Usability Evaluation of a Noninvasive Neutropenia Screening Device (PointCheck) for Patients Undergoing Cancer Chemotherapy: Mixed Methods Observational Study

Abstract

Background: Patients with cancer undergoing cytotoxic chemotherapy face an elevated risk of developing serious infection as a consequence of their treatment, which lowers their white blood cell count and, more specifically, their absolute neutrophil count. This condition is known as neutropenia. Neutropenia accompanied by a fever is referred to as febrile neutropenia, a common side effect of chemotherapy with a high mortality rate. The timely detection of severe neutropenia (<500 absolute neutrophil count/μL) is critical in detecting and managing febrile neutropenia. Current methods rely on blood draws, which limit them to clinical settings and do not allow frequent or portable monitoring. In this study, we demonstrated the usability of PointCheck, a noninvasive device for neutropenia screening, in a simulated home environment without clinical supervision. PointCheck automatically performs microscopy through the skin of the finger to image the blood flowing through superficial microcapillaries and enables the remote monitoring of neutropenia status, without requiring venipuncture.

Objective: This study aimed to evaluate the usability of PointCheck, a noninvasive optical technology for screening severe neutropenia, with the goal of identifying potential user interface, functionality, and design issues from the perspective of untrained users.

Methods: We conducted a multicenter study using quantitative and qualitative approaches to evaluate the usability of PointCheck across 154 untrained participants. We used a mixed method approach to gather usability data through user testing observations, a short-answer qualitative questionnaire, and a standardized quantitative System Usability Scale (SUS) survey to assess perceived usability and satisfaction.

Results: Of the 154 participants, we found that 108 (70.1%) scored above 80.8 on the SUS across all sites, with a mean SUS score of 86.1 across all sites. Furthermore, the SUS results indicated that, out of the 151 users who completed the SUS survey, 145 (96%) found that they learned how to use PointCheck very quickly, and 141 (93.4%) felt very confident when using the device.

Conclusions: We have shown that PointCheck, a novel technology for noninvasive, home-based neutropenia detection, can be safely and effectively operated by first-time users. In a simulated home environment, these users found it easy to use, with a mean SUS score of 86.1, indicating an excellent perception of usability and placing this device within the top tenth percentile of systems evaluated for usability by the SUS.

Trial registration: ClinicalTrials.gov NCT04448314; https://ichgcp.net/clinical-trials-registry/NCT04448314 (Hospital Universitario 12 de Octubre registration) and NCT04448301; https://ichgcp.net/clinical-trials-registry/NCT04448301 (Boston Medical Center registration).

Keywords: cancer; chemotherapy; decision support systems; diagnosis; digital health; infection; medical device; patient-centered care; remote monitoring; technology; usability; white blood cell; white blood cells.

Conflict of interest statement

Conflicts of Interest: GL, APT, IB, NB, RB, AB, ASF, and CCG are current employees and holders of stock options in a privately held company, patents, and royalties of Leuko Labs, Inc. IB and CCG have membership on the board of directors or advisory committees of Leuko Labs, Inc. JML received research funding from Roche, Novartis, Incyte, Astellas, and BMS and consulted for Janssen, BMS, Novartis, Incyte, Roche, GSK, and Pfizer. None of these items are related to this work. JMS has membership on the board of directors or advisory committees of Pharmacosmos and Astra Zeneca and received honoraria from Abbvie and Stemline. None of these items are related to this work. All other authors declared no other conflicts of interest.

©Ganimete Lamaj, Alberto Pablo-Trinidad, Ian Butterworth, Nolan Bell, Ryan Benasutti, Aurelien Bourquard, Alvaro Sanchez-Ferro, Carlos Castro-Gonzalez, Ana Jiménez-Ubieto, Tycho Baumann, Antonia Rodriguez-Izquierdo, Elizabeth Pottier, Anthony Shelton, Joaquin Martinez-Lopez, John Mark Sloan. Originally published in the Journal of Medical Internet Research (https://www.jmir.org), 09.08.2022.

Figures

Figure 1

The PointCheck device and its main components.

Figure 2

Screenshots of PointCheck’s user interface depicting the user walk-through tutorial in English for taking a measurement and device function via the touch screen interface. Language support for Spanish- and Haitian-speaking populations was implemented to translate the instructions.

Figure 3

One-page quick start guide provided to participants before attempting to take a measurement on their own.

Figure 4

SUS survey responses assessed individually. Percentage values are calculated using available data from a total of 151 participants. SUS surveys were incomplete for 3 participants. SUS: System Usability Scale.