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the microsampling blog

clinical trials: the challenge of subject retention

Clinical trials are an important component of research in drug development and in the advancement toward more modern healthcare. After preclinical research has been completed, it is through clinical trials that medications are tested for safety and efficacy.

Without clinical trials that involve human subjects participating in four critical phases to assess the safety and efficacy of new drugs, it would be challenging to make any medical breakthroughs that are formally approved for safe use in the people they are meant to help.

study subject taking medication in a clinical trial

Every potential new medical treatment must go through several clinical trial phases, and each phase has a specific purpose. The different phases are outlined in an example from the MD Anderson Cancer Center, which shows the process followed to assess new oncology medications.

MD Anderson Cancer Center-Clinical Trial Phases
Image Credit: Phases of Clinical Trial, Courtesy of MD Anderson Cancer Center

Like researchers in other scientific fields, medical and pharmaceutical researchers face clinical trial challenges.

Challenge #1: Getting People to Join Clinical Trials as Study Subjects

Recruitment and retention of people for clinical trials can be very challenging. Several factors lead to poor enrollment of study subjects that should be considered in order to run a successful clinical trial, including:

  • Types of trials not appropriate for the community being recruited – Diversity in clinical trials is good, but there is often a mismatch between the drug on trial and the types of diseases or conditions that are impacting the targeted community or demographic.

  • Insufficient infrastructure support for a community-based clinical trial – Even when trials have an appropriate match between the drug on trial and a community, there can be a lack of sufficient staffing or support to recruit and coordinate study subjects.

  • Overly restrictive eligibility requirements – Potential study subjects have reported that they wanted to volunteer for clinical trials but weren't recruited due to strict requirements. There is a need for broader eligibility criteria in trials to include a more diverse patient population, representative of the patients seen in practice.

  • Financial barriers – Lack of financial coverage via health insurance or financial incentives for trial participation was reported as a barrier to enrollment in some communities. This barrier is even greater if subjects have to take time away from work and travel long distances to a trial site as part of their participation. 

Challenge #2: Retaining People as Study Subjects in Clinical Trials

There are several reasons why subject retention is challenging, including:

  • Communication is key: Most clinical trials have a small population of patients who have the conditions being investigated. Once these study subjects have been found, it can be hard to keep them engaged. One reliable means of retaining subjects in these trials is communicating why the research is important. Once the patients are there, it’s important to let them know everything there is to know (that is reasonable to reveal) about the research. A training session in which the patients meet the scientists they will be working can be appropriate. It helps people understand what is expected of them and why they're doing this.

  • Fear is a factor: There is often a fear of side effects or fear of painful procedures. This can lead to patients dropping out of the research study (clinical trial) early. Fear usually affects patients at the initial stage of the study just before a trial begins. There is a psychological component that can be eased by creating awareness. Information helps put peoples' minds at ease and lets them know what to expect. Once the trial starts, informed patients are less likely to drop out of the study because of uncertainty; they already know what to expect.

    Procedures such as frequent blood draws may cause pain and stress. This could be minimized by using patient-friendly tools that reduce pain and improve the study experience. For example, portable microsampling devices can be used in-clinic or at home to collect blood samples with a quick and easy fingerstick.


    Remote microsampling tools like the Mitra® device or hemaPEN® allow for the collection of micro-sized blood samples – just a few drops from a fingertip. These devices also enable remote sample collection with minimal training which, in turn, enables remote monitoring of subjects. They self-collect their samples at home, mail them to the lab for analysis using standard mail, and their clinical trial team follows up via phone, email or video conference.

  • Changing circumstances: It is difficult to retain patients once a trial has started if the patient’s circumstances change. For example, their family may decide to relocate while the study is underway. An unforeseen distance barrier might make it difficult for a patient to continue participating in the trial, unless there is an option for remote participation that can continue despite a change of location.

Learn how to conduct clinical trials remotely and the benefits of decentralized clinical trials, by visiting our Decentralized Clinical Trials Resource Page:

Explore resources for designing a successful decentralized clinical trial (DCT) with remote microsampling.

Image Credits: MD Anderson Cancer Center, Shutterstock, Trajan Scientific and Medical, Neoteryx

In some territories our devices are supplied for therapeutic or IVD use Outside of those territories our devices are supplied for research use only

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