Observational research methods—Cohort studies, cross sectional studies, and case–control studies

There is accumulating evidence of the neurological and neuropsychiatric features of infection with SARS-CoV-2. In this systematic review and meta-analysis, we aimed to describe the characteristics of the early literature and estimate point prevalences for neurological and neuropsychiatric manifestations. We searched MEDLINE, Embase, PsycINFO and CINAHL up to 18 July 2020 for randomised controlled trials, cohort studies, case-control studies, cross-sectional studies and case series. Studies reporting prevalences of neurological or neuropsychiatric symptoms were synthesised into meta-analyses to estimate pooled prevalence. 13 292 records were screened by at least two authors to identify 215 included studies, of which there were 37 cohort studies, 15 case-control studies, 80 cross-sectional studies and 83 case series from 30 countries. 147 studies were included in the meta-analysis. The symptoms with the highest prevalence were anosmia (43.1% (95% CI 35.2% to 51.3%), n=15 975, 63 studies), weakness (40.0% (95% CI 27.9% to 53.5%), n=221, 3 studies), fatigue (37.8% (95% CI 31.6% to 44.4%), n=21 101, 67 studies), dysgeusia (37.2% (95% CI 29.8% to 45.3%), n=13 686, 52 studies), myalgia (25.1% (95% CI 19.8% to 31.3%), n=66 268, 76 studies), depression (23.0% (95% CI 11.8% to 40.2%), n=43 128, 10 studies), headache (20.7% (95% CI 16.1% to 26.1%), n=64 613, 84 studies), anxiety (15.9% (5.6% to 37.7%), n=42 566, 9 studies) and altered mental status (8.2% (95% CI 4.4% to 14.8%), n=49 326, 19 studies). Heterogeneity for most clinical manifestations was high. Neurological and neuropsychiatric symptoms of COVID-19 in the pandemic’s early phase are varied and common. The neurological and psychiatric academic communities should develop systems to facilitate high-quality methodologies, including more rapid examination of the longitudinal course of neuropsychiatric complications of newly emerging diseases and their relationship to neuroimaging and inflammatory biomarkers.

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The neurology and neuropsychiatry of COVID-19: a systematic review and meta-analysis of the early literature reveals frequent CNS manifestations and key emerging narratives

10.1101/2021.02.24.21252335 ◽

2021 ◽

Author(s):

Jonathan P Rogers ◽

Cameron Watson ◽

James Badenoch ◽

Benjamin Cross ◽

Matthew Butler ◽

...

Keyword(s):

Systematic Review ◽

Cohort Studies ◽

Meta Analysis ◽

Neuropsychiatric Symptoms ◽

Case Series ◽

Case Control ◽

Case Control Studies ◽

Cross Sectional ◽

Early Literature ◽

Cross Sectional Studies

Objectives There is accumulating evidence of the neurological and neuropsychiatric features of infection with SARS-CoV-2. In this systematic review and meta-analysis, we aimed to describe the characteristics of the early literature and estimate point prevalences for neurological and neuropsychiatric manifestations. Methods We searched MEDLINE, Embase, PsycInfo and CINAHL up to 18 July 2020 for randomised controlled trials, cohort studies, case-control studies, cross-sectional studies and case series. Studies reporting prevalences of neurological or neuropsychiatric symptoms were synthesised into meta-analyses to estimate pooled prevalence. Results 13,292 records were screened by at least two authors to identify 215 included studies, of which there were 37 cohort studies, 15 case-control studies, 80 cross-sectional studies and 83 case series from 30 countries. 147 studies were included in the meta-analysis. The symptoms with the highest prevalence were anosmia (43.1% [35.2-51.3], n=15,975, 63 studies), weakness (40.0% [27.9-53.5], n=221, 3 studies), fatigue (37.8% [31.6-44.4], n=21,101, 67 studies), dysgeusia (37.2% [30.0-45.3], n=13,686, 52 studies), myalgia (25.1% [19.8-31.3], n=66.268, 76 studies), depression (23.0 % [11.8-40.2], n=43,128, 10 studies), headache (20.7% [95% CI 16.1-26.1], n=64,613, 84 studies), anxiety (15.9% [5.6-37.7], n=42,566, 9 studies) and altered mental status (8.2% [4.4-14.8], n=49,326, 19 studies). Heterogeneity for most clinical manifestations was high. Conclusions Neurological and neuropsychiatric symptoms of COVID-19 in the pandemic's early phase are varied and common. The neurological and psychiatric academic communities should develop systems to facilitate high-quality methodologies, including more rapid examination of the longitudinal course of neuropsychiatric complications of newly emerging diseases and their relationship to neuroimaging and inflammatory biomarkers.

