Akaike's information criterion in generalized estimating equations

Host and microbiome multi-omics integration: applications and methodologies

The study of the microbial community-the microbiome-associated with a human host is a maturing research field. It is increasingly clear that the composition of the human's microbiome is associated with various diseases such as gastrointestinal diseases, liver diseases and metabolic diseases. Using high-throughput technologies such as next-generation sequencing and mass spectrometry-based metabolomics, we are able to comprehensively sequence the microbiome-the metagenome-and associate these data with the genomic, epigenomics, transcriptomic and metabolic profile of the host. Our review summarises the application of integrating host omics with microbiome as well as the analytical methods and related tools applied in these studies. In addition, potential future directions are discussed.

Occupational exposures and incidence of chronic bronchitis and related symptoms over two decades: the European Community Respiratory Health Survey

OBJECTIVES

Chronic bronchitis (CB) is an important chronic obstructive pulmonary disease (COPD)-related phenotype, with distinct clinical features and prognostic implications. Occupational exposures have been previously associated with increased risk of CB but few studies have examined this association prospectively using objective exposure assessment. We examined the effect of occupational exposures on CB incidence in the European Community Respiratory Health Survey.

METHODS

Population samples aged 20-44 were randomly selected in 1991-1993, and followed up twice over 20 years. Participants without chronic cough or phlegm at baseline were analysed. Coded job histories during follow-up were linked to the ALOHA Job Exposure Matrix, generating occupational exposure estimates to 12 categories of chemical agents. Their association with CB incidence over both follow-ups was examined with Poisson models using generalised estimating equations.

RESULTS

8794 participants fulfilled the inclusion criteria, contributing 13 185 observations. Only participants exposed to metals had a higher incidence of CB (relative risk (RR) 1.70, 95% CI 1.16 to 2.50) compared with non-exposed to metals. Mineral dust exposure increased the incidence of chronic phlegm (RR 1.72, 95% CI 1.43 to 2.06). Incidence of chronic phlegm was increased in men exposed to gases/fumes and to solvents and in women exposed to pesticides.

CONCLUSIONS

Occupational exposures are associated with chronic phlegm and CB, and the evidence is strongest for metals and mineral dust exposure. The observed differences between men and women warrant further investigation.

A global perspective on coal-fired power plants and burden of lung cancer

BACKGROUND

Exposure to ambient particulate matter generated from coal-fired power plants induces long-term health consequences. However, epidemiologic studies have not yet focused on attributing these health burdens specifically to energy consumption, impeding targeted intervention policies. We hypothesize that the generating capacity of coal-fired power plants may be associated with lung cancer incidence at the national level.

METHODS

Age- and sex-adjusted lung cancer incidence from every country with electrical plants using coal as primary energy supply were followed from 2000 to 2016. We applied a Poisson regression longitudinal model, fitted using generalized estimating equations, to estimate the association between lung cancer incidence and per capita coal capacity, adjusting for various behavioral and demographic determinants and lag periods.

RESULTS

The average coal capacity increased by 1.43 times from 16.01 gigawatts (GW) (2000~2004) to 22.82 GW (2010~2016). With 1 kW (KW) increase of coal capacity per person in a country, the relative risk of lung cancer increases by a factor of 59% (95% CI = 7.0%~ 135%) among males and 85% (95% CI = 22%~ 182%) among females. Based on the model, we estimate a total of 1.37 (range = 1.34 ~ 1.40) million standardized incident cases from lung cancer will be associated with coal-fired power plants in 2025.

CONCLUSIONS

These analyses suggest an association between lung cancer incidence and increased reliance on coal for energy generation. Such data may be helpful in addressing a key policy question about the externality costs and estimates of the global disease burden from preventable lung cancer attributable to coal-fired power plants at the national level.

Substance Use, Demographic and Socioeconomic Factors Are Independently Associated With Postpartum HIV Care Engagement in the Southern United States, 1999-2016

Background

Retention in care (RIC) and viral suppression (VS) are associated with reduced HIV transmission and mortality. Studies addressing postpartum engagement in HIV care have been limited by small sample size, short follow-up, and a lack of data from the Southeast United States.

Methods

HIV-positive adult women with ≥1 prenatal visit at the Vanderbilt Obstetrics Comprehensive Care Clinic from 1999 to 2015 were included. Poor RIC was defined as not having ≥2 encounters per year, ≥90 days apart; poor VS was a viral load >200 copies/mL. Modified Poisson regression was used to estimate adjusted relative risks (aRRs) of poor postpartum RIC and VS.

Results

Among 248 women over 2070 person-years of follow-up, 37.6% person-years had poor RIC and 50.4% lacked VS. Prenatal substance use was independently associated with poor RIC (aRR, 1.40; 95% confidence interval [CI], 1.08–1.80) and poor VS (aRR, 1.20; 95% CI, 1.04–1.38), and lack of VS at enrollment was associated with poor RIC (aRR, 1.64; 95% CI, 1.15–2.35) and poor VS (aRR, 1.59; 95% CI, 1.30–1.94). Hispanic women were less likely and women with lower educational attainment were more likely to have poor RIC. Women >30 years of age and married women were less likely to have poor VS.

Conclusions

In this population of women in prenatal care at an HIV primary medical home in Tennessee, women with prenatal substance use and a lack of VS at enrollment into prenatal care were at greater risk of poor RIC and lack of VS postpartum. Interventions aimed at improving postpartum engagement in HIV care among these high-risk groups are needed.

A risk score model for predicting intraprocedural cardiac injury during implantable cardioverter defibrillator implantation: Insights from the National Cardiovascular Data Registry

BACKGROUND

Individual risk factors of intraprocedural cardiac injury (cardiac perforation and tamponade) during implantable cardioverter defibrillator (ICD) placement have been documented. However, the prognostic impact of their coexistence has not been explored.

OBJECTIVE

To develop a risk score model to identify patients at risk for intraprocedural cardiac injury.

METHODS

We identified 438 679 patients from National Cardiovascular Data Registry (NCDR)-ICD who underwent de novo ICD implantation between 2010 and 2015, split randomly into a derivation cohort (n = 220 000) and a validation cohort (n = 218 679). The generalized estimating equations (GEEs) analysis with quasilikelihood under the independence model criterion goodness-of-fit statistics were used to identify the predictors of intraprocedural cardiac injury and a risk scoring model was developed. Model discrimination was assessed by receiver-operator characteristic curve and C-statistic.

RESULTS

The risk of intraprocedural cardiac injury in the overall cohort was 0.13%. GEE analysis yielded seven variables (points in parentheses) that were strongly associated with intraprocedural cardiac injury: age, greater than 75 years (1), female gender (1), body mass index, less than 18.5 kg/m ² (1), hypertension (1), chronic lung disease (1), left bundle branch block (1), and continued warfarin use (1). Only prior history of coronary artery bypass grafting (CABG) (-1) was associated with reduced risk. A risk scoring system was developed that had good discrimination with a C-statistic of 0.72. The risk of intraprocedural cardiac injury increased with the increase in risk score from low risk (0.03%) to high risk (1.37%).

CONCLUSION

A practical risk score model can stratify patients into high- and low-risk groups for cardiac perforation or tamponade before undergoing ICD implantation.

Potential of a statistical approach for the standardization of multicenter diffusion tensor data: A phantom study

BACKGROUND

Diffusion tensor imaging (DTI) parameters, such as fractional anisotropy (FA), allow examining the structural integrity of the brain. However, the true value of these parameters may be confounded by variability in MR hardware, acquisition parameters, and image quality.

PURPOSE

To examine the effects of confounding factors on FA and to evaluate the feasibility of statistical methods to model and reduce multicenter variability.

