Inverse U-shaped Association Research Articles

Differential Effect of Baseline Adiponectin on All-Cause Mortality in Hemodialysis Patients Depending on Initial Body Mass Index. Long-Term Follow-Up Data of 4.5 Years

We sought to investigate the interaction of adiponectin levels and body mass index (BMI) for predicting all-cause mortality in a cohort of hemodialysis (HD) patients. Longitudinal, observational cohort study. HD unit. Sixty patients (mean age: 64 ± 13 years, 39 men) with end-stage renal disease on maintenance HD followed up for 4.5 years represented the prospective study cohort. Associations between baseline plasma adiponectin levels and initial BMI with all-cause mortality were assessed taking into account the assumption of nonlinear correlations. The association between adiponectin, BMI, and serum levels of interleukin-10 (IL-10) and interleukin-6 (IL-6) with survival was determined cross-sectionally. All-cause mortality. Nonlinear survival modeling showed that there was a U-shaped association of BMI with all-cause mortality, whereas there was an inverse U-shaped association for plasma adiponectin levels. Using a BMI of 24 kg/m(2) as a cutoff, an interaction effect of BMI on the association between adiponectin and mortality was observed (P = .045). In participants with BMI ≥ 24 kg/m(2), each 15 μg/mL increase in plasma adiponectin levels was associated with a decreased hazard of death (hazard ratio: 0.57, 95% CI: 0.32 to 0.99) in unadjusted analysis. In HD patients with BMI < 24 kg/m(2), no significant association was observed between adiponectin and mortality (P = .989). Cross-sectional analysis showed that in the subgroup of patients in whom the protective effect of adiponectin was observed (BMI ≥ 24 kg/m(2)), a positive linear association existed between adiponectin and IL-10 levels (r = 0.345, P = .027) as well as a negative association with IL-6 levels (r = -0.322, P = .040). No association was observed in patients with BMI < 24 kg/m(2), neither with IL-10 nor with IL-6. Obesity possibly modifies the effect of adiponectin on all-cause mortality in HD patients, thus explaining the published conflicting results in recent literature regarding the association of plasma adiponectin levels and mortality in chronic kidney disease patients.

The Prevalence and Predictors of Gestational Diabetes Mellitus in Hungary

There are conflicting results regarding the frequency of gestational diabetes (GDM) in Hungary. The aim of this study was to estimate the prevalence of GDM and to clarify the association between selected maternal characteristics and GDM risk. In a population-based screening program of GDM in Tolna County, Hungary, 75 g OGTTs were offered to all pregnant women between 24-28 weeks of gestation and evaluated according to WHO criteria in 2000 (WHO GDM). Women were also classified based on the IADPSG criteria (IADPSG GDM). Selected risk factors were recorded by district nurses. OGTT results were available for 1,835 (81.2%) pregnancies out of 2,261. Altogether 159 (8.7%) were diagnosed as WHO GDM and 304 (16.6%) as IADPSG GDM. Gestational diabetes was related to older age, higher BMI, and an increasing number of deliveries (all p<0.005). The risk of IADPSG GDM monotonously increased with age, -pre-pregnancy BMI and number of deliveries. The risk of WHO GDM increased linearly with age, however, women with the highest BMI (≥ 29.2 kg/m2) had decreased risk compared to women with a BMI of 26.1-29.1 kg/m2 (p<0.05). There was an inverse U-shaped association between GDM risk and number of deliveries with the highest risk observed in those with 3 deliveries (p quadratic term=0.008). We found a high prevalence of GDM in this Caucasian Hungarian population. Our results suggest that pre-pregnancy BMI and previous deliveries elevate the risk of WHO GDM only to a certain level, above which the risk decreases.

Altered Cardiac Repolarization in Association with Air Pollution and Air Temperature among Myocardial Infarction Survivors

BackgroundEpidemiological studies have shown that ambient particulate matter (PM) and changes in air temperature are associated with increased cardiopulmonary events.ObjectiveWe hypothesized that patients with previous myocardial infarction (MI) experience changes in heart rate (HR) and repolarization parameters, such as Bazett-corrected QT interval (QTc), and T-wave amplitude (Tamp), in association with increases in air pollution and temperature changes.MethodsBetween May 2003 and February 2004, 67 MI survivors from the Augsburg KORA-MI registry repeatedly sent 16 sec electrocardiograms (ECGs) with a personal transmitter (Viapac) via telephone to the Philips Monitoring Center, where ECG parameters were immediately analyzed. Meteorological data and air pollutants were acquired from fixed monitoring sites on an hourly basis. Additive mixed models were used for analysis. Effect modification by patient characteristics was investigated.ResultsThe analysis of the 1,745 ECGs revealed an increased HR associated with interquartile range (IQR) increases in PM levels among participants not using beta-adrenergic receptor blockers and among those with body mass index ≥ 30 kg/m2. We observed a 24- to 47-hr lagged QTc prolongation [0.5% change (95% confidence interval, 0.0–1.0%)] in association with IQR increases in levels of PM ≤ 2.5 μm in aerodynamic diameter, especially in patients with one [0.6% (0.1–1.0%)] or two [1.2% (0.4–2.1%)] minor alleles of the nuclear factor (erythroid-derived 2)-like 2 (NFE2L2) single-nucleotide polymorphism rs2364725. Positive immediate (0–23 hr) and inverse delayed (48–71 hr up to 96–119 hr) associations were evident between PM and Tamp. We detected an inverse U-shaped association between temperature and Tamp, with a maximum Tamp at 5°C.ConclusionsIncreased air pollution levels and temperature changes may lead to changes in HR and repolarization parameters that may be precursors of cardiac problems.

