Prevalence of restless legs syndrome in an urban population of eastern Africa (Tanzania)

Objectives: Restless legs syndrome (RLS) is one of the most common neurological disorders in Caucasian populations with prevalence rates between 5% and 15%. A recent study conducted in rural northern Tanzania documented a prevalence of only 0.013%. This result requires further investigation of the epidemiology of RLS in Africa, as prevalence rates seem to vary among different ethnicities.

Patients/methods: We conducted a community-based door-to-door study in an urban environment in eastern Africa (Kinondoni district, Dar es Salaam, Tanzania), where 35.008 people aged 14 years and above were screened for RLS according to the essential diagnostic criteria. Sampling was performed by the method of cluster sampling with probability-proportional-to-size.

Results: One hundred and sixty-four people screened positively for RLS (0.47%). Ninety-two of those were subject to detailed history taking and physical examination. Four people could finally be diagnosed with RLS, yielding a RLS prevalence rate of 0.037% (95% CI 0.015%; 0.059%) among the people in Kinondoni.

Conclusion: These results support previous findings that RLS has a very low prevalence in Tanzania despite the fact that only part of the questionnaire-positive RLS people could be interviewed face-to-face, and show that this is independent of whether assessed in a rural or an urban population. According to our results it seems that indigenous Tanzanian people (which are considered representative for the population of Eastern Africa) are less prone to RLS compared to Caucasian populations. Whether the reasons for this discrepancy in prevalence are primarily genetic, environmental or have a cultural/social component remains to be determined. In addition, the study points to a limited application of the essential diagnostic criteria in settings of non-Caucasian populations. Irrespective of ethnic origin, we support the necessity of detailed history and physical examination as performed in the second part of our study to exclude RLS mimics and verify the diagnosis of RLS.