Patient Survival With Extended Home Hemodialysis Compared to In-Center Conventional Hemodialysis

Introduction

More frequent and/or longer hemodialysis (HD) has been associated with improvements in numerous clinical outcomes in patients on dialysis. Home HD (HHD), which allows more frequent and/or longer dialysis with lower cost and flexibility in treatment planning, is not widely used worldwide. Although, retrospective studies have indicated better survival with HHD, this issue remains controversial. In this multicenter study, we compared thrice-weekly extended HHD with in-center conventional HD (ICHD) in a large patient population with a long-term follow-up.

Methods

We matched 349 patients starting HHD between 2010 and 2014 with 1047 concurrent patients on ICHD by using propensity scores. Patients were followed-up with from their respective baseline until September 30, 2018. The primary outcome was overall survival. Secondary outcomes were technique survival; hospitalization; and changes in clinical, laboratory, and medication parameters.

Results

The mean duration of dialysis session was 418 ± 54 minutes in HHD and 242 ± 10 minutes in patients on ICHD. All-cause mortality rate was 3.76 and 6.27 per 100 patient-years in the HHD and the ICHD groups, respectively. In the intention-to-treat analysis, HHD was associated with a 40% lower risk for all-cause mortality than ICHD (hazard ratio [HR] = 0.60; 95% confidence interval [CI] 0.45 to 0.80; P < 0.001). In HHD, the 5-year technical survival was 86.5%. HHD treatment provided better phosphate and blood pressure (BP) control, improvements in nutrition and inflammation, and reduction in hospitalization days and medication requirement.

Conclusion

These results indicate that extended HHD is associated with higher survival and better outcomes compared to ICHD.

Adherence to Healthy Dietary Patterns and Glioma: A Matched Case-Control Study

Recent studies have revealed a putative relationship between diet and glioma development and prognosis, but few studies have examined the association between overall diet and glioma risk. This study, conducted in China, employed a hospital-based case-control approach. The researchers utilized an a priori method based on dietary data to evaluate compliance scores for five healthy dietary patterns (the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, the Mediterranean-DASH diet Intervention for Neurodegenerative Delay (MIND) diet, the Paleolithic diet, and the Planetary Health Diet) in 1012 participants. At the same time, data-driven methods were used to explore the association between dietary patterns and glioma via principal component analysis (PCA). In the multivariate model, adhering to the Mediterranean diet (odds ratio (OR) = 0.29; 95% confidence interval (95% CI): 0.17-0.52), the DASH diet (OR = 0.09; 95% CI: 0.04-0.18), the MIND diet (OR = 0.25; 95% CI: 0.14-0.44), and the Paleolithic diet (OR = 0.13; 95% CI: 0.06-0.25) was associated with a reduced glioma risk. The results of PCA suggested that increasing the intake of plant-based foods and fish and limiting foods rich in carbohydrates, fats, and salts were associated with a reduced glioma risk. There was a substantial nonlinear dose-response association between glioma and the Mediterranean diet score. However, the DASH diet score, the MIND diet score, and the Paleolithic diet score exhibited linear dose-response relationships. Therefore, this study finds that dietary patterns may be an influencing factor for glioma risk.

Association between ambient temperature and chronic rhinosinusitis

BACKGROUND

Chronic exposure to particulate matter air pollution (PM2.5 ) is associated with chronic rhinosinusitis (CRS). Elevated ambient temperature may increase PM2.5 levels and thereby exacerbate sinonasal symptoms. This study investigates the association between high ambient temperature and the risk of CRS diagnosis.

METHODS

Patients with CRS were diagnosed at Johns Hopkins hospitals from May to October 2013-2022, and controls were matched patients without CRS meanwhile. A total of 4752 patients (2376 cases and 2376 controls) were identified with a mean (SD) age of 51.8 (16.8) years. The effect of maximum ambient temperature on symptoms was estimated with a distributed lag nonlinear model (DLNM). Extreme heat was defined as 35.0°C (95th percentile of the maximum temperature distribution). Conditional logistic regression models estimated the association between extreme heat and the risk of CRS diagnosis.

RESULTS

Exposure to extreme heat was associated with increased odds of exacerbation of CRS symptoms (odds ratio [OR] 1.11, 95% confidence interval [CI] 1.03-1.19). The cumulative effect of extreme heat during 0-21 lag days was significant (OR 2.37, 95% CI 1.60-3.50) compared with the minimum morbidity temperature (MMT) at 25.3°C. Associations were more pronounced among young and middle-aged patients and patients with abnormal weight.

CONCLUSIONS

We found that short-term exposure to high ambient temperature is associated with increased CRS diagnosis, suggesting a cascading effect of meteorological phenomena. These results highlight climate change's potentially deleterious health effects on upper airway diseases, which could have a significant public health impact.

A Description of the Statistical Methods for the Vaccine Impact on Diarrhea in Africa (VIDA) Study

BACKGROUND

Diarrheal diseases remain a health threat to children in low- and middle-income countries. The Vaccine Impact on Diarrhea in Africa (VIDA) study was a 36-month, prospective, matched case-control study designed to estimate the etiology, incidence, and adverse clinical consequences of moderate-to-severe diarrhea (MSD) in children aged 0-59 months. VIDA was conducted following rotavirus vaccine introduction at 3 censused sites in sub-Saharan Africa that participated in the Global Enteric Multicenter Study (GEMS) ∼10 years earlier. We describe the study design and statistical methods of VIDA and where they differ from GEMS.

METHODS

We aimed to enroll 8-9 MSD cases every 2 weeks from sentinel health centers in 3 age strata (0-11, 12-23, 24-59 months) and 1 to 3 controls matched by age, sex, date of case enrollment, and village. Clinical, epidemiological, and anthropometric data were collected at enrollment and ∼60 days later. A stool specimen collected at enrollment was analyzed by both conventional methods and quantitative PCR for enteric pathogens. For the matched case-control study, we estimated the population-based, pathogen-specific attributable fraction (AF) and attributable incidence adjusted for age, site, and other pathogens, and identified episodes attributable to a specific pathogen for additional analyses. A prospective cohort study nested within the original matched case-control study allowed assessment of (1) the association between potential risk factors and outcomes other than MSD status and (2) the impact of MSD on linear growth.

CONCLUSIONS

GEMS and VIDA together comprise the largest and most comprehensive assessment of MSD conducted to date in sub-Saharan Africa populations at highest risk for morbidity and mortality from diarrhea. The statistical methods used in VIDA have endeavored to maximize the use of available data to produce more robust estimates of the pathogen-specific disease burden that might be prevented by effective interventions.

The Gut Microbiome Dynamically Associates with Host Glucose Metabolism throughout Pregnancy: Longitudinal Findings from a Matched Case-Control Study of Gestational Diabetes Mellitus

Though gut microbiome disturbance may be involved in the etiology of gestational diabetes mellitus (GDM), data on the gut microbiome's dynamic change during pregnancy and associations with gestational glucose metabolism are still inadequate. In this prospective study comprising 120 pairs of GDM patients and matched pregnant controls, a decrease in the diversity of gut microbial species and changes in the microbial community composition with advancing gestation are found in controls, while no such trends are observed in GDM patients. Multivariable analysis identifies 10 GDM-related species (e.g., Alistipes putredinis), and the integrated associations of these species with glycemic traits are modified by habitual intake of fiber-rich plant foods. In addition, the microbial metabolic potentials related to fiber fermentation (e.g., mannan degradation pathways) and their key enzymes consistently emerge as associated with both GDM status and glycemic traits. Microbial features especially those involved in fiber fermentation, provide an incremental predictive value in a prediction model with established risk factors of GDM. These data suggest that the gut microbiome remodeling with advancing gestation is different in GDM patients compared with controls, and dietary fiber fermentation contributes to the influence of gut microbiome on gestational glycemic regulation.

