Peizhong Peter Wang

The association between breastfeeding and childhood obesity: a meta-analysis

BackgroundThe increase in childhood obesity is a serious public health concern. Several studies have indicated that breastfed children have a lower risk of childhood obesity than those who were not breastfed, while other studies have provided conflicting evidence. The objective of this meta-analysis was to investigate the association between breastfeeding and the risk of childhood obesity.MethodsThe PubMed, EMBASE and CINAHL Plus with Full Text databases were systematically searched from start date to 1st August 2014. Based on the meta-analysis, pooled adjusted odds ratio (AOR) and 95% confidence interval (CI) were calculated. I2 statistic was used to evaluate the between-study heterogeneity. Funnel plots and Fail-safe N were used to assess publication bias and reliability of results, and results from both Egger test and Begg test were reported.ResultsTwenty-five studies with a total of 226,508 participants were included in this meta-analysis. The studies’ publication dates ranged from 1997 to 2014, and they examined the population of 12 countries. Results showed that breastfeeding was associated with a significantly reduced risk of obesity in children (AOR = 0.78; 95% CI: 0.74, 0.81). Categorical analysis of 17 studies revealed a dose-response effect between breastfeeding duration and reduced risk of childhood obesity.ConclusionResults of our meta-analysis suggest that breastfeeding is a significant protective factor against obesity in children.

Exploring the role of contextual factors in disability models

Purpose. The objective of this paper is to define and categorize the types of relationships that contextual factors have within models of disability according to the WHO International Classification of Disability, Functioning, and Health (ICF) conceptual scheme. Method. A conceptual analysis building on the disability literature specifies the causal relationships for contextual factors in relation to the association between activity limitation and participation using a person with arthritis as an example. Results. From a statistical point of view, in relation to disability process, contextual factors can act as an independent factor, confounding factor, moderating factor, and mediating factor. How the role of a particular contextual factor is specified depends on the researchers hypothesized disability framework and research goals. Moderating and mediating contextual factors are of particular importance in disability model specification. Various sub-types of moderating contextual factors are also identified. Conclusion. This paper provides a framework for the conceptualization of contextual factors in the examination of disability models. This framework has implications in constructing conceptual models as well as for setting up analytical plans. In light of the increasing awareness and application of the ICF model, we intend this work to stimulate additional discussion on this topic.

Long-term exposure to high particulate matter pollution and cardiovascular mortality: A 12-year cohort study in four cities in northern China

Epidemiologic studies have demonstrated that long-term exposure to relatively low levels of particulate air pollution is associated with adverse cardiovascular outcomes in Europe and North America. However, few studies have assessed the association with high level air pollutants. We aimed to assess the cardiovascular effects of long-term exposure to high level concentrations of inhalable particulate and to identify the characteristics of the Chinese population that are susceptible to the health effects. A retrospective cohort, containing 39,054 subjects from four cities in northern China, was followed for mortality of all cause and specific cardiovascular diseases from 1998 to 2009. Information on concentrations of PM10 (particulate matter<10 μm in aerodynamic diameter) was collected from the local Environmental Monitoring Centers. The estimated exposure for the study participants was the mean concentration of PM10 over their surviving years during the cohort period. Relative risk values were obtained using Cox proportional hazards regression models after adjusting for potential confounding factors. For each 10 μg/m(3) increase in PM10, the relative risk ratios (RRs) of all-cause mortality, cardiovascular disease mortality, ischemic heart disease mortality, heart failure disease mortality, and cerebrovascular disease mortality were 1.24 (95% CI, 1.22-1.27), 1.23 (95% CI, 1.19-1.26), 1.37 (95% CI, 1.28-1.47), 1.11(95% CI, 1.05-1.17), and 1.23(95% CI:1.18-1.28), respectively. Results from stratified analyses suggest that the effects of PM10 on cardiovascular mortality were more pronounced in males, smokers and people with a higher socioeconomic status. Long-term exposure to PM10 increases mortality from cardiovascular disease, especially from ischemic heart disease and this association seemed to be modified by other factors. Further research that focuses on exploring dose-response relationship and inter-population comparisons is warranted.

Assessing the validity of a self-administered food-frequency questionnaire (FFQ) in the adult population of Newfoundland and Labrador, Canada

