Collapsibility of odds ratios for a continuous outcome variable

The sign of an association measure between two varibles may be strongly affected and even be reversed after marginalization over a backgruoud variable, which is the well-known Yule-Simpson paradox.Odds ratios are strongly collapsible over a background variable if they remain unchanged no matter how the background variable is partially pooled.In this paper, we firstly give some definitions and notations about odds ratios between a dichotomous explanatory variable and a continuous response variable.Then, we present conditions for simple collapsibility of odds ratios.Further, necessary and sufficient conditions are given for strong collapsibility of odds ratios for continuous outcome variable.

Exposure to proton pump inhibitors and risk of diabetes:A systematic review and meta-analysis

BACKGROUND Exposure to proton pump inhibitors(PPIs)has been reported to have a potential role in the development of diabetes.AIM To determine the association between PPIs and diabetes.METHODS This meta-analysis is registered on PROSPERO(CRD42022352704).In August 2022,eligible studies were identified through a comprehensive literature search.In this study,odds ratios were combined with 95%confidence intervals using a random-effects model.The source of heterogeneity was assessed using sensitivity analysis and subgroup analysis.The publication bias was evaluated using Egger’s test and Begg’s test.RESULTS The meta-analysis included 9 studies with a total of 867185 participants.Results showed that the use of PPIs increased the risk of diabetes(odds ratio=1.23,95%confidence interval:1.05-1.43,n=9,I2=96.3%).Subgroup analysis showed that geographic location and study type had significant effects on the overall results.Both Egger’s and Begg’s tests showed no publication bias(P>0.05).Sensitivity analysis also confirmed the stability of the results.CONCLUSION The results of this study indicated that the use of PPIs was related to an increased risk of diabetes.However,more well-designed studies are needed to verify these results in the future.

Reduced risk of dementia in patients with type 2 diabetes mellitus using Chinese herbal medicine:A nested case-control study

BACKGROUND Dementia is a prevalent condition in type 2 diabetes mellitus(T2DM)patients.While Chinese herbal medicine(CHM)is often employed as complementary therapy for glycemic control,its effect in controlling likelihood of dementia has not yet been fully elucidated.AIM To compare the risk of dementia between T2DM patients with and without CHM treatment.METHODS We undertook a nested case-control study and obtained data on patients 20-70 years of age who received medical care for T2DM between 2001 and 2010 from the National Health Insurance Research database in Taiwan.Cases,defined as those with dementia that occurred at least one year after the diagnosis of T2DM,were randomly matched to controls without dementia from the study cohort at a 1:1 ratio.We applied conditional logistic regression to explore the associations between CHM treatment and dementia.RESULTS A total of 11699 dementia cases were matched to 11699 non-dementia controls.We found that adding CHM to conventional care was related to a lower risk of dementia[adjusted odds ratio(OR)=0.51],and high-intensity CHM treatment was associated with an adjusted OR of 0.22.CONCLUSION This study shows that the cumulative CHM exposure was inversely associated with dementia risk in an exposureresponse manner,implying that CHM treatment may be embraced as a disease management approach for diabetic patients to prevent dementia.

Everything You Wanted to Know but Could Never Find from the Cochran-Mantel-Haenszel Test

The Cochran-Mantel-Haenszel (CMH) test, developed in the 1950s, is a classic in health research, especially in epidemiology and other fields in which dichotomous and polytomous variables are frequent. This nonparametric test makes it possible to measure and check the effect of an antecedent variable X on a health outcome Y, statistically controlling the effect of a third variable Z that acts as a confounding variable in the relationship between X and Y. Both X and Y are measured on a dichotomous qualitative scale and Z on a polytomous-qualitative or ordinal scale. It is assumed that the effect of X on Y is homogeneous between the k strata of Z, which is usually tested by the Breslow-Day test with the Tarone’s correction or the Woolf’s test. The main statistical programs have the CMH test together with a test to verify the assumption of a homogeneous effect across the strata, so that it is easy to apply. However, its fundamentals and details of calculations are a mystery to most researchers, and even difficult to find or understand. The aim of this article is to present these details in a clear and concise way, including the assumptions and alternatives to non-compliance. This technical knowledge is applied to a simulated realistic example of the area of epidemiology in health and, finally, an interpretive synthesis of the analyses is given. In addition, some suggestions for the test report are made.

