Resources allocation in healthcare for cancer: a case study using generalised additive mixed models

Gender-based relationship between serum creatinine and carotid plaque stability: A cross-sectional study in China

OBJECTIVE

Carotid plaque instability is a risk factor for ischemic stroke, and changes in serum creatinine are associated with carotid plaque. However, the relationship between serum creatinine and carotid plaque stability is not well explained. This study aimed to interpret this relationship for clinical treatment of carotid plaque.

METHODS

A total of 4363 subjects aged 29-86 from December 2013 to December 2018 were included in this study. The stability of carotid plaque was determined based on ultrasound echoes and divided into two groups: carotid plaque stable group and carotid plaque unstable group. The relationship between serum creatinine and carotid plaque stability was determined using curve fitting methods as well as logistic regression.

RESULTS

After age stratification, there was an inverted U-shaped curve between the stability of right carotid plaque and serum creatinine in males, When serum creatinine levels were less than 84 μmol/L, the probability of carotid plaque instability gradually increased, and the carotid plaque became stable when creatinine levels were greater than 84 μmol/L. The relationship between left carotid female plaque stability and serum creatinine showed a U-shaped curve. When serum creatinine levels were less than 80 μmol/L, the carotid plaque stability stabilized, and the probability increased when creatitine levels were more than 80 μmol/L, as the carotid plaque instability rose.

CONCLUSION

There was an inverted U-shaped relationship between the stability of carotid plaque in the right carotid artery and serum creatinine in males, and a U-shaped relationship between the stability of carotid plaque in the left carotid artery and serum creatinine in females.

Implications of gender-based variabilities in bone mineral density and hemoglobin levels

BACKGROUND

Studies reported that there is a relationship between volumetric bone mineral density (vBMD) and hemoglobin (HGB) in sickle cell anemia, chronic obstructive pulmonary disease, inflammatory bowel disease, and chronic kidney disease, it is not clear whether this association exists in normal populations or different genders. In order to further clarify the relationship between vBMD and HGB, and provide the basis for the diagnosis of related diseases, this study was conducted in the physical examination population.

METHODS

A cross-sectional study was conducted on a health check-up population from Wannan area of China from January to December 2018. The study involved 1238 individuals aged 23 to 85 years. Linear regression analysis and smooth curve were applied to determine the relationship of HGB and vBMD.

RESULTS

The average level of vBMD in the population was 130.11 ± 79.51 mg/cm³, after adjusting for age, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), triglycerides (TG), glucose (GLU), high-density lipoprotein (HDL) and low-density lipoprotein (LDL). A U-shape relationship was established between vBMD and HGB, the cut off value of HGB was 130 g/L. After gender stratification, the results showed a U-shaped curve relationship between vBMD and HGB in male group, and a linear relationship between vBMD and HGB in female group. The vBMD decreased with HGB when HGB < 120 g/L, and increased when HGB ≥ 120 g/L in male group.

CONCLUSION

The relationship between vBMD and HGB in the male physical examination population presents a U-shaped curve.

Diagnostics for Statistical Variable Selection Methods for Prediction of Peptic Ulcer Disease in Helicobacter pylori Infection

BACKGROUND

The development of accurate classification models depends upon the methods used to identify the most relevant variables. The aim of this article is to evaluate variable selection methods to identify important variables in predicting a binary response using nonlinear statistical models. Our goals in model selection include producing non-overfitting stable models that are interpretable, that generate accurate predictions and have minimum bias. This work was motivated by data on clinical and laboratory features of Helicobacter pylori infections obtained from 60 individuals enrolled in a prospective observational study.

RESULTS

We carried out a comprehensive performance comparison of several nonlinear classification models over the H. pylori data set. We compared variable selection results by Multivariate Adaptive Regression Splines (MARS), Logistic Regression with regularization, Generalized Additive Models (GAMs) and Bayesian Variable Selection in GAMs. We found that the MARS model approach has the highest predictive power because the nonlinearity assumptions of candidate predictors are strongly satisfied, a finding demonstrated via deviance chi-square testing procedures in GAMs.

CONCLUSIONS

Our results suggest that the physiological free amino acids citrulline, histidine, lysine and arginine are the major features for predicting H. pylori peptic ulcer disease on the basis of amino acid profiling.

Association of vitamin D status with socio-demographic factors in Calgary, Alberta: an ecological study using Census Canada data

BACKGROUND

Low 25-hydroxyvitamin D levels are a global health problem with northern countries such as Canada at particular risk. A number of sociodemographic factors have been reported to be associated with low vitamin D levels but prior studies have been limited by the ability of the researchers to gather this data directly from clinical trial participants. The purpose of this study was to use a novel methodology of inferring sociodemographic variables to evaluate the correlates of vitamin D levels in individuals dwelling in the City of Calgary, Alberta, Canada.

METHODS

We utilized data on vitamin D test results from Calgary Laboratory Services between January 1 2010 and August 31 2011. In addition to vitamin D level, we recorded age, sex, and vitamin D testing month as individual-level variables. We inferred sociodemographic variables by associating results with census dissemination areas and using Census Canada data to determine immigration status, education, median household income and first nations status as clustered variables. Associations between vitamin D status and the individual- and dissemination area-specific variables were examined using the population-averaged regression model by a generalized estimating equations approach to account for the clustering in the data.

RESULTS

158,327 individuals were included. Age, sex, month of vitamin D testing (at an individual level), and education, immigrant status, first nations status and income (at an aggregate level) were all statistically significant predictors of vitamin D status.

CONCLUSIONS

Vitamin D status was associated with a number of sociodemographic variables. Knowledge of these variables may improve targeted education and public health initiatives.