Obtaining Confidence Intervals for the Risk Ratio in Cohort Studies

Biometrics ◽  
1978 ◽  
Vol 34 (3) ◽  
pp. 469 ◽  
Author(s):  
D. Katz ◽  
J. Baptista ◽  
S. P. Azen ◽  
M. C. Pike
Keyword(s):  
Cohort Studies ◽  
Confidence Intervals ◽  
Risk Ratio

TP7.2.16 Systematic review and meta analysis of pre operative antibiotics and bowel preparation on ileus following colorectal resection

2021 ◽  
Vol 108 (Supplement_7) ◽  
Author(s):  
Michael Kelly ◽  
Gerard McKnight ◽  
Alisdair J. Scott
Keyword(s):  
Systematic Review ◽  
Cohort Studies ◽  
Risk Ratio ◽  
Bowel Preparation ◽  
Colorectal Resection ◽  
Meta Analysis ◽  
Mechanical Bowel Preparation ◽  
Infectious Complications ◽  
Randomised Trials ◽  
Randomised Controlled

Abstract Aims Pre-operative oral antibiotics (OAB) and mechanical bowel preparation (MBP) may reduce rates of post-operative infectious complications following colorectal surgery but their effects on post-operative ileus (POI) are not well-established. We conducted a systematic review and meta-analysis to address this question. Methods Medline and Embase databases were searched to identify randomised controlled trials and cohort studies comparing pre-operative MBP or OAB to control in patients undergoing elective colorectal resection and reporting the rate of POI as an outcome. Risk ratios were pooled using a random-effects model to generate a summary risk ratio and 95% confidence interval. Results Five randomised trials and three cohort studies were included which reported the effect of pre-operative MBP on POI. Some 29056 patients received MBP compared to 13077 who did not. The rates of POI were 10.0% vs 12.0% respectively. Meta-analysis gave a risk ratio of 0.85 (0.80-0.91, p < 0.0001) for the development of POI with MBP versus control. Four randomised trials and four cohort studies were included which reported the effect of pre-operative OAB on POI. Some 9.5% of 19,903 patients receiving OAB developed POI compared to 11.8% of 23,884 control patients. The pooled risk ratio for the development of POI with OAB compared to control was 0.86 (0.81-0.91, p < 0.0001). However, when limiting analyses to randomised trials alone, neither MBP (RR 1.13, 0.67-1.90) nor OAB 1.01, 0.75-1.35) had a significant effect on the rate of POI. Conclusions Pre-operative MBP or OAB may reduce POI following colorectal resection but this has not been confirmed in randomised trials.

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.

scholarly journals Pregnancy and fertility-related adverse outcomes associated with Chlamydia trachomatis infection: a global systematic review and meta-analysis

2019 ◽  
Vol 96 (5) ◽  
pp. 322-329 ◽  
Author(s):  
Weiming Tang ◽  
Jessica Mao ◽  
Katherine T Li ◽  
Jennifer S Walker ◽  
Roger Chou ◽  
...  
Keyword(s):  
Cohort Studies ◽  
Risk Ratio ◽  
Low Income ◽  
Case Control ◽  
High Income ◽  
Adverse Outcomes ◽  
Chlamydia Infection ◽  
Case Control Studies ◽  
Middle Income ◽  
Middle Income Countries