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Caffeine Intake from Coffee or Tea and Cognitive Disorders: A Meta-Analysis of Observational Studies

Neuroepidemiology ◽

10.1159/000371710 ◽

2015 ◽

Vol 44 (1) ◽

pp. 51-63 ◽

Cited By ~ 29

Author(s):

Young-Seok Kim ◽

Sang Mi Kwak ◽

Seung-Kwon Myung

Keyword(s):

Cohort Studies ◽

Meta Analysis ◽

Cognitive Disorders ◽

Epidemiological Studies ◽

Case Control ◽

Caffeine Intake ◽

Case Control Studies ◽

Coffee Intake ◽

Cross Sectional ◽

Cross Sectional Studies

Background: Observational epidemiological studies such as cross-sectional, case-control, and cohort studies have reported inconsistent findings regarding the association between caffeine intake from coffee or tea and the risk of cognitive disorders such as dementia, Alzheimer's disease, cognitive impairment, and cognitive decline. Methods: We searched PubMed and EMBASE in September 2014. Three evaluators independently extracted and reviewed articles, based on predetermined selection criteria. Results: Out of 293 articles identified through the search and bibliographies of relevant articles, 20 epidemiological studies from 19 articles, which involved 31,479 participants (8,398 in six cross-sectional studies, 4,601 in five case-control studies, and 19,918 in nine cohort studies), were included in the final analysis. The pooled odds ratio (OR) or relative risk (RR) of caffeine intake from coffee or tea for cognitive disorders (dementia, Alzheimer's disease, cognitive impairment, and cognitive decline) was 0.82 (95% confidence interval [CI], 0.67-1.01, I2 = 63.2%) in a random-effects meta-analysis. In the subgroup meta-analysis by caffeine sources, the summary OR or RR of coffee intake was 0.83 (95% CI, 0.70-0.98; I2 = 44.8%). However, in the subgroup meta-analysis by study design, the summary estimates (RR or OR) of coffee intake for cognitive disorders were 0.70 (95% CI, 0.50-0.98; I2 = 42.0%) for cross-sectional studies, 0.82 (95% CI, 0.55-1.24; I2 = 33.4%) for case-control studies, and 0.90 (95% CI, 0.59-1.36; I2 = 60.0%) for cohort studies. Conclusions: This meta-analysis found that caffeine intake from coffee or tea was not associated with the risk of cognitive disorders.

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The Effect of Prophylactic HPV Vaccines on Oral and Oropharyngeal HPV Infection—A Systematic Review

Viruses ◽

10.3390/v13071339 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1339

Author(s):

Kristoffer Juul Nielsen ◽

Kathrine Kronberg Jakobsen ◽

Jakob Schmidt Jensen ◽

Christian Grønhøj ◽

Christian Von Buchwald

Keyword(s):

Cohort Study ◽

Oropharyngeal Cancer ◽

Hpv Infection ◽

Case Control ◽

Igg Antibodies ◽

Hpv Vaccines ◽

Case Control Studies ◽

Cross Sectional ◽

Post Vaccination ◽

Cross Sectional Studies

Human papillomavirus (HPV) imposes an increased risk of developing cervical, anal and oropharyngeal cancer. In the Western world, HPV infection is currently the major cause of oropharyngeal cancer. The effectiveness of HPV vaccines for oral or oropharyngeal HPV infection is yet to be determined. This study conducted a systematic literature search in Pubmed and Embase. Studies investigating the impact of HPV vaccines on oral or oropharyngeal HPV infection were enrolled. This review reports the relative prevention percentage (RPP), including a risk of bias assessment as well as a quality assessment study. Nine studies were included (48,777 participants): five cross-sectional studies; one randomized community trial study (RCT); one longitudinal cohort study; and two case-control studies. A significant mean RPP of 83.9% (66.6–97.8%) was calculated from the cross-sectional studies, 82.4% in the included RCT and 83% in the longitudinal cohort study. Further, two case-control studies that measured antibody response in participants immunized with HPV vaccines were included. Respectively, 100% and 93.2% of participants developed HPV-16 Immunoglobulin G (IgG) antibodies in oral fluids post-vaccination. Analysis of the studies identified a significant decrease in vaccine-type oral or oropharyngeal HPV infections in study participants immunized with HPV vaccines across study designs and heterogenous populations. Further, a significant percentage of participants developed IgG antibodies in oral fluid post-vaccination.

