Sleep Medicine 14 (2013) 1417–1418
Contents lists available at ScienceDirect
Sleep Medicine journal homepage: www.elsevier.com/locate/sleep
Brief Communication
Prevalence of restless legs syndrome in patients with chronic pain in Maputo, Mozambique K.F. Ferreira a,⇑, A. Eckeli a, F. Dach a, M.T. Schwalbach b, J. Schwalbach b, J.G. Speciali a a b
Department of Neurosciences and of Behaviour Sciences, Division of Neurology, University of Sao Paulo, Medical School of Ribeirao Preto, Sao Paulo, Brazil Central Hospital of Maputo, Eduardo Mondlane Avenue, Maputo, Mozambique
a r t i c l e
i n f o
Article history: Received 28 March 2013 Received in revised form 2 June 2013 Accepted 7 June 2013 Available online 8 October 2013 Keywords: Restless legs syndrome Chronic pain Epidemiology Africa Neuropathic pain Hypertension
a b s t r a c t Objectives: Because there is only one study to our knowledge on the prevalence of restless legs syndrome (RLS) in sub-Saharan Africa and RLS is more common in patients with some pain syndromes, we aimed to determine the prevalence of RLS in a population with chronic pain in Maputo, Mozambique. Methods: Our study was conducted in the Pain Unit of the Central Hospital of Maputo, Mozambique. Patients were individually interviewed by a neurologist, and only those fulfilling the criteria were included. After collection of demographic data and pain features, the patients answered the screening questions regarding RLS. Results: A total of 123 patients with pain were interviewed. Five individuals were excluded. RLS was found in eight (6.77%) of 118 patients. The mean age of the eight patients with RLS was 54.6 years. Five patients (62.5%) were women and six (75%) were black individuals. Seven (87.5%) patients were diagnosed with neuropathic pain; one of them had AIDS and another one (12.5%) had orthopedic pain. The presence of hypertension and neuropathies was more frequent in the RLS group. Conclusion: Despite the secondary causes involved, we believe that it is relevant to report the RLS prevalence detected in our study. Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
2. Methods
Restless legs syndrome (RLS) was first reported in 1672. In 1944, Karl Ekbom provided an accurate description of the syndrome [1]. Diagnostic criteria for RLS were established by the International Restless Legs Syndrome Study Group (IRLSSG) [2]. The prevalence of RLS ranges from 0.1% to 24%, with important geographic differences [2]. To our knowledge, there is only one study on the prevalence of RLS from a sub-Saharan Africa population. A community-based study on a population of Northern Tanzania has shown only one individual with RLS out of 7654 individuals who were interviewed (0.013%) [3]. Because there is only one study on the prevalence of RLS in sub-Saharan Africa and RLS is more common in patients with some pain syndromes such as neuropathic pain [4], we aimed to determine the prevalence of RLS in a population with chronic pain in the Pain Unit of the Central Hospital of Maputo, Mozambique.
Between October 2010 and July 2011, a survey was performed to identify and interview individuals with chronic pain older than the age of 18 years. Those who were not fluent in Portuguese, who did not agree to participate, and who did not have chronic pain according to the criteria of the International Association for the Study of Pain were excluded. The Ethics National Committee for Health of Mozambique approved the study (247-CNBS/10). The following information was obtained: demographic data, pain diagnosis, visual analog scale (VAS), medications use, comorbidities, diagnosis of RLS according to the criteria of the IRLSSG (diagnosis was based on the individual interviews by a neurologist), severity of RLS according to the Portuguese Restless Legs Syndrome rating scale of the IRLSSG, and depressive disorder or generalized anxiety disorder according to formal Diagnostic and Statistical Method of Mental Disorders, Fourth Edition, criteria. Data were entered and analyzed using SAS, version 8 (SAS/STATÒ User’s Guide, Version 8, Cary, NC: SAS Institute Inc., 1999).
⇑ Corresponding author. Address: Department of Neurosciences and of Behaviour Sciences, Division of Neurology, Clinical Hospital, Medical School of Ribeirao Preto, University of Sao Paulo, Avenida Bandeirantes, 3900 – Ribeirao Preto, Sao Paulo 14.048-900, Brazil. Tel./fax: +55 16 36022548. E-mail address: [email protected] (K.F. Ferreira). 1389-9457/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.sleep.2013.06.021
3. Results A total of 123 patients with pain were interviewed. Five individuals were excluded. RLS was found in eight (6.77%) of 118 patients.
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K.F. Ferreira et al. / Sleep Medicine 14 (2013) 1417–1418
Table 1 Comorbidities and medication use in patients with chronic pain in the Pain Unit, Central Hospital of Maputo, Mozambique from October 2010 to July 2011.
