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.

Intent-to-treat (ITT) population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

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.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

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".

ITT population. Last observation carried forward (LOCF) method was used. Here, 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

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.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

SSQ: Participant-rated instrument used to assess previous night's sleep profile. It is used to measure sleep quantity and quality and is comprised of 5 items yielding 5 subscale scores: latency (1 item), hours of sleep (1 item), number of awakenings (1 item), total WASO (1 item), quality of sleep (1 item). WASO is time spent awake from sleep onset to final awakening. Total WASO subscale (in minutes): numerical rating completed by the participant 30 minutes after waking; recall period is the night before. Total WASO subscale score ranges from 0-1440 minutes. Lower value indicates better sleep.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

SSQ: Participant-rated instrument used to assess previous night's sleep profile. It is used to measure sleep quantity and quality and is comprised of 5 items yielding 5 subscale scores: latency (1 item), hours of sleep (1 item), number of awakenings (1 item), total WASO (1 item), quality of sleep (1 item). WASO is time spent awake from sleep onset to final awakening. Total WASO subscale (in minutes): numerical rating completed by the participant 30 minutes after waking; recall period is the night before. Total WASO subscale score ranges from 0-1440 minutes. Lower value indicates better sleep.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

SSQ: Participant-rated instrument used to assess previous night's sleep profile. It is used to measure sleep quantity and quality and is comprised of 5 items yielding 5 subscale scores: latency (1 item), hours of sleep (1 item), number of awakenings (1 item), total WASO (1 item), quality of sleep (1 item). Latency subscale (in minutes): numerical rating completed by the participant 30 minutes after waking; recall period is the night before. Latency subscale score ranges from 0-840 minutes. Lower value indicates better sleep.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

SSQ: Participant-rated instrument used to assess previous night's sleep profile. It is used to measure sleep quantity and quality and is comprised of 5 items yielding 5 subscale scores: latency (1 item), hours of sleep (1 item), number of awakenings (1 item), total WASO (1 item), quality of sleep (1 item). Hours of sleep subscale: numerical rating completed by the participant 30 minutes after waking; recall period is the night before. Hours of sleep subscale score ranges from 0-16 hours. Higher value indicates better sleep.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

SSQ: Participant-rated instrument used to assess previous night's sleep profile. It is used to measure sleep quantity and quality and is comprised of 5 items yielding 5 subscale scores: latency (1 item), hours of sleep (1 item), number of awakenings (1 item), total WASO (1 item), quality of sleep (1 item). Number of awakenings subscale: numerical rating completed by the participant 30 minutes after waking; recall period is the night before. Number of awakenings subscale score ranges from 0-30. Lower value indicates better sleep.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

SSQ: Participant-rated instrument used to assess previous night's sleep profile. It is used to measure sleep quantity and quality and is comprised of 5 items yielding 5 subscale scores: latency (1 item), hours of sleep (1 item), number of awakenings (1 item), total WASO (1 item), quality of sleep (1 item). Quality of sleep subscale: numerical rating completed by the participant 30 minutes after waking; recall period is the night before. Quality of sleep subscale score ranges from 0-100. Higher score indicates better quality of sleep.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

The RLS-NDI is a participant-rated instrument designed to assess daytime performance as related to RLS and the participant's previous night's sleep. The instrument consists of 14 items that encompass 5 domains: tiredness; emotional functioning; social functioning; cognitive functioning; and activities of daily living. There is also 1 global item assessing overall well -being. Each item is scored on a 0-10 numeric rating scale. Total score is the sum of scores from question 1 to 14. The total score ranges from 0 to 140 where higher scores indicate a more severe impact.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

The RLS-NDI is a participant-rated instrument designed to assess daytime performance as related to RLS and the participant's previous night's sleep. The instrument consists of 14 items that encompass 5 domains: tiredness; emotional functioning; social functioning; cognitive functioning; and activities of daily living. There is also 1 global item assessing overall well -being. Each item is scored on a 0-10 numeric rating scale. Total score is the sum of scores from question 1 to 14. The total score ranges from 0 to 140 where higher scores indicate a more severe impact.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

