IRLS: Subject-rated instrument to assess RLS symptom severity and impact on daily living; 10 items yielding 2 subscale scores and 1 global (total) score. Subscale scores: symptom severity (6 items) and impact on daily living (3 items), with item 5 (daytime somnolence due to RLS) loaded equally on both subscales. Global score: calculated from all 10 items. Subscale score ranges: symptom severity 0-24, impact of daily living 0-12; global score range: 0-40. Lower scores reflect lower severity and better quality of life. Change from baseline = score at observation minus score at baseline.

ITT. Baseline statistics were calculated only for subjects who had a non-missing change from baseline at at least one post-baseline visit. Recall period = week prior to assessment.

Clinical Global Impression - Improvement Scale (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. Number of subjects responding to treatment at Week 6 with respect to dose level. CGI-I Responders = subjects who reported CGI-I scores of very much improved or much improved.

ITT; N=number of subjects in a treatment group; n=number of subjects with a clinical Global Impressions Improvement (CGI-I) rating.

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

ITT; N=number of subjects in a treatment group. LOCF: Last Observation Carried Forward.

Subjective Sleep Questionnaire (SSQ): subject-rated instrument used to assess sleep behavior; measures sleep quantity and quality. Comprised of 5 items yielding 5 subscale scores: latency, hours of sleep, number of awakenings, total wake time after sleep onset, and quality of sleep. Latency subscale (time to fall asleep [in minutes]): numerical rating completed by the subject 30 minutes after waking; recall period is the night before. Lower score reflects greater ease (shorter time) in falling asleep. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

Subjective Sleep Questionnaire (SSQ): subject-rated instrument used to assess sleep behavior; measures sleep quantity and quality. Comprised of 5 items yielding 5 subscale scores: latency, hours of sleep, number of awakenings, total wake time after sleep onset, and quality of sleep. Hours of sleep subscale reflects change in hours of sleep from baseline. Numerical rating completed by the subject 30 minutes after waking; recall period is the night before.

ITT; baseline statistics were calculated only for subjects who had a non-missing change from baseline at at least one post-baseline visit.

Subjective Sleep Questionnaire (SSQ): subject-rated instrument used to assess sleep behavior; measures sleep quantity and quality. Comprised of 5 items yielding 5 subscale scores: latency, hours of sleep, number of awakenings, total wake time after sleep onset, and quality of sleep. Number of awakenings subscale: numerical rating completed by the subject 30 minutes after waking; recall period is the night before. Fewer awakenings reflect better quality of sleep. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had a non-missing change from baseline in at least one post-baseline visit.

Subjective Sleep Questionnaire (SSQ): subject-rated instrument used to assess sleep behavior; measures sleep quantity and quality. Comprised of 5 items yielding 5 subscale scores: latency, hours of sleep, number of awakenings, total wake time after sleep onset, and quality of sleep. Total wake time after sleep onset subscale (in minutes): numerical rating completed by the subject 30 minutes after waking; recall period is the night before. Reduction = improvement. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had a non-missing change from baseline at at least one post-baseline visit.

Subjective Sleep Questionnaire (SSQ): subject-rated instrument used to assess sleep behavior; measures sleep quantity and quality. Comprised of 5 items yielding 5 subscale scores: latency, hours of sleep, number of awakenings, total wake time after sleep onset, and quality of sleep. Quality of sleep subscale: visual analog scale ranging from 1 (very poor) to 100 (excellent) completed by the subject 30 minutes after waking; recall period is the night before. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

MOS-SS: subject-rated instrument used to assess the key constructs of sleep quantity and quality over the past week; comprised of 12 items yielding 7 subscale scores and 2 composite index scores. Sleep Disturbance Subscale score (4 items): range 0-100; lower score indicates less disturbance. Change from baseline = score at observation minus score at baseline.

ITT, Baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

MOS-SS: subject-rated instrument used to assess the key constructs of sleep; assesses sleep quantity and quality over the past week. Comprised of 12 items yielding 7 subscale scores and 2 composite index scores. Snoring Subscale score (1 item): range 0-100, lower score indicates less snoring. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

MOS-SS: subject-rated instrument used to assess the key constructs of sleep over the past week ; comprised of 12 items yielding 7 subscale scores and 2 composite index scores. Awaken Short of Breath or with Headache subscale score range: 0-100; lower score indicates less difficulty. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

MOS-SS: subject-rated instrument used to assess the key constructs of sleep; assesses sleep quantity and quality and is comprised 12 items yielding 7 subscale scores and 2 composite index scores. Sleep Adequacy Subscale score range: 0-100; higher scores indicates greater sleep adequacy. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

MOS-SS: subject-rated instrument used to assess the key constructs of sleep over the past week; assesses sleep quantity and quality and is comprised 12 items yielding 7 subscale scores and 2 composite index scores. Sleep Somnolence Subscale score range: 0-100; higher score indicates less somnolence. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

MOS-SS: subject-rated instrument used to assess the key constructs of sleep over the past week; assesses sleep quantity and quality and is comprised 12 items yielding 7 subscale scores and 2 composite index scores. Sleep Quantity (1 item) subscale score range: 0-24 hours. Change from Baseline in number of hours slept. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

MOS-SS: subject-rated instrument used to assess the key constructs of sleep over the past week; assesses sleep quantity and quality and is comprised 12 items yielding 7 subscale scores and 2 composite index scores. Sleep Problems Index I (6 items): composite index score range 0-100; lower score indicates fewer sleep problems. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

MOS-SS: subject-rated instrument used to assess the key constructs of sleep over the past week; assesses sleep quantity and quality and is comprised 12 items yielding 7 subscale scores and 2 composite index scores. Composite index scores are sleep problems Index I (6 items) and sleep problems Index II (9 items). 9-Item Sleep Problems Index range: 0-100; lower score indicates fewer sleep problems. Change from baseline = score at observation minus score at baseline.

ITT; baseline statistics were calculated only for subjects who had non-missing change from baseline at at least one post-baseline visit.

MOS-SS: subject-rated instrument used to assess the key constructs of sleep over the past week; assesses sleep quantity and quality and is comprised 12 items yielding 7 subscale scores and 2 composite index scores. Optimal Sleep subscale is derived from sleep quantity average hours of sleep each night during the past week. Number of subjects with response: YES (Optimal) if sleep quantity was 7 or 8 hours of sleep per night.

ITT

RLS QoL: subject-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. Recall period is the month prior to the assessment. Change from baseline = score at observation minus score at baseline.

ITT; N = Subjects who were randomized and received at least one dose of study drug; baseline n = subjects who were randomized and received at least one dose of study drug, and had baseline and post-baseline values.

Subject-rated measure of health status comprised of 36 items: 8 subscale scores (physical functioning, role-physical, bodily pain, general health, vitality, social functioning, role-emotional, and mental health), 2 summary scores (physical component and mental component), and a self-evaluated change in health status. Subscale and summary scores range: 0-100. Higher subscale and summary scores = better health status. Recall period: month prior to the assessment. Change from baseline = score at observation minus score at baseline.

ITT; N = Subjects who were randomized and received at least one dose of study drug; baseline n = subjects who were randomized and received at least one dose of study drug, had baseline and post-baseline values.

Subject-rated measure of health status comprised of 36 items: 8 subscale scores (physical functioning, role-physical, bodily pain, general health, vitality, social functioning, role-emotional, and mental health), 2 summary scores (physical component and mental component), and a self-evaluated change in health status. Self-evaluated change in health status: 5 Likert-type response categories ranging from "much worse now" to much better now." Recall period: month prior to the assessment.

ITT; N = number of subjects in a treatment group.