Patient diaries: charting the course.

Clinical diaries are a way for patients to assess their own health status without clinician bias or interpretation. Diaries are especially useful in understanding symptoms' temporal dynamics, including triggers that exacerbate symptoms; they also help individuals to evaluate the impact of their treatment. Diary format should be patient-specific, with thoughtful consideration given to rating scales, symptom descriptors, number of daily entries required, and the duration of diary recording. While compliance, recall biases, and diary fatigue affect data quality, a diary's potential for individualizing treatment strategies is tremendous.