Does Helicobacter pylori infection play a role in iron deficiency anemia? A meta-analysis

AIM:To perform a meta-analysis of observational studies and randomized controlled trials(RCTs)on the association between Helicobacter pylori(H.pylori)and iron deficiency anemia(IDA).METHODS:A defined search strategy was used to search Medline,Embase,the Cochrane Library,Clinical Trials,Cochrane Central Register of Controlled Trials,Premedline and Healthstar.Odds ratio(OR)was used to evaluate observational epidemiology studies,and weighted mean difference(WMD)was used to demonstrate the difference between control and intervention groups.RESULTS:Fifteen observational studies and 5 RCTs were identified and used for calculation.The pooled OR for observational studies was 2.22(95%CI:1.52-3.24,P<0.0001).The WMD for hemoglobin(HB) was 4.06 g/L(95%CI:-2.57-10.69,P=0.01),and the WMD for serum ferritin(SF)was 9.47μg/L(95%CI:-0.50-19.43,P<0.0001).Results were heterogeneous for all comparisons.CONCLUSION:This meta-analysis on observational studies suggests an association between H.pylori and IDA.In RCTs,eradication of H.pylori can improve HB and SF levels but not significantly.

Cervical Infection of Oncogenic Human Papillomavirus(HPV) Types in Beijing,China

Objective This study was designed to determine the prevalence of oncogenic human papillomavirus（HPV） in cervical infections in Beijing,China,and to investigate the odds ratio（OR） of HPV single and multiple infections in abnormal cytology.Methods A total of 19,018 specimens from outpatients in the department of obstetric and gynecology were collected.They were detected using high-risk HPV genotyping real-time polymerase chain reaction（PCR） kit and analyzed by ThinP rep cytology test for cervical pathological diagnosis.HPV prevalence,age-specific prevalence,and OR of each type of HPV in abnormal cytology were analyzed.Results Overall,19.1%（3,623/19,018） of the individuals were positive for HPV infection,14.9%（2,833/19,018） were positive for a single HPV type,and 4.2%（790/19,018） were positive for multiple types.Among the 3,623 HPV-positive individuals,the most predominant HPV types were HPV52（4.4%,834/19,018）,HPV16（3.7%,710/19,018）,and HPV58（3.4%,644/19,018）.The OR of multiple infections and single infection differed significantly among disease severities.The OR of dual infection was higher than that of each of the two single infection types,respectively.Conclusion HPV prevalence in the outpatients was 19.1%,and the most predominant HPV types in the study were HPV52,HPV16,and HPV58.Women with multiple infectionswere more likely to have abnormal cytology.

hOGG1 Ser326Cys polymorphism modifies the significance of the environmental risk factor for colon cancer

AIM:To determine the association of hOGG1 (8-oxoguanine glycosylase I,OGG1) polymorphism of Ser326Cys substitution with colon cancer risk and possible interaction with known environmental risk factors. METHODS:A case-control study with 125 colon cancer cases and 247 controls was conducted, RESULTS:There was no major difference in Ser326Cys genotype distribution between cases and controls.The meat intake tended to increase the odds ratio for colon cancer with an OR of 1.72 (95 % confidence interval;CI=1.12-2.76). Such tendency was more prominent in Cys/Cys carriers (OR=4.31,95 % CI=1.64-11.48),but meat intake was not a significant risk factor for colon cancer in Ser/Ser or Ser/ Cys carriers.The OR for colon cancer was elevated with marginal significance in smokers who were Cys/Cys carriers (OR=2.75,95 % CI=1.07-7.53) but not in Ser/Ser or Ser/ Cys carriers. CONCLUSION:These results suggest that the hOGG1 Ser326Cys polymorphism is probably not a major contributor to individual colon cancer susceptibility overall,but the Cys/ Cys genotype may alter the impact of some environmental factors on colon cancer development.

