OBJECTIVES: Patient-reported outcome (PRO) measures are typically designed to instruct patients to consider a specific timeframe (recall period) when answering each item. Recall periods vary in length (i.e., 24 hours, 1 week, or 4 weeks) based upon the condition being assessed and the objectives of the research. The goal of this study was to assess patient adherence patterns to recall periods varying in duration by analyzing summaries of one-on-one qualitative patient interviews. METHODS: Data were reviewed from eight previously conducted cognitive debriefing interviews on condition specific measures that varied in recall period length. In all interviews, patients were specifically asked what recall period they had used when completing the PRO measure. The patient's response and the questionnaire's prespecified recall period were compared. RESULTS: Cognitive debriefing data for 115 patients (55% women) with a mean age of 57.1 was reviewed. The conditions of the ten PROs evaluated were: GERD (n=2), Dementia (n=2), Diabetes (n=3), and Overactive Bladder (n=3). Recall periods were: Daily (n=1); 1 week (n=2); 2 weeks (n=2); 2 to 4 weeks (n=1); and 4 weeks (n=4). The majority of patients (57.9%) stated the recall period specified on the PRO measure; 14.5% recalled a general period of time (e.g. since they had the condition); 13.8% stated a time over the recall period while 12.6% stated a time under the recall period. Shorter recall periods (e.g. 1 week) had more concordant patient responses than longer recall periods (80% vs. 53%). CONCLUSIONS: Patients tend to adhere better to shorter recall periods than longer recall periods when completing PRO measures. Questionnaires with longer recall periods often result with patients thinking in general terms of their condition or using a recall period of their own.