Establishing the Content Validity of the King’s Health Questionnaire in Men and Women with Overactive Bladder in the US

Background: Overactive bladder (OAB) consists of the symptoms of urinary urgency (with or without urgency incontinence) and increased urinary frequency and nocturia. As OAB is defined by symptoms, the patient is the best source of information for assessing the impact of the condition on health-related quality of life (HR-QOL). This assessment can be conducted through the use of valid patient-reported questionnaires, meaning the questionnaire has demonstrated content validity, among other acceptable psychometric properties. The aim of this study was to evaluate the content validity of the King’s Health Questionnaire (KHQ) in patients with OAB in the US. Methods: Men and women with continent or incontinent OAB were recruited from a clinical research site in the US. Participants completed the KHQ and were then asked about the instructions, items, and response options. Data were analyzed descriptively and qualitatively. Results: A total of 24 participants (18 women, 6 men; mean [±SD] age 59.0±11.1 years) with OAB were interviewed and provided feedback on the KHQ. Participants reported that overall, the KHQ covers the key aspects in which OAB impacts patients’ daily lives. Most KHQ items and response options were acceptable and understandable to the participants; however, a few minor issues were noted. In item 3, shopping was not considered by some participants to be a household task, while shopping and cleaning were not relevant to some of the men. Two sets of items (‘limit social life’ and ‘limit ability to see/visit friends’ and ‘bladder problem affect sleep’ and ‘feel worn out or tired’) were perceived as redundant, while ‘depressed’ (item 12) and ‘anxious or nervous’ (item 13) were perceived by some participants as too intense. Some participants were unsure if the intended meaning of ‘change your underclothes when they get wet’ was about changing wet underwear or frequency of incontinence episodes. Conclusion: The KHQ demonstrated content validity and can be considered a relevant and appropriate tool to assess the impact of OAB on HR-QOL in men and women in the US.