Science of Patient Input (SPI): Part one


 The first of three, in a series about the science of patient input.

It is tempting to think of the ultimate goal of healthcare as solving a health problem, curing a disease, or saving a life.  But at its root, healthcare is simply intended to improve a patient’s quality of life in some meaningful way.  Most of the time these goals overlap, but it is a big assumption to believe that all patients have the same priorities or expectations with regard to management of their health conditions.  Details about the specific health conditions, prognoses, treatment availability, cost, and patients’ social cultures all factor in their preferences.  So when designing and evaluating medical devices, what better guide to use than patients themselves?

At first blush, it is difficult to imagine how a typical patient could provide meaningful technical input, when most are not engineers or research experts or scientists, but no one has a better understanding of outcomes of import, or desired functionality and use characteristics (in cases where the patient is also the end user).  Patients can certainly provide useful feedback on device development regarding unmet needs, likes and dislikes of current products, inconveniences, and impracticalities under real-world circumstances.  Patient attitudes toward use of the product can provide valuable insight into its eventual market adoption.  Patients can explain which clinical outcomes matter most to them or even what amount of change would constitute a significant improvement for them.  Most importantly, patients can help us understand the level of risk they are willing to accept in order for a chance at achieving those desired outcomes.

Clinical trial sponsors may use those patient-determined thresholds for significant improvement and acceptable risks to create hypotheses and endpoints to use in trials evaluating medical devices.  FDA has stated a willingness to consider such patient preference data when evaluating the safety and effectiveness of a product under review for marketing approval.  In June 2018, FDA released a draft guidance on the topic, “Patient-Focused Drug Development: Collecting Comprehensive and Representative Input Guidance for Industry, Food and Drug Administration Staff, and Other Stakeholders.”  The title of the guidance specifies “drug development”, but the introduction clarifies that the guidance applies to medical product development, which it defines as “a drug, biological product, or medical device.”  The information may be used “for medical product development and regulatory decision making.”  This guidance is intended as the first in a series from FDA to provide recommendations and tools for collecting patient experience data.  For further information, FDA has previously provided two other associated guidances, “Patient-Reported Outcome Measures: Use in Medical Product Development to Support Labeling Claims” and “Patient Preference Information – Voluntary Submission, Review in Premarket Approval Applications, Humanitarian Device Exemptions, and De Novo Requests, and Inclusion in Decision Summaries and Device Labeling”.  Outside of FDA, valuable tools and best-practices recommendations for patient engagement are also available in materials from other groups such as Clinical Trials Transformation Initiative (CTTI) and Patient-Centered Outcomes Research Institute (PCORI) who offer them for free on their respective websites.

Please check back for additional posts describing the potential uses of patient preference information in designing more efficient clinical trials that are more likely to be successful and thus could save companies significant time and resources.

If you have any questions about how to design more efficient, cost-effective clinical trials, please call us at 855.463.1633 or visit our website

Developing Inclusion/Exclusion Criteria for Clinical Trials


There is frequently confusion about what items should be listed as inclusion criteria and what should be listed under exclusion criteria for clinical studies.  I offer the following concept for consideration.

Inclusion criteria should identify the patient population for which the treatment is intended.  Therefore, the inclusion criteria can be derived from the “intended use” or “indications for use” for the device.  A patient may be eligible for a clinical trial because s/he has some specific likelihood of benefiting from the treatment.  This has nothing to do with signing informed consent, or having the right sized vessels, or willingness to return for follow-up procedures.

Exclusion criteria are used to circumscribe a more homogeneous population to help reduce variability to make it possible to identify differences between treatments if they are really there, and to help weed out patients who are unlikely to complete the protocol.  Therefore, one might exclude patients with concomitant disease which could confound results; or patients of certain age (e.g., to exclude or include pediatric patients); or patients for whom the device is not appropriately sized.

For example, willingness to return for follow-up is necessary for being in a study, but it is not sufficient.  The patient must also have the indication for the specific treatment.  We don’t stent all patients just because they are willing to return for follow-up, or because they are over 18; they must also have a need for treatment. However, if a patient is unwilling to return, they must be excluded from the study.  Or, a patient may have exactly the right indication to be treated with the device under study, but if there is no size of the device that is appropriate for the patient’s anatomy, that patient must be excluded.

