Association between nonalcoholic fatty liver disease and left ventricular diastolic dysfunction: A 7-year retrospective cohort study of 3,380 adults using serial echocardiography

AIM

Left ventricular diastolic dysfunction (LVDD) has been observed in people with nonalcoholic fatty liver disease (NAFLD) in cross-sectional studies but the causal relationship is unclear. This study aimed to investigate the impact of NAFLD and the fibrotic progression of the disease on the development of LVDD, assessed by serial echocardiography, in a large population over a 7-year longitudinal setting.

METHODS

This retrospective cohort study included the data of 3,380 subjects from a medical health check-up program. We defined subjects having NAFLD by abdominal ultrasonography and assessed significant liver fibrosis by the aspartate transaminase (AST) to platelet ratio index (APRI), the NAFLD fibrosis score (NFS), and the fibrosis-4 (FIB-4) index. LVDD was defined using serial echocardiography. A parametric Cox proportional hazards model was used.

RESULTS

During 11,327 person-years of follow-up, there were 560 (16.0 %) incident cases of LVDD. After adjustment for multiple risk factors, subjects with NAFLD showed an increased adjusted hazard ratio (aHR) of 1.21 (95 % confidence interval [CI]=1.02-1.43) for incident LVDD compared to those without. The risk of LV diastolic dysfunction increased progressively with increasing degree of hepatic steatosis (P< 0.001). Compared to subjects without NAFLD, the multivariable-aHR (95 % CI) for LVDD in subjects with APRI < 0.5 and APRI ≥ 0.5 were 1.20 (1.01-1.42) and 1.36 (0.90-2.06), respectively (P= 0.036), while other fibrosis prediction models (NFS and FIB-4 index) showed insignificant results.

CONCLUSIONS

This study demonstrated that NAFLD was associated with an increased risk of LVDD in a large cohort. More severe forms of hepatic steatosis and/or significant liver fibrosis may increase the risk of developing LVDD.

Development and validation of multivariable quantitative ultrasound for diagnosing hepatic steatosis

This study developed and validated multivariable quantitative ultrasound (QUS) model for diagnosing hepatic steatosis. Retrospective secondary analysis of prospectively collected QUS data was performed. Participants underwent QUS examinations and magnetic resonance imaging proton density fat fraction (MRI-PDFF; reference standard). A multivariable regression model for estimating hepatic fat fraction was determined using two QUS parameters from one tertiary hospital (development set). Correlation between QUS-derived estimated fat fraction(USFF) and MRI-PDFF and diagnostic performance of USFF for hepatic steatosis (MRI-PDFF ≥ 5%) were assessed, and validated in an independent data set from the other health screening center(validation set). Development set included 173 participants with suspected NAFLD with 126 (72.8%) having hepatic steatosis; and validation set included 452 health screening participants with 237 (52.4%) having hepatic steatosis. USFF was correlated with MRI-PDFF (Pearson r = 0.799 and 0.824; development and validation set). The model demonstrated high diagnostic performance, with areas under the receiver operating characteristic curves of 0.943 and 0.924 for development and validation set, respectively. Using cutoff of 6.0% from development set, USFF showed sensitivity, specificity, positive predictive value, and negative predictive value of 87.8%, 78.6%, 81.9%, and 85.4% for diagnosing hepatic steatosis in validation set. In conclusion, multivariable QUS parameters-derived estimated fat fraction showed high diagnostic performance for detecting hepatic steatosis.

Increased risk of incident diabetes in patients with MAFLD not meeting the criteria for NAFLD

We aimed to compare the risk of incident diabetes according to fatty liver disease (FLD) definition, focusing on the comparison between those who met criteria for either metabolic dysfunction-associated fatty liver disease (MAFLD) or nonalcoholic fatty liver disease (NAFLD) but not the other. This was a 5.0-year (interquartile range, 2.4-8.2) retrospective longitudinal cohort study of 21,178 adults who underwent at least two serial health checkup examinations. The presence of hepatic steatosis was determined by abdominal ultrasonography at the first health examination. Cox proportional hazard analyses were used to compare the risk of incident diabetes among five groups. Incident diabetes cases occurred in 1296 participants (6.1%). When non-FLD without metabolic dysfunction (MD) group was set as a reference, the risk of incident diabetes increased in the order of NAFLD-only, non-FLD with MD, both FLD, and MAFLD-only groups. The presence of excessive alcohol consumption and/or hepatitis B virus (HBV)/hepatitis C virus (HCV) infection, FLD, and MD synergistically increased the risk of incident diabetes. MAFLD-only group showed a greater increase in incidence of diabetes than non-FLD with MD and NAFLD-only groups. The interaction among excessive alcohol consumption, HBV/HCV infection, MD, and hepatic steatosis on the development of diabetes should not be overlooked.

MAFLD and NAFLD in the prediction of incident chronic kidney disease

Whether metabolic dysfunction-associated fatty liver disease (MAFLD) can replace nonalcoholic fatty liver disease (NAFLD) is under debate. This study evaluated which definition better predicted incident chronic kidney disease (CKD). This was a 5.3-year (range, 2.8-8.3) retrospective cohort study of 21,713 adults who underwent at least two serial health examinations. Cox analyses were used to compare the risk of incident CKD among non-fatty liver disease (FLD) without metabolic dysregulation (MD; reference), non-FLD with MD, MAFLD-only, NAFLD-only, or both-FLD groups. Non-FLD with MD group (hazard ratio [HR] 1.23, 95% confidence interval [CI] 1.00-1.53), both-FLD group (HR 1.50, 95% CI 1.19-1.89), and MAFLD-only group (HR 1.97, 95% CI 1.49-2.60), but not NAFLD-only group (HR 1.06, 95% CI 0.63-1.79) demonstrated an increased risk of CKD. The increased risk of CKD was significant in MAFLD subgroups with overweight/obesity (HR 2.94, 95% CI 1.91-4.55), diabetes (HR 2.20, 95% CI 1.67-2.90), MD only (HR 1.50, 95% CI 1.19-1.89), excessive alcohol consumption (HR 2.71, 95% CI 2.11-3.47), and viral hepatitis (HR 2.38, 95% CI 1.48-3.84). The switch from NAFLD to MAFLD criteria may identify a greater number of individuals at CKD risk. The association was also significant in MAFLD patients with excessive alcohol consumption or viral hepatitis.

