Prevalence Of Metabolic Syndrome And Related Epidemic Issues

Study 1: Urban, semi-urban and rural difference in the prevalence of metabolic syndromeThe ongoing rapid urbanization in China offers rural population opportunities not only for economic improvement but also for substantial health risks. Albeit some researches related to rural-urban difference of metabolic syndrome(MS), there lacks studies focusing on this point in undeveloped provinces in China.Objective: The data of the 2007-08 China National Diabetes and Metabolic Disorders Study were used to evaluate the rural-urban differences in prevalence of MS and its individual components in Shaanxi province, northwestern China.Methods: This cross-sectional survey, as part of China National Diabetes and Metabolic Disorders Study, was conducted from June 2007 through May 2008. A multistage, stratified sampling method was used to select a representative sample of persons with age 20 or older in the general population in Shaanxi province. A total of 3,930 individuals were randomly chosen and 3297 completed the survey and examination(response rate: 83.9%). We finally included only 3,196 individuals with complete data of waist circumference, fasting blood glucose, blood pressure, serum triglycerides, and serum high-density lipoprotein cholesterol(HDL-c) as study participants, of which 1,467 individuals were from urban areas(street district from urban city), 839 from semi-urban areas(street district of country-seat), and 890 from rural areas(villages from rural township). A standardized questionnaire was designed and performed collect data on demographic characteristics, lifestyle risk factors, personal medical history, and family history of diseases. All participants were administered an oral glucose tolerance test to measure blood glucose. Blood samples were also collected to measure serum triglycerides and HDL-c level.Results: The age-standardized prevalence of MS in all, male and female urban participants was 25.9%, 27.6% and 24.4%, respectively. In all and female subgroups, rural participants had a significant higher prevalence compared with urban counterparts(29.0% vs. 25.9% and 30.2% vs. 24.4%, respectively). However, no significant difference in the prevalence of MS was observed between semi-urban and urban participants in all, male and female subgroups(24.2% vs 25.9% 、 26.9% vs 27.6% and 23.6% vs 24.4%, respectively). Rural residents had a 27.6% increased risk of having MS than urban residents(OR: 1.276, 95% CI: 1.017-1.601, P=0.036) after adjusted for age, sex, ethnics, educational level, yearly family income, cigarette smoking, alcohol drinking, physical activities, and family history of diabetes and hypertension., With respect to MS components, the crude prevalence of raised fasting glucose and raised blood pressure was significantly greater in rural than in urban participantsConclusion: Rural residents in Shaanxi province, northwest China, are at increased risk of MS, which could be partly explained by sociodemographic and lifestyle differences. In addition, the gap between urban and semi-urban areas seems to be minimized in related to MS prevalence. Much more attention should be paid and strategies for intervention are in need to address the rural-urban disparities in China.Study 2: Metabolic Syndrome, Insulin Resistance and Chronic Kidney DiseaseOf dozens of studies on MS and CKD, an insufficient number involves epidemiologic studies focusing on the Chinese population and most of these were regional or involved a single province. In the past decade, China is undergoing a rapid transition to an urbanized and Western diet pattern, which worsens the public health burden of MS and CKD. Therefore, our knowledge needs to be updated. In addition, although several observational and prospective studies have indicated a relationship between IR and CKD in general or nondiabetic population, there were not enough studies concerning this relationship in populations without MS and these results were debatable. We hypothesized that IR may not be independently associated with CKD, because MS may modify the association of IR with CKD.Objective: The data from the 2007-08 China National Diabetes and Metabolic Disorders Study were used to estimate the prevalence of CKD among adults with MS and to evaluate the association between MS and CKD in Chinese adults. We also aimed to evaluate whether IR is independently associated with CKD in population without MS.Methods: A multi-stage stratified sampling method was used to select a nationwide representative sample of Chinese adults with age above 20 years. A total of 17 study group field centers participated in the study, and 54240 individuals from the general population were selected and invited. Of those individuals, 87.3% participated and 85.2% completed the study. We included 15987 individuals with complete data on SCr, fasting plasma glucose, systolic blood pressure, diastolic blood pressure, serum triglyceride level, serum high-density lipoprotein cholesterol(HDL-c), and waist circumference as study sample 1 to estimate the prevalence of CKD and to evaluate the association between MS and CKD. We included 11143 individuals as study sample 2, which had complete data on SCr, fasting serum insulin, fasting plasma glucose, systolic blood pressure, diastolic blood pressure, serum