STUDY TYPE

Longitudinal multicenter study.

PHANTOM

DTI single strand phantom (HQ imaging).

FIELD STRENGTH/SEQUENCE

3T diffusion tensor imaging.

ASSESSMENTS

Thirteen European imaging centers participated. DTI scans were acquired every 6 months and whenever maintenance or upgrades to the system were performed. A total of 64 scans were acquired in 2 years, obtained by three scanner vendors, using six individual head coils, and 12 software versions.

STATISTICAL TESTS

The variability in FA was assessed by the coefficients of variation (CoV). Several linear mixed effects models (LMEM) were developed and compared by means of the Akaike Information Criterion (AIC).

RESULTS

The CoV was 2.22% for mean FA and 18.40% for standard deviation of FA. The variables "site" (P = 9.26 × 10^-5 ), "vendor" (P = 2.18 × 10^-5 ), "head coil" (P = 9.00 × 10^-4 ), "scanner drift," "bandwidth" (P = 0.033), "TE" (P = 8.20 × 10^-6 ), "SNR" (P = 0.029) and "mean residuals" (P = 6.50 × 10^-4 ) had a significant effect on the variability in mean FA. The variables "site" (P = 4.00 × 10^-4 ), "head coil" (P = 2.00 × 10^-4 ), "software" (P = 0.014), and "mean voxel outlier intensity count" (P = 1.10 × 10^-4 ) had a significant effect on the variability in standard deviation of FA. The mean FA was best predicted by an LMEM that included "vendor" and the interaction term of "SNR" and "head coil" as model factors (AIC -347.98). In contrast, the standard deviation of FA was best predicted by an LMEM that included "vendor," "bandwidth," "TE," and the interaction term between "SNR" and "head coil" (AIC -399.81).

DATA CONCLUSION

Our findings suggest that perhaps statistical models seem promising to model the variability in quantitative DTI biomarkers for clinical routine and multicenter studies.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:955-965.

Pediatric Bone Mineral Accrual Z-Score Calculation Equations and Their Application in Childhood Disease

Annual gains in BMC and areal bone mineral density (aBMD) in children vary with age, pubertal status, height-velocity, and lean body mass accrual (LBM velocity). Evaluating bone accrual in children with bone health-threatening conditions requires consideration of these determinants. The objective of this study was to develop prediction equations for calculating BMC/aBMD velocity SD scores (velocity-Z) and to evaluate bone accrual in youth with health conditions. Bone and body compositions via DXA were obtained for up to six annual intervals in healthy youth (n = 2014) enrolled in the Bone Mineral Density in Childhood Study (BMDCS) . Longitudinal statistical methods were used to develop sex- and pubertal-status-specific reference equations for calculating velocity-Z for total body less head-BMC and lumbar spine (LS), total hip (TotHip), femoral neck, and 1/3-radius aBMD. Equations accounted for (1) height velocity, (2) height velocity and weight velocity, or (3) height velocity and LBM velocity. These equations were then applied to observational, single-center, 12-month longitudinal data from youth with cystic fibrosis (CF; n = 65), acute lymphoblastic leukemia (ALL) survivors (n = 45), or Crohn disease (CD) initiating infliximab (n = 72). Associations between BMC/aBMD-Z change (conventional pediatric bone health monitoring method) and BMC/aBMD velocity-Z were assessed. The BMC/aBMD velocity-Z for CF, ALL, and CD was compared with BMDCS. Annual changes in the BMC/aBMD-Z and the BMC/aBMD velocity-Z were strongly correlated, but not equivalent; LS aBMD-Z = 1 equated with LS aBMD velocity-Z = -3. In CF, BMC/aBMD velocity-Z was normal. In posttherapy ALL, BMC/aBMD velocity-Z was increased, particularly at TotHip (1.01 [-.047; 1.7], p < 0.0001). In CD, BMC/aBMD velocity-Z was increased at all skeletal sites. LBM-velocity adjustment attenuated these increases (eg, TotHip aBMD velocity-Z: 1.13 [0.004; 2.34] versus 1.52 [0.3; 2.85], p < 0.0001). Methods for quantifying the BMC/aBMD velocity that account for maturation and body composition changes provide a framework for evaluating childhood bone accretion and may provide insight into mechanisms contributing to altered accrual in chronic childhood conditions. © 2018 American Society for Bone and Mineral Research.

Differential Impact According to Mission's Operational Intensity on Psychoactive Substance Use: A Retrospective Cohort of French Male Army Service Members

BACKGROUND

Stressful deployments in combat areas are known to increase the risk of substance abuse in military personnel.

OBJECTIVES

The aim of the study was to compare deployment on stressful, high-intensity missions (HIMs) to deployment on low-intensity missions (LIMs) in order to understand factors associated with substance use variations across the mission.

METHODS

A retrospective cohort study based on a one-shot self-questionnaire was performed four months after their return on two samples of male French Army service members: one returning from an HIM and one from an LIM. The questionnaire focused on tobacco, alcohol, cannabis, cocaine, and psychoactive medication use at three times: before, during, and after the mission.

RESULTS

During an HIM, the frequency of tobacco use increased, alcohol use remained stable - although 38% declared a decrease in consumption - and illicit drug use decreased. During an LIM, tobacco and alcohol use increased, cannabis use remained stable, and only cocaine and medication use decreased. After their return, use levels among both samples reverted to values similar to those reported before the mission, except for a decrease in tobacco use observed at return from an HIM. The main factors perceived as related to variations were stress in an HIM and low cost in an LIM. Conclusions/importance: The study suggests a differential impact of deployment on substance use according to the operational intensity of the mission. Variations in use are predominant during the mission with a washout effect after returning home.

Preoperative Noninvasive Radiomics Approach Predicts Tumor Consistency in Patients With Acromegaly: Development and Multicenter Prospective Validation

Background: Prediction of tumor consistency before surgery is of vital importance to determine individualized therapeutic schemes for patients with acromegaly. The present study was performed to noninvasively predict tumor consistency based on magnetic resonance imaging and radiomics analysis. Methods: In total, 158 patients with acromegaly were randomized into the primary cohort (n = 100) and validation cohort (n = 58). The consistency of the tumor was classified as soft or firm according to the neurosurgeon's evaluation. The critical radiomics features were determined using the elastic net feature selection algorithm, and the radiomics signature was constructed. The most valuable clinical characteristics were then selected based on the multivariable logistic regression analysis. Next, a radiomics model was developed using the radiomics signature and clinical characteristics, and 30 patients with acromegaly were recruited for multicenter validation of the radiomics model. The model's performance was evaluated based on the receiver operating characteristic (ROC) curve, area under the ROC curve (AUC), accuracy, and other associated classification measures. Its calibration, discriminating capacity, and clinical usefulness were also evaluated. Results: The radiomics signature established according to four radiomics features screened in the primary cohort exhibited excellent discriminatory capacity in the validation cohort. The radiomics model, which incorporated both the radiomics signature and Knosp grade, displayed favorable discriminatory capacity and calibration, and the AUC was 0.83 (95% confidence interval, 0.81-0.85) and 0.81 (95% confidence interval, 0.78-0.83) in the primary and validation cohorts, respectively. Furthermore, compared with the clinical characteristics, the as-constructed radiomics model is more effective in prediction of the tumor consistency in patients with acromegaly. Moreover, the multicenter validation and decision curve analysis suggested that the radiomics model was clinically useful. Conclusions: This radiomics model can assist neurosurgeons in predicting tumor consistency in patients with acromegaly before surgery and facilitates the determination of individualized therapeutic schemes.