Low skeletal muscle mass Accompanied by Abdominal Obesity Additively Increases the Risk of Incident Type 2 Diabetes

CONTEXT

Low skeletal muscle mass often accompanies abdominal obesity in the aging process.

OBJECTIVE

We aimed to investigate the effect of reduced skeletal muscle mass and its interaction with abdominal obesity on incident type 2 diabetes.

METHODS

This retrospective longitudinal study included a total of 36,304 diabetes-free Koreans who underwent two or more health check-ups annually or biennially. Appendicular skeletal muscle mass was measured by bioelectrical impedance analysis and was presented as a skeletal muscle mass index (SMI) adjusted for body weight. Pre-sarcopenia was defined as an SMI <1 standard deviation of the sex-specific mean for a healthy young reference group. Abdominal obesity was defined using waist circumference ≥ 90 cm for men and ≥ 85 cm for women. Participants were classified into four groups of normal, pre-sarcopenia alone, abdominal obesity alone, and pre-sarcopenic obesity according to initial body composition.

RESULTS

The cumulative incidence of diabetes was 9.1% during the 7-year follow-up. Compared with the highest tertile, the lowest sex-specific SMI tertile was significantly associated with a greater risk of incident type 2 diabetes (adjusted hazard ratio [HR] = 1.31, 95% confidence interval [CI] 1.18-1.45) in a fully adjusted model. Pre-sarcopenic obesity significantly increased incident diabetes risk (adjusted HR = 1.57, 95% CI 1.42-1.73) compared with normal body composition, pre-sarcopenia alone, or abdominal obesity alone.

CONCLUSIONS

Low skeletal muscle mass and its coexistence with abdominal obesity additively increased the risk of incident type 2 diabetes independent of the glycometabolic parameters.

The Prevalence of Thyroid Dysfunction in Korean Women Undergoing Routine Health Screening: A Cross-Sectional Study

Background: Women are more likely to experience thyroid diseases than men. However, thyroid dysfunction risk in women undergoing the menopausal transition remains largely unknown. We explored the prevalence of thyroid dysfunction across menopausal stages. Methods: We conducted a cross-sectional study of 53,230 women aged 40 years or older who underwent health screening between 2014 and 2018. Menopausal stages were categorized into 4 based on the Stages of Reproductive Aging Workshop +10 criteria. A multinomial logistic regression model was used to estimate the prevalence ratios (PRs) with confidence intervals [CIs] for thyroid dysfunction in menopausal stages compared with that in premenopause. Results: The prevalence of overt hypothyroidism was significantly increased during late transition and postmenopause; it remained significant after further adjustments for potential confounders (age, center, year of examination, age at menarche, parity, education level, smoking status, alcohol consumption, physical activity, and body mass index) with corresponding multivariable-adjusted PRs [CI] of 1.61 [1.12-2.30] and 1.66 [1.16-2.37] in the late transition and postmenopausal stages, respectively. A significant increase in the prevalence of subclinical hypothyroidism was also observed in the late transition and postmenopausal stage with multivariable-adjusted PRs [CI] of 1.22 [1.06-1.40] and 1.24 [1.07-1.44], respectively. In contrast, subclinical and overt hyperthyroidism were not significantly associated with menopausal stages. Conclusions: In this study of pre- and perimenopausal Korean women, the prevalence of overt and subclinical hypothyroidism was significantly elevated in the late menopausal transition. Future prospective studies are warranted to investigate the clinical and prognostic significance of thyroid dysfunction in women during menopausal transition.

Bone-density testing interval and transition to osteoporosis in differentiated thyroid carcinoma patients on TSH suppression therapy

OBJECTIVE

Thyrotropin (TSH) suppression therapy is a standard treatment after surgery for differentiated thyroid carcinoma (DTC). It may be associated with osteoporosis in postmenopausal women. However, there are no guidelines for bone mineral density (BMD) testing intervals to screen for osteoporosis in these patients. Therefore, we evaluated the timing of repeated BMD testing in DTC patients with TSH suppression according to baseline T-scores.

DESIGN, PATIENTS, AND MEASUREMENT

We retrospectively evaluated 658 DTC patients who underwent BMD testing more than twice between January 2007 and January 2020. A 1:3 propensity score matching was conducted to compare the timing of repeated BMD tests between the DTC and non-DTC groups. We stratified the participants into four groups based on their baseline T-scores: normal (-1.00 or higher), mild osteopenia (-1.01 to -1.49), moderate osteopenia (-1.50 to -1.99), and severe osteopenia (-2.00 to -2.49). Additionally, the 10% of patients in each group that transitioned to osteoporosis were analysed.

RESULTS

The estimated BMD testing interval for 10% of patients who developed osteoporosis was 85 months for patients with initially mild osteopenia, 65 months for those with moderate osteopenia, and 15 months for those with severe osteopenia in the DTC group. In the non-DTC group, the testing intervals for mild, moderate, and severe osteopenia were 98, 57, and 13 months, respectively. On multivariate analysis, baseline T-score (mild osteopenia: hazard ratio [HR] 5.91, p = .105; moderate osteopenia: HR, 25.27, p = .02; and severe osteopenia: HR, 134.82, p < .001) and duration of TSH suppression (tertile 2: HR, 2.25, p = .005; Tertile 3: 1.78, p = .033) were independent risk factors for osteoporosis in the DTC group.

CONCLUSION

This study provides guidance for the timing of repeated BMD tests in women over 50 years of age with TSH suppression. The rescreening interval for BMD testing can be modified based on the baseline T-score. The appropriate BMD testing intervals in female DTC patients were similar to those in non-DTC females.

Delayed heart rate recovery after exercise predicts development of metabolic syndrome: A retrospective cohort study

AIMS/INTRODUCTION

Several cross-sectional studies have shown that delayed heart rate recovery (HRR) after exercise is associated with the development of metabolic syndrome (MetS). However, there has been a lack of comprehensively designed longitudinal studies. Therefore, our aim was to evaluate the longitudinal association of delayed HRR following a graded exercise treadmill test (GTX) with incident MetS.