Association of Folic Acid Supplementation, Dietary Folate Intake and Serum Folate Levels with Risk of Gestational Diabetes Mellitus: A Matched Case-Control Study

Periconceptional folate supplementation is prevalent, raising concerns about possible side effects. The aim of this study was to investigate the associations of folic acid supplementation, dietary folate, serum folate with gestational diabetes mellitus (GDM) risk. In this matched case-control study, 81 pregnant women with GDM (cases) and 81 pregnant women with non-GDM (controls) were identified through age difference (≤3 y) and parity (Both primipara or multipara women) matching, and serum folate levels were measured during the GDM screening (24-28 gestational wk). Folic acid supplementation and dietary folate intake from three months prepregnancy through midpregnancy were assessed using a self-reported questionnaire and food frequency questionnaire. Multivariate binary logistic regression models were used to evaluate the association between folate and GDM. After adjusting for confounding factors, we observed that compared with folic acid supplementation dose ≤400 μg/d, pregnancies without folic acid supplementation and supplemental dose >800 μg/d were associated with GDM risk (adjusted odds ratio=7.25, 95% confidence interval: 1.34-39.36; adjusted odds ratio=4.20, 95% confidence interval: 1.03-17.22), while no significant association with a 400-800 μg/d dose of folic acid supplementation and GDM. Compared with folic acid supplementation dose ≤24 wk, pregnancies without folic acid supplementation were associated with GDM risk (adjusted odds ratio=6.70, 95% confidence interval: 1.22-36.77), while no significant association with folic acid supplementation dose >24 wk and GDM. No significant association of dietary folate and serum folate with GDM was found. No or a higher dose of folic acid supplementation would increase GDM risk and a dose of <800 μg/d is the safe dose.

Relationship between common telomere length-related genetic variations, telomere length, and risk of antituberculosis drug-induced hepatotoxicity in Chinese Han population: As assessed for causality using the updated Roussel Uclaf Causality Assessment Method

Antituberculosis drug-induced hepatotoxicity (ATDH) is a significant threat to tuberculosis control, and two recent studies indicated that leukocyte telomere length (LTL) might be a potential biomarker for ATDH. This study aimed to investigate the relationship between common telomere length-related genetic variations, LTL, and risk of ATDH in Eastern Chinese antituberculosis treatment patients. A 1:4 matched case-control study was conducted among 79 ATDH cases assessed for causality using the updated RUCAM and 316 controls. LTL was determined by quantitative real-time PCR, and nine SNPs involved in telomere biology reported by previous GWAS were assessed. Conditional logistic regression model was used to estimate the association between genotypes and risk of ATDH with odds ratios (ORs) and 95% confidence intervals (CIs). The average RUCAM score of cases was 7.1. The average LTL in cases was significantly shorter than that in controls (median = 1.239 vs. 1.481, P = 0.032). Differences in the distribution of LTL were statistically significant among three genotypes of SNP rs2736098 (CC vs. CT vs. TT, median = 1.544 vs. 1.356 vs. 1.337, P = 0.026) and rs2853677 (AA vs. AG vs. GG, median = 1.511 vs. 1.544 vs. 1.159, P = 0.005) in TERT. SNP rs7675998 in NAF1 was statistically associated with the risk of ATDH under the dominant model (adjusted OR = 1.725, 95% CI: 1.021-2.913, P = 0.042). This is the first study to investigate the relationship of LTL, common telomere length-related variations, and risk of ATDH. SNP rs2736098 and rs2853677 in TERT were significantly associated with LTL, and SNP rs7675998 in NAF1 may be associated with ATDH in Chinese population.

School Bullying Victimization and Associated Factors Among School-Aged Adolescents in China

There has been a significant amount of research on correlates of bullying victimization, but most prior studies are descriptive and do not distinguish between different types of bullying. The current study used a case-control study design to explore factors related to different types of bullying victimization, including physical, relational, verbal, sexual, property, and poly-bullying victimization. This study was conducted in a southern city in China, including 3054 cases who self-reported being victims of school bullying and 3054 controls who reported not being involved in any school bullying in the past 12 months. Each victim case was matched with a control on gender, school, and grade level. Univariate logistic analyses and multivariate conditional logistic regression analyses were used to identify factors associated with being a victim of school bullying. Results suggest physical bullying victimization was only associated with a family-level characteristic (parenting style) while the other four types of bullying victimization (relational, verbal, sexual, and property bullying) and poly-bullying victimization were associated with multiple social domain variables at individual, family, and school levels. Findings from this study provide evidence of factors for different types of bullying victimization and have implications for potential measures to prevent bullying. Measures from multiple social domains, including individual, family and school (e.g., developing healthy behaviors, improving social skills, positive parent-child interactions, building trust between teachers and peers, and forming strong friendships), should be considered in order to effectively prevent adolescent victimization from bullying.

Traction force profile in children with severe perinatal outcomes delivered with a digital vacuum extraction handle: A case-control study

INTRODUCTION

During the second stage of labor, vacuum-assisted delivery is an alternative to forceps delivery and emergency cesarean section. Extensive research concerning perinatal outcomes has indicated that the risk of complications, although rare, is higher than with a spontaneous vaginal delivery. An important factor related to perinatal outcomes is the traction force applied. Our research group previously developed a digital extraction handle, the Vacuum Intelligent Handle-3 (VIH3), that measures and records traction force. The objective of this study was to compare traction force profiles in children with and without severe perinatal outcomes delivered with the digital handle. A secondary aim was to establish a safe force limit.

MATERIAL AND METHODS

This was an observational case-control study at the delivery ward at Karolinska University Hospital, Sweden. In total, 573 children delivered with the digital handle between 2012 and 2018 were included. Cases were defined as a composite of severe perinatal outcomes, including subgaleal hematoma, intracranial hemorrhage, hypoxic ischemic encephalopathy 1-3, seizures or death. The cases in the cohort were matched 1:3 based on five matching variables. Traction profiles were analyzed using the MATLAB® software and conditional logistic regression.

RESULTS

The incidence of severe perinatal outcomes was 2.3%. The 13 cases were matched with three controls each (n = 39). A statistically significant increased odds for higher total traction forces was seen in the case group (odds ratio [OR] 1.004; 95% confidence interval [CI] 1.001-1.007) and for the peak force (OR 1.022; 95% CI 1.004-1.041). Several procedure-related parameters were significantly increased in the case group. As expected, some neonatal characteristics also differed significantly. An upper force limit of 343 Newton minutes (Nmin) revealed an 86% reduction in severe perinatal outcomes (adjusted OR 0.14; 95% CI 0.04-0.5).

CONCLUSIONS

Children with severe perinatal outcomes had traction force profiles with significantly higher forces. The odds for severe perinatal outcomes increased for every increase in Nmin and Newton used during the extraction procedure. A calculated total force level of 343 Nmin is suggested as an upper safety limit, but this must be tested prospectively to provide validity.

High leukocyte-to-lymphocyte ratio is associated with acute relapse in multiple sclerosis patients

BACKGROUND

Multiple sclerosis (MS) is an immune-mediated chronic disease characterized by inflammatory demyelination in the central nervous system (CNS).As there is limited evidence on whether leukocyte-to-lymphocyte ratios (LLRs) are associated with MS, we carried out an investigation on the association between LLRs and MS as favorable markers and aimed to determine the cut-off LLR for the identification of early-stage MS patients.