Machine Learning-Based Radiomics Predicts Radiotherapeutic Response in Patients With Acromegaly

Background: Prediction of radiotherapeutic response before radiotherapy could help determine individual treatment strategies for patients with acromegaly. Objective: To develop and validate a machine-learning-based multiparametric MRI radiomics model to non-invasively predict radiotherapeutic response in patients with acromegaly. Methods: This retrospective study included 57 acromegaly patients who underwent postoperative radiotherapy between January 2008 and January 2016. Manual lesion segmentation and radiomics analysis were performed on each pituitary adenoma, and 1561 radiomics features were extracted from each sequence. A radiomics signature was built with a support vector machine using leave-one-out cross-validation for feature selection. Multivariable logistic regression analysis was used to select appropriate clinicopathological features to construct a clinical model, which was then combined with the radiomics signature to construct a radiomics model. The performance of this radiomic model was assessed using receiver operating characteristics (ROC) analysis and its calibration, discriminating ability, clinical usefulness. Results: At 3-years after radiotherapy, 25 patients had achieved remission and 32 patients had not. The clinical model incorporating seven clinical features had an area under the ROC (AUC) of 0.86 for predicting radiotherapeutic response, and performed better than any single clinical feature. The radiomics signature constructed with six radiomics features had a significantly higher AUC of 0.92. The radiomics model showed good discrimination abilities and calibration, with an AUC of 0.96. Decision curve analysis confirmed the clinical utility of the radiomics model. Conclusion: Using pre-radiotherapy clinical and MRI data, we developed a radiomics model with favorable performance for individualized non-invasive prediction of radiotherapeutic response, which may help in identifying acromegaly patients who are likely to benefit from radiotherapy.

Perceived Devaluation among a Cohort of Street-Involved Youth in Vancouver, Canada

BACKGROUND

Perceived devaluation is a barrier to seeking mental and physical health services among people who use illicit drugs.

OBJECTIVE

Assessing the prevalence and correlates of perceived devaluation within a cohort of street-involved youth.

METHODS

Data were drawn from an open prospective cohort of street-involved youth who use illicit drugs (aged 14-26 at study enrollment) between December 2013 and May 2015 in Vancouver, Canada. Perceived devaluation was measured using an adapted version of Perceived Devaluation and Discrimination scale. Multivariable generalized estimating equations were constructed to examine factors independently associated with high perceived devaluation.

RESULTS

Among 411 street-involved youth, 95.1% reported high perceived devaluation at some point during the study period. In a multivariable analysis, youth who reported high perceived devaluation were significantly more likely to engage in: unprotected sex (Adjusted Odds Ratio [AOR] = 1.56, 95% Confidence Interval 1.03-2.37); heavy alcohol use (AOR = 2.31, 95% CI 1.22-4.36); and daily heroin use (AOR = 2.07, 95% CI 1.16-3.70). Youth who resided in the Downtown Eastside neighborhood were significantly less likely to report high perceived devaluation (AOR = 0.41, 95% CI 0.26-0.65).

CONCLUSIONS

Perceived devaluation was extremely prevalent among street-involved youth in our sample. We also observed that youth most in need of health and social services were significantly more likely to report high levels of perceived devaluation which may result in a reluctance to seek out key services and supports. These findings highlight the need to implement stigma reduction interventions for vulnerable youth in this setting.

TENSOR GENERALIZED ESTIMATING EQUATIONS FOR LONGITUDINAL IMAGING ANALYSIS

Longitudinal neuroimaging studies are becoming increasingly prevalent, where brain images are collected on multiple subjects at multiple time points. Analyses of such data are scientifically important, but also challenging. Brain images are in the form of multidimensional arrays, or tensors, which are characterized by both ultrahigh dimensionality and a complex structure. Longitudinally repeated images and induced temporal correlations add a further layer of complexity. Despite some recent efforts, there exist very few solutions for longitudinal imaging analyses. In response to the increasing need to analyze longitudinal imaging data, we propose several tensor generalized estimating equations (GEEs). The proposed GEE approach accounts for intra-subject correlation, and an imposed low-rank structure on the coefficient tensor effectively reduces the dimensionality. We also propose a scalable estimation algorithm, establish the asymptotic properties of the solution to the tensor GEEs, and investigate sparsity regularization for the purpose of region selection. We demonstrate the proposed method using simulations and by analyzing a real data set from the Alzheimer's Disease Neuroimaging Initiative.

Optimizing community screening for tuberculosis: Spatial analysis of localized case finding from door-to-door screening for TB in an urban district of Ho Chi Minh City, Viet Nam

BACKGROUND

Tuberculosis (TB) is the deadliest infectious disease globally. Current case finding approaches may miss many people with TB or detect them too late.

DATA AND METHODS

This study was a retrospective, spatial analysis of routine TB surveillance and cadastral data in Go Vap district, Ho Chi Minh City. We geocoded TB notifications from 2011 to 2015 and calculated theoretical yields of simulated door-to-door screening in three concentric catchment areas (50m, 100m, 200m) and three notification window scenarios (one, two and four quarters) for each index case. We calculated average yields, compared them to published reference values and fit a GEE (Generalized Estimating Equation) linear regression model onto the data.

RESULTS

The sample included 3,046 TB patients. Adjusted theoretical yields in 50m, 100m and 200m catchment areas were 0.32% (95%CI: 0.27,0.37), 0.21% (95%CI: 0.14,0.29) and 0.17% (95%CI: 0.09,0.25), respectively, in the baseline notification window scenario. Theoretical yields in the 50m-catchment area for all notification window scenarios were significantly higher than a reference yield from literature. Yield was positively associated with treatment failure index cases (beta = 0.12, p = 0.001) and short-term inter-province migrants (beta = 0.06, p = 0.022), while greater distance to the DTU (beta = -0.02, p<0.001) was associated with lower yield.

CONCLUSIONS

This study is an example of inter-departmental collaboration and application of repurposed cadastral data to progress towards the end TB objectives. The results from Go Vap showed that the use of spatial analysis may be able to identify areas where targeted active case finding in Vietnam can help improve TB case detection.

Education and Physical Health Trajectories in Later Life: A Comparative Study

The cumulative (dis)advantage hypothesis states that health disparities between education groups increase with age. The present study examined this hypothesis in a comparative analysis of the United States, the United Kingdom, the Netherlands, and Sweden. These countries offer sharp contrasts in the social conditions that may intensify or inhibit processes of cumulative (dis)advantage. Using harmonized panel data from the HRS, ELSA, and SHARE, the study applied Poisson multilevel regression models to trace changes in the number of chronic conditions and functional limitations of people aged 50–76 (N = 16,887 individuals; 71,154 observations). The four countries showed a clear gradient in levels of physical health and in the extent to which health trajectories were shaped by education. Across all ages and cohorts, health problems were most prevalent in the United States, less prevalent in the United Kingdom and the Netherlands, and least prevalent in Sweden. A similar cross-national gradient was found for the size of health gaps between education groups and for the extent to which these gaps widened with age. Gaps were largest in the United States, smaller in the United Kingdom and in the Netherlands, and smallest in Sweden.

Acceptability of a decision-support electronic health record system and its impact on diabetes care goals in South Asia: a mixed-methods evaluation of the CARRS trial

AIMS

To describe physicians' acceptance of decision-support electronic health record system and its impact on diabetes care goals among people with Type 2 diabetes.

METHODS

We analysed data from participants in the Centre for Cardiometabolic Risk Reduction in South Asia (CARRS) trial, who received the study intervention (care coordinators and use of a decision-support electronic health record system; n=575) using generalized estimating equations to estimate the association between acceptance/rejection of decision-support system prompts and outcomes (mean changes in HbA_1c , blood pressure and LDL cholesterol) considering repeated measures across all time points available. We conducted in-depth interviews with physicians to understand the benefits, challenges and value of the decision-support electronic health record system and analysed physicians' interviews using Rogers' diffusion of innovation theory.

