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

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 5-7. months, 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.