MATERIALS AND METHODS

This was a retrospective longitudinal cohort study of participants without MetS, diabetes, or cardiovascular diseases. The HRR was calculated as the peak heart rate minus the resting heart rate after a 1 min rest (HRR1), a 2 min rest (HRR2), and a 3 min rest (HRR3). Multivariate Cox proportional hazards analysis was performed to investigate the association between HRR and development of MetS.

RESULTS

There were 676 (31.2%) incident cases of MetS identified during the follow-up period (9,683 person-years). The only statistically significant relationship was between HRR3 and the development of MetS. The hazard ratios (HRs) (95% confidence interval [CI]) of incident MetS comparing the first and second tertiles to the third tertile of HRR3 were 1.492 (1.146-1.943) and 1.277 (1.004-1.624) with P = 0.003 after adjustment for multiple risk factors. As a continuous variable, the HR (95% CI) of incident MetS associated with each one-beat decrease in HRR3 was 1.015 (1.005-1.026) with P = 0.004 after full adjustments. An HRR3 value ≤45 beats per minute (bpm) was associated with a higher risk of incident MetS compared with values >45 bpm, with an HR (95% CI) of 1.304 (1.061-1.602) and P = 0.001.

CONCLUSIONS

The slow phase of HRR, particularly HRR3, might be more sensitive at predicting the risk of MetS.

Effects of Aerobic and Resistance Exercise Training on Carotid Intima-Media Thickness in Abdominal Obese Women

Aims: The purpose of this study was to investigate the effects of a 12-week aerobic and resistance training program on waist circumference (WC) and carotid intima-media thickness (CIMT) in abdominal obese middle-aged women. Methods: Subjects were 40 middle-aged women with abdominal obesity (WC >85 cm) but no specific diseases. Subjects were divided into a combined exercise group (aerobic and resistance exercise) and a control group that did not participate in any lifestyle modification. Carotid variables were measured using B-mode ultrasound. A treadmill exercise test was conducted to directly assess the peak oxygen uptake (VO₂peak). Differences in the carotid variables and relative changes between baseline and after 12 weeks were evaluated. Results: After 12 weeks, body weight (70.6 ± 7.8 to 65.6 ± 6.3 kg, P < 0.05), WC (88.8 ± 3.6 to 85.6 ± 3.1 cm, P < 0.01), total cholesterol (215.5 ± 38.4 to 188.2 ± 25.8 mmHg, P < 0.05), low-density lipoprotein cholesterol (150.5 ± 30.6 to 131.6 ± 22.3 mmHg, P < 0.05), triglycerides (164.5 ± 82.3 to 119.9 ± 60.6 mmHg, P < 0.01), VO₂peak (24.2 ± 6.2 to 28.7 ± 4.4 mL/kg/min, P < 0.01), and CIMT (0.61 ± 0.13 to 0.58 ± 0.12 mm, P < 0.05) were significantly improved in the combined exercise group but not in the control group; changes in CIMT were associated with changes in WC decrease (r = 0.41, P < 0.01) and VO₂peak (r = -0.53, P < 0.01). Conclusions: Combined exercise training in abdominal obese women decreased CIMT; these changes were also associated with reduced WC and improved VO₂peak.

A Simple and High-throughput LC-MS/MS Method for Simultaneous Measurement of Nicotine, Cotinine, 3-OH cotinine, Nornicotine, and Anabasine in Urine and its Application in the General Korean Population

Measuring nicotine metabolites is the most objective method for identifying smoke exposure. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) can measure multiple metabolites and is sensitive enough to detect low concentrations of metabolites. Therefore, we developed a simple and high-throughput method for measuring nicotine, cotinine, trans-3'-hydroxycotinine (3-OH cotinine), nornicotine, and anabasine for population-based studies using LC-MS/MS. Each 30 µl of urine sample was diluted with 90 µL of acetonitrile containing five deuterated internal standards. Chromatographic separation used a C18 column and LC-MS/MS analysis was performed with a multiple reaction monitoring mode. The chromatographic run time for each sample was 6.5 min. The method was validated by evaluating selectivity, interference, limit of detection, lower limit of quantification, precision, accuracy, linearity, extraction recovery, matrix effect, and carry-over according to guidelines. Our methods required a short preparation time (about 20 minutes) while simultaneously measuring five markers for smoking status. No endogenous or exogenous interference was found. Our method showed excellent precision and accuracy: within-run CV 2.9-9.4%, between-run CV 4.8-8.7%, and bias -10.1 to 5.3%. Linear dynamic ranges were 1-10,000 ng/mL for nicotine, nornicotine, and anabasine; 2-5,000 ng/mL for cotinine; and 5-15,000 ng/mL for 3-OH cotinine. Extraction recovery was consistent (87-109%) across concentrations. No significant matrix effect or carry-over was observed. The validated method was applied to 849 urine samples. In samples from the 125 current smokers, nicotine, cotinine, 3-OH cotinine, nornicotine, and anabasine were detected in 97.6%, 99.2%, 98.4%, 96.8%, and 87.2%, respectively. No markers were detected in 93.9% of 609 non-smokers. The overlapping detection of multiple markers made it possible to identify smoking status even in current smokers with low concentration of cotinine. Our LC-MS/MS method using a simple sample preparation technique is sensitive and effective for screening of smoking status in the general population.

The Protective Effects of Increasing Serum Uric Acid Level on Development of Metabolic Syndrome

BACKGROUND

It has not been determined whether changes in serum uric acid (SUA) level are associated with incident metabolic syndrome (MetS). The aim of the current study was to investigate the relationship between changes in SUA level and development of MetS in a large number of subjects.

METHODS

In total, 13,057 subjects participating in a medical health check-up program without a diagnosis of MetS at baseline were enrolled. Cox proportional hazards models were used to test the independent association of percent changes in SUA level with development of MetS.

