J Neurol (2012) 259:1793–1800 DOI 10.1007/s00415-011-6405-2 O R I G I N A L C O M M U N I C A T I O N Health-related quality of life in Huntington’s disease patients: a comparison of proxy assessment and patient self-rating using the disease-speciﬁc Huntington’s disease health-related quality of life questionnaire (HDQoL) Mevhibe B. Hocaoglu • E. A. Gaffan • Aileen K. Ho Received: 3 October 2011 / Accepted: 28 December 2011 / Published online: 6 March 2012 Springer-Verlag 2012 Abstract Huntington’s disease (HD) is a fatal, neurode- generative disease for which there is no known cure. Proxy evaluation is relevant for HD as its manifestation might limit the ability of persons to report their health-related quality of life (HrQoL). This study explored patient–proxy ratings of HrQoL of persons at different stages of HD, and examined factors that may affect proxy ratings. A total of 105 patient–proxy pairs completed the Huntington’s dis- ease health-related quality of life questionnaire (HDQoL) and other established HrQoL measures (EQ-5D and SF- 12v2). Proxy–patient agreement was assessed in terms of absolute level (mean ratings) and intraclass correlation. Proxies’ ratings were at a similar level to patients’ self- ratings on an overall Summary Score and on most of the six Speciﬁc Scales of the HDQoL. On the Speciﬁc Hopes and Worries Scale, proxies on average rated HrQoL as better than patients’ self-ratings, while on both the Speciﬁc Cognitive Scale and Speciﬁc Physical and Functional Scale proxies tended to rate HrQoL more poorly than patients themselves. The patient’s disease stage and mental well- being (SF-12 Mental Component scale) were the two fac- tors that primarily affected proxy assessment. Proxy scores were strongly correlated with patients’ self-ratings of HrQoL, on the Summary Scale and all Speciﬁc Scales. The patient–proxy correlation was lower for patients at mod- erate stages of HD compared to patients at early and advanced stages. The proxy report version of the HDQoL is a useful complementary tool to self-assessment, and a promising alternative when individual patients with advanced HD are unable to self-report. M. B. Hocaoglu E. A. Gaffan A. K. Ho (&) School of Psychology and Clinical Language Sciences, University of Reading, Reading RG6 6AL, UK e-mail: aileenkho@netscape.net Keywords Huntington’s disease Health-related quality of life Proxy Patient-reported outcome Patient–proxy agreement Huntington’s disease health-related quality of life questionnaire (HDQoL) Proxy reports have been widely used in health services research [1]. The subjective nature of the concept of health- related quality of life (HrQoL) requires its assessment to be carried out by self-report where possible. Proxy reports are relevant when a condition could affect the ability of per- sons to report or evaluate their subjective states [2, 3] such as Huntington’s disease (HD). HD is an autosomal-domi- nant progressively disabling lethal neurodegenerative dis- order [4] characterized by a triad of movement disorder, cognitive dysfunction and behavioural disturbances [5]. The progression of HD is viewed in ﬁve primary disease stages [6]. At Stage 1 individuals experience slight changes in mood and motor control and remain fully function at home and at work. At moderate stages chorea becomes pronounced, gait is affected and difﬁculties are experienced with thinking, reasoning, speech and swallowing; individ- uals may be able to work but at lower capacity (Stage 2) or can no longer work and may need assistance with everyday activities (Stage 3). In advanced stages, HD patients are no longer able to carry out daily activities independently and require the assistance of a carer at home (Stage 4), or need nursing care (Stage 5). Two additional categories are Pre- symptomatic gene positive (with critical mutation but not yet symptomatic) and At Risk (HD family member but genetic status not yet known). This study considers all seven groups as persons living with HD, since the issue of HrQoL is relevant to all. In addition to motor impairments [7], cognitive dys- functions [8], behavioural and psychiatric disturbances 123