An association between sleep duration and a wide spectrum of diseases has been reported, but little is known about its relationship with bone mineral density (BMD). Previously conducted studies in Korea and abroad have reported results that are controversial. The present study sought to assess whether sleep duration can be considered an independent risk factor of osteoporosis.
We included participants over the age of 60 years with data on self-reported habitual sleep duration and BMD measured with dual X-ray absorptiometry. Comprehensive data on the study sample was obtained from the Korea National Health and Nutritional Survey performed from 2008 to 2010. Sex-stratified multiple regression analyses were conducted with adjustments for possible confounding factors.
There was a significant inverse dose-dependent association between sleep duration and BMD measured at total hip, femur neck, and lumbar spine for women and total hip and femur neck for men. Sex-stratified regression analyses adjusted for age and body mass index revealed that sleep duration had a negative correlation with BMD at total hip and femoral neck for both women (β = -0.0048; P = 0.0172 for total hip, β = -0.0037; P = 0.0303 for femur neck) and men (β = -0.0057; P = 0.0218 for total hip, β = -0.0057; P = 0.0143 for femur neck). For women, the significance remained after further adjustment of confounding variables.
Prolonged sleep duration appears to have a significant association with lower total hip and femur neck BMD in elderly women but not in elderly men.
Citations
Analysis of outpatient visits to primary care offers essential data for residency training by understanding 'reasons for encounter (RFE).' This study was designed to recognize the effect of population aging on demographic characteristics and RFEs.
We included all patients who had visited family practice clinic in Kyung Hee University Hospital in Seoul during each first 5 working days of September, October, and November in 2001 and 2008. New patients included those who hadn't visited within the last 6 months or more. Information on each patient's age, sex, and reason for encounter was obtained from the electronic medical record. The RFEs were compared using International Classification of Primary Care (ICPC)-2-E.
Mean age of overall outpatients was 50.5 and 52.4 years in 2001 and 2008 respectively. The number of new outpatient visits increased from 215 (21.3%) to 326 (29.7%) between 2001 and 2008 (P < 0.001) along with the number of patients aged 65 or more from 7.4% to 12.0% (P = 0.08). Mean age of established patients was 52.5 and 56.9 years (P < 0.001), and the patients aged 65 or more was 14.1% and 35.8% (P < 0.001) in 2001 and 2008 respectively. Analysis by ICPC-2-E revealed a decrease in chapter A in 2008 (P = 0.03) and an increase in chapter F, L, and X (P = 0.01, 0.003, <0.001). Component 1 had increased (P = 0.01), and component 2 had decreased (P = 0.04) in proportion.
Changes in population composition have brought a shift of the distribution of age in outpatients, more significantly in follow-up patients. Comparison by ICPC-2-E showed changes in RFEs of new patients between 2001 and 2008.