RESULTS

After adjustment for age, systolic blood pressure, body mass index, fat-free mass (%), estimated glomerular filtration rate, smoking status, fasting glucose, triglyceride, low density lipoprotein cholesterol, high density lipoprotein cholesterol, and baseline SUA levels, the hazard ratios (HRs) (95% confidence intervals [CIs]) for incident MetS in the second, third, and fourth quartiles compared to the first quartile of percent change in SUA level were 1.055 (0.936 to 1.190), 0.927 (0.818 to 1.050), and 0.807 (0.707 to 0.922) in male (P for trend <0.001) and 1.000 (0.843 to 1.186), 0.744 (0.615 to 0.900), and 0.684 (0.557 to 0.840) in female (P for trend <0.001), respectively. As a continuous variable in the fully-adjusted model, each one-standard deviation increase in percent change in SUA level was associated with an HR (95% CI) for incident MetS of 0.944 (0.906 to 0.982) in male (P=0.005) and 0.851 (0.801 to 0.905) in female (P<0.001).

CONCLUSION

The current study demonstrated that increasing SUA level independently protected against the development of MetS, suggesting a possible role of SUA as an antioxidant in the pathogenesis of incident MetS.

Utility of Serum Albumin for Predicting Incident Metabolic Syndrome according to Hyperuricemia

BACKGROUND

Serum albumin and uric acid have been positively linked to metabolic syndrome (MetS). However, the association of MetS incidence with the combination of uric acid and albumin levels has not been investigated. We explored the association of albumin and uric acid with the risk of incident MetS in populations divided according to the levels of these two parameters.

METHODS

In this retrospective longitudinal study, 11,613 non-MetS participants were enrolled among 24,185 individuals who had undergone at least four annual check-ups between 2006 and 2012. The risk of incident MetS was analyzed according to four groups categorized by the sex-specific medians of serum albumin and uric acid.

RESULTS

During 55,407 person-years of follow-up, 2,439 cases of MetS developed. The risk of incident MetS increased as the uric acid category advanced in individuals with lower or higher serum albumin categories with hazard ratios (HRs) of 1.386 (95% confidence interval [CI], 1.236 to 1.554) or 1.314 (95% CI, 1.167 to 1.480). However, the incidence of MetS increased with higher albumin levels only in participants in the lower uric acid category with a HR of 1.143 (95% CI, 1.010 to 1.294).

CONCLUSION

Higher levels of albumin were associated with an increased risk of incident MetS only in individuals with lower uric acid whereas higher levels of uric acid were positively linked to risk of incident MetS regardless of albumin level.

Relationship Between Relative Skeletal Muscle Mass and Nonalcoholic Fatty Liver Disease: A 7-Year Longitudinal Study

Nonalcoholic fatty liver disease (NAFLD) has been associated with relative skeletal muscle mass in several cross-sectional studies. We explored the effects of relative skeletal muscle mass and changes in relative muscle mass over time on the development of incident NAFLD or the resolution of baseline NAFLD in a large, longitudinal, population-based 7-year cohort study. We included 12,624 subjects without baseline NAFLD and 2943 subjects with baseline NAFLD who underwent health check-up examinations. A total of 10,534 subjects without baseline NAFLD and 2631 subjects with baseline NAFLD were included in analysis of changes in relative skeletal muscle mass over a year. Subjects were defined as having NAFLD by the hepatic steatosis index, a previously validated NAFLD prediction model. Relative skeletal muscle mass was presented using the skeletal muscle mass index (SMI), a measure of body weight-adjusted appendicular skeletal muscle mass, which was estimated by bioelectrical impedance analysis. Of the 12,624 subjects without baseline NAFLD, 1864 (14.8%) developed NAFLD during the 7-year follow-up period. Using Cox proportional hazard analysis, compared with the lowest sex-specific SMI tertile at baseline, the highest tertile was inversely associated with incident NAFLD (adjusted hazard ratio [AHR] = 0.44, 95% confidence interval [CI] = 0.38-0.51) and positively associated with the resolution of baseline NAFLD (AHR = 2.09, 95% CI = 1.02-4.28). Furthermore, compared with the lowest tertile of change in SMI over a year, the highest tertile exhibited a significant beneficial association with incident NAFLD (AHR = 0.69, 95% CI = 0.59-0.82) and resolution of baseline NAFLD (AHR = 4.17, 95% CI = 1.90-6.17) even after adjustment for baseline SMI. Conclusion: Increases in relative skeletal muscle mass over time may lead to benefits either in the development of NAFLD or the resolution of existing NAFLD.

Increase in relative skeletal muscle mass over time and its inverse association with metabolic syndrome development: a 7-year retrospective cohort study

BACKGROUND

Skeletal muscle mass was negatively associated with metabolic syndrome prevalence in previous cross-sectional studies. The aim of this study was to investigate the impact of baseline skeletal muscle mass and changes in skeletal muscle mass over time on the development of metabolic syndrome in a large population-based 7-year cohort study.

METHODS

A total of 14,830 and 11,639 individuals who underwent health examinations at the Health Promotion Center at Samsung Medical Center, Seoul, Korea were included in the analyses of baseline skeletal muscle mass and those changes from baseline over 1 year, respectively. Skeletal muscle mass was estimated by bioelectrical impedance analysis and was presented as a skeletal muscle mass index (SMI), a body weight-adjusted appendicular skeletal muscle mass value. Using Cox regression models, hazard ratio for developing metabolic syndrome associated with SMI values at baseline or changes of SMI over a year was analyzed.

RESULTS

During 7 years of follow-up, 20.1% of subjects developed metabolic syndrome. Compared to the lowest sex-specific SMI tertile at baseline, the highest sex-specific SMI tertile showed a significant inverse association with metabolic syndrome risk (adjusted hazard ratio [AHR] = 0.61, 95% confidence interval [CI] 0.54-0.68). Furthermore, compared with SMI changes < 0% over a year, multivariate-AHRs for metabolic syndrome development were 0.87 (95% CI 0.78-0.97) for 0-1% changes and 0.67 (0.56-0.79) for > 1% changes in SMI over 1 year after additionally adjusting for baseline SMI and glycometabolic parameters.

CONCLUSIONS

An increase in relative skeletal muscle mass over time has a potential preventive effect on developing metabolic syndrome, independently of baseline skeletal muscle mass and glycometabolic parameters.

Serum calcium changes and risk of type 2 diabetes mellitus in Asian population

AIMS

We examined the association between changes in serum calcium levels with the incidence of type 2 diabetes mellitus (T2DM) in apparently healthy South Korean subjects.

