Validation of the Quality of Life in Childhood Epilepsy Questionnaire in American epilepsy patients

Abstract

The aim of this study was to adapt the Australian Quality of Life in Childhood Epilepsy Questionnaire (QOLCE) and determine its psychometric properties in a North American population. Participants were North American families with children diagnosed with epilepsy. Parents were asked to complete the American QOLCE (USQOLCE) and the Child Health Questionnaire (CHQ). Seventy-one families completed the USQOLCE. The internal consistency reliability of the subscales was good. USQOLCE subscales correlated highly with theoretically similar subscales contained in the CHQ. Theoretically dissimilar subscales on the two instruments did not correlate as well. USQOLCE correlated significantly with a parental rating of seizure severity and an independent measure of degree of postoperative seizure control. This study demonstrated that the USQOLCE is suitable for a North American population with evidence of its reliability and validity including its sensitivity to seizure burden.

Introduction

The clinical management of epilepsy involves much more than control of seizures and requires recognition of potential adverse effects on all aspects of life. In epilepsy research, there is a clear and growing recognition that health-related quality of life (HRQOL) measurement adds new and important information to other traditional health outcome measures such as seizure control and cognitive improvement [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11].

To date most childhood epilepsy studies utilise surrogate measures of HRQOL which evaluate limited domains of life function [12], [13], [14]. These surrogate measures include generic instruments such as the Child Behaviour Checklist [12], Developmental Behaviour Checklist [13], and Child Health Questionnaire [14]. Recently we have seen the development of disease-specific instruments of HRQOL for children with epilepsy. These instruments are a useful addition to the questionnaires presently available to the practitioner, as they are more sensitive to the condition of interest [15]. However, some still offer a limited evaluation. The Hague Restrictions in Childhood Epilepsy Scale is restricted to assessment of a child’s physical function [16]. The Impact of Paediatric Epilepsy Scale focuses on the psychosocial impact of epilepsy on the family [17]. The recently developed and validated Quality of Life in Epilepsy Inventory for Adolescents is a valuable tool measuring a number of life domains such as cognition, physical function, social function, behaviour, health perceptions and attitudes [18], [19]. However, it is limited to those aged 11–17 years. Ronen et al. [20] have developed a HRQOL instrument for younger children but it has yet to be validated.

Our Australian centre was the first to construct and publish a multifaceted epilepsy-specific scale for evaluating the HRQOL of children aged 4–18 years (Quality of Life in Childhood Epilepsy Questionnaire, QOLCE) [10]. The QOLCE was developed from an original questionnaire containing 91 items. Item analysis and validation led to a final questionnaire containing 76 items with 16 subscales covering five domains of life function: physical function, social function, cognition, emotional and behavioural well-being. Each QOLCE subscale demonstrated a high level of internal consistency reliability. The QOLCE subscales correlated strongly with similar subscales in an existing generic health outcome measure, the Child Health Questionnaire (CHQ). In addition, 12 of 16 subscales of the QOLCE correlated with a measure of seizure severity. However, this measure of seizure severity was rated by parents, and, therefore, was not independent from the ratings obtained from the QOLCE. The validity of an instrument is better established by correlating it with an independent measure of seizure burden. We recently demonstrated that the QOLCE was sensitive to the impact of localisation-related epilepsy syndromes compared with relatively benign syndromes such as childhood absence epilepsy and benign rolandic epilepsy [21].

The primary aim of the present study was to adapt the original Australian QOLCE for use in the American population. This involved examining the original pool of 91 items from which the QOLCE was developed to determine if translation was required from Australian to U.S. English. This is important because there are recognised conceptual and semantic differences in the English language depending on the country [22], [23], [24]. The validity of the adapted instrument was then evaluated by investigating internal consistency reliability, construct validity, and clinical sensitivity. The validation was based on the methodology used for the Australian validation study so that equivalence of the two forms could be considered. The validation sample was recruited from one of the largest paediatric epilepsy surgical centres in the world: the Miami Children’s Hospital (MCH), Florida, USA. Therefore, we also recruited a subset of families that had children who have undergone epilepsy surgery to assess the sensitivity of the QOLCE to postoperative seizure outcome.