triglyceride level, serum(HDL-c), and waist circumference to evaluate whether IR is independently associated with CKD. A standard questionnaire was used to collect information on demographic characteristics, lifestyle risk factors, and personal medical history. Oral glucose tolerance test was performed on all subjects for the measurement of serum glucose and insulin. Fasting blood samples were also taken to measure serum creatine, triglyceride and HDL-c level. Glomerular filtration rate(GFR) was calculated using the abbreviated equation developed by the Modification of Diet in Renal Disease(MDRD) study with modification for the Chinese population. CKD) was defined as a GFR < 60 ml/min/1.73 m2.Results: Based on study sample 1, age-standardized prevalence of CKD in participants with MS was significantly higher for males, females and males and females combined compared with those without MS.(4.90% vs. 2.24%, 6.78% vs. 5.78%, and 4.64% vs. 3.30%, respectively, P < 0.001). The multivariate-adjusted odds ratio of CKD associated with MS was 1.495(95% CI: 1.190-1.879). Elevated blood pressure, elevated fasting glucose, elevated triglycerides, and reduced high-density lipoprotein cholesterol had statistically significant increased odds ratios of 1.218, 1.256, 1.325 and 1.797 for CKD, respectively.Based on study sample 2, the overall prevalence of CKD in general population was 3.7%. Participants in the higher quartiles of HOMA-IR tended to have higher prevalence of CKD in general population(P < 0.001). However, there was no significant difference among the four quartiles of HOMA-IR in participants without MS(P=0.288). In participants without MS the multivariate-adjusted ORs of CKD associated with HOMA-IR showed no significance in the second(OR: 1.183, 95% CI: 0.838-1.670), third(OR: 1.543, 95% CI: 1.103-2.158) and fourth(OR: 1.549, 95% CI: 1.079-2.223) quartile of HOMA-IR relative to the lowest quartile.Conclusions: The present paper suggests an increasing prevalence of CKD among Chinese adults with MS and a strong association between CKD and MS. In addition, IR was not an independently significant predictor of CKD in Chinese population, and MS may contribute greatly to the association between IR and CKD. With the increasing number of patients with MS in China, more studies, particular cohort studies, are required to confirm the present findings and the burden of CKD needs more effective control and prevention strategies.Study 3: The Association between Obstructive Sleep Apnea and Metabolic SyndromeObstructive sleep apnea(OSA) is characterized by repeated episodes of obstruction of the upper airway. Numerous studies have indicated a relationship between OSA and metabolic syndrome(MS), but the results remain debatable.Objective: To perform a systematic review and meta-analysis to evaluate the association between OSA and MS.Methods: Electronic databases(Pub Med, EMBASE, and ISO Web of Knowledge) were searched up to September 2014 with English-language restriction. Cross-sectional, case-control, and cohort studies in which the presence of OSA was assessed by objective measurements, the exposure of interest was OSA, and the outcome of interest was the presence(or incidence) of MS were included. studies that used type IV monitors, which cannot differentiate between obstructive and central apneas, devices that cannot estimate the apnea–hypopnea index(AHI), questionnaires, or self-reported snoring to assess OSA were excluded. For studies to be eligible for inclusion, they must have reported(or provided sufficient data to enable the calculation of) a risk estimate for MS related to OSA, together with a 95% confidence interval(CI), a P value, or a standard error(SE). Literature reviews, letters, and comments were excluded. Conference reports that were not subsequently published were excluded in the main body, but included as sensitivity analyses. The methodological quality of the included studies was evaluated based on the Newcastle–Ottawa Scale(NOS).Results: Overall, 5648 references were identified and 20 studies were finally included in the review. All of the included studies were reviewed by full text. Of the included studies, 15 were cross-sectional, five were case-control, and none were cohort studies. In total, 2456 patients with OSA and 1705 subjects with no OSA in cross-sectional studies, together with 1156 OSA patients and 404 controls in case-control studies, were included in the meta-analysis for the association of OSA with MS. The mean NOS score for the cross-sectional and case-control studies was 6.7 and 6.8, respectively. The pooled ORs of MS in individuals with OSA for cross-sectional and case-control studies were 2.87(95% CI: 2.41–3.42) and 2.56(95% CI: 1.98–3.31), respectively. There was clinically unimportant(I2 = 20%) and moderate(I2 = 35%) between-study heterogeneity of the analysis. The pooled crude ORs of MS in individuals with mild and moderate-to-severe OSA was 2.39(95% CI: 1.65–3.46) and 3.45(95% CI: 2.33–5.12), respectively, and there was substantial heterogeneity in the meta-analyses(I2 = 53% and I2 = 63%, respectively). However, no evidence of publication bias was detected.Conclusions: OSA is shown to be associated with MS, although causality between these two factors has not been demonstrated yet. Future cohort and randomized controlled studies are needed.