Silicosis in Automobile Foundry Workers: A 29-Year Cohort Study

Objectives The purposes were to determine the relationship between silicosis among foundry workers and their cumulative exposure to silica dust, and to establish a regression model to predict the risk for developing silicosis by a given length of employment and air concentrations of silica at worksites. Methods A 29-year cohort study was conducted, including all those employed for more than one year during January 1, 1980 to December 31, 1996 and all members of the cohort were followed-up to December 3 1, 2008. In total, 2 009 workers of an automobile foundry in Shiyan, Hubei province were recruited in the study, 1 300 at eight worksites including sand preparation, cast shakeout, and finishing, melting, moulding, core-making, overhead crane operation and pouring as exposed group, and the other 709 auxiliary workers at the same factory, such as electricians, inspectors, fitters, and so on, as control group. Person-years of observation were calculated by persons observed and years followed-up for each of them. Person-year incidence of silicosis and its relative risk （RR） or odds ratio （OR） and 95% confidence intervals （CI） among the workers were estimated, adjusted for relevant factors with logistic regression model using SPSS version 15.0 software. Results Totally, 2 009 workers were followed-up for 37 151 person-years and 48 cases of silicosis were found, with an overall incidence of 1.34 per thousand, 2.02 per thousand in exposed group, and 0.15 per thousand in control one. Risk of silicosis was significantly higher in the exposed group than that in the control one （RR=13.13, 95% CI 3.18-54.13）, higher in men than that in women （RR=13.92, 95% CI 1.92-100.93）. Risks of silicosis varied by job, highest in those exposed to cast shakeout and finishing （RR=28.14, 95% CI 6.43-123.11）, followed by those exposed to pouring （RR-22.23, 95% CI 5.01-98.55） in the foundry. Average length of employment at onset of silicosis was 25.94 years, and silicosis incidence increased with length of employment. Average age at onset of silicosis was 47.83 years old. The risk of silicosis in workers with pulmonary tuberculosis was 2.57 folds as those without it （P〈0.01）. Ten deaths were recorded in those with silicosis, with a case-fatality rate of 20.83 percent three of them died of lung cancer, three of liver cancer, two of ischemic heart disease, and two of other diseases as their immediate causes of death. Incidence of silicosis in foundry workers positively correlated with their cumulative silica exposure （OR-3.00, 95% CI 2.34-3.83）. Risks of silicosis increased by 4.38 folds with an increase of 1 mg/m^3-year of cumulative silica exposure, and by 3.79 folds with smoking, respectively, adjusted for alcohol drinking and age. Based on a logistic regression model fitted, incidence of silicosis is expected to be 44.6 per thousand for those with daily exposure to silica of 4.18 mg/m^3 in average for 30 years, and if incidence of silicosis is expected to be less than 1 per thousand, daily exposure to silica should be controlled below 0.2 mg/m^3 for those with 20 years of employment, or below 0.1 mg/m^3 for those with 30 or 40 years of silica exposure. Conclusions At present, foundry workers in China still face high risk of developing silicosis. For lowering occurrence of silicosis in exposed workers, it seems necessary that current occupational exposure limits for silica at worksites in China should be reexamined and silica dust control measures be strengthend.