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Study designs which can demonstrate and test causation

10.1093/med/9780199682898.003.0003 ◽

2017 ◽

Author(s):

Mark Elwood

Keyword(s):

Cohort Studies ◽

Case Control ◽

Control Group ◽

Case Control Studies ◽

Retrospective Case ◽

Community Based ◽

Cross Sectional ◽

Healthcare Interventions ◽

Intervention Trials ◽

Study Designs

This chapter presents study designs which can test and show causation. Cohort and intervention studies compare people exposed to an agent or intervention with those unexposed or less exposed. Case-control studies compare people affected by a disease or outcome with a control group of unaffected people or representing a total population. Surveys select a sample of people, not chosen by exposure or outcome. Cohort studies may be prospective or retrospective; case-control studies are retrospective; surveys are cross-sectional in time, but retrospective or prospective aspects can be added. In part two, strengths, weaknesses and applications of these designs are shown. Intervention trials, ideally randomised, are the prime method of assessing healthcare interventions; special types include crossover trials and community-based trials. Non-randomised trials are noted. The strengths and weaknesses of cohort studies, case-control studies, and surveys are shown.

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Critical appraisal

Practical Psychiatric Epidemiology ◽

10.1093/med/9780198735564.003.0017 ◽

2020 ◽

pp. 285-302

Author(s):

Jo Thompson Coon ◽

Rebecca Abbott

Keyword(s):

Clinical Trials ◽

Critical Appraisal ◽

Case Control ◽

Evidence Based ◽

Case Control Studies ◽

Cross Sectional ◽

Worked Example ◽

Cross Sectional Studies ◽

Critical Appraisal Skills ◽

Based Medicine

This chapter provides an introduction to the principles of critical appraisal and explains why critical appraisal skills are important in practice and research. Guidance is provided on how to approach the critical appraisal of different types of study including cross-sectional studies, case–control studies, cohort studies, clinical trials, systematic reviews, and qualitative studies. A worked example is provided at the end of the chapter to illustrate the process. Developing skills in critical appraisal will help readers to assess the credibility, relevance, and value of the results of research and is an essential component of practising evidence-based medicine.

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The Association between Helicobacter pylori Infection and Irritable Bowel Syndrome: A Meta-Analysis

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17072524 ◽

2020 ◽

Vol 17 (7) ◽

pp. 2524

Author(s):

Yun-A Kim ◽

Yoon Jeong Cho ◽

Sang Gyu Kwak

Keyword(s):

Helicobacter Pylori ◽

Irritable Bowel Syndrome ◽

Meta Analysis ◽

Case Control ◽

Case Control Studies ◽

Cross Sectional ◽

Cross Sectional Studies ◽

H Pylori ◽

Irritable Bowel ◽

The Relationship

The association of Helicobacter pylori (H. pylori) infection with functional dyspepsia has been well studied. However, the data on the relationship between H. pylori infection and irritable bowel syndrome (IBS) are conflicting. This study aims to elucidate the association between H. pylori infection and IBS. PubMed, Cochrane Library, CINAHL and SCOPUS databases were searched to identify eligible English articles published up to December 2019. Cross-sectional studies, case–control studies and cohort studies reporting both prevalence of H. pylori infection and IBS were selected for the detailed review. The pooled odds ratio (ORs) and their 95% confidence interval (CI) were calculated. A total of 7269 individuals in four cross-sectional studies and six case-control studies were included. The prevalence of H. pylori infection ranged from 12.8% to 73.4% in the control group, and 9.7% to 72.1% in the IBS group. The combined OR for H. pylori infection was 1.10 (95% CI: 0.93–1.29, I2: 37.5%). In a subgroup analysis of IBS defined according to Rome criteria, the OR for H. pylori infection was 1.10 (95% CI: 0.93–1.30, I2 = 31.7%). In this meta-analysis, H. pylori infection was not significantly associated with IBS. Well-designed studies are needed to identify the relationship between H. pylori infection and IBS.