METHODS

A retrospective longitudinal analysis was conducted with subjects who had participated in comprehensive health check-ups at least four times over a 7-year period (between 2006 and 2012). In total, 23,121 subjects were categorized into tertiles based on changes in their albumin-adjusted serum calcium levels. Multivariate Cox regression models were fitted to assess the association between changes in serum calcium levels during follow-up and the relative risk of diabetes incidence.

RESULTS

After a median follow-up of 57.4months, 1,929 (8.3%) new cases of T2DM occurred. Simple linear regression analysis showed serum calcium level changes correlated positively with changes in HbA1c and fasting plasma glucose (FPG) levels (B=5.72, p<0.001 for FPG; B=0.13, p<0.001 for HbA1c). An increase in albumin-adjusted serum calcium levels during follow-up was related to an increased risk of T2DM. After adjustment for potential confounders, the risk of T2DM was 1.6 times greater for subjects whose albumin-adjusted serum calcium levels were in the highest change tertile during follow-up than for subjects whose levels were in the lowest tertile (HR 1.65, 95% CI 1.44-1.88, P<0.001).

CONCLUSIONS

The elevation of albumin-adjusted serum calcium levels was associated with an increased risk of T2DM, independent of baseline glycemic status.

Hormetic effect of triiodothyronine in metabolically healthy obese persons

PURPOSE

Metabolically healthy obese is the designation for a subgroup of obese individuals with normal metabolic features. However, metabolically healthy obese individuals are prone to developing metabolic syndrome. Serum triiodothyronine (T3) levels are associated with various metabolic risk factors including obesity. Therefore, this longitudinal study aimed to explore the possible correlation between serum T3 concentration and the onset of MetS in metabolically healthy obese persons.

METHODS

A retrospective analysis of 992 euthyroid metabolically healthy obese subjects who underwent yearly health checkups over 6 years was performed. The risk of developing MetS was analyzed according to baseline T3 concentration, as both tertiles and continuous values, using Cox regression analysis. Serum T3 concentration at the end of the study was further analyzed according to the final metabolic phenotype.

RESULTS

The incidence of MetS was 464 cases (46.8%) during a median 3.3 years of follow-up (3168.2 person-years). The hazard ratio for incident MetS enhanced with increasing T3 concentration in both the crude and adjusted models. Higher baseline serum T3 levels were associated with unfavorable metabolic parameters. However, over the course of the study, serum T3 concentration significantly increased in subjects who sustained metabolically healthy phenotypes compared to baseline value, while it significantly decreased in the subjects who developed MetS.

CONCLUSIONS

Serum T3 concentrations exhibit distinct associations with development of metabolic syndrome in euthyroid metabolically healthy obese persons, but its increment during follow-up maintained metabolically healthy state. These findings suggest that serum T3 modulation might be an adaptive process to protect against metabolic deterioration.

Increase in serum albumin concentration is associated with prediabetes development and progression to overt diabetes independently of metabolic syndrome

Aim

Serum albumin concentration is associated with both type 2 diabetes and metabolic syndrome (MetS). We sought to investigate whether baseline serum albumin and change in serum albumin could be independent risk factors for prediabetes in subjects without MetS. We further examined the effect of serum albumin on progression to overt diabetes in subjects who developed prediabetes.

Methods

Among 10,792 participants without diabetes and MetS who consecutively underwent yearly health check-ups over six years, 9,807 subjects without incident MetS were enrolled in this longitudinal retrospective study. The risk of developing prediabetes (impared fasting glucose or hemoglobin A1c) was analyzed according to baseline and percent change in serum albumin concentration using Cox regression analysis. Serial changes in serum albumin concentration were measured from baseline to one year before prediabetes diagnosis, and then from the time of prediabetes diagnosis to progression to overt diabetes or final follow-up.

Results

A total of 4,398 incident cases of prediabetes developed during 35,807 person-years (median 3.8 years). The hazard ratio for incident prediabetes decreased as percent change in serum albumin concentration (quartiles and per 1%) increased in a crude and fully adjusted model. However, baseline serum albumin concentration itself was not associated with prediabetic risk. Serum albumin levels kept increasing until the end of follow-up in prediabetic subjects who returned to normal glycemic status, whereas these measures did not change in prediabetic subjects who developed type 2 diabetes. Serum albumin concentration measured at the end of follow-up was the highest in the regression group, compared to the stationary (p = 0.014) or progression groups (p = 0.009).

Conclusions

Increase in serum albumin concentration might protect against early glycemic deterioration and progression to type 2 diabetes even in subjects without MetS.

Serum 25-hydroxyvitamin D cutoffs for functional bone measures in postmenopausal osteoporosis

This study sought to determine the minimal serum 25-hydroxyvitamin D [25(OH)D] concentration required to maintain bone health in postmenopausal women with low bone mass. A serum 25(OH)D concentration of 20 ng/mL rather than 30 ng/mL was appropriate for bone health.

INTRODUCTION

There is no consensus on the minimal serum 25-hydroxyvitamin D [25(OH)D] concentration required to maintain bone health. The aim of this study was to investigate the relationship between 25(OH)D measured via liquid chromatography-mass spectrometry (LC-MS/MS), which is the current gold standard, and biochemical markers of bone turnover, PTH, and bone mineral densitometry (BMD).

METHODS

The medical records of 750 postmenopausal women newly diagnosed with osteoporosis or osteopenia at Samsung Medical Center from 2009 to 2014 were investigated. Subjects were divided into four groups according to serum 25(OH)D concentration: <10, 10-20, 20-30, and ≥30 ng/mL. Serum concentrations of bone-specific alkaline phosphatase (BS-ALP), carboxy-terminal cross-linking telopeptide of type 1 collagen (CTx), intact PTH (iPTH), and BMD were compared among the four groups using analysis of covariance. Thresholds of 25(OH)D were then assessed using spline plots and locally weighted regression smoothing (LOESS) plots.

RESULTS

25(OH)D was negatively correlated with serum BS-ALP, CTx, and iPTH. Only femur neck and total femur BMD had significant positive relationships with 25(OH)D. Cutoff values of 11.9 and 9.7 ng/mL were estimated from the spline plots of femur neck and total femur BMD, respectively. For iPTH, the LOESS plot showed a steep decrease to a serum 25(OH)D concentration of about 20 ng/mL, followed by a plateau.

