Validity of the Neurology Quality-of-Life (Neuro-QoL) measurement system in adult epilepsy

Abstract

Epilepsy is a chronic neurological disorder that results in recurring seizures and can have a significant adverse effect on health-related quality of life (HRQL). The Neuro-QoL measurement initiative is an NINDS-funded system of patient-reported outcome measures for neurology clinical research, which was designed to provide a precise and standardized way to measure HRQL in epilepsy and other neurological disorders. Using mixed-method and item response theory-based approaches, we developed generic item banks and targeted scales for adults and children with major neurological disorders. This paper provides empirical results from a clinical validation study with a sample of adults diagnosed with epilepsy. One hundred twenty-one people diagnosed with epilepsy participated, the majority of which were male (62%) and Caucasian (95%), with a mean age of 47.3 (SD=16.9). Baseline assessments included Neuro-QoL short forms and general and external validity measures. The Neuro-QoL short forms that are not typically found in other epilepsy-specific HRQL instruments include Stigma, Sleep Disturbance, Emotional and Behavioral Dyscontrol, and Positive Affect and Well-Being. Neurology Quality-of-Life short forms demonstrated adequate reliability (internal consistency range=.86-.96; test-retest range=.57-.89). Pearson correlations (p<.01) between Neuro-QoL forms of emotional distress (anxiety, depression, stigma) and the QOLIE-31 Emotional Well-Being subscale were in the moderate-to-strong range (r's=.66, .71 and .53, respectively), as were relations with the PROMIS Global Mental Health subscale (r's=.59, .74 and .52, respectively). Moderate correlations were observed between Neuro-QoL Social Role Performance and Satisfaction and the QOLIE-31 Social Function (r's=.58 and .52, respectively). In measuring aspects of physical function, the Neuro-QoL Mobility and Upper Extremity forms demonstrated moderate associations with the PROMIS Global Physical Function subscale (r's=.60 and .61, respectively). Neuro-QoL measures of perceived cognitive function (executive function and general concerns) produced moderate-to-strong correlations with the QOLIE-31 Cognition subscale (r's=.65 and .75, respectively) and moderate relations with the Liverpool Adverse Events Profile (r's=.51 and .69, respectively). Finally, the Neuro-QoL Fatigue measure demonstrated moderate associations with the QOLIE-31 Energy/Fatigue subscale (r=-.65), Liverpool Adverse Events Profile (r=.69), and the Liverpool Seizure Severity Scale (r=.50). Five Neuro-QoL short forms demonstrated statistically significant responsiveness to change at 5-7months, including Fatigue, Sleep Disturbance, Depression, Positive Affect and Well-Being, and Emotional and Behavioral Dyscontrol. Overall, Neuro-QoL instruments showed good evidence for internal consistency, test-retest reliability, convergent validity, and responsiveness to change over several months. These results support the validity of Neuro-QoL to measure HRQL in adults with epilepsy.

Keywords: Epilepsy; Measurement; Neuro-QoL; Psychometrics; Quality of life; Validation.