RESULTS

At end-of-trial, participants with diabetes for whom glycaemic, systolic blood pressure, diastolic blood pressure and LDL cholesterol decision-support electronic health record prompts were accepted vs rejected, experienced no reduction in HbA_1c [mean difference: -0.05 mmol/mol (95% CI -0.22, 0.13); P=0.599], but statistically significant improvements were observed for systolic blood pressure [mean difference: -11.6 mmHg (95% CI -13.9, -9.3); P ≤ 0.001], diastolic blood pressure [mean difference: -5.2 mmHg (95% CI -6.5, -3.8); P ≤ 0.001] and LDL cholesterol [mean difference: -0.7 mmol/l (95% CI -0.6, -0.8); P ≤0.001], respectively. The relative advantages and compatibility of the decision-support electronic health record system with existing clinic set-ups influenced physicians' acceptance of it. Software complexities and data entry challenges could be overcome by task-sharing.

CONCLUSION

Wider adherence to decision-support electronic health record prompts could potentially improve diabetes goal achievement, particularly when accompanied by assistance from a non-physician health worker.

An age-based analysis of nonmedical prescription opioid use among people who use illegal drugs in Vancouver, Canada

BACKGROUND

Nonmedical prescription opioid use (NMPOU) is a serious public health problem in North America. At a population-level, previous research has identified differences in the prevalence and correlates of NMPOU among younger versus older age groups; however, less is known about age-related differences in NMPOU among people who use illegal drugs.

METHODS

Data were collected between 2013 and 2015 from two linked prospective cohort studies in Vancouver, Canada: the At-Risk Youth Study (ARYS) and the Vancouver Injection Drug Users Study (VIDUS). Factors independently associated with NMPOU among younger (ARYS) and older (VIDUS) participants were examined separately using bivariate and multivariate generalized estimating equations.

RESULTS

A total of 1162 participants were included. Among 405 eligible younger participants (Median age = 25; Inter-Quartile Range [IQR]: 22-28), 40% (n = 160) reported engaging in NMPOU at baseline; among 757 older participants (Median age = 48, IQR: 40-55), 35% (n = 262) reported engaging in NMPOU at baseline. In separate multivariate analyses of younger and older participants, NMPOU was positively and independently associated with heroin use (younger: Adjusted Odds Ratio [AOR] = 3.12, 95% Confidence Interval [CI]: 2.08-4.68; older: AOR = 2.79, 95% CI: 2.08-3.74), drug dealing (younger: AOR = 2.22, 95% CI: 1.58-3.13; older: AOR = 1.87, 95% CI: 1.40-2.49), and difficulty accessing services (younger: AOR = 1.47, 95% CI: 1.04-2.09; older: AOR = 1.74, 95% CI: 1.32-2.29). Among the youth cohort only, NMPOU was associated with younger age (AOR = 1.12, 95% CI: 1.05-1.19), crack use (AOR = 1.56, 95% CI: 1.06-2.30), and binge drug use (AOR = 1.41, 95% CI: 1.00-1.97); older participants who engaged in NMPOU were more likely to report crystal methamphetamine use (AOR = 1.97, 95% CI: 1.46-2.66), non-fatal overdose (AOR = 1.76, 95% CI: 1.20-2.60) and sex work (AOR = 1.49, 95% CI: 1.00-2.22).

DISCUSSION

The prevalence of NMPOU is similar among younger and older people who use drugs, and independently associated with markers of vulnerability among both age groups. Adults who engage in NMPOU are at risk for non-fatal overdose, which highlights the need for youth and adult-specific strategies to address NMPOU that include better access to health and social services, as well as a range of addiction treatment options for opioid use. Findings also underscore the importance of improving pain treatment strategies tailored for PWUD.

Passive transfer of anti-HBc after intravenous immunoglobulin administration in patients with cancer: a retrospective chart review

BACKGROUND

Patients previously infected with hepatitis B virus (HBV; indicated by positivity for anti-HBc) can experience HBV reactivation during cancer chemotherapy. Intravenous immunoglobulin infusion, which is frequently used in supportive care, might facilitate passive transfer of anti-HBc. We aimed to estimate the probability of passive transfer of anti-HBc after intravenous immunoglobulin infusion in patients with cancer.

METHODS

We reviewed institutional databases to identify adult patients who received outpatient chemotherapy between Jan 1, 2004, and Dec 31, 2011, at the University of Texas MD Anderson Cancer Center, Houston, TX, USA. Eligible patients had received intravenous immunoglobulin therapy, had tested negative for both anti-HBc and HBsAg before infusion, and had been tested for anti-HBc after infusion. The primary endpoint was the proportion of patients who became positive for anti-HBc after intravenous immunoglobulin infusion.

FINDINGS

950 of 18 874 patients who underwent chemotherapy within the study time frame received intravenous immunoglobulin, of whom 870 had been tested for anti-HBc before infusion. 199 patients who were negative for anti-HBc before receiving intravenous immunoglobulin were retested after infusion, of whom 29 (15% [95% CI 10-20]) became positive for anti-HBc. The probability of anti-HBc conversion at 1 week after intravenous immunoglobulin infusion was 34% (95% CI 22-48) and at 12 weeks was 4% (2-7).

INTERPRETATION

Conversion of patients from anti-HBc negativity to anti-HBc positivity was common after intravenous immunoglobulin administration. However, the probability of a positive test decreased with time since infusion. Positive anti-HBc tests done shortly after intravenous immunoglobulin infusion should be interpreted with caution because they might indicate passive transfer instead of true infection.

FUNDING

None.

Practical issues in using generalized estimating equations for inference on transitions in longitudinal data: What is being estimated?

Generalized estimating equations (GEEs) are commonly used to estimate transition models. When the Markov assumption does not hold but first-order transition probabilities are still of interest, the transition inference is sensitive to the choice of working correlation. In this paper, we consider a random process transition model as the true underlying data generating mechanism, which characterizes subject heterogeneity and complex dependence structure of the outcome process in a very flexible way. We formally define two types of transition probabilities at the population level: "naive transition probabilities" that average across all the transitions and "population-average transition probabilities" that average the subject-specific transition probabilities. Through asymptotic bias calculations and finite-sample simulations, we demonstrate that the unstructured working correlation provides unbiased estimators of the population-average transition probabilities while the independence working correlation provides unbiased estimators of the naive transition probabilities. For population-average transition estimation, we demonstrate that the sandwich estimator fails for unstructured GEE and recommend the use of either jackknife or bootstrap variance estimates. The proposed method is motivated by and applied to the NEXT Generation Health Study, where the interest is in estimating the population-average transition probabilities of alcohol use in adolescents.

