Epidemiology and biostatistics

2019 ◽  
pp. 52-67
Author(s):  
Nizam Damani
Keyword(s):  
Cohort Studies ◽  
Confidence Intervals ◽  
Prevalence Rate ◽  
Statistical Significance ◽  
Case Control ◽  
Statistical Process ◽  
Practical Advice ◽  
Advantages And Disadvantages ◽  
Basic Concepts ◽  
Healthcare Associated

This section includes a chapter on basic epidemiology and biostatistics as applied to healthcare-associated infections (HAIs). The epidemiology section summarizes various types of studies and outlines the advantages and disadvantages of case–control and cohort studies. It describes the incidence and prevalence rate and how to calculate the most common HAIs. Practical advice is also given on how to avoid bias and confounders. The chapter describes basic concepts in biostatistics and tests of statistical significance used in investigating an outbreak. It also provides guidance on how to calculate the sensitivity and specificity of the test and describes how to interpret confidence intervals and statistical process charts.

Types of trials

2017 ◽  
Author(s):  
Mark Harrison
Keyword(s):  
Emergency Medicine ◽  
Cohort Studies ◽  
Case Reports ◽  
Meta Analysis ◽  
Case Series ◽  
Case Control ◽  
Controlled Trials ◽  
Case Control Studies ◽  
Advantages And Disadvantages ◽  
Randomized Controlled

This chapter describes types of trials as applied to Emergency Medicine, and in particular the Primary FRCEM examination. The chapter outlines the key details and advantages and disadvantages of case reports, case series, cohort studies, case–control studies, randomized controlled trials, crossover trials, systematic reviews, and meta-analysis. This chapter is laid out exactly following the RCEM syllabus, to allow easy reference and consolidation of learning.

SERUM PROLACTINE LEVEL IN PATIENTS OF PSORIASIS VULGARIS AND ITS CORRELATION WITH DISEASE SEVERITY: A CASE-CONTROL STUDY

2019 ◽  
Vol 3 (6) ◽  
Author(s):  
Pawan Kumar Saini ◽  
Devendra Yadav ◽  
Rozy Badyal ◽  
Suresh Jain ◽  
Arti Singh ◽  
...  
Keyword(s):  
Disease Severity ◽  
Prolactin Level ◽  
Case Control Study ◽  
Statistical Significance ◽  
Case Control ◽  
Serum Prolactin ◽  
P Value ◽  
Serum Prolactin Level ◽  
R Value ◽  
Control Study

Background: Psoriasis is an autoimmune chronic inflammatory disorder affecting the skin mediated by T-lymphocytes resulting in production of cytokines which cause hyperproliferation of keratinocytes.  Several factors and hormones like Prolactin have an action similar to these cytokines in promoting the multiplication of keratinocytes and other cells like lymphocytes and epithelial cells may have a role on the etiopathogenesis of psoriasis. Aim:-The aim of study is to compare the serum Prolactin levels in patients of psoriasis with a control group. Setting and study design: This is a case-control study conducted in the department of Dermatology, Venereology and Leprosy GMC, Kota over a period of 1year from July 2017 to June 2018 Material and method: The study included 100 cases of psoriasis (60 males and 40 females) and 100 controls similar for age and sex. Serum Prolactin levels were measured by ECLIA and results were obtained. Statistical analysis: Mean and standard deviation were calculated for each variable. Statistical significance of the results was analyzed using correlation analysis (Pearson correlation coefficient) and independent samples t-test. Statistical significance was assumed at p value<0.05. Result: Serum Prolactin level was significantly higher in cases of psoriasis compared to controls (p-value <0.001). PASI score and serum Prolactin levels were found to have a positive correlation (r value = 0.337; p-value: 0.001). No significant  correlation was found between serum levels of Prolactin and duration of disease r value= -0.034, P value =0.733). Serum Prolactin level was higher in male patients compared to females patients. Conclusion:- High serum Prolactin may be a biological marker of disease severity in psoriasis and may have a role in the pathogenesis of psoriasis. Further studies with large sample size are required to confirm this hypothesis.

scholarly journals COVID-19 and Its Symptoms’ Panoply: A Case-Control Study of 919 Suspected Cases in Locked-Down Ovar, Portugal

