1 University of Toronto Toronto Ontario Canada.
2 Hospital for Sick Children Toronto Ontario Canada.
3 Faculty of Health Sciences McMaster University Hamilton Ontario Canada.
4 Faculty of Health Sciences University of Ottawa Ottawa Ontario Canada.
5 Children's Hospital of Eastern Ontario Ottawa Ontario Canada.
6 Concordia University Montreal Quebec Canada.
7 University of California Irvine Irvine California USA.
8 CHOC Children's Hospital Orange California USA.
9 UCI Center on Stress and Health Orange California USA.
10 Ontario Parents Advocating for Children with Cancer Toronto Ontario Canada.
11 University of Victoria Victoria British Columbia Canada.
12 Pathverse Inc. Victoria British Columbia Canada.

Young children receiving outpatient cancer care are vulnerable to undermanaged pain. App-based solutions that provide pain treatment advice to parents in real-time and in all environments may improve access to quality pain care. We used a parent co-design approach involving iterative rounds of user testing and software modification to develop a usable Pain Caregiver Resource (PainCaRe) real-time pediatric cancer pain management app. Parents of children (2-11 years) with cancer completed three standardized modules using a PainCaRe prototype. App usability and acceptability were evaluated using the validated System Usability Scale and a thematic analysis of app testing sessions and interviews. Iterative testing sessions were conducted until data saturation. Interview themes were synthesized into action items that guided revisions to PainCaRe and additional testing rounds were conducted as necessary. Twenty-two parents participated in three testing cycles. Overall, parents described PainCaRe as an acceptable and potentially clinically useful pain management tool. Mean system usability scores were in the acceptable scale range during each testing cycle. Usability issues identified and resolved included those related to software malfunction, complicated app navigation logic, lack of clarity on pain assessment questions, and the need for pain management advice specifically tailored to child developmental stage. Using co-design methods, the PainCaRe cancer pain management app was successfully refined for its acceptability and utility to parents. Next steps will include a PainCaRe pilot study before evaluating the impact of the app on younger children's pain outcomes in a randomized controlled trial.