In short, if a patient has the indication for the treatment, s/he may be included in the study.  If the patient has any of the exclusion criteria, s/he must be excluded from the study. To state it another way, an inclusion criterion is sufficient all by itself for a patient to be treated with the device (i.e., the patient has the condition for which the device is indicated).  Conversely, the inverse of the inclusion criterion is sufficient to exclude the patient.  In contrast, while an exclusion criterion is sufficient all by itself to exclude a patient from the study, its inverse is not sufficient to include a patient.  For example, if subjects under the age of 18 are being excluded from the study, it is not also true that all people over the age of 18 are eligible to be enrolled in the study.

To learn more about MED Institute’s Clinical Trial services, please visit or contact us at

Honoring Ours and Serving Others

On August 31st, Med Institute celebrated another year of honoring employees at the annual awards banquet. The celebration was held at the Lafayette Country Club and began with a warm welcome followed by dinner, awards, and a presentation from a local nonprofit, Meals on Wheels. Several special guests from Cook Group were in attendance, including Steve Ferguson, Chairman of the Board for Cook Group, who presented an award to Neal Fearnot, President of MED Institute, for 35+ years of dedicated service to Cook.

Steve Ferguson, Chairman of the Board for Cook Group (left), presents a service award to Neal Fearnot, President of MED Institute and Cook Advanced Technologies (right).

In his 35+ years with Cook, Neal has served as the founding president of three Cook companies, each focused on bringing new products to patients. Ever true to his original commitment to Bill Cook, he has worked tirelessly in support of Cook Group and its mission. In 1983, he founded MED Institute to translate research from universities into products serving patients.  MED Institute spawned other companies, such as Cook Biotech and Cook Research, and currently provides product development services in a new outreach to external clients as well as Cook.   In 1995, Neal became the first president of Cook Biotech, licensing the SIS technology from Purdue University and embarking on a quest to serve patients through this novel regenerative biotechnology.  In 2009, he founded Muffin Incorporated, later called Cook Advanced Technologies, whose assignment is to evaluate cutting-edge technologies and to support Cook’s development of major technologies.  Neal currently leads Cook Advanced Technologies and MED Institute.  Despite the lengthy list of accomplishments and awards on his CV, Neal’s greatest contribution to Cook is his investment in people.  His heart for mentoring is reflected in the many people all around Cook Group in whom he has invested his time and wisdom, focusing on building next generation leaders.  Congratulations to Neal on this remarkable milestone!


Clinical Trials for Medical Device Innovators Part V: Important Points


The fifth and final, in a blog series about clinical trials for medical device innovators. Read part I: Designing Clinical Trials, part II: Regulatory Considerations for Clinical Studies, part III: Managing Clinical Trials, and part IV: Cost Drivers for Clinical Trials, here.

The development of a new medical device is both an exciting and rewarding time, but the ensuing process can be the most exhausting, frustrating, expensive, and time-consuming part of the entire process. To conclude the Clinical Trials for Medical Device Innovators series, we would like to leave you with a few important points as you move your product through the medical device lifecycle:

  • A clinical feasibility study may be needed when only formal testing in humans can provide the evidence that the device offers the expected benefit (Proof of Concept); you will need data about the therapeutic effect before designing a larger pivotal study (or if you plan to sell the device, for the company planning to purchase your device before closing close the deal.)
  • Clinical trials are grouped into two basic varieties: significant risk (SR) studies and nonsignificant risk (NSR) studies; all SR studies require an IDE (investigational device exemption), while NSR studies only require IRB approval.
  • If an IDE is necessary, an IDE Early Feasibility Study offers evidence of the amount of nonclinical testing required to support the IDE; the alternative is a traditional IDE which requires all nonclinical testing (bench and animal) to be completed prior to applying for an IDE.
  • If you want to complete development of the device and obtain regulatory approval, meet with the appropriate authorities of the FDA to discuss your plans and obtain their advice. This presubmission or pre-IDE meeting helps determine what nonclinical testing the FDA will require, the endpoints and follow-up for the clinical study, and agreement of the design of your proposed clinical protocol, but you need to be fully prepared!
  • Unless you are an experienced clinical trialist, do not try to manage a clinical trial yourself-hire a contract research organization (CRO) to manage the trial and one or more seasoned regulatory affairs professionals.
  • Conducting a clinical trial entails many important concepts, some of which include: the number of patients needed, number of sites for the trial, a contract with each site, local IRB (Institutional Review Board) review and approval, a plan for interim monitoring visits, a Clinical Events Committee, a Data Safety Monitoring Board, and possibly a core laboratory.
  • You may need an experienced biostatistician with particular expertise in the analysis of complex study designs.
  • All this is expensive! Be prepared for the costs included, not only for the trial (the most expensive part), but also if needed, a 510(k) application ($4690) and a premarket approval application (PMA) for a Class III device ($234,495).