Inflammatory Biomarkers in Left Ventricular Remodeling under Stem Cell and Pharmacological Treatment in a Rat Model of Myocardial Infarction

metropolitan Atlanta, GA area between 1/2008 and 6/2009. Results: Mean age of patients was 57.1 6 12.0 years; 66.7% were male; 58.2% were white and 35.6% black; NYHA I/II/III/IV was 40.0/40.0/15.7/4.3%, respectively; median ejection fraction was 22.5% (interquartile range [IQR]: 15.0e35.0%); 41.5% had coronary artery disease (CAD) and 33.3% had diabetes; 43.5% had a biventricular pacemaker + / defibrillator. On follow-up (median: 20 months; IQR: 18-22 months), 52/147 patients (35.4%) experienced an event. Table 1 presents levels of MMPs and TIMPs according to event status. In univariate Cox models, TIMP-1 (p 5 0.002) and TIMP-2 (p 5 0.028) were positively associated with risk of adverse outcomes, while MMP-1 had an inverse U-shape association (p 5 0.008). In models controlling for age, gender, race, diabetes, CAD, creatinine, and ejection fraction, only TIMP-1 levels were associated with risk of adverse outcomes (HR per 0.1 ng/mL: 2.19; 95% CI: 1.08e4.47; p 5 0.031). Conclusions: Elevated serum TIMP-1 levels were strongly associated with adverse outcomes in this cohort of stable outpatients with systolic HF; this association was independent of clinical characteristics.

Institutional Environments, Work and Human Resource Practices, and Unions: Canada versus England

This analysis of data from a 2003–2004 telephone survey of 750 Canadian and 450 English workers finds that work practices and human resource (HR) practices had important implications for unions. The effects differed by the type of practice (for example, traditional versus “new” HR), and were mediated by each country's institutional environment. For example, traditional personnel/HR practices were strongly positively related to the likelihood of union representation and strongly negatively related to workers' propensity to vote for a union in Canada, but made little difference to either of those union outcomes in England; and “alternative” work practices bore an inverse U-shaped association with union representation in Canada, versus a positive relationship with that outcome in England. In general, the Canadian findings are consistent with an adversarial dynamic, and the English findings with a more collaborative one.

Habitual coffee consumption and blood pressure: An epidemiological perspective

This paper summarizes the current epidemiological evidence on coffee consumption in relation to blood pressure (BP) and risk of hypertension. Data from cross-sectional studies suggest an inverse linear or U-shaped association of habitual coffee use with BP in different populations. Prospective studies suggest a protective effect of high coffee intake (4 or more cups per day) against hypertension, mainly in women. Furthermore, the risk of hypertension may be lower in coffee abstainers. Randomized controlled trials, which are mostly of short duration (1-12 weeks), have shown that coffee intake around 5 cups per day causes a small elevation in BP (approximately 2/1 mmHg) when compared to abstinence or use of decaffeinated coffee. With regard to underlying biological mechanisms, most research has been devoted to BP-raising effects of caffeine. However, there are many other substances in coffee, such as polyphenols, soluble fibre and potassium, which could exert a beneficial effect in the cardiovascular system. Although the precise nature of the relation between coffee and BP is still unclear, most evidence suggests that regular intake of caffeinated coffee does not increase the risk of hypertension.

