1 Department of Psychology and Health Studies, University of Saskatchewan, Saskatoon, SK, Canada.
2 Department of Psychology, Concordia University, Montreal, QC, Canada.
3 Department of Psychology, University of Regina, Regina, SK, Canada.
4 Faculty of Nursing, University of Calgary, Calgary, AB, Canada.
5 Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Toronto, ON, Canada.
6 Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, Toronto, ON, Canada.

Menstrual pain affects over half of menstruating adolescents, and there is a desire for accessible, adjunct treatments, such as behavioural health interventions in mobile health (mHealth) formats. To date, no mHealth apps for adolescents with menstrual pain have been designed with youth. Although user-centred design is best practice, many challenges can arise, particularly when working with industry partners in the design process. We report on the development and usability testing phase of an industry-developed app for adolescents with menstrual pain, along with exploration of challenges and emerging recommendations throughout the process. The user-centred design process was composed of three phases. In Phase 1 we identified an industry partner and established a patient advisory committee. In Phase 2, adolescents (N = 22) reviewed iteratively developed versions of app design and content using a think-aloud procedure, followed by a semi-structured interview. The app was well-received by adolescents, although in each phase, feedback related to (1) visual design, (2) interface design, (3) content, and (4) app features was observed. In Phase 3, research team members and a patient advisor reflected on the process of working with industry. Identified reflections were thematically analysed and an overarching theme of Integration of Research, Industry, Institutional, and Funding Needs was generated, with four subthemes: timeline considerations; genuine patient involvement; financial constraints; and establishing mutual understanding. We provide a checklist of recommendations for working with youth and industry in app design and practical considerations when working with industry partners and adolescent stakeholders are discussed.