METHODS

A matched case-control study enrolled a total of 120 MS inpatients and 120 age- and sex-matched non-MS inpatients from January 2013 to June 2018. LLRs were tested from peripheral venous blood routinely during hospitalization. Conditional logistic regression analyses were used to explore differences in LLRs between cases and controls. Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic ability of LLRs and determine the best cut-off value. Disease disability was assessed using the Expanded Disability Status Scale (EDSS).

RESULTS

The LLR was significantly associated with MS in hospitalized patients (OR: 2.372, 95% CI: 1.282 to 4.387, p < 0.001) after adjusting for potential confounders. The area under the curve (AUC) value was 0.793 (95% CI: 0.736 to 0.851). The cut-off value for LLR was 3.18, with sensitivity and specificity values of 62.5% (95% CI: 53.2% to 71.2%) and 88.3% (95% CI: 81.2% to 93.5%), respectively. The EDSS scores of the higher LLR group were significantly higher than the lower group.

CONCLUSION

Systemic inflammation measured using LLRs may be an inflammatory marker among MS inpatients. LLRs may serve as favorable inflammatory markers with which to discriminate MS among Chinese subjects.

Risk Factors Associated With School Bullying Behaviors: A Chinese Adolescents Case-Control Study, 2019

This research aimed to identify risk factors including individual characteristics and environment circumstances related to different types of school bullying (physical, relational, verbal, sexual, and possession bullying) among middle school students in China. Cases were the respondents reporting perpetrating bullying behaviors three or more times in the past year. One control was selected for each case from those participants who were not involved in school bullying in the past 12 months. Data were collected between April 2019 and May 2019 in China. After considering potential confounding variables including gender, grade level, and school, multivariable conditional logistic regression analysis was performed based on the univariate logistic analysis including 1,594 adolescents. According to conditional logistic regression analysis, alcohol use and lack of emotional management and control were the significant individual characteristics positively associated with involvement in school bullying. Alcohol use was related to all five types of school bullying perpetration. Poor relationships between family members, father's alcohol use, and parental neglect were strong risk factors for relational bullying. Lack of a sense of safety and absence of trusted people were associated with physical, relational, and verbal bullying perpetration. Results of this study provide evidence about risk factors for school bullying and have implications for potential policies to reduce bullying. Effective policies and programs need to take individual characteristics (social-emotional skills, anger control), family (parent training in conflict resolution, appropriate disciplining), peer and school factors (promoting prosocial networks, zero tolerance for bullying, appropriate disciplining policies against students who bully others, teacher training on building positive teacher-student relationships and positive discipling techniques) into consideration in order to develop effective prevention programs.

The role of the genetic variant FECH rs11660001 in the occurrence of anti-tuberculosis drug-induced liver injury

WHAT IS KNOWN AND OBJECTIVE

The pathogenic mechanism of anti-tuberculosis drug-induced liver injury (AT-DILI) is still largely unknown. Recent studies have indicated that rifampicin and isoniazid cotreatment causes the accumulation of endogenous protoporphyrin IX in the liver through the haem biosynthesis pathway. Alanine synthase 1 (ALAS1) and ferrochelatase (FECH) are the rate-limiting enzymes in the production of haem. The present study aimed to investigate the genetic contribution of the ALAS1 and FECH genes to the risk of AT-DILI in an Eastern Chinese Han population.

METHODS

A 1:4 matched case-control study was conducted, and eight SNPs in the ALAS1 and FECH genes were detected and assessed. A multivariate conditional logistic regression model was used to estimate the association between genotypes and the risk of AT-DILI by the odds ratios (ORs) with 95% confidence intervals (CIs), with liver disease history, hepatoprotectant use, smoking and drinking history as covariates.

RESULTS AND DISCUSSION

Overall, 202 AT-DILI cases and 808 controls were included in this study. The female patients carrying polymorphisms of rs11660001 in FECH had an increased risk of AT-DILI under the dominant and additive models (OR = 1.831, 95% CI: 1.014-3.307, p = 0.045; OR = 1.673, 95% CI: 1.015-2.760, p = 0.044, respectively). The peak aspartate transaminase level was significantly higher in female patients carrying the GA+AA genotype of rs11660001 than in those with the GG genotype during anti-TB treatment (p = 0.032).

WHAT IS NEW AND CONCLUSION

Based on this 1:4 individual matched case-control study, SNP rs11660001 in the FECH gene may be associated with susceptibility to AT-DILI in Chinese female anti-TB treatment patients. Further studies in larger varied populations are needed to validate our findings.

Matched Versus Unmatched Analysis of Matched Case-Control Studies

Although the need for addressing matching in the analysis of matched case-control studies is well established, debate remains as to the most appropriate analytical method when matching on at least 1 continuous factor. We compared the bias and efficiency of unadjusted and adjusted conditional logistic regression (CLR) and unconditional logistic regression (ULR) in the setting of both exact and nonexact matching. To demonstrate that case-control matching distorts the association between the matching variables and the outcome in the matched sample relative to the target population, we derived the logit model for the matched case-control sample under exact matching. We conducted simulations to validate our theoretical conclusions and to explore different ways of adjusting for the matching variables in CLR and ULR to reduce biases. When matching is exact, CLR is unbiased in all settings. When matching is not exact, unadjusted CLR tends to be biased, and this bias increases with increasing matching caliper size. Spline smoothing of the matching variables in CLR can alleviate biases. Regardless of exact or nonexact matching, adjusted ULR is generally biased unless the functional form of the matched factors is modeled correctly. The validity of adjusted ULR is vulnerable to model specification error. CLR should remain the primary analytical approach.

A validation study of the UGT1A4 rs2011404 variant and the risk of anti-tuberculosis drug-induced hepatotoxicity in an Eastern Chinese Han population

WHAT IS KNOWN AND OBJECTIVE

Anti-tuberculosis (anti-TB) drug-induced hepatotoxicity (ATDH) is a serious adverse drug reaction. A recent study found that the rs2011404 variant of uridine 5'-diphospho-glucuronosyl-transferase 1A4 (UGT1A4) is a marker of susceptibility to ATDH. The present study aimed to validate this relationship in an Eastern Chinese Han anti-TB treatment population.

METHODS

A 1:4 matched case-control study was conducted among anti-TB treatment patients in four regions of Jiangsu. ATDH was diagnosed based on the criteria from the Chinese Society of Hepatology and the updated Roussel Uclaf Causality Assessment Method. A conditional logistic regression model was used to estimate the association between rs2011404 genotypes and the risk of ATDH using odds ratios (ORs) with 95% confidence intervals (95% CIs) and smoking, drinking, hepatoprotectant use and liver diseases as covariates.

RESULTS AND DISCUSSION

A total of 202 ATDH cases and 808 controls were matched according to age, sex and treatment history. After correcting for potential confounding factors, conditional logistic regression analysis indicated no significant differences in genotypes between the two groups (CC vs. TC: OR = 0.933, 95% CI: 0.457-1.905, p = 0.849). Subgroup analysis suggested that patients carrying the CC genotype at rs2011404 in UGT1A4 were at a reduced risk of moderate or severe liver injury (OR = 0.293, 95% CI: 0.093-0.921, p = 0.036).

WHAT IS NEW AND CONCLUSION

Based on a 1:4 individual matched case-control study, possessing the CC genotype at rs2011404 of the UGT1A4 gene reduces the risk of moderate or severe liver injury in Eastern Chinese Han patients receiving anti-TB treatment. Further research is warranted to explain the role of the UGT1A4 gene and its contribution to individual differences in susceptibility to ATDH.