MED Institute can help guide your product through the medical device lifecycle. For more information, please visit our website at

This concludes our series on Clinical Trials for Medical Device Innovators. Please continue to follow our blog for more interesting topics.

Clinical Trials for Medical Device Innovators Part IV: Cost Drivers for Clinical Trials

clinical-blog-2The fourth, in a blog series about clinical trials for medical device innovators. Read part I: Designing Clinical Trials, part II: Regulatory Considerations for Clinical Studies, and Part III: Managing Clinical Trials, here.

There is no denying that clinical trials are expensive propositions. There is little economy of scale; by and large, big pivotal trials cost proportionally more than small studies. The best thing one can do is design the study well to collect only the most relevant data, size it properly based on solid statistical grounds, select investigative sites judiciously to provide sufficient numbers of subjects, and manage the trial efficiently. These actions will not make a study inexpensive, but emphasis on consistency and paying strict attention to all the details will help minimize the cost. The cost drivers for clinical studies are numerous, vary between studies, and are certainly subject to change over time. Rather than attempt to attach a current monetary value to each cost driver, it may be as valuable to provide a list of these drivers so that you, as the study sponsor, understand what estimates you will need to price the study. The following is a list of items that must be considered when estimating the cost of a clinical trial:

  • Starting up one investigative site:
    • Contract costs
    • IRB review (at each site or single central IRB?)
    • Site screening visit (if necessary)
    • Site initiation visit
    • Initial device inventory
  • Data management:
    • Creation of a database
    • Creation of a data collection system [typically electronic data collection (EDC)]
    • Training site personnel on data entry
  • Data collection:
    • Reimbursements to site for completed data forms (typically at patient screening, procedure, and follow-up; priced per form completed)
    • Reimbursement to site for tests and procedures that are not “standard of care” for the disease entity or procedure compensation to patients for travel and parking if nontrivial
    • Data review and queries
  • Project management:
    • Monitoring visits (interim visits [how many?], final closeout visit)
    • Establish or contract with a Clinical Events Committee (if needed)
    • How many meetings over course of study?
    • Establish or contract with a Data Safety Monitoring Board (if needed)
    • How many meetings over course of study?
    • Contract with core laboratories, for example, imaging (if needed)
    • Final data analysis (statistician) and preparation of the manuscript

Regulatory costs for conducting clinical studies are minimal. You may have the cost of a meeting with FDA if you decide to have a pre-IDE meeting; however, these meetings can be held by teleconference. There is no fee to submit the IDE application itself. The primary regulatory costs come when applying for market approval. If your device requires a 510(k) application, the fee is $4690 (USD 2017). For a premarket approval application (PMA) for a Class III device, the fee is $234,495 (USD 2017). If you qualify as a small business, the 2017 application fees for a 510(k) and PMA are $2345 and $58,624, respectively.

Small businesses with an approved small business designation are eligible to have the fee waived on their first PMA.

Clinical trials are exciting, exhausting, and expensive. As an innovator of a new medical device, you need to decide what role you want to play in the life cycle of your device (concept to commercialization). Do you want to give it up for adoption (sell the IP early), or do you want to try to raise it to adulthood (obtain full regulatory approval to market), or do you want to participate in something in between? That answer will help you decide if you need to conduct a clinical study on your device and if so, the type of study. Do not go into a clinical study lightly! You have an obligation to your subjects/patients to run the best possible study. They deserve to have their contribution count. Regulatory authorities demand accurate, truthful, and complete data. You must demand the same. After all, it is your reputation and that of your device on the line.

For more information, please visit our website at

Continue to follow our blog to view the upcoming Part V: Important Points.

Clinical Trials for Medical Device Innovators Part III: Managing Clinical Trials

5 tipsThe third, in a blog series about clinical trials for medical device innovators. Read part I: Designing Clinical Trials and part II: Regulatory Considerations for Clinical Studies, here.