P16 gene hypermethylation and hepatocellular carcinoma:A systematic review and meta-analysis

AIM:To quantitatively investigate the effect of p16 hypermethylation on hepatocellular carcinoma (HCC) and hepatocirrhosis using a meta-analysis of available casecontrol studies.METHODS:Previous studies have primarily evaluated the incidence of p16 hypermethylation in HCC and corresponding control groups,and compared the incidence of p16 hypermethylation in tumor tissues,pericancer liver tissues,normal liver tissues and non-tumor liver tissues with that in other diseases.Data regarding publication information,study characteristics,and incidence of p16 hypermethylation in both groups were collected from these studies and summarized.RESULTS:Fifteen studies,including 744 cases of HCC and 645 non-tumor cases,were identified for meta-analysis.Statistically significant odds ratios (ORs) of p16 hypermethylation were obtained from tumor tissues and non-tumorous liver tissues of HCC patients (OR 7.04,95% CI:3.87%-12.78%,P < 0.0001),tumor tissues of HCC patients and healthy liver tissues of patients with other diseases (OR 12.17,95% CI:6.64%-22.31%,P < 0.0001),tumor tissues of HCC patients and liver tissues of patients with non-tumorous liver diseases (OR 6.82,95% CI:4.31%-10.79%,P < 0.0001),and cirrhotic liver tissues and non-cirrhotic liver tissues (OR 4.96,95% CI:1.45%-16.96%,P=0.01).The pooled analysis showed significantly increased ORs of p16 hypermethylation (OR 6.98,95% CI:4.64%-10.49%,P < 0.001) from HCC tissues and cirrhotic tissues.CONCLUSION:P16 hypermethylation induces the inactivation of p16 gene,plays an important role in hepatocarcinogenesis,and is associated with an increased risk of HCC and liver cirrhosis.

Association between Helicobacter pylori infection and migraine: A meta-analysis

AIM: To quantify the association between Helicobacter pylori (H. pylori) infection and migraine.

Insulin-like growth factor-1, IGF binding protein-3, and the risk of esophageal cancer in a nested case-control study

To assess the relationship between serum levels of insulin-like growth factor-1 (IGF1)/IGF-binding protein-3 (IGFBP3) and the risk of esophageal carcinoma.METHODSWe assessed the relationship between the serum levels of these molecules and the risk of esophageal cancer in a prospective, nested case-control study of participants from the Japan Collaborative Cohort Study. A baseline survey was conducted from 1988 to 1990. Of the 110585 enrolled participants, 35% donated blood samples. Those who had been diagnosed with esophageal cancer were considered cases for nested case-control studies. A conditional logistic model was used to estimate odds ratios for the incidence of esophageal cancer associated with serum IGF1 and IGFBP3 levels.RESULTSThirty-one cases and 86 controls were eligible for the present assessment. The molar ratio of IGF1/IGFBP3, which represents the free and active form of IGF1, was not correlated with the risk of esophageal carcinoma. A higher molar difference between IGFBP3 and IGF1, which estimates the free form of IGFBP3, was associated with a decreased risk of esophageal carcinoma (P = 0.0146), and people in the highest tertile had the lowest risk (OR = 0.107, 95%CI: 0.017-0.669). After adjustment for body mass index, tobacco use, and alcohol intake, the molar difference of IGFBP3-IGF1 was inversely correlated with the risk of esophageal carcinoma (P = 0.0150).CONCLUSIONThe free form of IGFBP3, which is estimated by this molar difference, may be inversely associated with esophageal cancer incidence.

Urinary trypsinogen-2 for diagnosing acute pancreatitis:a meta-analysis

BACKGROUND: Currently, serum amylase and lipase are the most popular laboratory markers for early diagnosis of acute pancreatitis with reasonable sensitivity and specificity. Urinary trypsinogen-2 (UT-2) has been increasingly used but its clinical value for the diagnosis of acute pancreatitis and post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis has not yet been systematically assessed. DATA SOURCES: A comprehensive search was carried out using PubMed (MEDLINE), Embase, and Web of Science for clinical trials, which studied the usefulness of UT-2 as a diagnostic marker for acute pancreatitis. Sensitivity, specificity and the diagnostic odds ratios (DORs) with 95% confidence interval (CI) were calculated for each study and were compared with serum amylase and lipase. Summary receiver-operating curves were conducted and the area under the curve (AUC) was evaluated. RESULTS: A total of 18 studies were included. The pooled sensitivity and specificity of UT-2 for the diagnosis of acute pancreatitis were 80% and 92%, respectively (AUC=0.96, DOR=65.63, 95% CI: 31.65-139.09). The diagnostic value of UT-2 was comparable to serum amylase but was weaker than serum lipase. The pooled sensitivity and specificity for the diagnosis of post-ERCP pancreatitis were 86% and 94%, respectively (AUC=0.92, DOR=77.68, 95% CI: 24.99-241.48).CONCLUSIONS: UT-2 as a rapid test could be potentially used for the diagnosis of post-ERCP pancreatitis and to an extent, acute pancreatitis. Further studies are warranted to confirm these results.