Risk factors associated with acute hepatopancreatic necrosis disease at shrimp farm level in Bac Lieu Province, Vietnam

Background and Aim:

Acute hepatopancreatic necrosis disease (AHPND) is a severe disease in shrimp farms and adversely affected the shrimp industry of Vietnam. So far, the study on risk factors associated with AHPND outbreaks is limited. The objective of this study was to determine the potential risk factors of AHPND at the shrimp farm level in Bac Lieu Province, Vietnam.

Materials and Methods:

Real-time-Polymerase chain reaction was used to analyze data collected from an active surveillance program of shrimp farms in 2017 in the Vinh Tien and Vinh Lac villages, Vinh Thinh commune, Hoa Binh district in Bac Lieu Province, Vietnam. The matched case-control study selected 20 cases and 20 control farms from 134 shrimp farms. In 2018, face-to-face interviews using structured questionnaires were conducted with the farmers of these selected farms.

Results:

Of the 59 studied variables, seven had p≤0.2 based on bivariate analyses. The results of multivariable analysis showed that the presence of fish-eating birds on shrimp farms was a significant association with AHPND (odds ratio=8, p=0.049).

Conclusion:

To reduce the effect of AHPND, farmers should apply effective methods to manage wild animals such as using a grid or net to cover the pond, combined with improved biosecurity.

Acute diarrheal disease outbreak in Muzaffarpur Village, Chandauli District, Uttar Pradesh, India

Background

Acute diarrheal disease (ADD) outbreaks frequently occur in the Gangetic plains of Uttar Pradesh, India. In August 2017, Muzaffarpur village, Uttar Pradesh, reported an ADD outbreak.

Objectives

Outbreak investigation was conducted to find out the epidemiology and to identify the risk factors.

Methods

A 1:1 area-matched case-control study was conducted. Suspected ADD case was defined as ≥3 loose stools or vomiting within 24 h in a Muzaffarpur resident between August 7 and September 9, 2017. A control was defined as an absence of loose stools and vomiting in a resident between August 7 and September 9, 2017. A matched odds ratio (mOR) with 95% confidence intervals (CIs) was calculated. Drinking water was assessed to test for the presence of any contamination. Stool specimens were tested for Vibrio cholerae, and water samples were also tested for any fecal contamination and residual chlorine.

Results

Among 70 cases (female = 60%; median age = 12 years, range = 3 months-70 years), two cases died and 35 cases were hospitalized. Area-A in Muzaffarpur had the highest attack rate (8%). The index case washed soiled clothes at well - A1 1 week before other cases occurred. Among 67 case-control pairs, water consumption from well-A1 (mOR: 43.00; 95% CI: 2.60-709.88) and not washing hands with soap (mOR: 2.87; 95% CI: 1.28-6.42) were associated with illness. All seven stool specimens tested negative for V. cholerae. All six water samples, including one from well-A1, tested positive for fecal contamination with <0.2 ppm of residual chlorine.

Conclusion

This outbreak was associated with consumption of contaminated well water and hand hygiene. We recommended safe water provision, covering wells, handwashing with soap, access to toilets, and improved laboratory capacity for testing diarrheal pathogens.

Association of Red Blood Cell Indices with Mild Cognitive Impairment in Chinese Elderly Individuals: A Matched Case-control Study

BACKGROUND

Mild cognitive impairment (MCI) represents an intermediate and modifiable stage between normal aging and dementia. There is an urgent need for simple, non-invasive testing of MCI by blood biomarkers.

OBJECTIVE

This study aimed to retrospectively evaluate the association of red blood cell (RBC) indices with MCI, and select the best hematologic characteristic for detection of MCI in elderly Chinese.

METHODS

Matched case-control study was carried out with 85 pairs of MCI subjects and healthy controls. The matching criteria was age, gender and education attainment. All samples were analyzed for RBC indices, including hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC) and red cell distribution width-standard deviation (RDW-SD). A conditional logistic regression model was used to evaluate the association between RBC indices and MCI. The diagnostic efficacy of the biomarkers was evaluated by receiver operating characteristics (ROC).

RESULTS

Among all RBC indices, there were significant differences in HGB (124.82 ± 7.89 vs. 133.93 ± 4.52, P < 0.001) and RDW-SD (45.29 ± 2.03 vs. 41.34 ± 4.41, P < 0.001) between two groups. In the logistic regression model, after adjustment for lifestyle factors and comorbidities, significant statistically associations have been found between higher HGB and lower risk of MCI (adjusted OR: 0.831; 95% CI: 0.773-0.893), higher RDW-SD and a higher risk of MCI (adjusted OR: 1.575; 95% CI: 1.326- 1.872). ROC analysis suggested that the largest area under the ROC curve (AUC) was found with the combination of HGB and RDW-SD (AUC = 0.842), followed by HGB(AUC = 0.795), and finally by modest RDW-SD (AUC = 0.777). Combination of HGB <131 g/L and RDW-SD >43.4 fL yielded a sensitivity of 92% and a specificity of 89%, overall diagnosis efficiency of which were better than HBG and RDW-SD alone.

CONCLUSION

Lower HGB and higher RDW-SD alone were significantly found to be associated with increased risk of MCI, and offered modest sensitivity and specificity as a diagnostic marker. The combination of HGB and RDW-SD was more sensitive and had higher classification accuracy for differentiating MCI from healthy controls. Further prospective research is needed to clarify whether HGB in combination with RDW-SD may be a potential diagnostic tool for early diagnosis of AD.

Dynamic inference in general nested case-control designs

Nested case-control designs are attractive in studies with a time-to-event endpoint if the outcome is rare or if interest lies in evaluating expensive covariates. The appeal is that these designs restrict to small subsets of all patients at risk just prior to the observed event times. Only these small subsets need to be evaluated. Typically, the controls are selected at random and methods for time-simultaneous inference have been proposed in the literature. However, the martingale structure behind nested case-control designs allows for more powerful and flexible non-standard sampling designs. We exploit that structure to find simultaneous confidence bands based on wild bootstrap resampling procedures within this general class of designs. We show in a simulation study that the intended coverage probability is obtained for confidence bands for cumulative baseline hazard functions. We apply our methods to observational data about hospital-acquired infections.

Association of ABO blood group and antituberculosis drug-induced liver injury: A case-control study from a Chinese Han population

WHAT IS KNOWN AND OBJECTIVE

Antituberculosis drug-induced liver injury (ATLI) is a serious adverse drug reaction, and its pathogenic mechanism is still largely unknown. Rifampin (RIF) has been reported to cause haemolysis due to the production of drug-dependent antibodies, and haemolysis results in an increased level of free haem, which affects the function of hepatocytes. Blood group determinants can act as specific receptor sites for drug-antibody complexes, causing erythrocyte destruction in the presence of RIF. RIF-induced immune haemolysis may be a potential mechanism for ATLI. Thus, the study aimed to explore the role of ABO blood group systems in Chinese ATLI patients.

METHODS

A 1:4 matched case-control study was conducted among 146 ATLI cases and 584 controls. Multivariable conditional logistic regression and Cox proportional regression were used to estimate the association between ABO blood group and risk of ATLI by odds ratio (OR), hazards ratio (HR) and 95% confidence intervals (CIs), and liver disease history and taking hepatoprotectant were used as covariates.