BackgroundGenital chlamydia infection in women is often asymptomatic, but may result in adverse outcomes before and during pregnancy. The purpose of this study was to examine the strength of the relationships between chlamydia infection and different reproductive health outcomes and to assess the certainty of the evidence.MethodsThis review was registered and followed the Cochrane guidelines. We searched three databases to quantitatively examine adverse outcomes associated with chlamydia infection. We included pregnancy and fertility-related outcomes. We performed meta-analyses on different study designs for various adverse outcomes using unadjusted and adjusted analyses.ResultsWe identified 4730 unique citations and included 107 studies reporting 12 pregnancy and fertility-related outcomes. Sixty-eight studies were conducted in high-income countries, 37 studies were conducted in low-income or middle-income countries, and 2 studies were conducted in both high-income and low-income countries. Chlamydia infection was positively associated with almost all of the 12 included pregnancy and fertility-related adverse outcomes in unadjusted analyses, including stillbirth (OR=5.05, 95% CI 2.95 to 8.65 for case–control studies and risk ratio=1.28, 95% CI 1.09 to 1.51 for cohort studies) and spontaneous abortion (OR=1.30, 95% CI 1.14 to 1.49 for case–control studies and risk ratio=1.47, 95% CI 1.16 to 1.85 for cohort studies). However, there were biases in the design and conduct of individual studies, affecting the certainty of the overall body of evidence. The risk of adverse outcomes associated with chlamydia is higher in low-income and middle-income countries compared with high-income countries.ConclusionChlamydia is associated with an increased risk of several pregnancy and fertility-related adverse outcomes in unadjusted analyses, especially in low-income and middle-income countries. Further research on how to prevent the sequelae of chlamydia in pregnant women is needed.Trial registration numberCRD42017056818.

scholarly journals Patient relevant outcomes of unicompartmental versus total knee replacement: systematic review and meta-analysis

BMJ ◽  
2019 ◽  
pp. l352 ◽  
Author(s):  
Hannah A Wilson ◽  
Rob Middleton ◽  
Simon G F Abram ◽  
Stephanie Smith ◽  
Abtin Alvand ◽  
...  
Keyword(s):  
Systematic Review ◽  
Decision Making ◽  
Total Knee Replacement ◽  
Cohort Studies ◽  
Knee Replacement ◽  
Risk Ratio ◽  
Randomised Controlled Trials ◽  
Controlled Trials ◽  
Total Knee ◽  
Randomised Controlled

AbstractObjectiveTo present a clear and comprehensive summary of the published data on unicompartmental knee replacement (UKA) or total knee replacement (TKA), comparing domains of outcome that have been shown to be important to patients and clinicians to allow informed decision making.DesignSystematic review using data from randomised controlled trials, nationwide databases or joint registries, and large cohort studies.Data sourcesMedline, Embase, Cochrane Controlled Register of Trials (CENTRAL), and Clinical Trials.gov, searched between 1 January 1997 and 31 December 2018.Eligibility criteria for selecting studiesStudies published in the past 20 years, comparing outcomes of primary UKA with TKA in adult patients. Studies were excluded if they involved fewer than 50 participants, or if translation into English was not available.Results60 eligible studies were separated into three methodological groups: seven publications from six randomised controlled trials, 17 national joint registries and national database studies, and 36 cohort studies. Results for each domain of outcome varied depending on the level of data, and findings were not always significant. Analysis of the three groups of studies showed significantly shorter hospital stays after UKA than after TKA (−1.20 days (95% confidence interval −1.67 to −0.73), −1.43 (−1.53 to −1.33), and −1.73 (−2.30 to −1.16), respectively). There was no significant difference in pain, based on patient reported outcome measures (PROMs), but significantly better functional PROM scores for UKA than for TKA in both non-trial groups (standard mean difference −0.58 (−0.88 to −0.27) and −0.29 (−0.46 to −0.11), respectively). Regarding major complications, trials and cohort studies had non-significant results, but mortality after TKA was significantly higher in registry and large database studies (risk ratio 0.27 (0.16 to 0.45)), as were venous thromboembolic events (0.39 (0.27 to 0.57)) and major cardiac events (0.22 (0.06 to 0.86)). Early reoperation for any reason was higher after TKA than after UKA, but revision rates at five years remained higher for UKA in all three study groups (risk ratio 5.95 (1.29 to 27.59), 2.50 (1.77 to 3.54), and 3.13 (1.89 to 5.17), respectively).ConclusionsTKA and UKA are both viable options for the treatment of isolated unicompartmental osteoarthritis. By directly comparing the two treatments, this study demonstrates better results for UKA in several outcome domains. However, the risk of revision surgery was lower for TKA. This information should be available to patients as part of the shared decision making process in choosing treatment options.Systematic review registrationPROSPERO number CRD42018089972.