Association between Selenium in Soil and Diabetes in Chinese Residents Aged 35–74 Years:Results from the 2010 National Survey of Chronic Diseases and Behavioral Risk Factors Surveillance

Objective To explore the association between soil selenium levels and the risk of diabetes in Chinese adults aged 35–74 years.Methods Data for this study were derived from the China Chronic Diseases and Behavioral Risk Factors Surveillance 2010 survey.Selenium concentrations in soil were obtained from the Atlas of Soil Environmental Background Values in China.A two-level binary logistic regression model was used to determine the association between soil selenium concentrations and the risk of diabetes,with participants nested within districts/counties.Results A total of 69,332 participants aged 35–74 years,from 158 districts/counties were included in the analysis.Concentrations of selenium in soil varied greatly across the 158 districts/counties,with a median concentration of 0.219 mg/kg(IQR:0.185–0.248).The results showed that both Quartile 1(0.119–0.185 mg/kg)and Quartile 4(0.249–0.344 mg/kg)groups were positively associated with diabetes compared to a soil selenium concentration of 0.186–0.219 mg/kg(Quartile 2),crude odds ratios(ORs)(95%CI)were 1.227(1.003–1.502)and 1.280(1.048–1.563).The P values were 0.045 and 0.013,for Quartile 1 and Quartile 4 groups,respectively.After adjusting for all confounding factors of interest,the Quartile 1 group became non-significant,and the Quartile 4 group had an adjusted OR(95%CI)of 1.203(1.018–1.421)relative to the reference group(Quartile 2),the P values was 0.030.No significant results were seen for the Quartile 3 group(0.220–0.248 mg/kg)compared to the reference group.Conclusion Excessive selenium concentrations in soil could increase the risk of diabetes among Chinese adults aged 35–74 years.

Role of IL-17 gene polymorphisms in osteoarthritis:A meta-analysis based on observational studies

BACKGROUND Osteoarthritis(OA)is a chronic complex multifactorial joint disease,and a major degenerative form of arthritis.Existing studies on the association between polymorphisms of the IL-17 gene and the risk of OA in different populations have yielded conflicting findings.AIM To investigate the association between polymorphisms of the IL-17 gene and the risk of OA.METHODS We conducted a meta-analysis by systematically searching databases,including PubMed,EMBASE,MEDLINE,Cochrane Library,and Google Scholar to evaluate this association by calculating pooled odds ratios with 95%confidence intervals.Moreover,subgroup analyses stratified by ethnicity and OA type were also conducted.RESULTS In a total of 6 citations involving 8 studies(2131 cases and 2299 controls),4 single nucleotide polymorphisms were identified.Of these 4 polymorphisms,2(rs2275913,rs763780)were common in five case-control studies.Together,the pooled results revealed that the A allele and genotype AA/GA of the rs2275913 polymorphism,and the C allele and genotype CC of the rs763780 polymorphism in the IL-17 gene increased the risk of OA.Furthermore,stratification analyses by ethnicity and OA type showed that the rs2275913 polymorphism increased the risk of OA among Asians and in knee/hip OA,respectively.In addition,stratification analyses also revealed that the rs763780 polymorphism increased OA risk among both Asians and Caucasians in knee/hip OA.CONCLUSION The rs763780 polymorphism of the IL-17F gene increased the risk of OA,whereas the rs2275913 polymorphism of the IL-17A gene increased the risk of OA only among Asians.Due to the limitations of this study,these findings should be validated in future studies.