Opposite associations of age-dependent insulin-like growth factor-I standard deviation scores with nutritional state in normal weight and obese subjects

Insulin-like growth factor-I (IGF-I) has been suggested to be a prognostic marker for the development of cancer and, more recently, cardiovascular disease. These diseases are closely linked to obesity, but reports of the association of IGF-I with measures of obesity are divergent. In this study, we assessed the association of age-dependent IGF-I standard deviation scores with body mass index (BMI) and intra-abdominal fat accumulation in a large population. A cross-sectional, epidemiological study. IGF-I levels were measured with an automated chemiluminescence assay system in 6282 patients from the DETECT study. Weight, height, and waist and hip circumference were measured according to the written instructions. Standard deviation scores (SDS), correcting IGF-I levels for age, were calculated and were used for further analyses. An inverse U-shaped association of IGF-I SDS with BMI, waist circumference, and the ratio of waist circumference to height was found. BMI was positively associated with IGF-I SDS in normal weight subjects, and negatively associated in obese subjects. The highest mean IGF-I SDS were seen at a BMI of 22.5-25 kg/m2 in men (+0.08), and at a BMI of 27.5-30 kg/m2 in women (+0.21). Multiple linear regression models, controlling for different diseases, medications and risk conditions, revealed a significant negative association of BMI with IGF-I SDS. BMI contributed most to the additional explained variance to the other health conditions. IGF-I standard deviation scores are decreased in obesity and underweight subjects. These interactions should be taken into account when analyzing the association of IGF-I with diseases and risk conditions.

Habitual Caffeine Intake and the Risk of Hypertension in Women

Caffeine acutely increases blood pressure, but the association between habitual consumption of caffeinated beverages and incident hypertension is uncertain. To examine the association between caffeine intake and incident hypertension in women. Prospective cohort study conducted in the Nurses' Health Studies (NHSs) I and II of 155,594 US women free from physician-diagnosed hypertension followed up over 12 years (1990-1991 to 2002-2003 questionnaires). Caffeine intake and possible confounders were ascertained from regularly administered questionnaires. We also tested the associations with types of caffeinated beverages. Incident physician-diagnosed hypertension. During follow-up, 19,541 incident cases of physician-diagnosed hypertension were reported in NHS I and 13,536 in NHS II. In both cohorts, no linear association between caffeine consumption and risk of incident hypertension was observed after multivariate adjustment (NHS I, P for trend = .29; NHS II, P for trend = .53). Using categorical analysis, an inverse U-shaped association between caffeine consumption and incident hypertension was found. Compared with participants in the lowest quintile of caffeine consumption, those in the third quintile had a 13% and 12% increased risk of hypertension, respectively (95% confidence interval in NHS I, 8%-18%; in NHS II, 6%-18%). When studying individual classes of caffeinated beverages, habitual coffee consumption was not associated with increased risk of hypertension. By contrast, consumption of cola beverages was associated with an increased risk of hypertension, independent of whether it was sugared or diet cola (P for trend <.001). No linear association between caffeine consumption and incident hypertension was found. Even though habitual coffee consumption was not associated with an increased risk of hypertension, consumption of sugared or diet cola was associated with it. Further research to elucidate the role of cola beverages in hypertension is warranted.

Retinol intake and bone mineral density in the elderly: the Rancho Bernardo Study.

Retinol is involved in bone remodeling, and excessive intake has been linked to bone demineralization, yet its role in osteoporosis has received little evaluation. We studied the associations of retinol intake with bone mineral density (BMD) and bone maintenance in an ambulatory community-dwelling cohort of 570 women and 388 men, aged 55-92 years at baseline. Regression analyses, adjusted for standard osteoporosis covariates, showed an inverse U-shaped association of retinol, assessed by food-frequency questionnaires in 1988-1992, with baseline BMD, BMD measured 4 years later, and BMD change. Supplemental retinol use, reported by 50% of women and 39% of men, was an effect modifier in women; the associations of log retinol with BMD and BMD change were negative for supplement users and positive for nonusers at the hip, femoral neck, and spine. At the femoral neck, for every unit increase in log retinol intake, supplement users had 0.02 g/cm2 (p = 0.02) lower BMD and 0.23% (p = 0.05) greater annual bone loss, and nonusers had 0.02 g/cm2 (p = 0.04) greater BMD and 0.22% (p = 0.19) greater bone retention. However, among supplement users, retinol from dietary and supplement sources had similar associations with BMD, suggesting total intake is more important than source. In both sexes, increasing retinol became negatively associated with skeletal health at intakes not far beyond the recommended daily allowance (RDA), intakes reached predominately by supplement users. This study suggests there is a delicate balance between ensuring that the elderly consume sufficient vitamin A and simultaneously cautioning against excessive retinol supplementation.

The Measurement of Reciprocity in Ego-Centered Networks of Personal Relationships: A Comparison of Various Indices

This article deals with the reciprocity of social support in personal relationships and with its connection to well-being, particularly loneliness. After reviewing briefly the concept of reciprocity, w'e develop four methods for constructing indices of the reciprocity of social support based on data on ego-centered networks of personal relationships. The four indices showed that on the average, the respondents' relationship networks were strongly reciprocal. The results did not make it unequivocally clear whether overbenefiting (versus underbenefitingj and loneliness were linked via a U-shaped association, as suggested by the literature, or via a linear or inverse U-shaped association. The use of more specific indices is recommended for a more extensive investigation of the association between reciprocity and loneliness.