Chung Suk Lee

The Prevalence of and Risk Factors for Sleep-Disordered Breathing in an Elderly Korean Population

Background: There are just a few epidemiological studies on sleep-disordered breathing (SDB) in the elderly, and the results are inconsistent. Study Objectives: We sought to investigate the prevalence of and risk factors for SDB in a representative elderly population with the use of attended nocturnal polysomnography (NPSG). Methods: Among 6,959 individuals aged ≥60 years living in Yongin City, Korea, 696 subjects were selected using random sampling. All the subjects were invited to visit a hospital for NPSG, and SDB was defined as an apnea-hypopnea index ≥15. Results: Of the 696 participants investigated, 348 participants completed the sleep study and clinical evaluation. SDB was observed in 127 of the 348 participants, and the prevalence of SDB was 36.5% (52.6% in males and 26.3% in females). A body mass index ≥25 was associated with SDB in both male and female subjects, particularly in males, whereas snoring was independently associated with SDB in female participants only. In male participants, SDB was a significant risk factor for hypertension (p = 0.025). Conclusions: SDB was found to be common among elderly Koreans, and it was more prevalent and severe in male than in female subjects. Health consequences of SDB in the elderly need to be further explored.

Comparison of the efficacies of oral iron and pramipexole for the treatment of restless legs syndrome patients with low serum ferritin.

It is not clear which is preferred between iron supplement and a dopamine agonist in the treatment of restless legs syndrome (RLS) with iron deficiency. The efficacies of oral iron supplementation and pramipexole for treatment of RLS with low‐normal serum ferritin (15–50 ng/ml) were compared.

Impacts of comorbidities on the association between arterial stiffness and obstructive sleep apnea in the elderly.

Background: Although the impact of obstructive sleep apnea (OSA) on cardiovascular risk is reasonably well established in middle-aged patients, the debate persists as to whether OSA also increases this risk in the elderly. Arterial stiffness has been used as an early independent predictor of cardiovascular risk. Study Objectives: We sought to determine whether OSA has significant effects on the arterial stiffness in the elderly population and evaluate the impact of comorbidities on the association between arterial stiffness and OSA. Methods: We performed a cross-sectional study in a university hospital. Elderly participants (≥60 years) were invited to participate in our study between November 2010 and January 2013. OSA was diagnosed using gold standard polysomnography and arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV), cardio-ankle vascular index (CAVI) and central systolic and diastolic blood pressure (cSBP and cDBP). The high-sensitivity C-reactive protein (hs-CRP) level was also measured. Results: We found no significant association between the severity of OSA and the arterial stiffness-related parameters cSBP, cDBP, baPWV, CAVI and hs-CRP. However, in patients with no comorbid medical conditions or use of medications (n = 101), we showed a modest association between OSA and arterial stiffness-related parameters and hs-CRP. Conclusion: We conclude that OSA is associated with increased arterial stiffness in an otherwise healthy elderly population, although the association was obviated by comorbidities and medications perhaps due to ceiling effects.

Prevalence and clinical characteristics of insomnia and its subtypes in the Korean elderly

BACKGROUND Insomnia is known to be associated with psychiatric disorders, other sleep disorders and medical conditions, but the prevalence of insomnia diagnosis has never been estimated according to its subtypes. We studied the prevalence and clinical characteristics of insomnia diagnosis and its subtypes in the Korean elderly population. METHODS Among 1423 sampled elderly individuals aged 60 years or older, 881 subjects participated in this study. The Athens Insomnia Scale was applied to detect insomnia symptoms, and insomnia diagnosis was finally evaluated using the international classification of sleep disorders, 2nd edition. To define insomnia subtypes, the DSM-IV-based interview, detailed history on sleep disorders and semi-structured interview for medical conditions were performed. Subsyndromal depression was defined when depressive symptoms did not meet the criteria for depressive disorders. RESULTS The prevalence of insomnia disorder was 32.8% in all subjects, with the prevalence being significantly higher in women than in men (37.9% vs. 25.2%; p<0.001). The prevalence of insomnia subtypes was as follows; psychophysiological insomnia (PI), 20.5%; insomnia due to mental disorder 7.2%; insomnia due to general medical conditions 2.9%; insomnia in other sleep disorders 2.2%, and insomnia due to substance use 0.2%. Among subjects with PI, subsyndromal depression was diagnosed in 53.7%. CONCLUSIONS Nearly one third of Korean elderly individuals suffer from insomnia and insomnia patients showed diverse comorbid conditions, especially depressive symptoms. By establishing insomnia subtypes, we can plan to treat comorbid conditions as well as insomnia itself.