RESULTS AND DISCUSSION

Patients in the A, B, AB and non-O blood groups had a significantly higher risk of ATLI than those in the O blood group (OR = 1.832, 95% CI: 1.126-2.983, P = .015; OR = 1.751, 95% CI: 1.044-2.937, P = .034; OR = 2.059, 95% CI: 1.077-3.938, P = .029; OR = 1.822, 95% CI: 1.173-2.831, P = .007, respectively). After considering the time of ALTI occurrence, similar results were found in the A, B, AB and non-O blood groups (HR = 1.676, 95% CI: 1.072-2.620, P = .024; HR = 1.620, 95% CI: 1.016-2.584, P = .043; HR = 2.010, 95% CI: 1.130-3.576, P = .018; HR = 1.701, 95% CI: 1.138-2.542, P = .010, respectively). Furthermore, subgroup analysis also detected a significant association between ABO blood group and ATLI in patients taking RIF (P < .05). However, no significant difference was observed in patients not taking RIF (P > .05).

WHAT IS NEW AND CONCLUSION

The present study is the first to evaluate the role of ABO blood group systems in Chinese ATLI cases. Based on the present matched case-control study, the ABO blood group may be associated with susceptibility to ATLI in the Chinese antituberculosis population, especially in patients with blood groups A, B and AB who are taking RIF.

A preliminary comparison of the Aravind aurolab drainage implant with the Baerveldt glaucoma implant: A matched case-control study

PURPOSE

The Aurolab^® aqueous drainage implant is a low-cost alternative to the Baerveldt glaucoma implant. The aim of this study was to test the hypothesis that the two implants are comparable in terms of surgical success and safety.

METHODS

We conducted a retrospective case-control study of Aurolab aqueous drainage implant done at our institution from May 2015 and May 2017. Twenty-five consecutive patients who received an Aurolab aqueous drainage implant were matched by age and diagnosis to patients who received a Baerveldt glaucoma implant. Data were collected pre-operative and post-operative visits, including visual acuity and intraocular pressure, number of medications, and complications. Surgical success was defined as intraocular pressure between 5 and 21 mmHg with a minimum 20% reduction from baseline, without loss of light perception or the need for further glaucoma surgery. Cox regression analysis was used to predict factors associated with surgical success.

RESULTS

The median (interquartile range, IQR) intraocular pressure at 1 year was 16.0 (8.0) mmHg for the Baerveldt glaucoma implant and 13.0 (8.0) mmHg for the Aurolab aqueous drainage implant, p = 0.38. Success (mean ± SE) at 1 year for the intraocular pressure >21-mmHg failure criterion was 65% ± 15% for the Baerveldt glaucoma implant and 79% ± 11% for the Aurolab aqueous drainage implant (p = 0.80). The frequency of complications listed was similar for the two groups (Fisher's exact p = 0.71). In the Cox regression, the type of implant was not found to be associated with surgical success.

CONCLUSIONS

Our preliminary results suggest that the Aurolab aqueous drainage implant is comparable to the Baerveldt glaucoma implant. Further long-term data in a larger population are needed to confirm these findings.

Riding behavior and electric bike traffic crashes: A Chinese case-control study

Objective: The present case-control study sought to explore at-risk riding behaviors associated with e-bike related traffic crashes among e-bike riders in China.Methods: Cases were recruited from residents aged 16 years and over in communities which stated "selected e-bikes as travel tools and experienced traffic crashes in the last year". Two controls for each case were randomly selected from a population of e-bike riders who had not experienced a traffic crash in the past year. The cases and controls were matched by gender, age (within 5 years) and school education level. Data were collected using questionnaires and face-to-face interviews from July 2015 to September 2015 in China. After conducting univariate logistic analysis on study variables, a conditional logistic regression model based on the 1:2 matched case-control study design was developed.Results: Multiple-factor conditional logistic regression analysis of e-bike related traffic crashes showed that running red lights (always vs. never, AOR = 3.094, 95% CI, 1.077-8.891, P < .05), riding after drinking (yes vs. no, AOR = 1.578, 95% CI, 1.102-2.259, P < .05), carrying adults while riding (always vs. never, AOR = 2.140, 95% CI, 1.273-3.595, P < .05), turning without signaling (sometimes vs. never, AOR = 1.446, 95% CI, 1.805-1.928, P < .05), riding in the motor vehicle lane (always vs. never, AOR = 2.413, 95% CI, 1.576-3.695, P < .01), prior crash history (yes vs. no, AOR = 1.670, 95% CI, 1.257-2.220, P < .05), and type of e-bikes (scooter-style e-bikes vs. bicycle-style e-bikes, AOR = 1.471, 95% CI, 1.068-2.026, P < .05) were identified as possible risk factors for e-bike traffic crashes.Conclusion: The findings of this research provide evidence about specific risky behaviors related to road traffic crashes involving e-bikes and indicated that behavioral intervention and education need to be strengthened to reduce dangerous riding behaviors. These results will be helpful for design of e-bike road risk prevention programs.

Adjusting for differential misclassification in matched case-control studies utilizing health administrative data

In epidemiological studies of secondary data sources, lack of accurate disease classifications often requires investigators to rely on diagnostic codes generated by physicians or hospital systems to identify case and control groups, resulting in a less-than-perfect assessment of the disease under investigation. Moreover, because of differences in coding practices by physicians, it is hard to determine the factors that affect the chance of an incorrectly assigned disease status. What results is a dilemma where assumptions of non-differential misclassification are questionable but, at the same time, necessary to proceed with statistical analyses. This paper develops an approach to adjust exposure-disease association estimates for disease misclassification, without the need of simplifying non-differentiality assumptions, or prior information about a complicated classification mechanism. We propose to leverage rich temporal information on disease-specific healthcare utilization to estimate each participant's probability of being a true case and to use these estimates as weights in a Bayesian analysis of matched case-control data. The approach is applied to data from a recent observational study into the early symptoms of multiple sclerosis (MS), where MS cases were identified from Canadian health administrative databases and matched to population controls that are assumed to be correctly classified. A comparison of our results with those from non-differentially adjusted analyses reveals conflicting inferences and highlights that ill-suited assumptions of non-differential misclassification can exacerbate biases in association estimates.

Assessment of risk factors for coronary artery disease in military personnel: A study from Iran

Introduction:

Cardiovascular diseases are the most significant cause of mortality. Although the risk factors of this disease are well known, the strength of these factors varies in different populations and needs to be investigated.

Aim:

The aim of this study is to estimate the amount of the effect of each classic risk factor on CAD (coronary artery disease) among Aja personnel.

Materials and Methods:

This matched case-control study was conducted on 1000 male Aja personnel admitted selecting Aja hospitals in Tehran in 2017. The samples were selected using purposive-graded sampling method. The 250 military patients hospitalized for CAD were considered as a case group. Each case was individually matched for age and service force with tree military patients without CAD. Data were gathered using standard demographic information and history of risk factors questionnaire and analyzed using SPSS 23 and statistical tests. Odds ratio measured trough Cochran–Mantel–Haenszel test and used to estimate the amount of the effect of each classic risk factors on CAD.

Results:

Data analysis indicated that the risk factors including diabetes, hyperlipidemia, smoking, hypertension, and positive family history of CAD enhance the probability of CAD as much as 79.2%, 77.3%, 67.7%, 64.1%, and 56.6%, respectively.

Conclusion:

Diabetes and other modifiable risk factors have the greatest impact on CAD among the concerned Aja personnel. Hence, the authorities can consider the independent amount of the effect of each risk factor and modify them in order to prevent the disease more effectively and purposefully among the personnel.

