Defining the problem in patient identification safety events requires identifying the most frequent or impactful issues to focus improvement efforts effectively.

Option A (Review relevant policies and procedures): Reviewing policies is a later step to ensure alignment with best practices but does not directly define the problem or prioritize issues based on data.

Option B (Trend data with a control chart): Control charts monitor process stability over time, useful for tracking trends but not for initially defining the specific issues causing patient identification errors.

Option C (Use a Pareto chart to identify key issues): This is the correct answer. NAHQ CPHQ study materials advocate for Pareto charts to apply the 80/20 rule, identifying the few critical issues (e.g., wristband errors, miscommunication) responsible for most patient identification safety events. This focuses the action plan on high-impact areas.

Option D (Create a value stream map): Value stream mapping is a Lean tool for visualizing process flow, useful for analyzing workflows but less effective for initially defining the problem compared to prioritizing issues with a Pareto chart.