Use of the Long-Term Conditions Questionnaire (LTCQ) for monitoring health-related quality of life in people affected by cognitive impairment including dementia: pilot study in UK memory clinic services

Purpose The aim of this study was to validate the Long-Term Conditions Questionnaire (LTCQ) among patients using memory clinic services in England. LTCQ is a short self-administered measure of 'living well with long-term conditions' that has not been previously tested in patients with cognitive impairment. Methods The mixed-methods study included cognitive interviews to test the comprehensibility and content validity of LTCQ from the patient's perspective, followed by a pilot survey to test the measure's internal consistency, construct validity, structural validity, and responsiveness. Participants were recruited through memory clinics following a diagnosis of mild cognitive impairment or dementia. Results Interview respondents (n = 12) all found LTCQ's content relevant, with only minor formatting modifications required. Among survey respondents (n = 105), most patients (86%) were able to self-report answers to LTCQ. High multimorbidity among the sample was associated with reduced LTCQ and EQ-5D scores. Internal consistency of LTCQ was high (Cronbach's α = 0.93), no floor or ceiling effects were observed, and missing data levels were low. Factor analysis results further supported LTCQ's structural validity, and predicted positive correlation with EQ-5D indicated construct validity. Score changes observed in a four-month follow-up survey (n = 61) are suggestive of LTCQ's responsiveness. Conclusion LTCQ is a valid means of assessing health-related quality of life for people living with cognitive impairment (including dementia) in the early period of support following diagnosis. Owing to high levels of multimorbidity in this patient population, LTCQ offers an advantage over dementia-specific measures in capturing the cumulative impact of all LTCs experienced by the patient.