Land Use, anthropogenic disturbance, and riverine features drive patterns of habitat selection by a wintering waterbird in a semi-arid environment

River ecosystems in semi-arid environments provide an array of resources that concentrate biodiversity, but also attract human settlement and support economic development. In the southwestern United States, land-use change, drought, and anthropogenic disturbance are compounding factors which have led to departures from historical conditions of river ecosystems, consequently affecting wildlife habitat, including important wintering areas for migratory birds. The Rio Grande (River) in central New Mexico is the lifeblood of the Middle Rio Grande Valley (MRGV), maintaining large urban and agricultural centers and riparian and wetland resources, which disproportionately support a diversity of wildlife. The MRGV has been identified as the most important wintering area for the Rocky Mountain Population of greater sandhill cranes (Antigone canadensis tabida). Presently, however, changes in the hydrogeomorphology of the Rio Grande and landscape modification by humans have reshaped the MRGV and winter habitat for sandhill cranes. To evaluate these impacts, we investigated how land-use practices, anthropogenic disturbance, and river morphology influenced patterns of diurnal and roosting habitat selection by sandhill cranes. During the diurnal period, sandhill cranes relied heavily on managed public lands selecting agriculture crops, such as corn fields, and wetlands for foraging and loafing while avoiding areas with increasing densities of human structures. Sandhill cranes selected areas for roosting in the Rio Grande characterized by shallower water interspersed with sandbars, wide channel width, low bank vegetation, and farther away from disturbances associated with bridges. Our results establish and identify the central processes driving patterns of diel habitat selection by wintering sandhill cranes. Land use and riverine trends have likely gradually reduced winter habitat to managed public lands and limited reaches of the Rio Grande, underscoring the importance of natural resources agencies in supporting migratory birds and challenges involved when managing for wildlife in highly pressured semi-arid environments.

An R package for model fitting, model selection and the simulation for longitudinal data with dropout missingness

Missing data arise frequently in clinical and epidemiological fields, in particular in longitudinal studies. This paper describes the core features of an R package wgeesel, which implements marginal model fitting (i.e., weighted generalized estimating equations, WGEE; doubly robust GEE) for longitudinal data with dropouts under the assumption of missing at random. More importantly, this package comprehensively provide existing information criteria for WGEE model selection on marginal mean or correlation structures. Also, it can serve as a valuable tool for simulating longitudinal data with missing outcomes. Lastly, a real data example and simulations are presented to illustrate and validate our package.

Adult-larval vibrational communication in paper wasps: the role of abdominal wagging in Polistes dominula

Communication through vibrational signals is widespread among social insects and regulates crucial social activities. Females of the social wasp Polistes dominula produce substrate-borne vibrations on the combs by performing a conspicuous abdominal oscillatory behavior, known as abdominal wagging. Several studies have reported correlative evidence in support of its signaling role, but direct evidence is still lacking. Because abdominal wagging is strictly associated with the presence of larvae in the nest and with cell inspection, it has been suggested that it could be involved in adult-larvae communication. According to this hypothesis, abdominal wagging vibrations would have short-term effects related to food and trophallactic exchanges between adults and larvae by modulating salivary secretion (decreasing its amount, to prepare larvae to receive food, or stimulating the release of larval saliva to adults). Here, by using an electro-magnetic shaker, we assessed, for the first time, the short-term effects of abdominal wagging on larval behavior by recording larval responses and by measuring the amount of saliva released immediately after abdominal wagging playback. Our results show that larvae are able to perceive the substrate-borne vibrations produced by abdominal wagging and react by increasing the movement of their body, possibly in order to attract the attention of adult females during feeding nest inspection. Yet, we found that vibrations neither increase nor decrease the release of larval saliva. Our results support the hypothesis of the alleged role of vibrations in adult-larvae communications; however, they do not support the long-lasting hypothesis of salivary release modulation.

Navigating snowscapes: scale-dependent responses of mountain sheep to snowpack properties

Winters are limiting for many terrestrial animals due to energy deficits brought on by resource scarcity and the increased metabolic costs of thermoregulation and traveling through snow. A better understanding of how animals respond to snow conditions is needed to predict the impacts of climate change on wildlife. We compared the performance of remotely sensed and modeled snow products as predictors of winter movements at multiple spatial and temporal scales using a data set of 20,544 locations from 30 GPS-collared Dall sheep (Ovis dalli dalli) in Lake Clark National Park and Preserve, Alaska, USA from 2005 to 2008. We used daily 500-m MODIS normalized difference snow index (NDSI), and multi-resolution snow depth and density outputs from a snowpack evolution model (SnowModel), as covariates in step selection functions. We predicted that modeled snow depth would perform best across all scales of selection due to more informative spatiotemporal variation and relevance to animal movement. Our results indicated that adding any of the evaluated snow metrics substantially improved model performance and helped characterize winter Dall sheep movements. As expected, SnowModel-simulated snow depth outperformed NDSI at fine-to-moderate scales of selection (step scales < 112 h). At the finest scale, Dall sheep selected for snow depths below mean chest height (<54 cm) when in low-density snows (100 kg/m³ ), which may have facilitated access to ground forage and reduced energy expenditure while traveling. However, sheep selected for higher snow densities (>300 kg/m³ ) at snow depths above chest height, which likely further reduced energy expenditure by limiting hoof penetration in deeper snows. At moderate-to-coarse scales (112-896 h step scales), however, NDSI was the best-performing snow covariate. Thus, the use of publicly available, remotely sensed, snow cover products can substantially improve models of animal movement, particularly in cases where movement distances exceed the MODIS 500-m grid threshold. However, remote sensing products may require substantial data thinning due to cloud cover, potentially limiting its power in cases where complex models are necessary. Snowpack evolution models such as SnowModel offer users increased flexibility at the expense of added complexity, but can provide critical insights into fine-scale responses to rapidly changing snow properties.

Restoration of short chain fatty acid and bile acid metabolism following fecal microbiota transplantation in patients with recurrent Clostridium difficile infection

A significant proportion of individuals develop recurrent Clostridium difficile infection (CDI) following initial disease. Fecal microbiota transplantation (FMT), a highly effective treatment method for recurrent CDI, has been demonstrated to induce microbiota recovery. One of the proposed functions associated with restoration of colonization resistance against C. difficile has been recovery of bile acid metabolism. In this study, we aimed to assess recovery of short chain fatty acids (SCFAs) in addition to bile acids alongside microbial community structure in six patients with recurrent CDI following treatment with FMT over time. Using 16S rRNA gene-based sequencing, we observed marked similarity of the microbiota between recipients following FMT (n = 6, sampling up to 6 months post-FMT) and their respective donors. Sustained increases in the levels of the SCFAs butyrate, acetate, and propionate were observed post-FMT, and variable recovery over time was observed in the secondary bile acids deoxycholate and lithocholate. To correlate these changes with specific microbial taxa at an individual level, we applied a generalized estimating equation approach to model metabolite concentrations with the presence of specific members of the microbiota. Metabolites that increased following FMT were associated with bacteria classified within the Lachnospiraceae, Ruminococcaceae, and unclassified Clostridiales families. In contrast, members of these taxa were inversely associated with primary bile acids. The longitudinal aspect of this study allowed us to characterize individualized patterns of recovery, revealing variability between and within patients following FMT.

Preoperative prediction of cavernous sinus invasion by pituitary adenomas using a radiomics method based on magnetic resonance images

Objectives

To predict cavernous sinus (CS) invasion by pituitary adenomas (PAs) pre-operatively using a radiomics method based on contrast-enhanced T1 (CE-T1) and T2-weighted magnetic resonance (MR) imaging.

Methods

A total of 194 patients with Knosp grade two and three PAs (training set: n = 97; test set: n = 97) were enrolled in this retrospective study. From CE-T1 and T2 MR images, 2553 quantitative imaging features were extracted. To select the most informative features, least absolute shrinkage and selection operator (LASSO) was performed. Subsequently, a linear support vector machine (SVM) was used to fit the predictive model. Furthermore, a nomogram was constructed by incorporating clinico-radiological risk factors and radiomics signature, and the clinical usefulness of the nomogram was validated using decision curve analysis (DCA).

Results

Three imaging features were selected in the training set, based on which the radiomics model yielded area under the curve (AUC) values of 0.852 and 0.826 for the training and test sets. The nomogram based on the radiomics signature and the clinico-radiological risk factors yielded an AUC of 0.899 in the training set and 0.871 in the test set.