Except for small, clinical feasibility studies, unless you are an experienced clinical trialist, do not try to manage a clinical trial on your own. The larger the trial, the more help you will need. Hiring a contract research organization (CRO) to manage the trial may be your best, or only, option, but be prepared for the expense. Similarly, if FDA submissions are needed, you may be wise to seek the help of seasoned regulatory affairs professionals.

Conducting a clinical trial entails a lot of individual tasks. Your study design will have determined the number of patients you need to enroll. How many investigative sites will you need? This decision involves a trade-off between cost and speed of enrollment. Each site costs on the order of $75,000 (2017 USD) to bring up. You may wish to set a minimum number of patients to be enrolled per site, but that is no guarantee that each site will come through for you. Select sites judiciously, which may require on-site screening visits. Be careful, because the inclusion of a site that enrolls no, or only 1 or 2, patients is expensive and demoralizing. Remember, you will need a contract with each site, and each site will need local IRB (Institutional Review Board) review and approval unless you have contracted with a central IRB to oversee the entire study. Currently each IRB submission also usually costs money. You will need to perform an initial site visit, often with some level of training on the protocol and data entry for the investigators and the personnel who will actually be doing the study and collecting the data. Interim monitoring visits are required to ensure compliance with the protocol and to compare source data with data entered in the database according to a predetermined monitoring plan. Closeout visits are also needed at the end of a trial. As data come in, it is rarely perfect. Someone will be needed to review incoming data and prepare queries to the sites as necessary; we cannot stress how important this activity is to ensure the integrity and quality of the data.

Larger, more complex, multicenter clinical trials may also require (or benefit from) one or more of the following management tools.

Clinical Events Committee (CEC)

A group of unbiased physicians knowledgeable in the field of interest, typically charged with adjudicating whether or not individual serious adverse events (SAEs) are related to the use of the device or to the procedure under study.

Data Safety Monitoring Board (DSMB)

A group of unbiased physicians not involved in the trial but knowledgeable in the area. They are charged with developing rules for halting the trial based on anticipated aggregate rates of SAEs.

Core Laboratory

A central laboratory set up to provide unbiased analysis of specific results (e.g., imaging, measurements, or analysis of all clinical specimens); such a laboratory provides consistency in the analyses. Smaller studies, particularly early feasibility trials, will need this level of oversight only rarely.


Once again, smaller trials or observational studies that are simply reporting means and standard deviations and perhaps simple t-tests for comparisons may not require an independent biostatistician. In contrast, more complicated studies requiring complicated statistical analyses, studies with multiple endpoints, and studies requiring computational modeling, are all likely to need a biostatistician with particular expertise in the analysis of complex study designs.

For more information, please visit our website at

Continue to follow our blog to view the upcoming Part IV: Cost Drivers for Clinical Trials.

Clinical Trials for Medical Device Innovators Part II: Regulatory Considerations for Clinical Studies

MED Inst, Med,  regulatory science, regulatory data

The second, in a blog series about clinical trials for medical device innovators. Read part I: Designing Clinical Trials, here.

For regulatory purposes, clinical trials are grouped into two basic varieties: significant risk (SR) studies and nonsignificant risk (NSR) studies. The Food and Drug Administration (FDA) prefers that IRBs (Institutional Review Boards) make this determination; however, many IRBs put this back on the FDA to decide. Caution: If your study will involve multiple investigative sites and multiple IRBs, if any one of the IRBs decides it is a SR study, then the whole study will need to be so designated. You may wish to be proactive and write to the chief of the branch of the FDA which will hold authority over your device, describing your study and requesting determination by the FDA regarding the risk status of the study. This decision would then govern how your study is conducted.

All SR studies require an IDE (investigational device exemption). If your device is considered to present SR to patients, you will need to apply for an IDE and obtain FDA approval prior to conducting the study. In contrast, NSR studies only require approval of an IRB. If an IDE is required, an IDE Early Feasibility Study now may offer some leeway with respect to the amount of nonclinical testing required to support the IDE, so it is likely worthwhile to try this route. The alternative is a traditional IDE which often requires all nonclinical testing (bench and animal) to be completed prior to applying for an IDE.