BackgroundThe Food- Frequency Questionnaire (FFQ) is a dietary assessment tool frequently used in large-scale nutritional epidemiology studies. The goal of the present study is to validate a self-administered version of the Hawaii FFQ modified for use in the general adult population of Newfoundland and Labrador (NL).MethodsOver a one year period, 195 randomly selected adults completed four 24-hour dietary recalls (24-HDRs) by telephone and one subsequent self-administered FFQ. Estimates of energy and nutrients derived from the 24-HDRs and FFQs were compared (protein, carbohydrate, fibre, fat, vitamin A, carotene, vitamin D, and calcium). Data were analyzed using the Pearson’s correlation coefficients, cross-classification method, and Bland–Altman plots.ResultsThe mean nutrient intake values of the 24-HDRs were lower than those of the FFQs, except for protein in men. Sex and energy-adjusted de-attenuated Pearson correlation coefficients for each nutrient varied from 0.13 to 0.61. Except for protein in men, all correlations were statistically significant with p < 0.05. Cross-classification analysis revealed that on average, 74% women and 78% men were classified in the same or adjacent quartile of nutrient intake when comparing data from the FFQ and 24-HDRs. Bland–Altman plots showed no serious systematic bias between the administration of the two instruments over the range of mean intakes.ConclusionThis 169-item FFQ developed specifically for the adult NL population had moderate relative validity and therefore can be used in studies to assess food consumption in the general adult population of NL. This tool can be used to classify individual energy and nutrient intakes into quartiles, which is useful in examining relationships between diet and chronic disease.

Prevalence and Correlates of Latent Autoimmune Diabetes in Adults in Tianjin, China: A population-based cross-sectional study

OBJECTIVE Data on latent autoimmune diabetes in adults (LADA) from population-based studies are sparse. We sought to investigate the prevalence and correlates of LADA. RESEARCH DESIGN AND METHODS A total of 8,109 participants, who were aged ≥15 years and living in Tianjin, China, were assessed to identify individuals with type 2 diabetes (American Diabetes Association Criteria, 1997) and further to detect patients with LADA. LADA was ascertained by 1) the presence of type 2 diabetes and age ≥35 years, 2) the lack of a requirement for insulin at least 6 months after the diagnosis of type 2 diabetes, and 3) serum GAD antibody positivity. Data were analyzed using multinomial logistic regression with adjustment for potential confounders. RESULTS Of all participants, 498 (6.1%) were patients with type 2 diabetes. Of them, 46 (9.2%) were found to have LADA. The prevalence of LADA was 0.6% (46 of 8,109), and tended to increase with age up to 50–59 years in all participants. The odds ratios (95% CI) of LADA related to hypertension, family history of diabetes, waist-to-hip ratio ≥0.85, and major stressful events were 1.93 (1.02–3.65), 17.59 (9.08–34.06), 5.37 (2.31–12.49), and 4.09 (1.75–9.52), respectively. CONCLUSIONS The prevalence of LADA is ∼9% in patients with type 2 diabetes. Hypertension, family history of diabetes, central obesity, and major stressful events may be associated with the occurrence of LADA.

Sex Differences in All-Cause and Cardiovascular Mortality, Hospitalization for Individuals With and Without Diabetes, and Patients With Diabetes Diagnosed Early and Late

OBJECTIVE To compare risk of all-cause mortality, cardiovascular disease (CVD) mortality, acute myocardial infarction (AMI) mortality, stroke mortality, and hospitalizations for males and females with and without diabetes and those with diabetes diagnosed early and late. RESEARCH DESIGN AND METHODS We conducted a population-based retrospective cohort study including 73,783 individuals aged 25 years or older in Newfoundland and Labrador, Canada (15,152 with diabetes; 9,517 with late diagnoses). RESULTS Males and females with diabetes had an increased risk of all-cause mortality, CVD mortality, AMI mortality, and CVD hospitalizations compared with individuals without diabetes, and the risk was stronger in females than in males. For females, risks of all-cause mortality (hazard ratio [HR] 1.85 [95% CI 1.74–1.96]) and CVD hospitalizations (2.57 [2.24–2.94]) were significantly higher compared with their male counterparts (1.59 [1.51–1.69] and 1.92 [1.72–2.14]). Females with diabetes diagnosed late had an increased risk of CVD mortality (6.54 [4.80–8.91]) and CVD hospitalizations (5.22 [4.31–6.33]) compared with females without diabetes, and both were significantly higher compared with their male counterparts (3.44 [2.47–4.79]) and (3.33 [2.80–3.95]). CONCLUSIONS Females with diabetes have a greater risk of mortality than males with diabetes. CVD has a greater impact on females with diabetes than males, especially when diagnosed at a later stage. Different management strategies should be considered for males and females and those with early and late diagnoses of diabetes.

Comparison of surgical outcomes for small hepatocellular carcinoma in patients with hepatitis B versus hepatitis C: A Chinese experience

Background:  Although both hepatitis B virus (HBV) and hepatitis C virus (HCV) infection are well recognized risk factors for hepatocellular carcinoma (HCC), little is known with respect to how HBV and HCV infection affect HCC recurrence in postoperative HCC Chinese patients. The objective of this study was to determine if differences exist in preoperative characteristics and postoperative HCC recurrence in patients with different HBV and HCV infection status.