Conclusions

The nomogram developed in this study might aid neurosurgeons in the pre-operative prediction of CS invasion by Knosp grade two and three PAs, which might contribute to creating surgical strategies.

Key Points

• Pre-operative diagnosis of CS invasion by PAs might affect creating surgical strategies

• MRI might help for diagnosis of CS invasion by PAs before surgery

• Radiomics might improve the CS invasion detection by MR images.

Electronic supplementary material

The online version of this article (10.1007/s00330-018-5725-3) contains supplementary material, which is available to authorized users.

Assessing utility values for treatment-related health states of acute myeloid leukemia in the United States

Background

Preference valuations of health status are essential in health technology and economic appraisal. This study estimated utilities for treatment-related health states of acute myeloid leukemia (AML) and disutilities of severe adverse events (SAEs) using a representative sample of adults from the general population in the United States (US).

Methods

Treatment-related AML health states, defined based on literature and interviews with clinicians, included complete remission (CR), no CR, relapse, stem cell transplant (SCT), and post SCT short-term recovery. Six attributes with varying levels, including fever, lack of energy, problems with daily function, anxiety/depression, blood transfusions, and hospitalization, were used to define health states. An online survey using discrete choice experiment methodology was designed to capture preferences for health status scenarios including the identified attributes and key grade 3/4 chemotherapy-related SAEs. Health state utilities and SAE disutilities were generated from a conditional logistic regression with generalized estimating equations.

Results

Of the 300 survey participants, the demographic distributions were within a 3% margin of those in the 2010 US Census. CR had the highest utility value (0.875), followed by post-SCT short-term recovery (0.398), relapse (0.355), no CR (0.262), and SCT (0.158). Of the SAEs, serious infection had the highest decline in utility (0.218), followed by severe diarrhea (0.176), abnormally low blood cell counts (0.100), and severe redness/skin peeling (0.060).

Conclusions

AML and treatments can result in reduced quality of life and impaired ability to perform daily activities. Findings of this study underline the value that society places on treatment-related AML health states and SAEs.

Workplace violence among female sex workers who use drugs in Vancouver, Canada: does client-targeted policing increase safety?

Workplace violence, by clients or predators, poses serious negative health consequences for sex workers. In 2013, the Vancouver (British Columbia), Canada Police Department changed their guidelines with the goal of increasing safety for sex workers by focusing law enforcement on clients and third parties, but not sex workers. We sought to examine the trends and correlates of workplace violence among female sex workers (FSW) before and after the guideline change, using data collected from prospective cohorts of persons who use illicit drugs in Vancouver, Canada. Among 259 FSW, 21.0% reported workplace violence at least once during the study period between 2008 and 2014. There was no statistically significant change in rates of workplace violence after the guideline change. In our multivariable analysis, daily heroin use was independently associated with workplace violence. The 2013 policing guideline change did not appear to have resulted in decreased reports of workplace violence. Increased access to opioid agonist therapies may reduce workplace violence among drug-using FSW.

Seroprevalence, risk factor, and spatial analyses of Zika virus infection after the 2016 epidemic in Managua, Nicaragua

In 2015, a Zika epidemic in Brazil began spreading throughout the Americas. Zika virus (ZIKV) entered Managua, Nicaragua, in January 2016 and caused an epidemic that peaked in July-September 2016. ZIKV seropositivity was estimated among participants of pediatric (n = 3,740) and household (n = 2,147) cohort studies, including an adult-only subset from the household cohort (n = 1,074), in Managua. Seropositivity was based on a highly sensitive and specific assay, the Zika NS1 blockade-of-binding ELISA, which can be used in dengue-endemic populations. Overall seropositivity for the pediatric (ages 2-14), household (ages 2-80), and adult (ages 15-80) cohorts was 36, 46, and 56%, respectively. Trend, risk factor, and contour mapping analyses demonstrated that ZIKV seroprevalence increased nonlinearly with age and that body surface area was statistically associated with increasing seroprevalence in children. ZIKV seropositivity was higher in females than in males across almost all ages, with adjusted prevalence ratios in children and adults of 1.11 (95% CI: 1.02-1.21) and 1.14 (95% CI: 1.01-1.28), respectively. No household-level risk factors were statistically significant in multivariate analyses. A spatial analysis revealed a 10-15% difference in the risk of ZIKV infections across our 3-km-wide study site, suggesting that ZIKV infection risk varies at small spatial scales. To our knowledge, this is the largest ZIKV seroprevalence study reported in the Americas, and the only one in Central America and in children to date. It reveals a high level of immunity against ZIKV in Managua as a result of the 2016 epidemic, making a second large Zika epidemic unlikely in the near future.

Young children's capacity to imagine and prepare for certain and uncertain future outcomes

The current study used a minimalist paradigm to examine young children's capacity to imagine and prepare for certain and uncertain immediate future outcomes. In a counterbalanced order, 2.5-year-old children (N = 32) completed twelve trials each of two tasks: (1) the forked tube task, which assessed their ability to cover two possible tube exits to ensure they would catch a single target with an uncertain future trajectory, and (2) the double tube task, which assessed their ability to cover two separate tube exits to ensure they would catch two targets with certain future trajectories. Even though the optimal preparatory action was the same across both tasks, children were much more likely to spontaneously and consistently demonstrate this action in the double tube task than the forked tube task. Children's responses were unaffected by the number of targets seen in the demonstration phase, and instead appeared to be based on the particular contingencies of each apparatus. These results are consistent with the possibility that young children specifically struggle to imagine and prepare for mutually exclusive versions of uncertain future events.

Capture, swallowing, and egestion of microplastics by a planktivorous juvenile fish

Microplastics (<5 mm) have been found in many fish species, from most marine environments. However, the mechanisms underlying microplastic ingestion by fish are still unclear, although they are important to determine the pathway of microplastics along marine food webs. Here we conducted experiments in the laboratory to examine microplastic ingestion (capture and swallowing) and egestion by juveniles of the planktivorous palm ruff, Seriolella violacea (Centrolophidae). As expected, fish captured preferentially black microplastics, similar to food pellets, whereas microplastics of other colours (blue, translucent, and yellow) were mostly co-captured when floating close to food pellets. Microplastics captured without food were almost always spit out, and were only swallowed when they were mixed with food in the fish's mouth. Food probably produced a 'gustatory trap' that impeded the fish to discriminate and reject the microplastics. Most fish (93% of total) egested all the microplastics after 7 days, on average, and 49 days at most, substantially longer than food pellets (<2 days). No acute detrimental effects of microplastics on fish were observable, but potential sublethal effects of microplastics on the fish physiological and behavioural responses still need to be tested. This study highlights that visually-oriented planktivorous fish, many species of which are of commercial value and ecological importance within marine food webs, are susceptible to ingest microplastics resembling or floating close to their planktonic prey.

Downsizing and purchases of psychotropic drugs: A longitudinal study of stayers, changers and unemployed

BACKGROUND

The evidence is insufficient regarding the association between organizational downsizing and employee mental health. Our aim was to analyze trajectories of prescribed sedatives and anxiolytics with a sufficiently long follow-up time to capture anticipation, implementation and adaption to a downsizing event among stayers, changers and those who become unemployed compared to unexposed employees.