2021 ◽  
pp. 1-8
Author(s):  
Regina Sá ◽  
Tiago Pinho-Bandeira ◽  
Guilherme Queiroz ◽  
Joana Matos ◽  
João Duarte Ferreira ◽  
...  
Keyword(s):  
Large Scale ◽  
Case Control Study ◽  
Statistical Significance ◽  
Case Control ◽  
Case Definition ◽  
Suspected Case ◽  
Risk Characteristics ◽  
Increased Risk ◽  
Wide Range ◽  
Control Study

<b><i>Background:</i></b> Ovar was the first Portuguese municipality to declare active community transmission of SARS-CoV-2, with total lockdown decreed on March 17, 2020. This context provided conditions for a large-scale testing strategy, allowing a referral system considering other symptoms besides the ones that were part of the case definition (fever, cough, and dyspnea). This study aims to identify other symptoms associated with COVID-19 since it may clarify the pre-test probability of the occurrence of the disease. <b><i>Methods:</i></b> This case-control study uses primary care registers between March 29 and May 10, 2020 in Ovar municipality. Pre-test clinical and exposure-risk characteristics, reported by physicians, were collected through a form, and linked with their laboratory result. <b><i>Results:</i></b> The study population included a total of 919 patients, of whom 226 (24.6%) were COVID-19 cases and 693 were negative for SARS-CoV-2. Only 27.1% of the patients reporting contact with a confirmed or suspected case tested positive. In the multivariate analysis, statistical significance was obtained for headaches (OR 0.558), odynophagia (OR 0.273), anosmia (OR 2.360), and other symptoms (OR 2.157). The interaction of anosmia and odynophagia appeared as possibly relevant with a borderline statistically significant OR of 3.375. <b><i>Conclusion:</i></b> COVID-19 has a wide range of symptoms. Of the myriad described, the present study highlights anosmia itself and calls for additional studies on the interaction between anosmia and odynophagia. Headaches and odynophagia by themselves are not associated with an increased risk for the disease. These findings may help clinicians in deciding when to test, especially when other diseases with similar symptoms are more prevalent, namely in winter.

scholarly journals Linguistic feature of anorexia nervosa: a prospective case–control pilot study

2021 ◽  
Author(s):  
Vittoria Cuteri ◽  
Giulia Minori ◽  
Gloria Gagliardi ◽  
Fabio Tamburini ◽  
Elisabetta Malaspina ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Language Processing ◽  
Statistical Significance ◽  
Case Control ◽  
Pathological Process ◽  
Linguistic Features ◽  
Level Of Evidence ◽  
Linguistic Feature ◽  
Linguistic Markers ◽  
Clinical Conditions

Abstract Purpose Attention has recently been paid to Clinical Linguistics for the detection and support of clinical conditions. Many works have been published on the “linguistic profile” of various clinical populations, but very few papers have been devoted to linguistic changes in patients with eating disorders. Patients with Anorexia Nervosa (AN) share similar psychological features such as disturbances in self-perceived body image, inflexible and obsessive thinking and anxious or depressive traits. We hypothesize that these characteristics can result in altered linguistic patterns and be detected using the Natural Language Processing tools. Methods We enrolled 51 young participants from December 2019 to February 2020 (age range: 14–18): 17 girls with a clinical diagnosis of AN, and 34 normal-weighted peers, matched by gender, age and educational level. Participants in each group were asked to produce three written texts (around 10–15 lines long). A rich set of linguistic features was extracted from the text samples and the statistical significance in pinpointing the pathological process was measured. Results Comparison between the two groups showed several linguistics indexes as statistically significant, with syntactic reduction as the most relevant trait of AN productions. In particular, the following features emerge as statistically significant in distinguishing AN girls and their normal-weighted peers: the length of the sentences, the complexity of the noun phrase, and the global syntactic complexity. This peculiar pattern of linguistic erosion may be due to the severe metabolic impairment also affecting the central nervous system in AN. Conclusion These preliminary data showed the existence of linguistic parameters as probable linguistic markers of AN. However, the analysis of a bigger cohort, still ongoing, is needed to consolidate this assumption. Level of evidence III Evidence obtained from case–control analytic studies.