scholarly journals Privacy-protecting estimation of adjusted risk ratios using modified Poisson regression in multi-center studies

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Di Shu ◽  
Jessica G. Young ◽  
Sengwee Toh
Keyword(s):  
Data Analysis ◽  
Confidence Intervals ◽  
Risk Ratio ◽  
Poisson Regression ◽  
Binary Outcomes ◽  
Real World Data ◽  
Individual Level ◽  
Adjusted Risk ◽  
Level Data ◽  
Risk Ratios

Abstract Background Multi-center studies can generate robust and generalizable evidence, but privacy considerations and legal restrictions often make it challenging or impossible to pool individual-level data across data-contributing sites. With binary outcomes, privacy-protecting distributed algorithms to conduct logistic regression analyses have been developed. However, the risk ratio often provides a more transparent interpretation of the exposure-outcome association than the odds ratio. Modified Poisson regression has been proposed to directly estimate adjusted risk ratios and produce confidence intervals with the correct nominal coverage when individual-level data are available. There are currently no distributed regression algorithms to estimate adjusted risk ratios while avoiding pooling of individual-level data in multi-center studies. Methods By leveraging the Newton-Raphson procedure, we adapted the modified Poisson regression method to estimate multivariable-adjusted risk ratios using only summary-level information in multi-center studies. We developed and tested the proposed method using both simulated and real-world data examples. We compared its results with the results from the corresponding pooled individual-level data analysis. Results Our proposed method produced the same adjusted risk ratio estimates and standard errors as the corresponding pooled individual-level data analysis without pooling individual-level data across data-contributing sites. Conclusions We developed and validated a distributed modified Poisson regression algorithm for valid and privacy-protecting estimation of adjusted risk ratios and confidence intervals in multi-center studies. This method allows computation of a more interpretable measure of association for binary outcomes, along with valid construction of confidence intervals, without sharing of individual-level data.

Predictors of episodic migraine transformation to chronic migraine: A systematic review and meta-analysis of observational cohort studies

Cephalalgia ◽  
2019 ◽  
Vol 40 (5) ◽  
pp. 503-516 ◽  
Author(s):  
Jingjing Xu ◽  
Fanyi Kong ◽  
Dawn C Buse
Keyword(s):  
Risk Factors ◽  
Systematic Review ◽  
Cohort Studies ◽  
Chronic Migraine ◽  
Risk Ratio ◽  
Household Income ◽  
Meta Analysis ◽  
Episodic Migraine ◽  
Annual Household Income ◽  
Increased Risk

Background and purpose An estimated 2.5–3.1% of people with episodic migraine develop chronic migraine in a year. Several risk factors are associated with an increased risk for this transformation. We conducted a systematic review and meta-analysis to provide quantitative and qualitative data on predictors of this transformation. Methods An electronic search was conducted for published, prospective, cohort studies that reported risk factors for chronic migraine among people with episodic migraine. Risk of bias was assessed using the Newcastle-Ottawa Quality Assessment Scale. Quality of evidence was determined according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines. Effect estimates were retrieved and summarized using risk ratios. Results Of 5695 identified publications, 11 were eligible for inclusion. The pooled analysis (GRADE system) found “high” evidence for monthly headache day frequency ≥ 10 (risk ratio = 5.95), “moderate” evidence for depression (risk ratio = 1.58), monthly headache day frequency ≥ 5 (risk ratio = 3.18), and annual household income ≥ $50,000 (risk ratio = 0.65) and “very low” evidence for allodynia (risk ratio = 1.40) and medication overuse (risk ratio = 8.82) in predicting progression to chronic migraine. Conclusions High frequency episodic migraine and depression have high quality evidence as predictors of the transformation from episodic migraine to chronic migraine, while annual household income over $50,000 may be protective.

Sign in / Sign up

Export Citation Format

Share Document