Quantifying Likelihood in Digital Forensic Investigations

While the conventional forensic scientists routinely validate and express the results of their investigations quantitatively using statistical measures from probability theory,digital forensics examiners rarely if ever do so.In this paper,we review some of the quantitative tools and techniques which are available for use in digital forensic investigations,including Bayesian networks,complexity theory,information theory and probability theory,and indicate how they may be used to obtain likelihood ratios or odds ratios for the relative plausibility of alternative explanations for the creation of the recovered digital evidence.The potential benefits of such quantitative measures for modern digital forensics are also outlined.

Global prevalence,mortality,and main risk factors for COVID-19 associated pneumocystosis:A systematic review and meta-analysis

Objective:Pneumocystis pneumonia(PcP)is a life-threatening infection caused by the opportunistic fungi Pneumocystis jirovecii.The emergence of the COVID-19 pandemic forced the focus of attention of health policymakers on these two infections due to their clinical and paraclinical similarities,which cause diagnostic dilemmas.This study was undertaken to evaluate and estimate the global prevalence and main leading risk factors of coronavirus-associated pneumocystosis(CAP).Methods:We searched related databases between December 2019 and May 2022 for studies reporting CAP.Meta-analysis was performed using StatsDirect software(version 2.7.9)according to the DerSimonian and Laird method applying the random-effects model.We evaluated heterogeneity using theχ2-based Q statistic(significant for P<0.05)and the I2 statistic(>75%indicative of“notable”heterogeneity).Moreover,an odds ratio(OR)analysis was performed for eligible data.Results:Our meta-analysis included eight studies with 923 patients hospitalized with COVID-19;among them,92 were PcP cases.The overall pooled prevalence of CAP was estimated at 11.5%.The mortality among CAP patients was lower than that of non-PcP patients(OR 1.93;95%CI 0.86-4.31).Long-term corticosteroid therapy(OR 28.22;95%CI 0.54-1480.84)was the most predisposing factor for PcP among COVID-19 patients,followed by pulmonary diseases(OR 1.46;95%CI 0.43-4.98),kidney diseases(OR 1.26;95%CI 0.21-7.49),and acute respiratory destruction syndrome(OR 1.22;95%CI 0.05-29.28).Conclusions:The prevalence of PcP among the COVID-19 population is almost similar to the pre-COVID era.However,PcP-related mortality was decreased by the emergence of the COVID-19 pandemic.Women with COVID-19 are more susceptible to PcP than men.Acute respiratory distress syndrome,kidney diseases,pulmonary diseases,and long-term corticosteroid therapy increased the risk of PcP;however,transplantation and malignancy decreased the risk for PcP among COVID-19 patients.Further retrospective,case-control,prospective,and more precisely systematic review and meta-analysis studies are needed in this field.

Logistic Regression for Prediction and Diagnosis of Bacterial Regrowth in Water Distribution System

This paper focuses on the quantitative expression of bacterial regrowth in water distribution system. Considering public health risks of bacterial regrowth,the experiment was performed on a distribution system of selected area.Physical,chemical,and microbiological parameters such as turbidity,temperature,residual chlorine and pH were measured over a three-month period and correlation analysis was carried out.Combined with principal components analysis(PCA) ,a logistic regression model is developed to predict and diagnose bacterial regrowth and locate the zones with high risks of microbiology in the distribution system.The model gives the probability of bacterial regrowth with the number of heterotrophic plate counts as the binary response variable and three new principal components variables as the explanatory variables.The veracity of the logistic regression model was 90%,which meets the precision requirement of the model.