scholarly journals Non-autoimmune diabetes mellitus and the risk of virus infections: a systematic review and meta-analysis of case-control and cohort studies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eric Lontchi-Yimagou ◽  
Charly Feutseu ◽  
Sebastien Kenmoe ◽  
Alexandra Lindsey Djomkam Zune ◽  
Solange Fai Kinyuy Ekali ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Systematic Review ◽  
Cohort Studies ◽  
H1n1 Virus ◽  
Autoimmune Diabetes ◽  
Meta Analysis ◽  
Case Control ◽  
Cochrane Central Register ◽  
Virus Infections ◽  
Autoimmune Diabetes Mellitus

AbstractA significant number of studies invoked diabetes as a risk factor for virus infections, but the issue remains controversial. We aimed to examine whether non-autoimmune diabetes mellitus enhances the risk of virus infections compared with the risk in healthy individuals without non-autoimmune diabetes mellitus. In this systematic review and meta-analysis, we assessed case-control and cohort studies on the association between non-autoimmune diabetes and viruses. We searched PubMed, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and Web of Science with no language restriction, to identify articles published until February 15, 2021. The main outcome assessment was the risk of virus infection in individuals with non-autoimmune diabetes. We used a random-effects model to pool individual studies and assessed heterogeneity (I2) using the χ2 test on Cochrane’s Q statistic. This study is registered with PROSPERO, number CRD42019134142. Out of 3136 articles identified, we included 68 articles (90 studies, as the number of virus and or diabetes phenotype varied between included articles). The summary OR between non-autoimmune diabetes and virus infections risk were, 10.8(95% CI: 10.3–11.4; 1-study) for SARS-CoV-2; 3.6(95%CI: 2.7–4.9, I2 = 91.7%; 43-studies) for HCV; 2.7(95% CI: 1.3–5.4, I2 = 89.9%, 8-studies;) for HHV8; 2.1(95% CI: 1.7–2.5; 1-study) for H1N1 virus; 1.6(95% CI: 1.2–2.13, I2 = 98.3%, 27-studies) for HBV; 1.5(95% CI: 1.1–2.0; 1-study) for HSV1; 3.5(95% CI: 0.6–18.3 , I2 = 83.9%, 5-studies) for CMV; 2.9(95% CI: 1–8.7, 1-study) for TTV; 2.6(95% CI: 0.7–9.1, 1-study) for Parvovirus B19; 0.7(95% CI: 0.3–1.5 , 1-study) for coxsackie B virus; and 0.2(95% CI: 0–6.2; 1-study) for HGV. Our findings suggest that, non-autoimmune diabetes is associated with increased susceptibility to viruses especially SARS-CoV-2, HCV, HHV8, H1N1 virus, HBV and HSV1. Thus, these viruses deserve more attention from diabetes health-care providers, researchers, policy makers, and stakeholders for improved detection, overall proper management, and efficient control of viruses in people with non-autoimmune diabetes.

scholarly journals Association of placental chorangiosis with pregnancy complication and prenatal outcome: a case-control study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Homeira Vafaei ◽  
Zinat Karimi ◽  
Mojgan Akbarzadeh-Jahromi ◽  
Fatemeh Asadian
Keyword(s):  
Case Control Study ◽  
Gestational Hypertension ◽  
Statistical Significance ◽  
Placental Tissue ◽  
Case Control ◽  
Low Grade ◽  
Amniotic Fluid Index ◽  
Significance Level ◽  
Adverse Pregnancy ◽  
Control Study