CONCLUSIONS

According to this study, a serum 25(OH)D concentration of 20 ng/mL, rather than 30 ng/mL, was appropriate for bone health.

Decline in lung function rather than baseline lung function is associated with the development of metabolic syndrome: A six-year longitudinal study

This study was conducted to investigate whether baseline lung function or change in lung function is associated with the development of metabolic syndrome (MS) in Koreans. We analyzed clinical and laboratory data from 3,768 Koreans aged 40–60 years who underwent medical check-ups over a six-year period between 2006 and 2012. We calculated the percent change in forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁) over the study period. We tested for an association between baseline lung function or lung function change during the follow-up period and the development of MS. The 533 subjects (14.1%) developed MS after the six-year follow-up. The baseline FVC and FEV₁ were not different between the subjects who developed MS after six years and the subject without MS after six years. The percent change in FVC over six years in subjects who developed MS after six years was higher than that in subjects who did not develop MS (-5.75 [-10.19 –-1.17], -3.29 [-7.69–1.09], respectively, P = 0.001). The percent change in FVC over six years was associated with MS development after adjusting for age, sex, body mass index (BMI), glucose, HDL, triglyceride, waist circumferences (WC), and systolic blood pressure. However, these association was not significant after adjusting for change of BMI and change of WC over six years (P = 0.306). The greater change in vital capacity over six years of follow-up was associated with MS development, predominantly due to obesity and abdominal obesity. The prospective study is needed to determine the relationship between lung function decline and MS.

TSH increment and the risk of incident type 2 diabetes mellitus in euthyroid subjects

PURPOSE

Thyroid function is known to influence glucose metabolism, and thyroid-stimulating hormone is the most useful parameter in screening for thyroid dysfunction. Therefore, the aim of this study was to investigate the incidence of type 2 diabetes according to baseline thyroid-stimulating hormone level and thyroid-stimulating hormone change in euthyroid subjects.

METHODS

We identified and enrolled 17,061 euthyroid subjects without diabetes among participants who had undergone consecutive thyroid function tests between 2006 and 2012 as a part of yearly health check-up program. Thyroid-stimulating hormone changes were determined by subtracting baseline thyroid-stimulating hormone level from thyroid-stimulating hormone level at 1 year before diagnosis of diabetes or at the end of follow-up in subjects who did not develope diabetes.

RESULTS

During 84,595 person-years of follow-up, there were 956 new cases of type 2 diabetes. Cox proportional hazards models showed the risk of incident type 2 diabetes was significantly increased with each 1 μIU/mL increment in TSH after adjustment for multiple confounding factors (hazard ratio = 1.13, 95% confidence interval: 1.07-1.20, P < 0.001). Compared with individuals in the lowest tertile (-4.08 to 0.34 μIU/mL), those in the highest thyroid-stimulating hormone change tertile (0.41-10.84 μIU/mL) were at greater risk for incident type 2 diabetes (hazard ratio = 1.25, 95% confidence interval: 1.05-1.48, P for trend = 0.011). However, baseline thyroid-stimulating hormone level and tertile were not associated with the risk for diabetes.

CONCLUSIONS

Prominent increase in thyroid-stimulating hormone concentration can be an additional risk factor for the development of type 2 diabetes in euthyroid subjects.

Increment of serum bilirubin as an independent marker predicting new-onset type 2 diabetes mellitus in a Korean population

BACKGROUND AND AIMS

Several cross-sectional studies reported that serum bilirubin concentrations had an inverse association with type 2 diabetes mellitus (T2DM) prevalence. The aim of the current study was to investigate the relationship between percentage change in bilirubin levels (PCB) and incident risk of T2DM using a longitudinal model.

METHODS AND RESULTS

22,084 participants who received regular health check-ups between 2006 and 2012 were enrolled. Multivariable-adjusted Cox regression models were used to determine the hazard ratio (HR) of incident T2DM based on PCB. PCB was determined by subtracting baseline serum bilirubin level (BB) from the bilirubin level at the end of follow-up or a year before the last date of diagnosis, dividing by BB and multiplying by 100. Compared to non-diabetics, BB was lower in the diabetic group at the initial visit. There were 20,098 participants without T2DM at the initial visit; 1253 new cases occurred during follow-up. As PCB increased, T2DM incidence also increased (P < 0.001). After adjusting for confounders, the HR of incident T2DM in the highest PCB quartile was 2.08 (95% confidence interval [CI] 1.76-2.46). This trend remained significant when PCB was analyzed as a continuous variable (HR for 1-SD increment, 1.25; 95% CI 1.19-1.31). Additional analysis comparing the rate of PCB during the follow-up period revealed that the serum bilirubin level of the Incident T2DM group increased before T2DM development and decreased rapidly thereafter compared to others (P < 0.001).

CONCLUSIONS

Bilirubin level increment over time is associated with T2DM development.

Serum Calcium and the Risk of Incident Metabolic Syndrome: A 4.3-Year Retrospective Longitudinal Study

BACKGROUND

An association between serum calcium level and risk of metabolic syndrome (MetS) has been suggested in cross-sectional studies. This study aimed to evaluate the association between baseline serum calcium level and risk of incident MetS in a longitudinal study.

METHODS

We conducted a retrospective longitudinal study of 12,706 participants without MetS who participated in a health screening program, had normal range serum calcium level at baseline (mean age, 51 years), and were followed up for 4.3 years (18,925 person-years). The risk of developing MetS was analyzed according to the baseline serum calcium levels.

RESULTS

A total of 3,448 incident cases (27.1%) of MetS developed during the follow-up period. The hazard ratio (HR) for incident MetS did not increase with increasing tertile of serum calcium level in an age- and sex-matched model (P for trend=0.915). The HRs (95% confidence interval [CI]) for incident MetS comparing the second and the third tertiles to the first tertile of baseline serum calcium level were 0.91 (95% CI, 0.84 to 0.99) and 0.85 (95% CI, 0.78 to 0.92) in a fully adjusted model, respectively (P for trend=0.001). A decreased risk of incident MetS in higher tertiles of serum calcium level was observed in subjects with central obesity and/or a metabolically unhealthy state at baseline.

