The Nocturia Impact Diary: a self-reported impact measure to complement the voiding diary.

BACKGROUND Nocturia is a chronic, fluctuating disease that disrupts sleep and has a wide-ranging impact on quality of life. Valid tools to measure the patient-reported impact of nocturia are essential for evaluating the value of treatment, but the available tools are suboptimal. OBJECTIVES This study reports the development and validation of the Nocturia Impact Diary-an augmented form of the Nocturia Quality of Life questionnaire designed to be completed in conjunction with the widely used 3-day voiding diary. METHODS The process comprised three steps: Step 1: Development of a concept pool using the Nocturia Quality of Life questionnaire and data from relevant studies; Step 2: Content validity study; Step 3: Psychometric testing of construct validity, reliability, and sensitivity of the diary in a randomized, placebo-controlled study in patients with nocturia. RESULTS Step 1: Fourteen items and 4 domains were included in the first draft of the diary. Step 2: Twenty-three patients with nocturia participated in the cognitive debriefing study. Items were adjusted accordingly, and the content validity was high. Step 3: Fifty-six patients were randomized to desmopressin orally disintegrating tablet or placebo. The diary demonstrated high construct validity, with good sensitivity and a good fit to Rasch model, as well as high internal consistency, discriminatory ability, and acceptable sensitivity to change. Results indicated that the diary was unidimensional. CONCLUSIONS The Nocturia Impact Diary is a convenient, validated patient-reported outcome measure. It should be used in conjunction with a voiding diary to capture the real-life consequences of nocturia and its treatment.