Abstract Background Chorangiosis is a vascular change involving the terminal chorionic villi in the placenta. It results from longstanding, low-grade hypoxia in the placental tissue, and is associated with such conditions as intrauterine growth restriction (IUGR), diabetes, and gestational hypertension in pregnancy. Chorangiosis rarely occurs in normal pregnancies. However, its prevalence is 5–7% of all placentas from infants admitted to newborn intensive care units. The present study was aimed at determining the association of chorangiosis with pregnancy complications and perinatal outcomes. Methods In this case-control study, 308 chorangiosis cases were compared with 308 controls (with other diagnoses in pathology) in terms of maternal, placental, prenatal, and neonatal characteristics derived from the medical records of participants retrospectively. R and SPSS version 22 software tools were used, and the statistical significance level was considered 0.05 for all the tests. Results Preeclampsia, diabetes mellitus, maternal hemoglobin, maternal hematocrit, C/S, oligohydramnios, fetal anomaly, dead neonates, NICU admissions were significantly higher in the chorangiosis group OR = 1.6, 3.98, 1.68, 1.92, 2.1, 4.47, 4.22, 2.9, 2.46, respectively (p-value< 0.05 for all). Amniotic fluid index, birth weight, cord PH amount, 1st, and 5th Apgar score was lower in the chorangiosis group OR = 0.31, 1, 0.097, 0.83, 0.85, respectively (p-value< 0.05 for all). Moreover, fundal placenta, retro placental hemorrhage, perivillous fibrin deposition, calcification, and acute chorioamnionitis were higher in the chorangiosis group OR = 2.1, 11.8, 19.96, 4.05, and 6.38 respectively, (p-value< 0.05). There was a high agreement between the two pathologists, and the power of the study was estimated at 99%. Conclusion Although chorangiosis is an uncommon condition, it is associated with a higher incidence of perinatal and neonatal morbidity and mortality. Therefore, it should be considered an important clinical sign of adverse pregnancy outcomes and should be reported in the pathology evaluation.

Ethnic differences in risk factors for subarachnoid hemorrhage

2007 ◽  
Vol 107 (3) ◽  
pp. 522-529 ◽  
Author(s):  
Vibhor Krishna ◽  
Dong H. Kim
Keyword(s):  
Risk Factors ◽  
Subarachnoid Hemorrhage ◽  
Alcohol Consumption ◽  
Cohort Studies ◽  
Odds Ratio ◽  
Case Control ◽  
Ethnic Composition ◽  
Effect Estimate ◽  
Case Control Studies ◽  
Current Smoking

Object Studies on risk factors for subarachnoid hemorrhage (SAH) show heterogeneity. For example, hypertension has been found to be a significant risk factor in some studies but not in others. The authors hypothesized that differences in the ethnicity of the populations studied could account for these findings. Methods A metaanalysis was performed using 17 case-control and 10 cohort studies that met specified inclusion criteria. The authors used a random-effect model to calculate the pooled effect estimates for current smoking, hypertension, and alcohol consumption. A meta–regression analysis was performed using the ethnic composition of the study populations as a covariate. Studies were classified as multiethnic or monoethnic, and the pooled effect estimates were compared. Results Analysis of the cohort studies yielded a pooled effect estimate or risk ratio of 3.18 (95% confidence interval [CI] 2.37–4.26) for current smoking, 3.05 (95% CI 2.09–4.44) for hypertension, and 2.46 (95% CI 1.42–4.24) for alcohol consumption at a rate of 150 g/week or more. The results were similar for the case-control studies. For current smoking, the ethnic composition of the study population was a statistically significant predictor of heterogeneity among case-control studies (p < 0.001, even after application of the Bonferroni correction). The risk for SAH among current smokers was higher in multiethnic populations (odds ratio 3.832) than in monoethnic populations (odds ratio 2.487). Conclusions The results of this metaanalysis suggest that differences in susceptibility to the harmful health effects of smoking may be one cause of the observed differences in SAH incidence for different ethnic groups. The role of ethnicity in risk factors for SAH should be considered in future studies.

Soy Consumption with Risk of Coronary Heart Disease and Stroke: A Meta-Analysis of Observational Studies

2016 ◽  
Vol 46 (4) ◽  
pp. 242-252 ◽  
Author(s):  
Danfei Lou ◽  
Yuehua Li ◽  
Guoliang Yan ◽  
Jianhong Bu ◽  
Haihui Wang
Keyword(s):  
Coronary Heart Disease ◽  
Heart Disease ◽  
Cohort Studies ◽  
Observational Studies ◽  
Meta Analysis ◽  
Case Control ◽  
Inverse Association ◽  
Case Control Studies ◽  
Relative Risks ◽  
Product Consumption