METHOD

Swedish residents aged 20-54 years in 2007, with stable employment between 2004 and 2007, were followed between 2005 and 2013 (n = 2,305,795). Employment at a workplace with staff reductions ≥18% between two subsequent years in 2007-2011 (n = 915,461) indicated exposure to, and timing of, downsizing. The unexposed (n = 1,390,334) were randomized into four corresponding sub-cohorts. With generalized estimating equations, we calculated the odds ratios (OR) of purchasing prescribed anxiolytics or sedatives within nine 12-month periods, from four years before to four years after downsizing. In order to investigate whether the groups changed their probability of purchases over time, odds ratios (OR) and their 95% confidence intervals (95% CI) were calculated contrasting the prevalence of purchases during the first and the last 12-month period within four time periods for each exposure group.

RESULTS

The odds of purchasing anxiolytics increased more for stayers (OR 1.03, 95% CI 1.01-1.06) and unemployed (OR 1.08, 95% CI 1.03-1.14) compared to unexposed before downsizing, and purchases continued to increase after downsizing for stayers. Among those without previous sickness absence, stayers increased their purchases of anxiolytics from the year before the event up to four years after the event. Trajectories for sedatives were similar but less pronounced.

CONCLUSION

This study indicates that being exposed to downsizing is associated with increased use of sedatives and anxiolytics, especially before the event, if the employee stays in the organization or becomes unemployed.

Rare variant association test in family-based sequencing studies

The objective of this article is to introduce valid and robust methods for the analysis of rare variants for family-based exome chips, whole-exome sequencing or whole-genome sequencing data. Family-based designs provide unique opportunities to detect genetic variants that complement studies of unrelated individuals. Currently, limited methods and software tools have been developed to assist family-based association studies with rare variants, especially for analyzing binary traits. In this article, we address this gap by extending existing burden and kernel-based gene set association tests for population data to related samples, with a particular emphasis on binary phenotypes. The proposed approach blends the strengths of kernel machine methods and generalized estimating equations. Importantly, the efficient generalized kernel score test can be applied as a mega-analysis framework to combine studies with different designs. We illustrate the application of the proposed method using data from an exome sequencing study of autism. Methods discussed in this article are implemented in an R package 'gskat', which is available on CRAN and GitHub.

Identifying people at risk of developing type 2 diabetes: A comparison of predictive analytics techniques and predictor variables

BACKGROUND

The present study aims to identify the patients at risk of type 2 diabetes (T2D). There is a body of literature that uses machine learning classification algorithms to predict development of T2D among patients. The current study compares the performance of these classification algorithms to identify patients who are at risk of developing T2D in short, medium and long terms. In addition, the list of predictor variables important for prediction for T2D progression is provided.

METHODS

This study uses 10,911 records generated in 36 clinics from the 15th of November 2008-15th of November 2016. Syntactic minority oversampling and random under sampling were used to create a balanced dataset. The performance of Neural Networks, Support Vector Machines, Decision Tress and Logistic Regression to identify patients developing T2D in short, medium and long terms was compared. The measures were Area Under Curve, Sensitivity, Specificity, Matthew correlation coefficient and Mean Calibration Error. Through importance analysis and information fusion techniques the predictors of developing T2D were identified for short, medium and long-term risk analysis.

RESULTS

The findings show that the performance of analytics techniques depends on both period and purpose of prediction whether the prediction is to identify people who will not develop T2D or to determine at risk patients. Oversampling as opposed to under sampling improved performance. 16 predictors and their importance to determine patients at risk of T2D in short, medium and long terms were identified.

CONCLUSIONS

This study provides guidelines for an automated system to prompt patients for screening. Several predictors are reportable by patients, others can be examined by physicians or ordered for further lab examination, which offers a potential reduction of the burden placed upon the clinical settings.

Serum potassium as a predictor of adverse clinical outcomes in patients with chronic kidney disease: new risk equations using the UK clinical practice research datalink

BACKGROUND

To address a current paucity of European data, this study developed equations to predict risks of mortality, major adverse cardiac events (MACE) and renin angiotensin-aldosterone system inhibitor (RAASi) discontinuation using time-varying serum potassium and other covariates, in a UK cohort of chronic kidney disease (CKD) patients.

METHODS

This was a retrospective observational study of adult CKD patients listed on the Clinical Practice Research Datalink, with a first record of CKD (stage 3a-5, pre-dialysis) between 2006 and 2015. Patients with heart failure at index were excluded. Risk equations developed using Poisson Generalized Estimating Equations were utilised to estimate adjusted incident rate ratios (IRRs) between serum potassium and adverse outcomes, and identify other predictive clinical factors.

RESULTS

Among 191,964 eligible CKD patients, 86,691 (45.16%), 30,629 (15.96%) and 9440 (4.92%) experienced at least one hyperkalaemia episode, when defined using serum potassium concentrations 5.0-< 5.5 mmol/L, 5.5-< 6.0 mmol/L and ≥ 6.0 mmol/L, respectively. Relative to the reference category (4.5 to < 5.0 mmol/L), adjusted IRRs for mortality and MACE exhibited U-shaped associations with serum potassium, with age being the most important predictor of both outcomes (P < 0.0001). A J-shaped association between serum potassium and RAASi discontinuation was observed; estimated glomerular filtration rate was most predictive of RAASi discontinuation (P < 0.0001).

CONCLUSIONS

Hyperkalaemia was associated with increased mortality and RAASi discontinuation risk. These risk equations represent a valuable tool to predict clinical outcomes among CKD patients; and identify those likely to benefit from strategies that treat hyperkalaemia, prevent RAASi discontinuation, and effectively manage serum potassium levels.

Maternal and child patterns of Medicaid retention: a prospective cohort study

BACKGROUND

We sought to determine whether maternal Medicaid retention influences child Medicaid retention because caregivers play a critical role in assuring children's health access.

METHODS

We conducted a longitudinal prospective cohort study of a convenience sample of 604 Medicaid-eligible mother-child dyads followed from the infant's birth through 24 months of age with parent surveys. Individual enrollment status was abstracted from administrative Medicaid eligibility files. Generalized estimating equations quantified the effect of maternal Medicaid enrollment status on child Medicaid retention, adjusting for relevant covariates. Because varying lengths of gaps may have different effects on child health outcomes, Medicaid enrollment status was further categorized by length of gap: any gap, > 14-days, and > 60-days.

RESULTS

This cohort consists primarily of African-American (94%), unmarried mothers (88%), with a mean age of 23.2 years. In multivariable analysis, children whose mothers experienced any gaps in coverage had 12.6 times greater odds of experiencing gaps when compared to children whose mothers were continuously enrolled. Use of varying thresholds to define coverage gaps resulted in similar odds ratios (> 14-day gap = 11.8, > 60-day gap = 16.8). Cash assistance receipt and maternal knowledge of differences between Temporary Assistance to Needy Families and Medicaid eligibility criteria demonstrated strong protective effects against child Medicaid disenrollment.

CONCLUSIONS

Medicaid disenrollment remains a significant policy problem and maternal Medicaid retention patterns show strong effects on child Medicaid retention. Policymakers need to invest in effective outreach strategies, including family-friendly application processes, to reduce enrollment barriers so that all eligible families can take advantage of these coverage opportunities.

An Ecological Momentary Assessment of Cigarette and Cigar Dual Use Among African American Young Adults

Introduction

The dual use of cigarettes and cigars among African American young adults is a significant public health issue. Patterns of and reasons for dual use are difficult to capture using traditional self-report methods. This study used ecological momentary assessment (EMA) to characterize patterns of dual smoking and examine the personal and environmental predictors of cigarette and cigar smoking among African American young adult dual users (ages 18-29) in real-time.

Methods

For 14 days, 64 participants smoked ad libitum and were prompted four times daily to record their smoking, craving, emotions, social smoking, and environment via text message on their mobile phones. The odds of single product and dual use were examined using adjusted generalized estimating equations.