CONCLUSION

There was no positive correlation between baseline serum calcium levels and incident risk of MetS in this longitudinal study. There was an association between higher serum calcium levels and decreased incident MetS in individuals with central obesity or two components of MetS at baseline.

The effect of TSH change per year on the risk of incident chronic kidney disease in euthyroid subjects

The objective of this study is to evaluate the predictive values of baseline thyroid-stimulating hormone and the rate of thyroid-stimulating hormone change within the euthyroid state on the development of chronic kidney disease. We conducted a longitudinal study in 17,067 Korean adults with normal thyroid function and no history of thyroid disease. Incident chronic kidney disease was defined as an estimated glomerular filtration rate <60 ml/min/1.73 m². The rate of thyroid-stimulating hormone change was determined by subtracting the baseline thyroid-stimulating hormone level from the thyroid-stimulating hormone level measured at the last visit prior to the diagnosis of chronic kidney disease or at the final visit in subjects without chronic kidney disease, divided by the observation period (years). Subjects were stratified into quintiles according to rates of thyroid-stimulating hormone change. During 86,583 person-years of follow-up (median follow-up 5.2 years), there were 561 incident cases of chronic kidney disease. The risk of incident chronic kidney disease was significantly higher in subjects with rapid increases (quintile 5) or decreases (quintile 1) in thyroid-stimulating hormone levels compared to the reference group (quintile 3). In fully adjusted models, the hazard ratios of quintiles 1 and 5 were 3.15 (95 % confidence interval 2.34 to 4.24; p < 0.001) and 3.37 (95 % confidence interval 2.52 to 4.51; p < 0.001), respectively. However, there was no significant association between baseline thyroid-stimulating hormone and risk of incident chronic kidney disease. The development of chronic kidney disease is associated with the rate of changes in thyroid-stimulating hormone level rather than with baseline thyroid-stimulating hormone levels.

Association Between Changes in Thyroid Hormones and Incident Type 2 Diabetes: A Seven-Year Longitudinal Study

BACKGROUND

Thyroid hormones are important regulators of glucose homeostasis. However, the association between thyroid hormones within the reference range and type 2 diabetes mellitus (T2DM) remains unclear. The aim of this study was to clarify the incidence of T2DM according to the baseline levels and changes of thyrotropin (TSH) and thyroid hormones (free thyroxine and triiodothyronine) in euthyroid subjects.

METHODS

Among the participants who consecutively underwent thyroid function tests between 2006 and 2012 through a yearly health checkup program, 6235 euthyroid subjects (3619 men and 2616 women) without T2DM were enrolled in the study. The change in each hormone was calculated by subtracting the baseline value from the level at the end of follow-up or one year before the diagnosis of diabetes.

RESULTS

During 25,692 person-years of follow-up, there were 229 new cases of T2DM. After full adjustment for potential confounders including HbA1c and fasting glucose in Cox proportional hazards models, the individuals in the highest tertile of TSH change (2.5-4.2 μIU/mL) had a greater risk of incident T2DM (hazard ratio [HR] = 1.44 [confidence interval (CI) 1.04-1.98], p = 0.027) in comparison with individuals in the lowest tertile (-4.1 to -0.5 μIU/mL). Simultaneously, the highest tertile of triiodothyronine change (16.3-104.7 ng/dL) and free thyroxine change (0.2-1.6 ng/dL) conferred protective effects against diabetes (HR = 0.60 [CI 0.43-0.85], p = 0.002, and HR = 0.34 [CI 0.24-0.48], p < 0.001, respectively) compared with those in the lowest tertile (-76.5 to -1.8 ng/dL and -0.6 to 0.0 ng/dL, respectively). These associations remained significant when each of the hormones was analyzed as a continuous variable. However, baseline levels or tertiles of TSH and thyroid hormones were not associated with the risk of diabetes.

CONCLUSIONS

Individual changes in TSH and thyroid hormones, even within the normal reference range, were an additional risk factor of incident T2DM.

Change in Serum Bilirubin Level as a Predictor of Incident Metabolic Syndrome

Aim

Serum bilirubin level was negatively associated with the prevalence of metabolic syndrome (MetS) in previous cross-sectional studies. However, bilirubin variance preceding the development of MetS has yet to be investigated. We aimed to determine the effect of change in bilirubin concentration on the risk of incident MetS in healthy Korean adults.

Methods

We conducted a retrospective longitudinal study of subjects who had undergone at least four yearly health check-ups between 2006 and 2012. Of 24,185 total individuals who received annual check-ups, 11,613 non-MetS participants with a baseline bilirubin level not exceeding 34.2 μmol/l were enrolled. We evaluated the association between percent change in bilirubin and risk of incident MetS.

Results

During 55,407 person-years of follow-up, 2,439 cases of incident MetS developed (21.0%). Baseline serum bilirubin level clearly showed no association with the development of MetS in men but an independent significant inverse association in women which attenuated (hence may be mediated) by elevated homeostatic model assessment index 2 for insulin resistance (HOMA2-IR). However, increased risk for incident MetS was observed in higher percent change in bilirubin quartiles, with hazard ratios of 2.415 (95% CI 2.094–2.785) in men and 2.156 (95% CI 1.738–2.675) in women in the fourth quartile, compared to the lowest quartile, after adjusting for age, smoking status, medication history, alanine aminotransferase, uric acid, estimated glomerular filtration rate, fasting glucose, baseline diabetes mellitus prevalence, systolic blood pressure, waist circumference, and body mass index. The hazard ratios per one standard deviation increase in percent change in bilirubin as a continuous variable were 1.277 (95% CI 1.229–1.326) in men and 1.366 (95% CI 1.288–1.447) in women.

Conclusions

Increases in serum bilirubin concentration were positively associated with a higher risk of incident MetS. Serum bilirubin increment might be a sensitive marker for the development of MetS.

Change in serum albumin concentration is inversely and independently associated with risk of incident metabolic syndrome

BACKGROUND

Low serum albumin concentration is associated with a high risk of morbidity and mortality from cardiovascular diseases. However, high serum albumin level appears to be linked to metabolic syndrome (MetS). This study aimed to dissect the relative contributions of baseline and change in serum albumin concentration to the risk of incident metabolic syndrome.