If you conduct a clinical feasibility study and decide that you want to complete development of the device and obtain regulatory approval for it on your own, this may be the perfect time to meet with the appropriate authorities of the FDA to discuss your plans and obtain their advice. Assuming a pivotal clinical study will be necessary to obtain data for approval, early in the planning stage of the study is a good time for a “presubmission” meeting (in this case, probably a “pre-IDE” meeting). Your request for the meeting will include a description of the device, proposed indications for use, overview of product development, planned nonclinical testing, the design for the proposed clinical study, and specific questions for the FDA. The FDA makes available numerous guidance documents on their processes. In this meeting, you can determine what nonclinical testing the FDA will require in order to approve the IDE, the endpoints and follow-up for the clinical study, and agreement that the design of your proposed clinical protocol is likely to prove adequate to yield sufficient analyzable data for determining if the device is approvable. FDA reviewers/scientists generally look for objective, measureable endpoints (e.g., procedural success, long-term success, rates of adverse events). If you are also interested in collecting data to support a coverage decision, third-party payers tend to be interested in more subjective endpoints (e.g., quality of life and effect on patients), which may be difficult to validate. Nevertheless, it is beneficial to work these subjective endpoints into the pivotal study so that the data are available when it is time to discuss cost coverage for your device.

The most important thing you can bring to a pre-IDE meeting is a well-reasoned clinical protocol. Here is where decisions begin to become difficult. What kind of a clinical trial is needed? Your options for the design of a clinical study may be broader than you think. Investing in consultation with an experienced biostatistician may be well worth the time and investment at this point. Selecting the trial design that maximizes the likelihood of obtaining relevant data while minimizing time and expense is both a science and an art; therefore, do your homework and choose a statistician you trust.

Your options for a pivotal clinical trial will depend to some extent on what is already known about your device and the condition it will be used to treat; is it an incremental improvement on a current product, or is it a novel technology? Do you plan to show superiority to the current standard of care with respect to effectiveness, or do you expect to show noninferiority, while perhaps demonstrating an improved safety profile or a less expensive device?

Of course, the gold standard for clinical trials that always comes to mind first is the prospective, blinded, randomized, controlled study. Such studies can be large and expensive, but if recent, well-conducted studies have been published using the standard of care, you may very well be able to use their results to develop a performance goal to which your new device can be compared given sufficient data from an observational study with a single-arm registry and appropriate hypothesis testing. Having an experienced biostatistician is crucial to developing the most efficient study design possible and justifying it to the appropriate regulatory authorities.

For more information, please visit our website at

Continue to follow our blog to view the upcoming Part III: Managing Clinical Trials.

Clinical Trials for Medical Device Innovators Part I: Introduction and Designing Clinical Trials

The first, in a blog series about clinical trials for medical device innovators.

In 2017, Cook was approached to co-author the recently published book, “Medical Innovation Concept to Commercialization.”  William D. Voorhees III, Ph.D., Vice President and Chief Science Officer and Theodore Heise, Ph.D., RAC, Vice President Regulatory and Clinical Services, both of MED Institute, collaborated to write the chapter, “Clinical Trials for Medical Device Innovators.” Overall, the purpose of this book is to provide physician-inventors and entrepreneurs with a practical, step by step approach to move a novel concept from the back of a napkin to a tangible, commercially successful product.

Cook News August 2018 MED InstituteWilliam D. Voorhees III, left, and Theodore Heise, holding a copy of “Medical Innovation Concept to Commercialization”.

Dr. Voorhees earned his A.B. in Biology from Hamilton College and a Ph.D. from the Department of Veterinary Physiology & Pharmacology at Purdue University.  As a faculty member of the Hillenbrand Biomedical Engineering Center at Purdue, Bill conducted a wide variety of original research in applied physiology including CPR, transchest cardiac pacing, electroventilation, hyperthermia therapy for solid tumors, hypothermia to protect the myocardium during myocardial infarction, and respiratory function monitoring.  He has authored over 70 refereed scientific articles resulting from this research.  He also served as liaison with the R&D Department of Methodist Hospital of Indiana in Indianapolis.  Bill has been with MED Institute for 28 years, joining the newly formed Clinical Trials/New Product Approvals Group in September 1990.  He was named Vice President/Chief Science Officer in September 2001.  Bill also serves as the Director of Regulatory Affairs and Director of Scientific Communications.  He takes seriously his commitment to patients to ensure the quality and scientific integrity of the research conducted by MED Institute.