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Androgenetic Alopecia and its Association with Metabolic Syndrome: A Systematic Review and Meta-analysis

Acta Medica Philippina ◽

10.47895/amp.v53i2.175 ◽

2019 ◽

Vol 53 (2) ◽

Author(s):

Leah Antoinette M. Caro-Chang ◽

Mia Katrina R. Gervasio ◽

Claudine Yap-Silva

Keyword(s):

Metabolic Syndrome ◽

Early Onset ◽

Meta Analysis ◽

Case Control ◽

Androgenetic Alopecia ◽

Case Control Studies ◽

Cross Sectional ◽

Newcastle Ottawa Scale ◽

Independent Review ◽

Cross Sectional Studies

Objectives. The study aimed to confirm the association between androgenetic alopecia (AGA) and Metabolic Syndrome (MetS). It also aimed to determine if early-onset AGA among males and AGA among females increases the risk of developing MetS, and if severity of AGA increases the odds of developing MetS. Methods. Observational studies from electronic databases were selected by the consensus of three independent review authors. The Newcastle-Ottawa Scale for assessing the quality of non-randomized studies in meta-analysis was used. Statistical analyses were accomplished using Review Manager software. Results. A total of 11 case-control studies, one prospective cohort study, and five cross-sectional studies were selected. In the meta-analysis of ten case-control studies and three cross-sectional studies (3840 participants), AGA was significantly correlated with MetS (OR 2.59, 95% CI 1.51 to 4.44; p<0.0005). Early-onset AGA among males (<35 years old) showed significant association (OR 3.69, 95% CI 2.15 to 6.33; p<0.00001). AGA among females also increased the odds of developing MetS (OR 5.59, 95% CI 2.06 to 15.12; p<0.0007). Moderate to severe AGA in males, Norwood-Hamilton IV or higher, was also significant (OR 1.65, 95% CI 1.12 to 2.42; p=0.01). The same trend was noted for females with Ludwig II and III (OR 5.82, 95% CI 2.54 to 13.34; p<0.00001). Conclusion. Although the pathophysiology still remains under investigation, the present study points to an association between AGA and MetS. It can be used as a marker to identify patients who should be screened for MetS and managed accordingly.

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Relationship between Vitamin C and Periodontal Diseases: A Systematic Review

10.20944/preprints201906.0007.v1 ◽

2019 ◽

Author(s):

Akio Tada ◽

Hiroko Miura

Keyword(s):

Systematic Review ◽

Vitamin C ◽

Periodontal Disease ◽

Blood Level ◽

Case Control ◽

Cochrane Library ◽

Case Control Studies ◽

Cross Sectional ◽

Lower Blood ◽

Cross Sectional Studies

Vitamin C is important in preventing and slowing the progression of many diseases. There is significant evidence linking periodontal disease and vitamin C. We aimed to systematically review studies addressing the relationship between vitamin C and periodontal disease and the preventive ability of vitamin C against periodontal disease. Electric searches were performed using PubMed, EMBASE, Cochrane Library, and Web of Science. Studies addressing the relationships between periodontal disease and vitamin C in adults aged over 18 years were included. Quality assessment was done using Critical Appraisal Skills Program guideline and GRADE-CERQual. Seventy hundred and sixteen articles were retrieved and fifteen articles (7 cross-sectional studies, 2 case-control studies, 2 cohort studies, and 4 randomized controlled trial [RCT]) were selected by reviewing all articles. Vitamin C intake and blood level were negatively related to periodontal disease in all 7 cross-sectional studies. Subjects who suffer from periodontitis presented lower vitamin C intake and lower blood vitamin C level than subjects without periodontal disease in the two case-control studies. Patients with lower dietary intake or lower blood level of vitamin C showed greater progression of periodontal disease than did the controls. Intervention using vitamin C administration improved gingival bleeding in gingivitis but not in periodontitis. Alveolar bone absorption was also not improved. The present systematic review suggested that vitamin C contributes to reduced risk of periodontal disease.

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