METHODS

This was a 5-year (63,060 person-years) retrospective longitudinal study of 12,567 participants without metabolic syndrome, diabetes, or cardiovascular disease who were enrolled in a health screening program. The risk of developing MetS was analyzed according to baseline and change in serum albumin concentration.

RESULTS

A total of 2582 incident cases of metabolic syndrome developed. The hazard ratio (HR) for incident MetS increased with increasing quartile of baseline serum albumin level compared with those in the lowest quartile, in a fully adjusted model (p for trend = 0.013). The HRs [95% confidence intervals (CIs)] of incident MetS comparing the second, third, and fourth quartiles to the first quartile of change in serum albumin level were 0.478 (0.421-0.544), 0.353 (0.307-0.405), and 0.262 (0.224-0.305) in the fully adjusted model, respectively (p for trend <0.001). Percent change in serum albumin concentration inversely correlated with percent change in serum level of high-sensitivity C-reactive protein (r=-3.5444, p<0.001).

CONCLUSIONS

Although a higher baseline level of serum albumin was linked to increased risk of incident metabolic syndrome, increase in serum albumin concentration might be a protective factor against the risk of MetS.

Delayed heart rate recovery after exercise as a risk factor of incident type 2 diabetes mellitus after adjusting for glycometabolic parameters in men

BACKGROUND

Some studies have reported that delayed heart rate recovery (HRR) after exercise is associated with incident type 2 diabetes mellitus (T2DM). This study aimed to investigate the longitudinal association of delayed HRR following a graded exercise treadmill test (GTX) with the development of T2DM including glucose-associated parameters as an adjusting factor in healthy Korean men.

MATERIAL AND METHODS

Analyses including fasting plasma glucose, HOMA-IR, HOMA-β, and HbA1c as confounding factors and known confounders were performed. HRR was calculated as peak heart rate minus heart rate after a 1-min rest (HRR 1). Cox proportional hazards model was used to quantify the independent association between HRR and incident T2DM.

RESULTS

During 9082 person-years of follow-up between 2006 and 2012, there were 180 (10.1%) incident cases of T2DM. After adjustment for age, BMI, systolic BP, diastolic BP, smoking status, peak heart rate, peak oxygen uptake, TG, LDL-C, HDL-C, fasting plasma glucose, HOMA-IR, HOMA-β, and HbA1c, the hazard ratios (HRs) [95% confidence interval (CI)] of incident T2DM comparing the second and third tertiles to the first tertile of HRR 1 were 0.867 (0.609-1.235) and 0.624 (0.426-0.915), respectively (p for trend=0.017). As a continuous variable, in the fully-adjusted model, the HR (95% CI) of incident T2DM associated with each 1 beat increase in HRR 1 was 0.980 (0.960-1.000) (p=0.048).

CONCLUSIONS

This study demonstrated that delayed HRR after exercise predicts incident T2DM in men, even after adjusting for fasting glucose, HOMA-IR, HOMA-β, and HbA1c. However, only HRR 1 had clinical significance.

Serum uric acid: A strong and independent predictor of metabolic syndrome after adjusting for body composition

BACKGROUND

Some observational studies have suggested that serum uric acid (SUA) levels are one of the determinants of the metabolic syndrome (MetS). However, previous studies reported combined results for men and women after adjusting for sex and few studies take body composition into consideration. Therefore, we performed this sex-specific longitudinal study to investigate how baseline SUA levels influence incident MetS, including body composition as an adjusting factor in a large number of subjects.

METHODS

A total of 14,442 participants (8715 men and 5727 women) participating in a medical health check-up program without diagnosed MetS at baseline were enrolled. Separate analyses were performed for men and women including body composition as a confounding factor. Cox proportional hazards models were used to quantify independent associations between SUA levels and incident MetS.

RESULTS

During 63,940person-years of follow-up, there were 4215 (2974 men, 1241 women) incident cases of MetS between 2006 and 2012. After adjustments for age, systolic BP, diastolic BP, BMI, eGFR, smoking status, TG, LDL-C, HDL-C, fasting glucose, and proportion of fat-free mass (100-fat mass, %), the hazard ratios (HR) [95% confidence interval (CI)] for incident MetS comparing the second, the third, and the fourth quartiles to the first quartile of SUA levels were 0.862 (0.770-0.965), 1.102 (0.991-1.225), and 1.246 (1.121-1.385) in men (p for trend<0.001), and 1.045 (0.862-1.266), 1.251 (1.050-1.490), and 1.321 (1.109-1.574) in women (p for trend<0.001), respectively. As a continuous variable, in fully-adjusted models, the HRs (95% CI) for incident MetS associated with each increase of 1mg/dl of SUA levels were 1.094 (1.060-1.130) in men (p<0.001) and 1.148 (1.072-1.228) in women (p<0.001), respectively.

CONCLUSION

We demonstrated that SUA levels are strong and independent predictors of MetS. This relationship remained significant after full adjustments for multiple associated confounders including body composition in both men and women.

Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management

Current bioelectric impedance analysis (BIA) systems are often large, cumbersome devices which require strict electrode placement on the user, thus inhibiting mobile capabilities. In this work, we developed a handheld BIA device that measures impedance from multiple frequencies (5 kHz~200 kHz) with four contact electrodes and evaluated the BIA device against standard body composition analysis systems: a dual-energy X-ray absorptiometry (DXA) system (GE Lunar Prodigy, GE Healthcare, Buckinghamshire, UK) and a whole-body BIA system (InBody S10, InBody, Co. Ltd, Seoul, Korea). In the study, 568 healthy participants, varying widely in body mass index, age, and gender, were recruited at two research centers: the Samsung Medical Center (SMC) in South Korea and the Pennington Biomedical Research Center (PBRC) in the United States. From the measured impedance data, we analyzed individual body fat and skeletal muscle mass by applying linear regression analysis against target reference data. Results indicated strong correlations of impedance measurements between the prototype pathways and corresponding InBody S10 electrical pathways (R = 0.93, p < 0.0001). Additionally, body fat estimates from DXA did not yield significant differences (p > 0.728 (paired t-test), DXA mean body fat 29.45 ± 10.77 kg, estimated body fat 29.52 ± 12.53 kg). Thus, this portable BIA system shows a promising ability to estimate an individual's body composition that is comparable to large stationary BIA systems.