RLS is a very common disorder. Unfortunately, because of misconceptions and lack of adequate knowledge about RLS, this condition remains underdiagnosed or goes undiagnosed. The diagnosis is based on the essential criteria outlined in next Question, which are based on the patient’s history and physical examination.
Before the essential criteria for diagnosis were defined, any patients with restlessness were often diagnosed as having RLS or suffering from a psychoneurotic disorder.
For this reason, the number of cases diagnosed before the essential criteria were agreed upon is considered unreliable. Surveys from North American, Northern European, and Western European populations, taking into consideration the essential criteria, have shown the prevalence as varying from 2.5% to 10%.
The prevalence of more severe cases (people who have symptoms at least twice weekly with distress) is approximately 2.7%. Some surveys have found a lower prevalence, suggesting a possible ethnic and racial difference in RLS prevalence. In surveys from some Asian countries (e.g., South Korea), the prevalence found was similar to that observed in Western countries. The differences in the prevalence rates may be due to factors other than ethnic and racial differences.
For example, local environmental factors (e.g., a particular diet, presence of toxins in the environment, lifestyle factors) may play a role in the development of RLS. These issues have not been definitively identified, how-ever, and have not been addressed adequately in different surveys. Some of the known risk factors associated with RLS are increasing age, female gender, pregnancy, iron deficiency, neuropathy (damage to peripheral nerves), and end-stage kidney disease .
Risk Factors for Restless Legs Syndrome
Population Characteristics
Increasing age
Female gender
Lower socioeconomic status
Residents of North America and Western and Northern Europe
Physiological Factors
Pregnancy
Poor physical and general health
Lifestyle Factors (Preventable)
Smoking
Inactive lifestyle
Obesity from overeating
High-altitude living
Alcohol use
Medical and Neurological Disorders
Family History of RLS
Up until recently, all of the studies of RLS have addressed prevalence (i.e., the number of cases, whether old or new, existing within a given population at a stated point in time). No study is available to ascertain incidence (i.e., the number of new cases in a given population during a stated period).
Furthermore, all of the investigations involving RLS have addressed the severity of the disease based on standardized scales, but have not adequately addressed the severity based on frequency and intensity of symptoms.
For example, a patient with frequent (occurring three to four times per week in the evening or daytime), severe symptoms is certainly different from a patient with an occasional symptom (occurring once every few weeks) of short duration.
Various surveys have shown that 20% of the patients will have daily or almost daily symptoms, 40% will have symptoms at least weekly (one to three times per week) but not daily, and 40% will have symptoms every few weeks or months (less than weekly symptoms).