Sleep Breath DOI 10.1007/s11325-014-1089-3
ORIGINAL ARTICLE
Restless legs syndrome among pregnant women in China: prevalence and risk factors Xiaoping Shang & Jinjian Yang & Yu Guo & Shengli Ma & Zhankui Jia & Rui Xue
Received: 30 July 2014 / Revised: 22 October 2014 / Accepted: 24 November 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Background The goal of this study was to identify the prevalence and clinical correlates and severity of restless legs syndrome (RLS) among pregnant women in mainland China. Methods This cross-sectional study enrolled 1584 women (18–40 years old) who came to a prenatal outpatient clinic to consult an obstetrician. Pregnant women were studied in each trimester, and assessments included interviews about RLS symptoms and related questions. Standardized questionnaires include the International Restless Syndrome Scale and the Pittsburgh Sleep Quality Questionnaire. Blood tests included levels of hemoglobin and mean corpuscular volume.
Results RLS was diagnosed in 177 of 1584 women (11.2 %); 4.2 % were categorized as having pre-existing RLS and 54.8 % reported onset of RLS symptoms after the 24th week. Multivariate analysis revealed that anemia was positively correlated with RLS. For the participants who first experienced RLS in pregnancy, RLS severity in the third trimester was more severe when compared with the first and second trimesters. Sleep disorders occurred more frequently in the third trimester. Conclusions In our study, RLS was frequent in pregnant Chinese women, and anemia was identified as an independent predictor of the disease. Further, most participants reported their symptoms during the third trimester, and the severity of RLS and sleep disorders of participants was more prominent in the third trimester.
Xiaoping Shang and Jinjian Yang contributed equally to this study.
Keywords Restless legs syndrome . Anemia . Pregnancy . Sleep . Cross-sectional study . Prevalence . China
X. Shang Department of Medical Records, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China J. Yang : R. Xue Department of Urology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China Y. Guo Ultrasound Department, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China S. Ma : Z. Jia Department of Neurology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China R. Xue (*) Department of Urology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China e-mail: [email protected]
Introduction Restless legs syndrome (RLS) is a sleep-related disorder characterized by unpleasant sensations in the legs that occur at rest and nighttime. The disorder causes sudden urges for the affected individual to move their legs to relieve symptoms [1]. Restless leg syndrome first appeared in 1945 and was named by the neurologist Karl-Axel Ekbom, who first discovered the prevalence of RLS in pregnant women which was 11.3 % in Sweden [2]. The standardized criteria for the diagnosis of RLS were first proposed in 1995 [3] and revised in 2002 [1] and were upheld by the International RLS Study Group (IRLSSG). The prevalence of RLS in the general population is 2–10 % [4], and women are affected twice as often as men [5]. A recent systematic review indicated that pregnancy is a risk factor for RLS by showing that prevalence of RLS during pregnancy is
Sleep Breath
Methods
of 15 questions was administered during this process. Data including demographic characteristics, personal behavior, and past medical illness of the participants were collected. We also obtained medical information from medical records of all participants, which included previous pregnancies and drug history. Diagnosis of RLS was administrated during this interview by a neurologist using the essential criteria of the International Restless Legs Syndrome Study Group (IRLSSG) defined in 2002 [1]. Additionally, in order to prevent confusion between defining symptoms of RLS and diseases with similar symptoms, we added the following criterion to eliminate potential false positives: “Do the uncomfortable and unpleasant feelings in your legs companied with an urge to move the legs similar to jerks, cramps, musculoskeletal disorders or something else?” To have an RLS diagnosis, the participants must have answered “Yes” to all four criteria suggested by the IRLSSG and “No” to the additional criterion. The frequency of occurrence of RLS symptoms was also included in the RLS diagnosis. In the present study, women who fulfilled the IRLSSG criteria and had symptoms at least three times in the same month or four times in two consecutive months were diagnosed as having RLS. Further questions were raised to participants who met the diagnostic criteria by the same neurologist in the interview. These questions included RLS history of the participants and their first-degree relatives, age at the onset of RLS symptoms, therapy history, RLS severity, and sleep quality. The International RLS Study Group Rating Scale [23] and Chinese version of Pittsburgh Sleep Quality Index [24] were used to estimate the situation of RLS severity and sleep quality separately. Hemoglobin and mean corpuscular volume were obtained from routine blood tests after the interview.