Hypertension, n (%) Diabetes mellitus, n (%) Neuropathy, n (%) Depressive disorder, n (%) Anxiety disorder, n (%)
Without RLS
With RLS
P value*
14 (12.7) 32 (29.0) 7 (6.3) 34 (30.9) 38 (34.5) 14 (12.7)
1 6 1 7 1 1
1.0 .013** .43 .002** .26 .99
(12.5) (75) (12.5) (87.5) (12.5) (12.5)
Abbreviation: RLS, restless legs syndrome; n, number of patients. * Fisher exact test. ** Significantly more prevalent in the studied population.
The mean age of the eight patients with RLS was 54.6 years. Five (62.5%) patients were women and six patients (75%) were black. RLS severity scale mean was 10.38 (standard deviation, 3.068). Seven (87.5%) patients were diagnosed with neuropathic pain (one of them had AIDS) and one patient (12.5%) had orthopedic pain. Mean VAS pain score was 8.75. The mean age of the 110 patients without RLS was 52.25 years. Seventy-four patients (67.2%) were women and 101 patients (91.8%) were black. Thirty-four patients (30.9%) were diagnosed with neuropathic pain, seven patients (6.36%) had pain related to AIDS, 17 patients (15.4%) had oncologic pain, 39 patients (35.4%) had osteomuscular pain, and 13 patients (11.8%) reported other types of pain such as fibromyalgia or visceral pain. The mean VAS score for pain was 8.35. The presence of hypertension and neuropathies was more frequent in the RLS group. There was no significant difference between groups in the presence of diabetes mellitus, anemia, depressive disorder, and generalized anxiety disorder; there also were no significant differences in the use of tricyclic antidepressant agents (Table 1). Regarding anemia, we relied on self-report and did not perform a hematologic test, which should be considered as a limitation of our study. 4. Discussion In a chronic pain population, we do not have previous data about RLS. We can describe a relation between pain and RLS. Pain is defined as any unpleasant sensation with a negative affective component. The symptoms of RLS meet this criterion, and some pain syndromes such as fibromyalgia and neuropathies can be related to RLS [4–5]. Regarding ethnic groups, Lee et al. [6] reported that black individuals revealed the same prevalence of RLS as white
individuals. On the other hand, there is only one prevalence study on RLS from sub-Saharan Africa [3]. We do not know if the prevalence of RLS found in our study can be explained by secondary causes. We found two important secondary causes to be reported (i.e., neuropathies, hypertension). First, we found that most RLS patients had neuropathy. It is likely that the prevalence of neuropathy in our study was detected by clinical diagnosis. Electrophysiologic, hematologic, and biopsy tests were not performed. It also is important to note that a previous study reported that women with RLS had a higher prevalence of hypertension [7]. In conclusion, despite the secondary causes involved in our study and the knowledge that our approach was not the best way to compare data (population studies vs chronic pain populations), we believe that our data are relevant to report the RLS prevalence detected in our study, as the literature about RLS in Africa is scarce. Conflict of interest The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2013.06.021.
References [1] Ekbom KA. Asthenia crurum paraesthetica. A new syndrome consisting of weakness, sensation of cold and nocturnal paraesthesia in the legs, responding to a certain extent to treatment with Priscol and Doryl note on paresthesia in general. Acta Med Scand 1944;118:197–209. [2] Allen RP, Pichietti D, Hening WA, Trenkwaldera C, Walters AS, Montplaisir J. Restless legs syndrome: diagnostic criteria, special considerations, and epidemiology. A report from the restless legs syndrome diagnosis and epidemiology workshop at the National Institutes of Health. Sleep Med 2003;4:101–19. [3] Winkler AS, Trendafilova A, Meindl M, Kaaya J, Schmutzhard E, Kassubeck J. Restless legs syndrome in a population of Northern Tanzania: a communitybased study. Mov Disord 2010;25:596–601. [4] Nineb A, Rosso C, Dumurgier J, Nordine T, Lefaucheur JP, CrZˇange A. Restless legs syndrome is frequently overlooked in patients being evaluated for polyneuropathies. Eur J Neurol 2007;14:788–92. [5] Gemignani F, Vitetta F, Brindani F, Contini M, Negrotti A. Painful polyneuropathy associated with restless legs syndrome. Clinical features and sensory profile. Sleep Med 2013;14:79–84. [6] Lee HB, Hening WA, Allen RP, Earley CJ, Eaton WW, Lyketsos CG. Race and restless legs syndrome symptoms in an adult community sample in east Baltimore. Sleep Med 2006;7:642–5. [7] Batool-Anwar S, Malhotra A, Forman J, Winkelman J, Li Y, Gao X. Restless legs syndrome and hypertension in middle-aged women. Hypertension 2011;58:791–6.