Different fates of excessive daytime sleepiness: survival analysis for remission.

Excessive daytime sleepiness (EDS) is a symptom frequently presented in sleep clinics. Only a paucity of data has addressed clinical courses of sleep disorders with EDS. Therefore, we sought to compare clinical outcomes of patients presenting EDS.

Subjective memory complaints in an elderly population with poor sleep quality.

ABSTRACT Objectives: The association between sleep disturbances and cognitive decline in the elderly has been putative and controversial. We evaluated the relation between subjective sleep quality and cognitive function in the Korean elderly. Method: Among 459 community-dwelling subjects, 352 subjects without depression or neurologic disorders (mean age 68.2 ± 6.1) were analyzed in this study. All the participants completed the Korean version of the consortium to establish a registry for Alzheimers disease neuropsychological battery (CERAD-KN) as an objective cognitive measure and subjective memory complaints questionnaire (SMCQ). Based on the Pittsburgh sleep quality index, two types of sleepers were defined: ‘good sleepers’ and ‘poor sleepers’. Results: There were 192 good sleepers (92 men) and 160 poor sleepers (51 men). Poor sleepers reported more depressive symptoms and more use of sleep medication, and showed higher SMCQ scores than good sleepers, but there was no difference in any assessments of CERAD-KN. In the regression analysis, depressive symptoms and subjective sleep quality were associated with subjective memory complaints (β = 0.312, p < 0.001; β = 0.163, p = 0.005). Conclusion: In the elderly without depression, poor sleep quality was associated with subjective memory complaints, but not with objective cognitive measures. As subjective memory complaints might develop into cognitive disorders, poor sleep quality in the elderly needs to be adequately controlled.

Symptom Severity of Restless Legs Syndrome Predicts Its Clinical Course

OBJECTIVE This study examines the clinical course of restless legs syndrome according to its severity and factors associated with the remission of restless legs syndrome symptoms. METHODS The remission or persistence of restless legs syndrome symptoms was investigated by considering patients with restless legs syndrome at the sleep clinic of Seoul National University Bundang Hospital. All subjects were observed for at least 18 months, and an incidence of remission was defined as having no restless legs syndrome symptoms for at least 1 year. Restless legs syndrome severity was evaluated by the International Restless Legs Syndrome Study Group Rating Scale. RESULTS A total of 306 patients participated in this study. Over the observation periods of 4.1 ± 1.6 years, the cumulative incidence of remission is 32.5% (95% confidence interval [CI], 27.0-38.0) and decreased with baseline restless legs syndrome severity (P < .001): 60% (95% CI, 44.9-75.1), 44% (95% CI, 34.4-53.6), and 16.7% (95% CI, 10.6-22.8) in mild, moderate, and severe to very severe restless legs syndrome cases, respectively. Most cases of remission (82/96) were observed within 1 year, and the remission occurred sooner for mild restless legs syndrome. The hazard ratios of remission by Cox proportional hazards model were lower for moderate (0.556; 95% CI, 0.340-0.909) and severe to very severe (0.193; 95% CI, 0.108-0.343) restless legs syndrome than for mild restless legs syndrome. The remission incidence was lower for those patients who had a family history of restless legs syndrome and were older at restless legs syndrome diagnosis. CONCLUSIONS Mild restless legs syndrome severity, no family history, and young age at restless legs syndrome diagnosis were significant predictors of restless legs syndrome remission. More than 80% of patients with severe restless legs syndrome showed a chronic clinical course.