic physiological insulin levels during the course of the day. Each injection requires a calculation of the appropriate insulin bolus, depending on the insulin sensitivity of the person, the amount of carbohydrates consumed with meals, and the current glucose concentration. Automated bolus calculators as part of SMBG systems are standard today. Around 2004, the first commercial continuous glucose monitoring (CGM) systems for self-monitoring were introduced [19], measuring glucose with a sensor in the interstitial fluid. While any SMBG test provides only a snapshot of the actual glucose concentration, CGM systems typically provide a value every few minutes, display trends, send alarms when glucose thresholds are crossed and even predictive alarms when thresholds are approached. SMBG and CGM have been shown in randomized controlled trials to reduce potentially life-threatening hypo- and hyperglycemia, reduce glucose variability and hemoglobin A_1c [20], and increase the ‘time in range’, a newly introduced concept of glycemic control [21]. Glucose self-monitoring has completely changed diabetes management and offers a self-empowered approach to people with disease. Replacing insulin pens with insulin pumps and developing algorithms allowing CGM systems to steer insulin pumps (semi-closed loop, closed loop) resulted in further clinical improvements [22]. Automated connection to the cloud for data sharing and smart and intuitive display of data allows HCP together with people with disease to identify and solve problems. SMBG and CGM are perfect examples how DTC testing has improved care. People with type 1 diabetes see their treating HCP few times a year and are completely self-contained regarding their diabetes management >99% of the time.

Further arguments for DTC testing

The ageing of the population in many countries is associated with an increase of particularly chronic diseases such as diabetes, hypertension, cardiovascular and kidney disease, rheumatoid diseases and cancer. E.g., the number of people with diabetes world-wide was 537 million in 2021 and is expected to rise to 783 million in 2045 [23]. At the same time, with baby boomers retiring, HCP positions often cannot be refilled. Further, healthcare systems are frequently not prepared for extra spending. Even with the current spending, small hospitals may not survive, driving further the centralization of health care hubs. As a consequence, home testing using DTC tests can partly alleviate the constraints associated with these conditions. Self-empowerment of people with chronic disease will be a necessity in the future to cope with the challenges of healthcare systems. People with disease can monitor their conditions in a self-dependent manner and request additional healthcare resources only when necessary. In many countries, people have to pay for HCP visits. Here DTC testing can help to reduce cost. Some people who are afraid of HCP visits (iatrophobia) appreciate that DTC testing can reduce consultations.

In low and middle-income countries (LMIC), people often have limited access to healthcare resources, i.e. distances to medical services are long and the services often expensive. On the diagnostic side, DTC tests can also alleviate these constraints. Collecting samples in communities can be an efficient way to manage sexually transmitted diseases. Therefore, WHO recommends self-sampling for sexually transmitted agents such as Neisseria gonorrhoeae, Chlamydia trachomatis, Treponema pallidum, and Trichomonas vaginalis [2]. Further, WHO recommends that HPV self-sampling (HPVSS) should be made available as an additional approach to sampling in cervical cancer screening services for individuals aged 30–60 years [2].

In unexpected situations such as the rapidly developing COVID-19 pandemic, health care services are temporarily overstrained and cannot provide the required diagnostic capacities fast enough. DTC tests can contribute to managing such situations better.

Questionable concerns about DCT tests

Despite all the benefits and opportunities that DTC testing can provide, HCP are often skeptical about DTC tests and concerned that people with disease are unable to correctly deal with them. The following concerns about DTC testing are sometimes raised:

1. People with disease are not able to perform tests correctly.

2. People with disease cannot interpret test results correctly.

3. People with disease don’t understand the consequences of test results.

4. Results for tests such as HIV tests require immediate support by HCP.

5. Physicians are losing control over patients.

6. Self-testing delays consultations and prevents early treatment.

These concerns might apply in individual cases but there is no proof that they are valid in general [14, 24]. Again, SARS-CoV-2 antigen tests provide a good example that most people have quickly learned how to perform them and how to interpret the results.

Valid concerns about DTC and how to address them

Of course, DTC tests need to fulfill what they claim. In particular, DTC tests need to be safe and effective, performance with lay users needs to be demonstrated, and they must fulfill certain performance criteria (e.g. traceability, accuracy), laid down e.g. in regulations, clinical guidelines, or international standards such as ISO standards. SARS-CoV-2 antigen tests are an example that this does not always apply [25].

Concerns include that some DTC tests are difficult to perform or interpret, some have been reported not have the medically required performance, in particular accuracy, diagnostic sensitivity, diagnostic specificity, positive and negative predictive value, which may lead to delayed, missed or unnecessary treatment, and may generate additional healthcare cost. Some DTC tests seem to over-promise on the claimed medical benefit or seem to intend to advocate additional purchases (e.g. nutritional supplements). The risks of DCT testing have been reviewed elsewhere [26].

While it is necessary to describe, address and resolve these issues as effectively as possible, this though should not detract from the advantages DTC tests can provide. HCP and in particular professional societies should collaborate with regulators, authorities and industry in identifying issues and helping to resolve them.

Educating about DTC testing

Like for many aspects of healthcare, education of the public through mass media and social media is a good – and perhaps the quickest – way to help people to correctly perform DTC tests, how to correctly interpret the results, and how to distinguish between useful and not useful DTC tests. HCP should play an important role in this effort and try to gain greater visibility.

A study has shown that explaining the concept of SARS-CoV-2 self-testing, providing an educational video and even a training session are beneficial for encouraging regular self-testing [27].

The U.S. Food & Drug Administration (FDA) provides comprehensive information about DTC testing for the public, in particular on genetic tests, on its website [28].

The British Medical Journal (BMJ) has addressed the topic of DTC genetic tests in its BMJ Talk Medicine podcast for the general public, accompanied by an educational article [29].

Another positive example has been provided by the German industry-independent consumer protection organization Stiftung Warentest: On its website [30] it lists the diagnostic sensitivity and specificity of 90 CE-marked SARS-CoV 2 self-tests, based on data obtained from the German Paul Ehrlich Institute (PEI) and the German Federal Institute for Drugs and Medical Devices (BfArM). The information is supplemented by an explanatory video. Likewise, Stiftung Warentest tests e.g. blood pressure monitors, blood glucose meters, and other devices. The fact that these devices are tested by a consumer protection organization also reflects that the public has a high interest in these devices.

Conclusions

In certain conditions, many people prefer DTC testing over testing performed by HCP. Reasons include rapid decision-making, monitoring chronic conditions between consultations, screening for disease when no symptoms are present, saving time and reducing consultations, or maintaining privacy. Chronic diseases such as diabetes require patients to be empowered for self-management. In LMCI, DTC can enhance access to care. Valid concerns about DTC testing need to be resolved with the help of authorities, regulators and industry in collaboration with HCP. HCP should play a more prominent role in educating the public through mass media and social media on the proper use of DTC tests and help to pinpoint problem areas.