Population and setting
Subgroup classification and statistical analysis
This was a cross-sectional study conducted from February 2013 to May 2014. We enrolled pregnant women aged 18– 40 years at any stage of pregnancy. Pregnant women (N=1633) admitted to the outpatient clinic of the Obstetrics Department of the First Affiliated Hospital of Zhengzhou University for attending routine pregnancy checkup were contacted. Of the total, 1602 women agreed to participate. Women affected by severe pregnancy complications such as preeclampsia and miscarriage were excluded, as well as those who were receiving drug therapy (except for supplemental iron and folate). Ultimately, 1584 were included in the study. The study participants were informed about the nature of the research and signed an informed consent approved by the local ethics committee (no. CHN253/14).
According to the above criteria, women were classified into two groups: healthy group and total RLS group (tRLS). According to the onset time of RLS, the tRLS group was subclassified into two subgroups: the pre-existing RLS group (pRLS) included participants who were affected by RLS before their current pregnancy and had no experience of RLS during pregnancy. The second group called the new RLS group (nRLS) included participants who experienced RLS symptoms for the first time during their current pregnancy. SPSS (version 17.0) was used for statistical analysis. The continuous variables were expressed as means±SD, and Student’s t tests were used to compare the means between two groups. One-way analysis of variance (ANOVA) was followed by Bonferroni post hoc analysis to compare the means among three groups. For categorical variables, the χ2 test was used to test the differences between groups. Bivariate logistic regression was applied to identify significant predictive factors for RLS. Unless otherwise stated, P
ORIGINAL ARTICLE
Restless legs syndrome among pregnant women in China: prevalence and risk factors Xiaoping Shang & Jinjian Yang & Yu Guo & Shengli Ma & Zhankui Jia & Rui Xue
Received: 30 July 2014 / Revised: 22 October 2014 / Accepted: 24 November 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Background The goal of this study was to identify the prevalence and clinical correlates and severity of restless legs syndrome (RLS) among pregnant women in mainland China. Methods This cross-sectional study enrolled 1584 women (18–40 years old) who came to a prenatal outpatient clinic to consult an obstetrician. Pregnant women were studied in each trimester, and assessments included interviews about RLS symptoms and related questions. Standardized questionnaires include the International Restless Syndrome Scale and the Pittsburgh Sleep Quality Questionnaire. Blood tests included levels of hemoglobin and mean corpuscular volume.
Results RLS was diagnosed in 177 of 1584 women (11.2 %); 4.2 % were categorized as having pre-existing RLS and 54.8 % reported onset of RLS symptoms after the 24th week. Multivariate analysis revealed that anemia was positively correlated with RLS. For the participants who first experienced RLS in pregnancy, RLS severity in the third trimester was more severe when compared with the first and second trimesters. Sleep disorders occurred more frequently in the third trimester. Conclusions In our study, RLS was frequent in pregnant Chinese women, and anemia was identified as an independent predictor of the disease. Further, most participants reported their symptoms during the third trimester, and the severity of RLS and sleep disorders of participants was more prominent in the third trimester.
Xiaoping Shang and Jinjian Yang contributed equally to this study.