Contents lists available at ScienceDirect
Sleep Medicine journal homepage: www.elsevier.com/locate/sleep
Brief Communication
Prevalence of restless legs syndrome in patients with chronic pain in Maputo, Mozambique K.F. Ferreira a,⇑, A. Eckeli a, F. Dach a, M.T. Schwalbach b, J. Schwalbach b, J.G. Speciali a a b
Department of Neurosciences and of Behaviour Sciences, Division of Neurology, University of Sao Paulo, Medical School of Ribeirao Preto, Sao Paulo, Brazil Central Hospital of Maputo, Eduardo Mondlane Avenue, Maputo, Mozambique
a r t i c l e
i n f o
Article history: Received 28 March 2013 Received in revised form 2 June 2013 Accepted 7 June 2013 Available online 8 October 2013 Keywords: Restless legs syndrome Chronic pain Epidemiology Africa Neuropathic pain Hypertension
a b s t r a c t Objectives: Because there is only one study to our knowledge on the prevalence of restless legs syndrome (RLS) in sub-Saharan Africa and RLS is more common in patients with some pain syndromes, we aimed to determine the prevalence of RLS in a population with chronic pain in Maputo, Mozambique. Methods: Our study was conducted in the Pain Unit of the Central Hospital of Maputo, Mozambique. Patients were individually interviewed by a neurologist, and only those fulfilling the criteria were included. After collection of demographic data and pain features, the patients answered the screening questions regarding RLS. Results: A total of 123 patients with pain were interviewed. Five individuals were excluded. RLS was found in eight (6.77%) of 118 patients. The mean age of the eight patients with RLS was 54.6 years. Five patients (62.5%) were women and six (75%) were black individuals. Seven (87.5%) patients were diagnosed with neuropathic pain; one of them had AIDS and another one (12.5%) had orthopedic pain. The presence of hypertension and neuropathies was more frequent in the RLS group. Conclusion: Despite the secondary causes involved, we believe that it is relevant to report the RLS prevalence detected in our study. Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
2. Methods
Restless legs syndrome (RLS) was first reported in 1672. In 1944, Karl Ekbom provided an accurate description of the syndrome [1]. Diagnostic criteria for RLS were established by the International Restless Legs Syndrome Study Group (IRLSSG) [2]. The prevalence of RLS ranges from 0.1% to 24%, with important geographic differences [2]. To our knowledge, there is only one study on the prevalence of RLS from a sub-Saharan Africa population. A community-based study on a population of Northern Tanzania has shown only one individual with RLS out of 7654 individuals who were interviewed (0.013%) [3]. Because there is only one study on the prevalence of RLS in sub-Saharan Africa and RLS is more common in patients with some pain syndromes such as neuropathic pain [4], we aimed to determine the prevalence of RLS in a population with chronic pain in the Pain Unit of the Central Hospital of Maputo, Mozambique.
Between October 2010 and July 2011, a survey was performed to identify and interview individuals with chronic pain older than the age of 18 years. Those who were not fluent in Portuguese, who did not agree to participate, and who did not have chronic pain according to the criteria of the International Association for the Study of Pain were excluded. The Ethics National Committee for Health of Mozambique approved the study (247-CNBS/10). The following information was obtained: demographic data, pain diagnosis, visual analog scale (VAS), medications use, comorbidities, diagnosis of RLS according to the criteria of the IRLSSG (diagnosis was based on the individual interviews by a neurologist), severity of RLS according to the Portuguese Restless Legs Syndrome rating scale of the IRLSSG, and depressive disorder or generalized anxiety disorder according to formal Diagnostic and Statistical Method of Mental Disorders, Fourth Edition, criteria. Data were entered and analyzed using SAS, version 8 (SAS/STATÒ User’s Guide, Version 8, Cary, NC: SAS Institute Inc., 1999).
⇑ Corresponding author. Address: Department of Neurosciences and of Behaviour Sciences, Division of Neurology, Clinical Hospital, Medical School of Ribeirao Preto, University of Sao Paulo, Avenida Bandeirantes, 3900 – Ribeirao Preto, Sao Paulo 14.048-900, Brazil. Tel./fax: +55 16 36022548. E-mail address: [email protected] (K.F. Ferreira). 1389-9457/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.sleep.2013.06.021
3. Results A total of 123 patients with pain were interviewed. Five individuals were excluded. RLS was found in eight (6.77%) of 118 patients.
1418
K.F. Ferreira et al. / Sleep Medicine 14 (2013) 1417–1418
Table 1 Comorbidities and medication use in patients with chronic pain in the Pain Unit, Central Hospital of Maputo, Mozambique from October 2010 to July 2011.