Physicians’ Attitudes and Practice Toward Treating Injection Drug Users Infected with Hepatitis C Virus: Results from a National Specialist Survey in Canada

BACKGRound: In Canada, more than 70% of new cases of hepatitis C virus (HCV) infection per year involve injection drug users (IDUs) and, currently, there is no consensus on how to offer them medical care. oBJeCtive: To examine the characteristics of Canadian specialist physicians and their likelihood to provide treatment to HCV patients who are IDUs. Methods: A nationwide, cross-sectional study was conducted in the specialty areas of hepatology, gastroenterology and infectious diseases to examine HCV services. The questionnaire requested information regarding basic demographics, referral pathways and opinions (yes/no), and examined how a physician’s treatment regimen is influenced by factors such as treatment eligibility, HCV care management and barriers to providing quality service. Results: Despite the fact that the majority of prevalent and incident cases of HCV are associated with injection drug use, very few specialist physicians actually provide the necessary therapy to this population. Only 19 (19.79%) comprehensive service providers were likely to provide treatment to a current IDU who uses a needle exchange on a regular basis. The majority of comprehensive service providers (n=86 [89.58%]) were likely to provide treatment to a former IDU who was stable on substitution therapy. On bivariate analysis, factors associated with the likelihood to provide treatment to current IDUs included physicians’ type, ie, infectious disease specialists compared with noninfectious specialists (OR 3.27 [95% CI 1.11 to 9.63]), and the size of the community where they practice (OR 4.16 [95% CI 1.36 to 12.71] [population 500,000 or greater versus less than 500,000]). Results of the multivariate logistic regression analysis were largely consistent with the results observed in the bivariate analyses. After controlling for other confounding variables, only community size was significantly associated with providing treatment to current IDUs (OR 3.89 [95% CI 1.06 to 14.26] [population 500,000 or greater versus less than 500,000]). ConClusion: The present study highlighted the reluctance of specialists to provide treatment to current IDUs infected with HCV. Providing treatment services for HCV-infected substance abusers is challenging and there are many treatment barriers. However, effective delivery of treatment to this population will help to limit the spread of HCV. The present study clearly identified a need for improved HCV treatment accessibility for IDUs. les attitudes et la pratique des medecins envers le traitement des consommateurs de drogues par injection infectes par le virus de l’hepatite C : les resultats d’un sondage national aupres de specialistes du Canada

Improving the accuracy of long-term prognostic estimates in hepatitis C virus infection

Summary.  Obtaining unbiased estimates of HCV prognosis is difficult because of potential biases associated with study design and calculation methods. We propose a new method for estimating fibrosis progression rates. A Markov model with fibrosis health states (F0–F4) was created. The maximum likelihood method was used to estimate stage‐specific progression rates. We compared the standard method to the new method using two well‐known cohort studies. The known stage distribution at the end of follow‐up was compared with stage predicted by the Markov model using both methods of calculating transition rates. We also compared rates obtained using both methods to known fibrosis rates in a series of Monte Carlo simulations. For Kenny‐Walshs study (1999), transition rates between F0–F1, F1–F2, F2–F3, and F3–F4 were 0.042, 0.045, 0.097 and 0.070 fibrosis units/year (new method) and 0.045 units/year (standard method). The new method predicted fibrosis stage and known transition rates in Monte Carlo simulations more accurately. The standard method underestimates 30‐year cirrhosis rates by up to 40%. The new (Markov maximum likelihood or MML) method allows accurate estimation of stage‐specific transition probabilities from the many studies in which only a single biopsy is available. Application of the method supports the hypothesis that rates of fibrosis vary between stages.

Vitamin D Intake Is Negatively Associated with Promoter Methylation of the Wnt Antagonist Gene DKK1 in a Large Group of Colorectal Cancer Patients

Diet and lifestyle influence colorectal cancer (CRC) risk but the molecular events that mediate these effects are poorly characterized. Several dietary and lifestyle factors can modulate DNA methylation suggesting that they may influence CRC risk through epigenetic regulation of cancer-related genes. The Wnt regulatory genes DKK1 and Wnt5a are important contributors to colonic carcinogenesis and are often silenced by promoter hypermethylation in CRC; however, the dietary contributions to these events have not been explored. To investigate the link between dietary/lifestyle factors and epigenetic regulation of these Wnt signaling genes, we assessed promoter methylation of these genes in a large cohort of Canadian CRC patients from Ontario (n = 549) and Newfoundland (n = 443) and examined associations to dietary/lifestyle factors implicated in CRC risk and/or DNA methylation including intake of vitamins, fats, cholesterol, fiber, and alcohol as well as body mass index (BMI), and smoking status. Several factors were associated with methylation status including alcohol intake, BMI, and cigarette smoking. Most significantly, however, dietary vitamin D intake was strongly negatively associated with DKK1 methylation in Newfoundland (P = 0.001) and a similar trend was observed in Ontario. These results suggest that vitamin D and other dietary/lifestyle factors may alter CRC risk by mediating extracellular Wnt inhibition.