Factors Related to Functional Capacity and Quality of Life for Elderly People in a Middle-Sized City of São Paulo, Brazil

Introduction: It is a fact that the elderly population has been increasing all around the world and also in Brazil. This has been a challenge for governments and managers in the development of public policies to promote healthy and quality aging. And one of the conditions for healthy aging is to assess the functional capacity and quality of life of elderly people. Objective: The aim of the present study was to evaluate the factors that influence the loss of functional capacity and the worsening of the quality of life of a representative sample of elderly people from a medium-sized city in the inner of São Paulo State, Brazil. Methodology: Questionnaires about activities of daily living (ADL), instrumental activities of daily living (IADL), Flanagan quality of life scale (FQOLS), sociodemographic and morbidities aspects were applied to the elderly people. In order to assess associated factors to functional capacity and quality of life, chi-square tests and logistic regression models were fitted including variables: gender, age group, marital status, income, education level, body mass index, abdominal circumference and some morbidities reported by the elderly people. The level of significance adopted for the statistical tests was 5%. Results: Elderly with age over 75 years old and not married had more risk to be dependent on ADL, while elderly with more than 75 years old, not married, income below one minimal wage, cardiovascular disease and be diabetic had more risk to be dependent by IADL. Already, people with excess of weight had smallest risk to be dependent by IADL, paradoxically. The elderly not married and with an income below a minimum wage had the worst quality of life. Conclusions: Population aging in Brazil is an evident factor, so it is hoped that this study will contribute to the greatest diligence on the issues of the elderly and related social problems.

Issues Related to Categorization of Continuous Independent Variables in Multiple Logistic Regression Analysis in Clinical Trials

Effect of with and without categorization of continuous variables on the number and nature of statistically significant predictors was examined while analyzing clinical trial data. The number of categories required to have consistent statistical inference was also explored. Multiple Logistic Regression Analysis was employed with the dependent variable in the model may be a dichotomous/multi-category in nature while the independent variables （predictors） may be either continuous or categorical or ordinal. Real-life clinical trial data was used to answer the objectives. It was found that there was no hard and fast rule to categorize the continuous variables. Sometimes, it was observed that the set of significant predictors identified might change with the criteria of categorization. Certain variables without categorization produced too large odds ratios to interpret meaningfully. The nature as well as number of significant predictors altered with classification criteria often forcing the authors to categorize variables, it is recommended that the independent variables need not be coded, unless otherwise warranted. Coding is needed when the odds ratio is extremely high. In this situation, two or more categories, including regression analysis. median cut off point, will be sufficient to undertake the logistic

Association between Systolic Blood Pressure Difference ≥10 mm Hg and Ankle-Brachial Index

Background: In new outpatients, blood pressure should be measured in both arms. A previous study reported that an inter-arm systolic blood pressure difference (ΔSBP) of ≥10 mm Hg is associated with an increased risk of mortality. Aim: The aim was to identify the associations with absolute values of ΔSBP (|ΔSBP|) ≥10 mm Hg. Subjects and Methods: This study included 2481 patients. Patients with a body mass index ≥25 kg/m2 were defined as obese. The group of A was defined as following: ankle-brachial index (ABI) was <0.9 or ≥1.3. ΔSBP was expressed as right arm BP minus left arm BP. |ΔSBP| ≥10 mm Hg were analyzed using multivariate logistic analysis. Results: |ΔSBP| ≥10 mm Hg was found in 6.0% of patients and |ΔSBP| < 5 mm Hg in 80.4%. In multivariate analysis, the odds ratios (ORs) of the associations with |ΔSBP| ≥10 mm Hg were significantly associated with abnormal ABI and obesity regardless of sex and age. Moreover, the OR of the combined effects of abnormal ABI and obesity was higher than that of abnormal ABI and obesity alone. Conclusion: |ΔSBP| ≥10 mm Hg was associated with abnormal ABI and obesity. In a primary care setting, blood pressure should be actively measured in both arms. This study suggests that the associations with |ΔSBP| ≥10 mm Hg may be a useful part of screening for abnormal ABI.