Background: The association of soy product consumption with the relative risk of cardiovascular disease remains controversial. This meta-analysis aimed at investigating whether an association exists between soy consumption and the risk of stroke and coronary heart disease (CHD) in observational studies. Methods: A systematic search of the PubMed and EMBASE databases was performed for case-control and cohort studies that assessed soy consumption and the risk of stroke and CHD. Summary relative risks (SRRs) and 95% CIs were combined by using a random-effects model. Results: Of a total of 1,266 abstracts, 5 prospective cohort and 6 case-control studies met our inclusion criteria, and comprised 4,954 stroke and 7,616 CHD events. Based on the high vs. low analyses, combining cohort studies showed no association between soy intake and risk of stroke (SRR 0.92; 95% CI 0.70-1.10; Pheterogeneity = 0.236; I2 = 29.4%) or CHD (SRR 0.97; 95% CI 0.74-1.27; Pheterogeneity = 0.020; I2 = 62.7%), although a significantly inverse association between soy intake and the risk of stroke (SRR 0.54; 95% CI 0.34-0.87; Pheterogeneity = 0.001; I2 = 79.3%) and CHD (SRR 0.66; 95% CI 0.56-0.77; Pheterogeneity = 0.421; I2 = 0) was observed in case-control studies. No association between soy isoflavone intake and the risk of stroke and CHD was identified. Conclusion: There was limited evidence to indicate that soy consumption was inversely associated with the risk of stroke and CHD, although further studies, with prospective designs that use validated questionnaires and control for important confounders, are warranted.

Association between blood transfusion and ventilator-associated events: a nested case-control study

2021 ◽  
pp. 1-6
Author(s):  
Wen Wang ◽  
Qiao He ◽  
Shichao Zhu ◽  
Mingqi Wang ◽  
Yan Kang ◽  
...  
Keyword(s):  
Blood Transfusion ◽  
Case Control Study ◽  
Case Control ◽  
Incidence Density ◽  
Cox Models ◽  
Hospital System ◽  
Increased Risk ◽  
Healthcare Associated ◽  
Nested Case Control ◽  
Control Study

Abstract Objectives: The association between blood transfusion and ventilator-associated events (VAEs) has not been fully understood. We sought to determine whether blood transfusion increases the risk of a VAE. Design: Nested case-control study. Setting: This study was based on a registry of healthcare-associated infections in intensive care units at West China Hospital system. Patients: 1,657 VAE cases and 3,293 matched controls were identified. Methods: For each case, 2 controls were randomly selected using incidence density sampling. We defined blood transfusion as a time-dependent variable, and we used weighted Cox models to calculate hazard ratios (HRs) for all 3 tiers of VAEs. Results: Blood transfusion was associated with increased risk of ventilator-associated complication-plus (VAC-plus; HR, 1.47; 95% CI, 1.22–1.77; P <.001), VAC-only (HR, 1.29; 95% CI, 1.01–1.65; P = .038), infection-related VAC-plus (IVAC-plus; HR, 1.78; 95% CI, 1.33–2.39; P < .001), and possible ventilator-associated pneumonia (PVAP; HR, 2.10; 95% CI, 1.10–3.99; P = .024). Red blood cell (RBC) transfusion was also associated with increased risk of VAC-plus (HR, 1.34; 95% CI, 1.08–1.65; P = .007), IVAC-plus (HR, 1.70; 95% CI, 1.22–2.36; P = .002), and PVAP (HR, 2.49; 95% CI, 1.17–5.28; P = .018). Compared to patients without transfusion, the risk of VAE was significantly higher in patients with RBC transfusions of >3 units (HR, 1.73; 95% CI, 1.25–2.40; P = .001) but not in those with RBC transfusions of 0–3 units. Conclusion: Blood transfusions were associated with increased risk of all tiers of VAE. The risk was significantly higher among patients who were transfused with >3 units of RBCs.

Confidence intervals for predictive values with an emphasis to case–control studies

2007 ◽  
Vol 26 (10) ◽  
pp. 2170-2183 ◽  
Author(s):  
Nathaniel D. Mercaldo ◽  
Kit F. Lau ◽  
Xiao H. Zhou
Keyword(s):  
Confidence Intervals ◽  
Case Control ◽  
Case Control Studies ◽  
Predictive Values
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