Keywords Restless legs syndrome . Anemia . Pregnancy . Sleep . Cross-sectional study . Prevalence . China
X. Shang Department of Medical Records, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China J. Yang : R. Xue Department of Urology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China Y. Guo Ultrasound Department, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China S. Ma : Z. Jia Department of Neurology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China R. Xue (*) Department of Urology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jian She Dong Avenue, Zhengzhou 450002, People’s Republic of China e-mail: [email protected]
Introduction Restless legs syndrome (RLS) is a sleep-related disorder characterized by unpleasant sensations in the legs that occur at rest and nighttime. The disorder causes sudden urges for the affected individual to move their legs to relieve symptoms [1]. Restless leg syndrome first appeared in 1945 and was named by the neurologist Karl-Axel Ekbom, who first discovered the prevalence of RLS in pregnant women which was 11.3 % in Sweden [2]. The standardized criteria for the diagnosis of RLS were first proposed in 1995 [3] and revised in 2002 [1] and were upheld by the International RLS Study Group (IRLSSG). The prevalence of RLS in the general population is 2–10 % [4], and women are affected twice as often as men [5]. A recent systematic review indicated that pregnancy is a risk factor for RLS by showing that prevalence of RLS during pregnancy is
Sleep Breath
Methods
of 15 questions was administered during this process. Data including demographic characteristics, personal behavior, and past medical illness of the participants were collected. We also obtained medical information from medical records of all participants, which included previous pregnancies and drug history. Diagnosis of RLS was administrated during this interview by a neurologist using the essential criteria of the International Restless Legs Syndrome Study Group (IRLSSG) defined in 2002 [1]. Additionally, in order to prevent confusion between defining symptoms of RLS and diseases with similar symptoms, we added the following criterion to eliminate potential false positives: “Do the uncomfortable and unpleasant feelings in your legs companied with an urge to move the legs similar to jerks, cramps, musculoskeletal disorders or something else?” To have an RLS diagnosis, the participants must have answered “Yes” to all four criteria suggested by the IRLSSG and “No” to the additional criterion. The frequency of occurrence of RLS symptoms was also included in the RLS diagnosis. In the present study, women who fulfilled the IRLSSG criteria and had symptoms at least three times in the same month or four times in two consecutive months were diagnosed as having RLS. Further questions were raised to participants who met the diagnostic criteria by the same neurologist in the interview. These questions included RLS history of the participants and their first-degree relatives, age at the onset of RLS symptoms, therapy history, RLS severity, and sleep quality. The International RLS Study Group Rating Scale [23] and Chinese version of Pittsburgh Sleep Quality Index [24] were used to estimate the situation of RLS severity and sleep quality separately. Hemoglobin and mean corpuscular volume were obtained from routine blood tests after the interview.
Population and setting
Subgroup classification and statistical analysis
This was a cross-sectional study conducted from February 2013 to May 2014. We enrolled pregnant women aged 18– 40 years at any stage of pregnancy. Pregnant women (N=1633) admitted to the outpatient clinic of the Obstetrics Department of the First Affiliated Hospital of Zhengzhou University for attending routine pregnancy checkup were contacted. Of the total, 1602 women agreed to participate. Women affected by severe pregnancy complications such as preeclampsia and miscarriage were excluded, as well as those who were receiving drug therapy (except for supplemental iron and folate). Ultimately, 1584 were included in the study. The study participants were informed about the nature of the research and signed an informed consent approved by the local ethics committee (no. CHN253/14).
According to the above criteria, women were classified into two groups: healthy group and total RLS group (tRLS). According to the onset time of RLS, the tRLS group was subclassified into two subgroups: the pre-existing RLS group (pRLS) included participants who were affected by RLS before their current pregnancy and had no experience of RLS during pregnancy. The second group called the new RLS group (nRLS) included participants who experienced RLS symptoms for the first time during their current pregnancy. SPSS (version 17.0) was used for statistical analysis. The continuous variables were expressed as means±SD, and Student’s t tests were used to compare the means between two groups. One-way analysis of variance (ANOVA) was followed by Bonferroni post hoc analysis to compare the means among three groups. For categorical variables, the χ2 test was used to test the differences between groups. Bivariate logistic regression was applied to identify significant predictive factors for RLS. Unless otherwise stated, P