Dr. Heise has 25 years’ experience in regulatory affairs, currently serving as Vice President of Regulatory and Clinical Services at MED Institute.  In this capacity, Ted leads the company in designing scientifically robust regulatory and clinical study strategies for its clients: entrepreneurs, consultants and physicians bringing novel medical products through the complex steps of the development process. Graduating with a BS in chemistry from the University of Nebraska at Omaha, Ted went on to earn a Ph.D. in analytical chemistry from Iowa State University.   He has been a member of the Regulatory Affairs Professionals Society since 1993, and the American Chemical Society since 1988. Ted is a U.S. delegate to the technical committee for international consensus standards that governs biocompatibility testing and clinical investigations of medical devices, and serves as convener of its working group on chemical characterization. Ted is also active in developing processes to generate real world evidence for medical devices, representing Cook Medical on the corporate stakeholder board for the SVS/Vascular Quality Initiative and participating in projects within MDEpiNet and Harmonization by Doing.

In their chapter from the book, “Medical Innovation Concept to Commercialization,” presented here as a series of 5 blog posts, Bill and Ted share the wisdom they have gained from their 20 plus-year adventure designing, conducting, and analyzing clinical trials on novel medical devices.

Designing Clinical Trials

Perhaps the most exciting and rewarding time in the development of a new medical device is the first time one sees it work successfully in a patient, but the ensuing clinical trial can be the most exhausting, frustrating, expensive, and time-consuming part of the entire enterprise. So before rushing headlong into the unknown, consider the following: “Is it necessary for me to conduct a clinical trial of my new device?” The answer is “It depends.”

It depends on what you are trying to accomplish. Maybe you just want to show that your device works (i.e., the Proof of Concept). Perhaps you have reached a point at which no more can be learned without testing in humans, for example, pain relief cannot be studied on the bench at all and rarely well in animals. Your goal may be to demonstrate product effectiveness to investors and to raise additional funds. Maybe all you want is enough clinical data to improve your chances of selling the rights to the intellectual property. Perhaps you just want to enhance market awareness and exposure to the device (such as having a few key opinion leaders use it and write a paper), or maybe you want to take it all the way to regulatory approval with proof of safety and effectiveness, which is collected typically in what is called a pivotal study. Even if you want to own the regulatory approval of your device, keep in mind that a clinical study may not be needed if you can show that all relevant risks can be mitigated by bench and/or animal testing or with appropriate labeling. This is why a rigorous risk-analysis is imperative to your plan for development of the device.

Assume you have developed your device to the point that you have made prototypes that you have bench-tested adequately to satisfy yourself that they function as expected and they appear safe to use in humans. The “Grandmother Test” is a good benchmark; would you let your grandmother be treated with this device? Even if the answer is “Yes,” you probably need a clinical feasibility study first. Conducting a clinical feasibility study may also be a good first step when only formal testing in humans can provide the evidence that the device offers the expected benefit (Proof of Concept) or is required for making any final changes in design (e.g., to apply to specific human anatomy). Such data can simply be gathered no other way than to test in humans. Even if you know you will need a pivotal study for regulatory approval, it is likely that you will need initial information about how large a therapeutic effect the device will have before you can design a larger pivotal study to compare its results with state-of-the-art therapy (often a currently marketed device) in a statistically rigorous clinical study. A feasibility clinical study can be used to provide this crucial information.

If your interest lies only in developing the new device to the point that the concept (intellectual property) can be sold to another company to finalize its development and take it to commercialization, then conducting a clinical feasibility study may be adequate to provide the information that the company planning to purchase your device will need to decide to close the deal.

For more information, please visit our website at

Continue to follow our blog to view the upcoming Part II: Regulatory Considerations for Clinical Studies.

White Paper: Radial Force

Radial Force Testing
Radial force testing is used to determine the stiffness (hoop strength) of a medical device when placed under radial compressive forces, both loading and unloading. Devices that are commonly tested include balloons, stents, stent grafts, and feminine hygiene products, among other devices that are required to apply a chronic outward force. The importance of radial force testing in the medical device development process is perhaps best illustrated with an example. The following case study shows the importance of radial force in the functionality of a self-expandable stent.

Case Study: The Self-Expandable Stent
Accurate stent sizing is crucial. If a stent does not exert enough radial force to stay lodged in its desired position, it may migrate. Stent migration can cause a number of different problems, paravalvular leakage being one of them [1]. When paravalvular leakage occurs, blood flows through the stent and proceeds through cardiac tissue. Paravalvular leakage can cause heart failure, hemolytic anemia, and infectious endocarditis. [2]

Conversely, a stent that exerts too much force on its host vessel can cause vessel wall degeneration and damage. [1] Self-expandable stents, in particular, can be difficult to match to the proper vessel size. Self-expandable stents show a chronic outward radial force once they are deployed in the body. This can result in negative chronic recoil. Negative chronic recoil causes the vessel to expand outward, becoming larger than it naturally was. Other adverse reactions that may occur from improper stent sizing include: in-stent restenosis, thrombosis, and neo intimal proliferation.