Change in radial artery pulse wave in stroke hemiplegic patients: Protocol for a case-control study

INTRODUCTION

About 55% to 75% of stroke survivors have motor disorders and problems that affect their quality of life. The prevention of secondary neurological damages through relapse prevention and the rehabilitation of stroke patients suffering from morbidities are crucial to improve the prognosis of patients with stroke. Pulse examinations can be used to determine the stroke progression. This study will investigate the differences and changes in radial artery pressure-pulse waves during the treatment of hemiplegia caused by stroke.

METHODS/DESIGN

This study protocol is for a prospective matched case-control study. A total of 84 participants will be recruited, 56 patients with hemiplia caused by stroke, and 28 control patients matched by age, gender, and body mass index. The primary outcome of this study will be the differences and changes in the radial augmentation index.

DISCUSSION

The results of the study will help to determine the differences and changes in radial artery pressure-pulse waves during the treatment of hemiplegia caused by stroke. The findings will provide information about the physiological and hemodynamic mechanisms.

CONCLUSION

This will be the first study to analyze the pulse wave of the radial artery (PWRA) on the affected side and on the normal side in stroke patients with hemiplegia. This study will clarify whether the radial artery pressure pulse wave can be used to evaluate the result of stroke treatment objectively. The results of the study will be available in February 2019. The version of the protocol is v1.6 written in March 7, 2016.

ETHICS AND DISSEMINATION

Written informed consent will be obtained from all participants. This study has been approved by the Institutional Review Board (IRB) of Wonkwang University Gwangju Hospital, Gwangju, Republic of Korea (WKIRB-2016/8). The study findings will be published in peer-reviewed journals and presented at national and international conferences.

TRIAL REGISTRATION NUMBER

This trial was registered with the Clinical Research Information Service (CRIS) of the Korea National Institute of Health (NIH), Republic of Korea (KCT0002147).

Bayesian analysis of pair-matched case-control studies subject to outcome misclassification

We examine the impact of nondifferential outcome misclassification on odds ratios estimated from pair-matched case-control studies and propose a Bayesian model to adjust these estimates for misclassification bias. The model relies on access to a validation subgroup with confirmed outcome status for all case-control pairs as well as prior knowledge about the positive and negative predictive value of the classification mechanism. We illustrate the model's performance on simulated data and apply it to a database study examining the presence of ten morbidities in the prodromal phase of multiple sclerosis.

Clinical Characteristics and Treatment Patterns Among Patients Diagnosed With Cluster Headache in U.S. Healthcare Claims Data

OBJECTIVE

To characterize demographics, clinical characteristics, and treatment patterns of patients with cluster headache (CH).

BACKGROUND

CH is an uncommon trigeminal autonomic cephalalgia with limited evidence-based treatment options. Patients suffer from extremely painful unilateral headache attacks and autonomic symptoms with episodic and chronic cycles.

DESIGN/METHODS

This retrospective analysis used insurance claims from Truven Health Analytics MarketScan® research databases from 2009 to 2014. Two cohorts were compared: CH patients (with ≥2 CH claims) were propensity score matched with 4 non-headache controls, all with continuous enrollment for 12 months before and after the date of first CH claim or matched period among controls.

RESULTS

CH patients (N = 7589) were mainly male (57.4%) and 35-64 years old (73.2%), with significantly more claims for comorbid conditions vs controls (N = 30,341), including depressive disorders (19.8% vs 10.0%), sleep disturbances (19.7% vs 9.1%), anxiety disorders (19.2% vs 8.7%), and tobacco use disorders (12.8% vs 5.3%), with 2.5 times greater odds of suicidal ideation (all P < .0001). Odds of drug dependence were 3-fold greater among CH patients (OR = 2.8 [95% CI 2.3-3.4, P < .0001]). CH patients reported significantly greater use of prescription medications compared with controls; 25% of CH patients had >12 unique prescription drug claims. Most commonly prescribed drug classes for CH patients included: opiate agonists (41%), corticosteroids (34%), 5HT-1 agonists (32%), antidepressants (31%), NSAIDs (29%), anticonvulsants (28%), calcium antagonists (27%), and benzodiazepines (22%). Only 30.4% of CH patients received recognized CH treatments without opioids during the 12-month post-index period. These patients were less likely to visit emergency departments or need hospitalizations (26.8%) as compared to CH patients with no pharmacy claims for recognized CH treatments or opioids (33.6%; P < .0001).

CONCLUSIONS

The burden of CH is associated with significant co-morbidity, including substance use disorders and suicidal ideation, and treatment patterns indicating low use of recognized CH treatments.

Combining evidence from multiple electronic health care databases: performances of one-stage and two-stage meta-analysis in matched case-control studies

PURPOSE

Clustering of patients in databases is usually ignored in one-stage meta-analysis of multi-database studies using matched case-control data. The aim of this study was to compare bias and efficiency of such a one-stage meta-analysis with a two-stage meta-analysis.

METHODS

First, we compared the approaches by generating matched case-control data under 5 simulated scenarios, built by varying: (1) the exposure-outcome association; (2) its variability among databases; (3) the confounding strength of one covariate on this association; (4) its variability; and (5) the (heterogeneous) confounding strength of two covariates. Second, we made the same comparison using empirical data from the ARITMO project, a multiple database study investigating the risk of ventricular arrhythmia following the use of medications with arrhythmogenic potential. In our study, we specifically investigated the effect of current use of promethazine.

RESULTS

Bias increased for one-stage meta-analysis with increasing (1) between-database variance of exposure effect and (2) heterogeneous confounding generated by two covariates. The efficiency of one-stage meta-analysis was slightly lower than that of two-stage meta-analysis for the majority of investigated scenarios. Based on ARITMO data, there were no evident differences between one-stage (OR = 1.50, CI = [1.08; 2.08]) and two-stage (OR = 1.55, CI = [1.12; 2.16]) approaches.

CONCLUSIONS

When the effect of interest is heterogeneous, a one-stage meta-analysis ignoring clustering gives biased estimates. Two-stage meta-analysis generates estimates at least as accurate and precise as one-stage meta-analysis. However, in a study using small databases and rare exposures and/or outcomes, a correct one-stage meta-analysis becomes essential.

Estimating marginal causal effects in a secondary analysis of case-control data

When an initial case-control study is performed, data can be used in a secondary analysis to evaluate the effect of the case-defining event on later outcomes. In this paper, we study the example in which the role of the event is changed from a response variable to a treatment of interest. If the aim is to estimate marginal effects, such as average effects in the population, the sampling scheme needs to be adjusted for. We study estimators of the average effect of the treatment in a secondary analysis of matched and unmatched case-control data where the probability of being a case is known. For a general class of estimators, we show the components of the bias resulting from ignoring the sampling scheme and demonstrate a design-weighted matching estimator of the average causal effect. In simulations, the finite sample properties of the design-weighted matching estimator are studied. Using a Swedish diabetes incidence register with a matched case-control design, we study the effect of childhood onset diabetes on the use of antidepressant medication as an adult. Copyright © 2017 John Wiley & Sons, Ltd.

Comparison of body mass index at diagnosis of diabetes in a multi-ethnic population: A case-control study with matched non-diabetic controls

AIMS

To investigate the probability of developing type 2 diabetes mellitus (T2DM) at different body mass index levels compared to matched non-diabetic controls in a multi-ethnic population.

MATERIALS AND METHODS

This was a case-control study of 90 367 patients with incident diabetes and 362 548 age-sex-ethnicity matched controls from UK primary care. The probability of developing T2DM was estimated.