Results

Participants smoked an average of 7.9 cigarettes and 4.2 cigars per day. Cigarettes and cigars were smoked as frequently during periods of dual use as they were during periods of single product use. Cigarette craving was positively associated with cigarette-only smoking (OR: 1.07), whereas cigar craving was positively associated with cigar-only smoking (OR: 1.43) and dual use (OR: 1.08). Cigars had the greatest odds of dual use when with others (OR: 4.69) and in others' homes (OR: 4.33). Cigarettes had the greatest odds of being smoked while alone (OR: 1.57).

Conclusions

EMA was useful for capturing variable smoking patterns and predictors. In this study population, cigarettes and cigars appeared to be smoked additively, and cigars smoked socially. These findings can inform future interventions addressing dual use in this high priority population.

Implications

This is the first study to use EMA to examine naturalistic patterns and predictors of multiple tobacco use in real-time. African American young adults smoked cigarettes and cigars during periods of dual use as frequently as during periods of single product use. This suggests that most use was additive (one product smoked in addition to another) and less often as substitution (one product smoked instead of another). Social smoking and craving were strongly associated with cigar smoking in single and dual use periods. This study suggests the need for cessation messaging specifically targeted to reduce dual use in this population.

Which factors can aid clinicians to identify a risk of pain during the following month in patients with bone metastases? A longitudinal analyses

PURPOSE

Explore clinical factors associated with higher pain intensity and future pain in patients with bone metastases to identify patients who can benefit from closer follow-up or pain-modifying interventions.

METHODS

This is a secondary analysis of 606 patients with bone metastases included in a multicenter longitudinal study. The dependent variables were "average pain" and "worst pain" in the last 24 h (0-10 NRS). Twenty independent variables with potential association to pain intensity were selected based on previous literature. Cross-sectional analyses were performed with multiple linear regression to explore factors associated with pain intensity at baseline. Longitudinal data were analyzed with a generalized equation models to explore current factors associated with pain intensity at the next visit in 1 month.

RESULTS

Current pain intensity (p < 0.001), sleep disturbances (p 0.01 and 0.006), drowsiness (p 0.003 and 0.033) and male gender (p 0.045 and 0.001) were associated with higher average and worst pain intensity in 1 month. In addition, breakthrough pain was related to higher worst pain intensity (p 0.003) in 1 month. The same variables were also associated with higher average pain intensity at baseline.

CONCLUSION

Higher current pain intensity, sleep disturbances, drowsiness, male gender, and breakthrough pain are factors associated with higher pain intensity in patients with bone metastases at the next follow-up in 1 month. These factors should be assessed in clinical practice and may aid clinicians in identifying patients that can benefit from closer follow-up or interventions to prevent lack of future pain control. TRIAL REGISTRATION IN CLINICALTRIALS.GOV : NCT01362816.

Informal recycling, income generation and risk: Health and social harms among people who use drugs

BACKGROUND

Informal recycling refers to the street-based collection of discarded materials for reuse, resale, or return to a recycling facility for money. While qualitative research has explored experiences and perceptions of informal recycling, little is known about the scope and exposures associated with informal recycling among people who use drugs (PWUD).

METHODS

Using data from two prospective longitudinal cohorts of PWUD, we examined the prevalence of informal recycling and its association with social, structural and health risks, including criminal justice system involvement.

RESULTS

Between June 2010 and May 2015, of 1664 participants, 557 (33.5%) reported engaging in informal recycling during the study period. In multivariable generalised estimating equations (GEE) analyses, informal recycling was positively associated with injection drug use (Adjusted Odds Ratio (AOR) = 1.43, 95% Confidence Interval (CI) 1.21-1.68), public injection (AOR = 1.27, 95% CI 1.09-1.49), methamphetamine use (AOR = 1.35, 95% CI 1.05-1.72), difficulty finding harm reduction equipment (AOR = 1.16, 95% CI 1.02-1.32), and police interactions (AOR = 1.35, 95% CI 1.18-1.55). Sub-analyses revealed PWUD engaged in informal recycling were more likely to be told to move on, ticketed, stopped for jaywalking, and directed to services by police.

CONCLUSIONS

These findings suggest informal recycling as a situated practice for PWUD, with potential indications for higher-risk drug use, experiencing greater surveillance, and difficulty accessing health and addiction treatment services. This research highlights the significance of the broader risk environment and the need for health-promoting policies for socioeconomically marginalised PWUD engaged in informal recycling.

Impact of hypertension on health-related quality of life among different age subgroups in Shanghai: the subpopulation treatment effect pattern plot analysis

The aim of our study was to investigate the effect of hypertension on health-related quality of life (HRQoL) among different age subgroups of people in Shanghai using subpopulation treatment effect pattern plot (STEPP) methodology. We utilized data from the fifth Health Service Survey of Shanghai, 2013, which utilizes a cross-sectional study design. The participants were selected into the survey by using a three-stage, stratified, random sampling method. HRQoL was evaluated by the EuroQol five-dimensional 3 level (EQ-5D-3L) questionnaire, and the EuroQol-visual analog scales (EQ-VAS) score was the main outcome. A generalized estimating equations (GEE) model adjusted for socio-demographic covariates was used to determine the effect of hypertension on HRQoL. STEPP analysis was performed to explore the effect of hypertension within overlapping age subpopulations. Subgroup analyses for gender were conducted for the main outcome. A total of 28,730 residents who were 18 years or older were included in our study. The results of the multivariate GEE model showed that hypertension negatively affected HRQoL in the study population (estimate = -1.85, p < 0.0001). According to the STEPP analysis, we found that the EQ-VAS score in the hypertension group was lower than that in non-hypertension group for every age group. Additionally, the results of subgroup analyses indicated that the difference of score between two groups was larger among young women. When compared to respondents without hypertension, respondents with hypertension experienced lower HRQoL regardless of gender or any range of age. Furthermore, the impact of hypertension on HRQoL of young women might be more obvious.

Type of cardioplegic solution as a factor influencing the clinical outcome of open-heart congenital procedures

Introduction

Cardioplegia is one of the most important modalities of myocardial protection during heart surgery.

Aim

To assess the impact of blood cardioplegia on postoperative variables, in comparison with two types of crystalloid cardioplegic solutions during pediatric heart surgery.

Material and methods

One thousand one hundred and twenty-nine patients underwent surgical correction of congenital heart disease with cardioplegia administration between 2006 and 2012. Nonlinear regression models of postoperative low cardiac output syndrome (LCOS) incidence, catecholamine index and total complication count were developed using a genetic algorithm. The Akaike information criterion was applied for selection of the best model. The following explanatory variables were evaluated: cardioplegia type (ST - Saint Thomas, n = 440; FR - Fresenius, n = 432; BL - Calafiore, n = 257), congenital heart diseases (CHD) type, age, sex, genetic disorder presence, body surface area (BSA), cardiopulmonary bypass (CBP) time, aortic cross-clamp time, operation urgency, redo surgery, surgeon.

Results

Low cardiac output syndrome presence and higher than average catecholamine indexes were negatively influenced by use of crystalloid cardioplegia (ST or FR), presence of specific CHDs, redo surgery and prolonged CBP time. Increased complication count was related to: crystalloid cardioplegia, presence of specific CHDs, redo surgery, urgency of operation, operation time and CBP time. Higher BSA had a protective effect against higher catecholamine index and increased complication count. Older age was protective against LCOS.

Conclusions

Cardioplegic solutions type influences postoperative variables in children after heart surgery by the negative impact of crystalloid cardioplegia. Blood cardioplegia presents potential advantages for patients - its application may reduce the incidence of low cardiac output syndrome and related complications.