PTT Advisor: A CDC-supported initiative to develop a mobile clinical laboratory decision support application for the iOS platform

Objectives: This manuscript describes the development of PTT (Partial Thromboplastin Time) Advisor, one of the first of a handful of iOS-based mobile applications to be released by the US Centers for Disease Control and Prevention (CDC). PTT Advisor has been a collaboration between two groups at CDC (Informatics R&D and Laboratory Science), and one partner team (Clinical Laboratory Integration into Healthcare Collaborative - CLIHC). The application offers clinicians a resource to quickly select the appropriate follow-up tests to evaluate patients with a prolonged PTT and a normal Prothrombin Time (PT) laboratory result. Methods: The application was designed leveraging an agile methodology, and best practices in user experience (UX) design and mobile application development. Results: As it is an open-source project, the code to PTT Advisor was made available to the public under the Apache Software License. On July 6, 2012, the free app was approved by Apple, and was published to their App Store. Conclusions: Regardless of the complexity of the mobile application, the level of effort required in the development process should not be underestimated. There are several issues that make designing the UI for a mobile phone challenging (not just small screen size): the touchscreen, users' mobile mindset (tasks need to be quick and focused), and the fact that mobile UI conventions/expectations are still being defined and refined (due to the maturity level of the field of mobile application development).