RESULTS

Case and control patients were 56 years old at index and 56% were male. Patients with T2DM had significantly higher mean BMI levels by about 5 kg/m² at diagnosis (32.2 kg/m² ) compared to the matched controls (27.4 kg/m² ). White Europeans (n = 79 270), African-Caribbeans (n = 4115) and South Asians (n = 7252) were 58, 48 and 46 years old with a mean BMI of 32.5, 31.1 and 29.2 kg/m² , respectively, at diagnosis. More South Asians developed T2DM at BMI below 30 kg/m² (38%) than White Europeans (26%) and African-Caribbeans (29%) (all P  < .01). Within the 18 to 70-year age range, South Asian males and females had a significantly higher probability of developing diabetes in the continuously measured BMI range of 18 to 30 kg/m² , compared to White Europeans and African-Caribbeans. Across all age groups <70 years, South Asians and African-Caribbeans had a significantly higher probability of developing T2DM in the normal weight and overweight categories, compared to White Europeans. However, this risk pattern of developing diabetes was reversed amongst the obese in all age groups.

CONCLUSION

Risk patterns of developing diabetes at different levels of obesity varies among ethnic groups across all ages, while South Asians and African-Caribbeans carry the highest risk at a younger age and at lower adiposity burden.

Risk Factors for Sustained Cholera Transmission, Juba County, South Sudan, 2014

We conducted a case–control study to identify risk factors for the 2014 cholera outbreak in Juba County, South Sudan. Illness was associated with traveling or eating away from home; treating drinking water and receiving oral cholera vaccination were protective. Oral cholera vaccination should be used to complement cholera prevention efforts.

Association between monovalent influenza A (H1N1) pdm09 vaccine and pneumonia among the elderly in the 2009-2010 season in Japan: A case-control study

We investigated the association between monovalent influenza A (H1N1) pdm09 (H1N1pdm) vaccine and pneumonia in elderly people. Study design was a hospital-based, matched case-control study. Cases comprised patients ≥ 65 years old who had been newly diagnosed with pneumonia. For each case, 2 controls were defined as individuals with other diseases (not pneumonia) who were matched by sex, age, entry date, and the visited hospital. Study period was the interval from 1 September 2009 until 30 September 2010. Because a pandemic of influenza A (H1N1) occurred during study period, we analyzed selected subjects who had enrolled during the influenza A (H1N1) pandemic. We calculated the odds ratios (ORs) and 95% confidence intervals (CIs) for pneumonia in H1N1pdm-vaccinated subjects compared with unvaccinated subjects using a conditional logistic regression model to assess the association between H1N1pdm vaccine and pneumonia. The subjects during the period of the influenza A (H1N1) pandemic were 20 cases and 40 controls. Subjects who had received H1N1pdm vaccine showed a significantly decreased OR for pneumonia (OR = 0.10, 95% CI = 0.01-0.98) compared with unvaccinated subjects. In conclusion, H1N1pdm vaccination may have prevented pneumonia among the elderly during the 2009-2010 influenza A (H1N1) pandemic in Japan.

Calibration and seasonal adjustment for matched case-control studies of vitamin D and cancer

Vitamin D measurements are influenced by seasonal variation and specific assay used. Motivated by multicenter studies of associations of vitamin D with cancer, we formulated an analytic framework for matched case-control data that accounts for seasonal variation and calibrates to a reference assay. Calibration data were obtained from controls sampled within decile strata of the uncalibrated vitamin D values. Seasonal sine-cosine series were fit to control data. Practical findings included the following: (1) failure to adjust for season and calibrate increased variance, bias, and mean square error and (2) analysis of continuous vitamin D requires a variance adjustment for variation in the calibration estimate. An advantage of the continuous linear risk model is that results are independent of the reference date for seasonal adjustment. (3) For categorical risk models, procedures based on categorizing the seasonally adjusted and calibrated vitamin D have near nominal operating characteristics; estimates of log odds ratios are not robust to choice of seasonal reference date, however. Thus, public health recommendations based on categories of vitamin D should also define the time of year to which they refer. This work supports the use of simple methods for calibration and seasonal adjustment and is informing analytic approaches for the multicenter Vitamin D Pooling Project for Breast and Colorectal Cancer. Published 2016. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

On the use and misuse of scalar scores of confounders in design and analysis of observational studies

We assess the asymptotic bias of estimates of exposure effects conditional on covariates when summary scores of confounders, instead of the confounders themselves, are used to analyze observational data. First, we study regression models for cohort data that are adjusted for summary scores. Second, we derive the asymptotic bias for case-control studies when cases and controls are matched on a summary score, and then analyzed either using conditional logistic regression or by unconditional logistic regression adjusted for the summary score. Two scores, the propensity score (PS) and the disease risk score (DRS) are studied in detail. For cohort analysis, when regression models are adjusted for the PS, the estimated conditional treatment effect is unbiased only for linear models, or at the null for non-linear models. Adjustment of cohort data for DRS yields unbiased estimates only for linear regression; all other estimates of exposure effects are biased. Matching cases and controls on DRS and analyzing them using conditional logistic regression yields unbiased estimates of exposure effect, whereas adjusting for the DRS in unconditional logistic regression yields biased estimates, even under the null hypothesis of no association. Matching cases and controls on the PS yield unbiased estimates only under the null for both conditional and unconditional logistic regression, adjusted for the PS. We study the bias for various confounding scenarios and compare our asymptotic results with those from simulations with limited sample sizes. To create realistic correlations among multiple confounders, we also based simulations on a real dataset.

Sporadic salmonellosis in Lower Saxony, Germany, 2011-2013: raw ground pork consumption is associated with Salmonella Typhimurium infections and foreign travel with Salmonella Enteritidis infections

To investigate risk factors for sporadic salmonellosis, for each notified case four randomly selected population controls matched for age, sex and geographical region were interviewed via self-administered questionnaire. Conditional logistic regression analysis of 285 matched pairs revealed significant associations for raw ground pork consumption [odds ratio (OR) 6·0, 95% confidence interval (CI) 1·8-20·1], taking antacids (OR 5·8, 95% CI 1·4-24·5), eating meat outside the home (OR 5·7, 95% CI 2·2-14·6) and daily changing or cleaning of dishcloth (OR 2·1, 95% CI 1·2-3·9). Animal contact and ice cream consumption were negatively associated with salmonellosis (OR 0·5, 95% CI 0·2-1 and OR 0·3, 95% CI 0·1-0·6, respectively). S. Typhimurium infections were significantly associated with raw ground pork consumption (OR 16·7, 95% CI 1·4-194·4) and S. Enteritidis infections with having travelled abroad (OR 9·7, 95% CI 2·0-47·3). Raw egg consumption was not a risk factor, substantiating the success of recently implemented national control programmes in the poultry industry. Unexpectedly, hygienic behaviour was more frequently reported by cases, probably because they overestimated their hygiene precautions retrospectively. Although animal contact might enhance human immunocompetence, underreporting of salmonellosis by pet owners could have occurred. Eating raw pork products is the major risk factor for sporadic human S. Typhimurium infections in Lower Saxony.

Survival analysis of 272 patients with pancreatic cancer undergoing combined treatment

BACKGROUND

In China, traditional Chinese herbal medicine (TCHM) has been widely used for pancreatic cancer. This retrospective, matched case-control study aimed to assess factors affecting the survival time of patients with pancreatic cancer.

