Objective Although errors in insulin pen devices have recently been reported, little research has been conducted to determine how such critical problems can be fixed. We integrated heuristic evaluation and failure mode and effects analysis (FMEA) to identify and prioritize important usability problems in insulin pen devices.

Research Design and Methods Four insulin pen devices were selected and evaluated according to ten standardized steps used for patient instruction. Two evaluators performed modified heuristic evaluation to determine usability problems and quantify these with clinical severity rate, based on 14 heuristic measurements. Finally, the risk priority number (RPN) for each usability problem was calculated with a probability of occurrence and detectability, to prioritize the problems. The number of heuristic violations in each of the 10 steps, the number of each of the 14 heuristic violations, and the RPN for four devices were analyzed.

Results Twenty-five heuristic problems were detected. The number of heuristic violations varied between the 10 steps. More than eight violations were found for: (1) dialing the number of units, and (2) simultaneous use of different devices. Visibility, feedback and error were the three most common heuristic violations observed. There were seven usability problems that had an RPN >100, reflecting urgency.

Conclusion Our approach of heuristic evaluation integrated with RPN calculation screened for usability problems, prioritized urgency and suggested remedial actions. This straightforward and practical approach may be used by clinicians, purchasers and other decision makers in hospitals.