Task analysis of in-home SARS-CoV-2 rapid antigen testing by families

INTRODUCTION

Ideal SARS-CoV-2 testing platforms must be simple, accessible, and timely, to ensure that symptomatic and exposed individuals are tested, positive-results are identified, and isolation, quarantine and contact tracing begin as soon as possible. Many children remain unvaccinated and as other respiratory viruses surge, families have a pressing need for reliable and practical SARS-CoV-2 testing options.

Point-of-care rapid antigen SARS-CoV-2 tests address many of the challenges associated with real-time reverse transcription–polymerase chain reaction by offering the convenience of in-home testing for individuals (including parents), tolerability (anterior nasal swab), and rapid results (within 15 minutes).¹ SARS-CoV-2 antigen test performance data suggest lower sensitivity when performed by non-healthcare professionals;² however, limited information exists on specific testing barriers parents face.

Identifying in-home testing pitfalls and strategies that facilitate high quality testing is essential to inform test kit design and result follow up. We applied hierarchical task analysis (HTA) to 1) model the task of in-home rapid antigen testing by parents; 2) identify potential failure modes; 3) identify and categorize strategies used to address potential failure modes.

METHODS

Participants were enrolled as part of a larger study aimed at increasing safe return to school for children with complex medical conditions.³ Participants were parents/caregivers of children enrolled in the University of Wisconsin’s Pediatric Complex Care Program (cohort average of 5 affected organ systems, 7 subspecialists, 10 scheduled medications, and 3 medical devices).⁴

The BinaxNOW Antigen Self-Test (Abbott) is a point-of-care, lateral flow immunoassay intended for the qualitative detection of the SARS-CoV-2 nucleocapsid protein antigen in direct anterior nasal swabs (symptomatic testing sensitivity range; 57–74%; specificity range=99.0–100%).^{2, 5} (https://www.abbott.com/corpnewsroom/diagnostics-testing/BinaxNOW-what-you-need-to-know.html).

We conducted a contextual inquiry over video-conferencing software to observe parents testing their children in their home environment. Contextual inquiry is a design research method that pairs observation with opportunistic questioning with the goal of uncovering details implicit in how people approach and conduct tasks.⁶ Sessions were recorded, transcribed, then analyzed using team-based content analysis.^{7, 8} Hierarchical task analysis (HTA) is a Human Factors method used to decompose a task into actions that are required to meet the overall objective of the task. By combining Human Factors expertise and protocol comparison, the resultant HTA informs task re-design by pointing to potential failure modes. We applied HTA to visualize the primary steps and secondary sub-tasks required to complete an in-home test. Potential failure modes and associated family-generated strategies were identified through the HTA by comparing the task as prescribed by the manufacturer and as performed by the family.^{3, 9}

RESULTS

We enrolled 20 caregivers in July 2021, average age of 40 years (Range=32–59), who mostly identified as women (90%).

HTA revealed that in-home testing required 14 primary steps, 10 of which required sub-tasks for a total of 44 steps to achieve 3 sub-goals (Figure 1). Fifteen potential failure modes were identified and were addressed with 29 strategies (Table 1).

Figure 1.

Hierarchical task analysis of rapid antigen point-of-care SARS-CoV-2 test conducted by families of children with medical complexity. Shaded boxes indicate steps that have associated potential failure modes, lettered for reference in Table 1.

Table 1.

Potential failure modes with associated strategies used by families to overcome them.

Potential failure modes	Strategies used by families to overcome failure mode
A. Remember to conduct the test	Plan to do test as part of a pre-established routine
	Set alarm or reminder
	Leave testing materials in line of sight (e.g., on the kitchen table)
B. Remember in which order to do the steps of the test	Refer to instructions while conducting the test
C. Cannot locate testing materials	Keep all materials in original box
	Keep all materials in a designated location (e.g., kitchen cabinet, desk drawer, supply drawer in child’s room, etc.)
D. Perforation on testing card package is small and hard to see/find	Keep scissors with materials and use those to open testing card package
E. Child or pet knocks testing card off surface	Set up testing card in a carefully selected location (e.g., out of the child’s reach, on a high countertop, within eyesight, etc.)
F. Cannot tell if there were 6 drops administered
G. Cannot remember how many drops to use	Write ‘6’ on the bottle to cue use of 6 drops
H. Cannot tell which end is the swab end versus the handle end when opening, potential for contamination
I. Child does not like swabbing	Do swab while child is sleeping
	Explain testing steps to the child verbally
	Have child do swab themselves (while coaching them, e.g., “swirl it like you’re swirling your French fries in ketchup”)
	Keep child in a comfortable/distracting setting (e.g., watching TV, counting, singing, etc.)
	Have child in a chair that supports child’s head and neck to prevent bucking
	Ask child which nostril to swab first
	Have another caregiver help restrain the child during swabbing
	Model test swabbing on oneself first
	Distinguish the test explicitly from a deep nasal swab
J. Fear of not getting enough sample	Do more circles in each nostril
	Observe swab to see if it looks wet
K. Sticker can be hard to peel off	Peel sticker tab off before swabbing (so that both hands are free)
L. Remember to go back to read results after 15 minutes and before 30 minutes	Set timer (e.g., using smart home system, stand-alone timer, or phone)
	Sit and wait 15 minutes in front of the card
	Place the test card in a location to cue reading it in 15 minutes (e.g., next to them at their desk)
	Write time of test administration onto the testing card
	Read results prior to 15 minutes passing
M. Confuse testing cards (if conducting test on more than one person)	Write name on the testing card
N. Read the lines due to poor vision	Use zoom feature on phone camera to observe results
O. Remember to record the results	Record test date and details while waiting and place the recording sheet next to the test card to cue recording results

DISCUSSION

In-home testing requires multiple steps that can be vulnerable to failure. Although families developed strategies to address failure modes, the influence of these strategies on test sensitivity and specificity is unknown.

Rapid antigen tests are challenged by lower than ideal sensitivity; influenced by test timing, frequency, and testing procedures.^{2, 5} The failure modes uncovered may contribute to sensitivity discrepancies observed between healthcare and non-healthcare professionals. Findings can be used by manufacturers to update instructional materials and test kit designs (Appendix A). For example, addressing failure modes F and G by including only the amount of reagent needed or designing the test card (sub-task 1.4) such that only the correct amount of reagent can be added. Further, improved visual design on packaging could address failure modes D and H by directing attention to the test card packaging’s perforation and to the swab packaging’s peelable end, respectively.

Our findings uncover vulnerable areas that could be useful to clinicians. For example, when speaking with patients, clinicians may probe about failure modes to guide proper testing procedures. Knowing how to evaluate high quality test procedures will bolster confidence among those depending on reliable results, e.g., clinicians, employers, school administrators, etc. For example, clinicians could work with families to alert them to potential challenges and advise on any strategies that may compromise test performance.

Our findings may not generalize to all populations. Families of children with medical complexity have familiarity with medical care. Replicating this study in other populations, e.g., caregivers having disabilities, could identify additional failure modes. We used one point-of-care SARS-CoV-2 antigen testing platform.

The many steps, potential failure modes, and strategies involved with in-home rapid antigen SARS-CoV-2 testing by families may influence test performance. Given growing direct-to-consumer test availability, similar studies are needed to quantify failure rates and ensure appropriate conclusions are drawn from reported results.

Abbreviations:

HTA

Hierarchical task analysis