METHODS

From 2004 to 2012, a total of 411 patients with pathologically confirmed pancreatic cancer were enrolled, and 272 patients were matched and divided into TCHM and non-TCHM groups (control group) based on received TCHM or not. The match was according to gender, age of onset, radiotherapy, and chemotherapy. Both groups received comprehensive treatments, the TCHM group simultaneously received the TCHM spleen-invigorating compound for more than 3 months. The Cox model was used for prognostic factor analysis and the Kaplan-Meier method for estimating median overall survival (OS) and disease-free survival (DFS).

RESULTS

In 130 patients with advanced pancreatic cancer, COX analysis showed the Karnofsky Performance Scale (KPS; P = .000), radiotherapy (P = .003), and TCHM (P = .001) were independent prognostic factors for OS, with median OS of 12.7 and 9.9 months in TCHM and non-TCHM groups, respectively (hazard ratio [HR] = 0.520; 95% confidence interval [CI] = 0.353-0.766; P = .033). In 142 patients undergoing radical surgery, KPS (P = .000) and TCHM (P = .000) were independent prognostic factors for OS and DFS, median OS was 23.8 and 12.4 months in TCHM and non-TCHM groups, respectively (HR = 0.373; 95% CI = 0.251-0.554; P = .000), and the median DFS was 21.5 and 10.2 months in TCHM and non-TCHM groups, respectively (HR = 0.352; 95% CI = 0.237-0.522; P = .000).

CONCLUSIONS

KPS was an important prognostic factor of pancreatic cancer. Spleen-invigorating compounds could have an effect on improving the prognosis of pancreatic cancer patients.

The walking environment in Lima, Peru and pedestrian-motor vehicle collisions: an exploratory analysis

OBJECTIVE

Pedestrians comprise 78% of the road fatalities in Peru. The objective of this study was to explore the relationship between the walking environment and pedestrian-motor vehicle collisions.

METHODS

A matched case-control study was used to detect the odds of a pedestrian-motor vehicle collision at a pedestrian crossing location. Data were collected from 11 sampled police commissaries in Lima, Peru.

RESULTS

In a multivariable model adjusting for vehicle and pedestrian flow, pedestrian collisions were less likely in the presence of a curb and sidewalk on both roadway sides (odds ratio [OR] = 0.19, 95% confidence interval [CI], 0.11-0.33) or a pedestrian barricade (OR = 0.11, 95% CI, 0.01-0.81). There was a greater risk of collisions for each street vendor present (OR = 2.82, 95% CI, 1.59-5.00) or whether any parked vehicles (OR = 3.67, 95% CI, 1.18-11.4) were present.

CONCLUSIONS

Improving or addressing these potentially modifiable features of the walking environment could improve pedestrian safety in Lima and in similar urban settings in low- and middle-income countries.

Risk of hyponatremia with diuretics: chlorthalidone versus hydrochlorothiazide

BACKGROUND

Chlorthalidone and hydrochlorothiazide are often considered as interchangeable. However, greater (nighttime) blood pressure reduction, and alleged pleiotropic effects have renewed the interest in chlorthalidone. A recent study showed an increased risk of adverse events with chlorthalidone, including hyponatremia.

METHODS

To investigate differences in risk of hyponatremia between chlorthalidone and hydrochlorothiazide, adjusted for daily dose, we conducted a population-based case-control study within the Dutch IPCI (Integrated Primary Care Information) database. The study population included all subjects ≥18 years without diabetes mellitus, heart failure, liver failure, and malignancy, who were registered in the IPCI database from 1996 to 2011. Cases were subjects with a serum sodium <130 millimoles per liter or hospitalization due to hyponatremia. Controls were matched on practice, age within 5 years, sex, and date of onset.

RESULTS

A total of 1033 cases of hyponatremia were identified. Hyponatremia was more common with chlorthalidone than with hydrochlorothiazide at equal dose per day: adjusted odds ratio was 2.09 (95% confidence interval [CI], 1.13-3.88) for 12.5 milligrams per day and 1.72 (95% CI, 1.15-2.57) for 25 milligrams per day. Risks were not significantly increased with chlorthalidone compared with twice the dose per day of hydrochlorothiazide.

CONCLUSIONS

This is the first study that shows an increased risk of hyponatremia with chlorthalidone relative to hydrochlorothiazide at equal milligram-to-milligram dose per day. The need for a lower dose of chlorthalidone than hydrochlorothiazide to achieve similar blood pressure reduction likely compensates for the increased risk of hyponatremia at equal dose.

Heavy alcohol intake is a risk factor for esophageal squamous cell carcinoma among middle-aged men: A case-control and simulation study

Despite the advances in surgical techniques and treatments, the prognosis of esophageal cancer remains poor, since the disease is usually diagnosed at an advanced stage. Therefore, prevention plays an important role in reducing mortality. Smoking and alcohol intake are modifiable habits and are important risk factors for esophageal cancer. However, the number of large-scale studies that have investigated the association of the amount and duration of smoking and alcohol intake with esophageal cancer risk, while accounting for the effects of gender and cancer subtypes (squamous cell carcinoma and adenocarcinoma), is limited. Therefore, in this hospital-based matched case-control study we investigated this association while accounting for gender and subtype differences. Chinese male patients <60 years of age with esophageal squamous cell carcinoma (ESCC) from the Fourth Hospital of Hebei Medical University in China and healthy individuals were enrolled between January, 2002 and December, 2006. Each ESCC patient was age-matched to a control subject and a total of 535 pairs were enrolled in this study. The combined variables of amount and duration were created to elucidate their effect and association with ESCC. Multiple conditional logistic regression analysis was used to estimate the odds ratio (OR) and 95% confidence interval (CI) in this model, which included a family history of esophageal cancer, a combined smoking variable and a combined alcohol variable. A simulation study was subsequently performed to confirm the reliability of the results. The results of the present study demonstrated that a family history of esophageal cancer and the combined alcohol variable were significantly associated with ESCC risk. Heavy alcohol consumption and intake for ≤20 years increased the risk compared with no intake (OR=1.91, 95% CI: 1.25–2.92). Heavy alcohol consumption and intake for >20 years exhibited an even higher risk (OR=7.25, 95% CI: 3.12–16.83). These results were similar to those of the simulation. Heavy alcohol intake, even for a short duration, is a critical risk factor and may lead to the development of ESCC in Chinese males.

Retrospective analysis of wound characteristics and tetanus development in captive macaques

Traumatic wounds and access to outdoor enclosures containing soil contribute to development of tetanus in nonhuman primates. A retrospective, matched case-control study was conducted at a primate center to evaluate these factors by analysis of medical records of animals sustaining traumatic injuries during a 3-yr study period. Thirty-one macaques with traumatic injuries and a clinical diagnosis of tetanus were selected as cases, and 62 macaques with traumatic injuries and no diagnosis of tetanus were selected as controls. For an animal with injuries to the digits, the odds of developing tetanus were 9.6 times those of a similar animal without injuries to the digits (Odds Ratio [OR] = 9.55, 95% CI = 1.56-58.59); with injuries to the tail, the odds of developing tetanus were 8.0 times those of a similar animal without injuries to the tail (OR = 7.95, 95% CI = 0.82-77.04); and with injuries in more than one location, the odds of developing tetanus were 8.5 times those for a similar animal with injuries in just one location (OR = 8.45, 95% CI = 1.01-70.46). A nonhuman primate with injuries to the leg was less likely to develop tetanus than a similar nonhuman primate without injuries to the leg (OR = 0.19, 95% CI = 0.03-1.2). Results indicated that wound location is associated with development of tetanus infection in rhesus macaques. Identification of high-risk trauma cases will allow better allocation of wound management and tetanus prophylaxis in institutions, especially in those housing nonhuman primates outdoors.