100 millimeter (mm) line (Visual Analog Scale) marked by participant. Intensity of pain range (over past week): 0 mm = no pain to 100 mm = worst possible pain.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

100 mm line (VAS) marked by participant. Intensity of pain range (over past week): 0 mm = no pain to 100 mm = worst possible pain. Change = observation mean minus baseline mean.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

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.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

CGI-S: 7-point clinician rated scale to assess severity of participant's current illness state; range: 1 (normal-not ill at all) to 7 (among the most extremely ill participants). Higher score = more affected.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

MOS-SS: Participant rated instrument to assess sleep quantity, quality; comprised of 12 items yielding 7 subscale scores: sleep disturbance, snoring, awakening short of breath/headache, sleep adequacy, somnolence, sleep quantity, optimal sleep, 2 composite index scores: sleep problems Index I, II. Sleep adequacy data was reported at week 12 and not for first 12 weeks (average). Subscale scores range: 0-100; exception quantity of sleep (range 0-24 hours). With exception of sleep quantity and sleep adequacy, higher scores reflect poorer sleep outcomes.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, 'n' is signifying those participants who were evaluable for particular category for each group respectively.

MOS-SS: Participant rated instrument to assess sleep quantity, quality; comprised of 12 items yielding 7 subscale scores: sleep disturbance, snoring, awakening short of breath/ headache, sleep adequacy, somnolence, sleep quantity, optimal sleep, 2 composite index scores: sleep problems Index I, II. Optimal sleep subscale scores range: 0-1; Optimal sleep = 1 if 'Average hours sleep' = 7 or 8, is 0 if 'Average hours sleep' is non-missing and less than 7, and is missing if 'Average hours sleep' is missing. Higher scores reflect better sleep outcomes.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

POMS are participant-rated instrument comprising 6 sub-scales (tension-anxiety, depression-dejection, anger-hostility, vigor-activity, fatigue-inertia, and confusion-bewilderment) and each subscale comprising 5 items, on 'How you feel right now?' (Scale: 0=not at all, 1=a little, 2=moderately, 3=quite a bit, 4=extremely). All items were rated in the same direction except for vigor-activity. A total score is obtained for each scale. The range of total score is 0 - 100, with higher score indicating more mood disturbance.

Data for this pre-specified outcome measure was collected and reported in individual participant listings but not statistically summarized for analysis due to lack of sufficient knowledge as how to analyze mood data inferentially in RLS population.

RLS QoL: Participant rated instrument used to assess the impact of RLS on quality of life and health status function (symptom severity, daily activity, social functioning, sleep, concentrating and decision making, traveling, sexual activity, and work) yielding a summary score ranging from 0-100. Higher scores reflect better quality of life.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

SF-36 is a standardized survey evaluating 8 aspects of functional health and well being (physical and social functioning, physical and emotional role limitations, bodily pain, general health, vitality, mental health); 2 summary scores (physical and mental component); and self evaluated change in health status (summary of health status). The score for subscale scores and 2 summary score is an average of the individual question scores, which are scaled 0-100 (100=highest level of functioning). Summary of health status is a 5-point Likert scale ranging from "0=much worse now" to "4=much better now". Higher subscale and summary score reflect better health status.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, the 'N' (number of participants analyzed) is signifying those participants who were evaluable for this measure for each group respectively.

WPAI: 6 question participant rated questionnaire to determine degree to which SHP affected work productivity while at work and outside of work. Four scores are derived: percentage of absenteeism and presenteeism (reduced productivity while at work), overall work impairment score combining absenteeism and presenteeism, percentage of impairment in activities performed outside of work. Score range: 0 (not affected/no impairment) to 10 (completely affected/impaired). WPAI outcomes expressed as impairment percentages with higher numbers indicating greater impairment and less productivity.

ITT population included all randomized participants who took at least 1 dose of study medication and had at least one post-randomization efficacy assessment on any efficacy scale. Here, 'n' is signifying those participants who were evaluable for particular category for each group respectively.