In this review of the literature, we distinguish between experimental and observationalstudies, highlighting the importance that the later have gained in the era of evidence-based medicine. We further analyze the value of observationalstudies in light of experimental stud- ies. We present a taxonomy for observationalstudies based on units of observation and measurement (cross-sectional or longitudinal). We distinguish between descriptive studies and analytical studies. Then, and given its specificity, we define and present a classification for ecological studies. We define and consider the advantages and disadvantages of cross-sectional, case control and cohort studies. We analyze the strength of the evidence given by each study design. We finished by examining what should guide the choice of a study design.
Fourteen observationalstudies involving thirteen cohort studies and one case-control study were included in the meta-analysis. Exposure to fluoride in drinking water does not signifi- cantly increase the incidence of hip fracture (RRs, 1.05; 95% CIs, 0.96–1.15). Sensitivity analyses based on adjustment for covariates, effect measure, country, sex, sample size, quality of Newcastle–Ottawa Scale scores, and follow-up period validated the strength of the results. Meta-regression showed that country, gender, quality of Newcastle–Ottawa Scale scores, adjustment for covariates and sample size were not sources of heterogeneity. Little evidence of publication bias was observed.
Methods: A systematic search was conducted in the following databases: MEDLINE (via PubMed), Lilacs, Scopus and Web of Science. There were no applied restrictions in terms of the publication date. In addition, a manual search was performed on the references of published studies. Observationalstudies assessing the prevalence of acute clinical manifestations in victims of toxic smoke inhalation in closed environments were included. Results : Of the 4,603 articles identified, eight were included, comprising a total of 233 patients. The signs and symptoms were identified and ranked according to frequency. Dyspnea (58.80%, six studies), carbonaceous sputum (54.51%, four studies), hoarseness (39.91%, three studies), wheezing (34.33%, five studies) and sore throat (33.90%, two studies) were the most frequent acute clinical manifestations of smoke inhalation. Besides these, chest pain and pulmonary edema were observed, respectively in 13.30%, 5.15% of the studies. Conclusion : The results suggest that dyspnea, carbonaceous sputum, hoarseness, wheezing and sore throat were the most frequent acute clinical manifestations in victims of smoke inhalation. Further studies of a higher level of evidence and greater methodological rigor are required.
examined to detect any significant influence on the risk of CV events and CHD. Moreover, pooled ORs adjusted for possible confounders and their 95% CIs were calculated for the risk of CV events in the cohort studies by the random-effect model weighted with inverse variance. The Cochrane x2 test and the I-squared test were used to evaluate heterogeneity among studies, with a threshold value of p = 0.10 being considered significant . Publication bias was evaluated by creating a funnel plot of each study’s effect size versus the SE. Funnel plot asymmetry was assessed by Begg’s test and Egger’s test. Then trim-and-fill computation was used to estimate the influence of publication bias . All statistical analyses were performed with Stata 11.0 software (StataCorp, College Station, TX). Results are expressed as the mean with 95% CI, unless otherwise indicated. Except for tests of heterogeneity, a P value of less than 0.05 was considered significant. All procedures were performed in accordance with the guideline for the meta-analysis of observationalstudies in epidemiology  and the PRISMA statement .
Keeping track of the fate of individual seeds represents a major challenge in seed dispersal studies. This challenge is particularly strong with seeds that pass through the gastro-intestinal track of an animal vector, and thus disappear from observers’ view after ingestion. Studies which calculate seed dispersal distances and fitted seed dispersal curves from observationalstudies make the assumption that seeds voided with faeces can be assigned to a source tree when the outlined rigid criterion (see Introduction) is applied. In our study, we validated for the first time the observational approach through the employment of DNA fingerprinting that allows an unambiguous assignment of seeds to their source tree. We have shown that the seed dispersal distances and fitted dispersal curves resulting from behavioural observations can be considered as reliable, as suggested by the high concordance of observationally and genetically determined dispersal distances and curves, respectively. The application and compliance of a rigid criterion for inclusion of seeds into the observational determination of seed dispersal distances is essential for the reliability of the behavioural approach. Studies that applied this criterion [7–10] thus can be considered as yielding valid results. Thus, previous data sets based on observational work alone can be legitimately used in the analyses of spatial patterns of tamarin seed dispersal. Deviations between observationally and genetically determined mean seed dispersal distances per mother tree are generally small (Table 1) and would not affect the general spatial pattern.