Hypertension, n (%) Diabetes mellitus, n (%) Neuropathy, n (%) Depressive disorder, n (%) Anxiety disorder, n (%)
Without RLS
With RLS
P value*
14 (12.7) 32 (29.0) 7 (6.3) 34 (30.9) 38 (34.5) 14 (12.7)
1 6 1 7 1 1
1.0 .013** .43 .002** .26 .99
(12.5) (75) (12.5) (87.5) (12.5) (12.5)
Abbreviation: RLS, restless legs syndrome; n, number of patients. * Fisher exact test. ** Significantly more prevalent in the studied population.
The mean age of the eight patients with RLS was 54.6 years. Five (62.5%) patients were women and six patients (75%) were black. RLS severity scale mean was 10.38 (standard deviation, 3.068). Seven (87.5%) patients were diagnosed with neuropathic pain (one of them had AIDS) and one patient (12.5%) had orthopedic pain. Mean VAS pain score was 8.75. The mean age of the 110 patients without RLS was 52.25 years. Seventy-four patients (67.2%) were women and 101 patients (91.8%) were black. Thirty-four patients (30.9%) were diagnosed with neuropathic pain, seven patients (6.36%) had pain related to AIDS, 17 patients (15.4%) had oncologic pain, 39 patients (35.4%) had osteomuscular pain, and 13 patients (11.8%) reported other types of pain such as fibromyalgia or visceral pain. The mean VAS score for pain was 8.35. The presence of hypertension and neuropathies was more frequent in the RLS group. There was no significant difference between groups in the presence of diabetes mellitus, anemia, depressive disorder, and generalized anxiety disorder; there also were no significant differences in the use of tricyclic antidepressant agents (Table 1). Regarding anemia, we relied on self-report and did not perform a hematologic test, which should be considered as a limitation of our study. 4. Discussion In a chronic pain population, we do not have previous data about RLS. We can describe a relation between pain and RLS. Pain is defined as any unpleasant sensation with a negative affective component. The symptoms of RLS meet this criterion, and some pain syndromes such as fibromyalgia and neuropathies can be related to RLS [4–5]. Regarding ethnic groups, Lee et al. [6] reported that black individuals revealed the same prevalence of RLS as white
individuals. On the other hand, there is only one prevalence study on RLS from sub-Saharan Africa [3]. We do not know if the prevalence of RLS found in our study can be explained by secondary causes. We found two important secondary causes to be reported (i.e., neuropathies, hypertension). First, we found that most RLS patients had neuropathy. It is likely that the prevalence of neuropathy in our study was detected by clinical diagnosis. Electrophysiologic, hematologic, and biopsy tests were not performed. It also is important to note that a previous study reported that women with RLS had a higher prevalence of hypertension [7]. In conclusion, despite the secondary causes involved in our study and the knowledge that our approach was not the best way to compare data (population studies vs chronic pain populations), we believe that our data are relevant to report the RLS prevalence detected in our study, as the literature about RLS in Africa is scarce. Conflict of interest The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2013.06.021.
References [1] Ekbom KA. Asthenia crurum paraesthetica. A new syndrome consisting of weakness, sensation of cold and nocturnal paraesthesia in the legs, responding to a certain extent to treatment with Priscol and Doryl note on paresthesia in general. Acta Med Scand 1944;118:197–209. [2] Allen RP, Pichietti D, Hening WA, Trenkwaldera C, Walters AS, Montplaisir J. Restless legs syndrome: diagnostic criteria, special considerations, and epidemiology. A report from the restless legs syndrome diagnosis and epidemiology workshop at the National Institutes of Health. Sleep Med 2003;4:101–19. [3] Winkler AS, Trendafilova A, Meindl M, Kaaya J, Schmutzhard E, Kassubeck J. Restless legs syndrome in a population of Northern Tanzania: a communitybased study. Mov Disord 2010;25:596–601. [4] Nineb A, Rosso C, Dumurgier J, Nordine T, Lefaucheur JP, CrZˇange A. Restless legs syndrome is frequently overlooked in patients being evaluated for polyneuropathies. Eur J Neurol 2007;14:788–92. [5] Gemignani F, Vitetta F, Brindani F, Contini M, Negrotti A. Painful polyneuropathy associated with restless legs syndrome. Clinical features and sensory profile. Sleep Med 2013;14:79–84. [6] Lee HB, Hening WA, Allen RP, Earley CJ, Eaton WW, Lyketsos CG. Race and restless legs syndrome symptoms in an adult community sample in east Baltimore. Sleep Med 2006;7:642–5. [7] Batool-Anwar S, Malhotra A, Forman J, Winkelman J, Li Y, Gao X. Restless legs syndrome and hypertension in middle-aged women. Hypertension 2011;58:791–6.
