International Restless Legs Syndrome Study Group Rating Scale (IRLS) is psychometrically and clinically valid and reliable clinician-administered instrument used to assess the severity of RLS. It assesses RLS symptom severity and impact on daily living and is comprised of 10 items, scored on 0 to 4 scale, where lower score indicates lower symptom severity/impact on living. Two subscale scores are symptom severity (6 items) ranging from 0-24 (lower score indicates lower symptom severity) and impact on daily living (3 items) ranging from 0-12 (lower score indicates lower impact on living). Item 3 is unrelated to the other items. The global score is calculated from all 10 items, range from 0 to 40, where lower scores reflect lower severity and better quality of life.

IRLS is psychometrically and clinically valid and reliable clinician-administered instrument used to assess the severity of RLS. It assesses RLS symptom severity and impact on daily living and is comprised of 10 items, scored on 0 to 4 scale, where lower score indicates lower symptom severity/impact on living. Two subscale scores are symptom severity (6 items) ranging from 0-24 (lower score indicates lower symptom severity) and impact on daily living (3 items) ranging from 0-12 (lower score indicates lower impact on living). Item 3 is unrelated to the other items. The global score is calculated from all 10 items, range from 0 to 40, where lower scores reflect lower severity and better quality of life.

CGI-I: 7-point clinician rated scale ranging from 1 (very much improved) to 7 (very much worse). Improvement is defined as a score of 1 (very much improved), 2 (much improved), or 3 (minimally improved) on the scale. Higher score = more affected. Responders were defined as participants who report CGI-I score of "very much improved" or "much improved".

Augmentation was worsening of RLS symptoms, attributable to a specific long-term therapeutic intervention for RLS. Percentage of participants with augmentation was evaluated by centralized evaluation board using a set of assessment criteria for potential augmentation which included structured interview for diagnosis of augmentation during RLS treatment (SIDA-RLS), augmentation severity rating scale (ASRS), clinical judgment. ASRS measures severity of augmentation and consist of three items to be completed by clinician. Clinician would score participants' answers by comparing post-baseline evaluations to those at baseline. ASRS total score range: 0-24, with higher score indicating more severe augmentation.