Performing radial force testing on your device can help quantitatively characterize device functionality and performance, in turn allowing you to accurately assess the safety and effectiveness of your product.

Our Method
Our lab is ISO 17025 accredited in regards to radial force testing per ASTM 3067-14 and ISO 25539. Additionally, with over 30 years of experience developing test methods and evaluating a wide variety of medical devices, we have the ability to develop unique test methods tailored to your needs.

Radial ForceFigure 1. MSI RX550 Radial Force Tester at MED Institute.

Our Services
At MED Institute, we have the tools and experience to help with your radial force needs. Contact us so that we can help you make products and therapies that will improve patient outcomes.

If you have any questions or need any additional information, please contact:

Justin Metcalf, Director of Engineering Services


[1] M. S. Cabrera, C. W. Oomens and F. P. Baaijens, “Understanding the requirements of self-expandable stents for heart valve replacement: Radial force, hoop force and equilibrium,” Journal of the Mechanical Behavior of Biomedical Materials, vol. 68, pp. 252-264, 2017.
[2] D. Smolka and M. W. Wojakowski, “Paravalvular leak – important complication after implantation of prosthetic valve,” European Society of Cardiology, 8 November 2010. [Online]. Available: [Accessed 30 August 2017].

How Mobile Health Technology can Lead to Clinical Trial Success


Mobile Health Technology (mHealth) is a general term for the use of mobile phones or other communication devices in medical care. The use of mHealth has received significant attention recently, with good reason. mHealth is making a strong case for its ability to improve clinical trial management and participant engagement. For a technology to be effective in this area, it must provide necessary features and benefits and fit effortlessly into the patient’s daily schedule.

mHealth may help to improve data quality and participant trial adherence. Sponsors/CROs can equip participants with mobile devices and tablets to capture health data from home. Participants can complete diaries and surveys on mobile applications (apps) and submit the information from home versus onsite at the research center. Such convenience increases the likelihood of patients’ full participation in the trial and decreases the likelihood of noncompliances in the participants’ performance. Data can be captured real-time using mHealth which generally improves data fidelity. Timely data capture also allows for prompt identification of participant noncompliance. Action can then be taken to swiftly address any issues and ensure participant compliance going forward—correcting potential problems before they become widespread.  Some apps are developed to assist sponsors/CROs with patient recruitment for clinical trials. For example, Novartis Oncology developed a mobile app, Clinical Trial Seek, where patients and physicians can look for trial information.

In addition to more effectively and conveniently capturing trial data, mHealth may also increase participant engagement in a trial by making it easier to communicate information. If a participant has a trial-related question, it may be possible to check the mobile app and get the answer when needed, either through documentation available on the app or by direct communication with trial staff. Additionally, using mHealth, trial protocols can be set up with flexible schedules that can be fixed, randomized, or event-triggered. Schedules can be set up for daily, weekly, or monthly events and could even be customized with personalized instructions for an individual participant. Educational programs with web-based content can be scheduled on mobile apps to provide the latest information to participants in the trial. Solid participant engagement is key to minimizing the incidence of noncompliance with the trial protocol. mHealth could also increase the reach of certain trials by encouraging patients to participate from a greater distance, as burdensome patient travel requirements of trials are reduced.

As mentioned above, mHealth has a number of potential uses in the clinical research space, and could help make your trial more participant-centric. It could also provide solutions to two of the biggest challenges: participant recruitment and continued participant engagement. Although these technologies may not be appropriate for every trial, they should be considered in trial design as a tool to help optimize chances for success and participants’ best interests.  Despite the expected benefits of using mHealth in clinical trials, the regulatory status with the FDA is not yet entirely clear. Evolving acceptance by regulators will help drive implementation of mHealth in clinical research.

MED Institute has decades of experience in designing and executing clinical trials, and would be pleased to discuss with you how we can help you achieve success in your clinical trial objectives.

Visit to sign up for our newsletter and to learn more about how we can partner with you.