SEATTLE, WA—Sodium oxybate improved health-related quality-of-life (HRQoL) measures in patients with narcolepsy in a dose-dependent manner, with the 9g/night dose having a positive impact on specific domains of the 36-Item Short-Form Health Survey (SF-36), results from randomized placebo-controlled trial presented at SLEEP 2015 have found.

Specifically, the Physical Component Summary score and the individual SF-36 domains of Vitality, General Health, and Physical and Social Function were positively affected, said Richard Bogan, MD, of the University of South Carolina School of Medicine in Columbia, SC.

Sodium oxybate is approved in the United States to treat narcolepsy-related excessive daytime sleepiness (EDS) and cataplexy. The objective of the study was to evaluate HRQoL using the SF-36 questionnaire during an eight-week, placebo-controlled trial of sodium oxybate.

A total of 228 patients with narcolepsy ages 16–75 years with moderate-to-severe EDS were randomly assigned to placebo or sodium oxybate 4.5g, 6g, or 9g total nightly dose for eight weeks. The 6g and 9g/night doses were titrated weekly, in 1.5g increments. Dr. Bogan noted that HRQoL was assessed at baseline and end-of-treatment using the SF-36. Changes from baseline were compared between active treatment groups and placebo.

“For all SF-36 domains, mean values at baseline showed impaired HRQoL,” he reported.

After eight weeks of treatment, mean improvement from baseline on the Physical Component Summary was 1.5 for placebo (n=58), compared with 6.3 for the sodium oxybate 9g/night dose (n=47); this difference was statistically significant (P=0.005).

The sodium oxybate 9g/night dose resulted in significantly greater improvement on the individual domains of Physical Functioning (4.4±9.2 vs. 1.0 ± 8.0; P=0.016; ES=0.394), General Health (3.1±7.0 vs. 0.4±6.8; P=0.036; ES=0.395), and Social Function (6.8±16.8 vs 1.1±9.6; P=0.033; ES=0.417).

On the Vitality domain, all of the sodium oxybate doses resulted in significant improvements from baseline compared with placebo.

None of the differences between sodium oxybate and placebo were significant on the Mental Health component score, and no significant differences vs. placebo were observed on the domains of Role Physical, Role Emotional, and Mental Health. “Assessment of HRQoL and its changes with treatment are important not only because they represent the impact on patients’ lives and functioning, but also because measures of well-being may be predictive of future healthcare resource utilization and costs,” Dr. Bogan concluded.