pollutants, and genetic conditions . Our meta-analysis of one nested case-control study, eight case-control studies, and five cross- sectional studies provides evidence that PD is associated with an increased risk of COPD and can increase a significantly the risk by 2.08 times. When the subjects were stratified by ethnicity, this association did not differ: the ORs were 1.69 for North Americans (95%CI = 1.43–2.00), 1.93 for Asians (95%CI = 1.15–3.26), and 3.89 for Europeans (95%CI = 2.05–7.38). When the analysis was restricted to studies with control for conventional rsik factors, including age, gender, and especially smoking, PD was identified as a probable independent risk factor for COPD (OR = 1.78, 95%CI = 1.23–2.58; P,0.001). When the groups were stratified the group by study design, the results also suggested that PD is a significant risk factor for COPD in both case-control and cross- sectional studies, with the association gaining more powerful from the cross-sectional studies (OR = 1.35, 95%CI = 1.66–1.36; P,0.001) to the case-control studies (OR = 2.26, 95%CI = 1.38– 3.70; P,0.001) to the nested case-control study (OR = 2.77, 95%CI = 1.27–2.47; P,0.001). This finding can be attributed to the fact that the cross-sectional study design suffers from more confounding biases compared with the case–control study design and the case–control study design suffers from more confounding biases compared with the nested case–control study design. The prospective cohort study design is the best among observationalstudies, and it can control confounding biases very well. We therefore suggest that this study design be used in future research. Table 2. Results of subgroups analyses of pooled ORs (95% CIs).
Methods and Findings: We performed a systematic review of community-based controlled observationalstudies. We conducted comprehensive literature searches, extracted adjusted relative risk (RR) estimates, and pooled the estimates for major cardiovascular events associated with use of individual NSAIDs, in different doses, and in populations with low and high background risks of cardiovascular events. We also compared individual drugs in pair-wise (within study) analyses, generating ratios of RRs (RRRs). Thirty case-control studies included 184,946 cardiovascular events, and 21 cohort studies described outcomes in .2.7 million exposed individuals. Of the extensively studied drugs (ten or more studies), the highest overall risks were seen with rofecoxib, 1.45 (95% CI 1.33, 1.59), and diclofenac, 1.40 (1.27, 1.55), and the lowest with ibuprofen, 1.18 (1.11, 1.25), and naproxen, 1.09 (1.02, 1.16). In a sub-set of studies, risk was elevated with low doses of rofecoxib, 1.37 (1.20, 1.57), celecoxib, 1.26 (1.09, 1.47), and diclofenac, 1.22 (1.12, 1.33), and rose in each case with higher doses. Ibuprofen risk was seen only with higher doses. Naproxen was risk-neutral at all doses. Of the less studied drugs etoricoxib, 2.05 (1.45, 2.88), etodolac, 1.55 (1.28, 1.87), and indomethacin, 1.30 (1.19, 1.41), had the highest risks. In pair-wise comparisons, etoricoxib had a higher RR than ibuprofen, RRR = 1.68 (99% CI 1.14, 2.49), and naproxen, RRR = 1.75 (1.16, 2.64); etodolac was not significantly different from naproxen and ibuprofen. Naproxen had a significantly lower risk than ibuprofen, RRR = 0.92 (0.87, 0.99). RR estimates were constant with different background risks for cardiovascular disease and rose early in the course of treatment.
Ayurveda is as old as human civilization based on two ideologies i.e. maintaining health of the healthy persons and curing the disease of diseased one. According to Ayurvedic point of view mandagni (reduced digestive power) is the mother of all diseases including Amlapitta. On Amlapitta more than 153 research works in PG/PhD level have been reported so far from various research institutions across India. Among these, 36 research works (PG-32/ PhD-4) were carried out at Institute for Post Graduate Training & Research in Ayurveda (I.P.G.T. & R.A.). Out of 36 research works 7 were from dept. of Kayachikitsa, 4 were from Dravyaguna department, 10 were from Basic Principles, 2 were from Rogavigyana Vikritivigyana & 13 were done from dept. of Rasashastra & Bhaisajyakalpana. Research works include 24 clinical studies and 12 experimental cum clinical studies. 21 single drug formulations ( Sunthi, Bhringaraj, Patola, Shatavari, Amalaki, Guduchi etc.) & 20 compound drug formulations ( Sutashekhara rasa, Sunthi Khanda, Puga Khanda etc.) were studied. Maximum drugs used in these research works possess kapha-pitta shamaka, grahi, kledahara, dipana, pachana & medhya properties with Madhura, Tikta & Kasaya predominant rasa, Shita virya (potency) which very easily counteract the etiopathogenesis of Amlapitta.
Gastric cancer, which account for about 10% of annual cancer-related deaths, remains one of the most common malignant tumors worldwide, especially in developing countries, such as EasternAsia, Eastern Europe, and South America. Development of gastric cancer is a com- plex and multifactorial process. Epidemiological studies have suggested that Helicobacter pylori infection and dietary factors play important roles in the etiology of gastric cancer[1, 2].A distinction has been further observed between tumors arising in the proximal cardiac region (gastriccardia adenocarcinoma,GCA) and those arising in distal region (gastric non-cardia ade- nocarcinoma, GNCA).For example, Helicobacter pylori infection was reported to be posi- tively associated with the riskof GNCAbut not ofGCA, while overweight and obesity seem to be associated with increased risk of GCA but not ofGNCA.However, an expert panel,con- vened by the World Cancer Research Fund andthe American Institute for Cancer Research, pointed out that no dietary factorcan be convincingly proved to be risk factors for gastric can- cer. In spite of that, consumption of salty food, salted preserved food, red meat, and pro- cessed meat is generally thought to increase the risk of gastric cancer[7–9], while consumption of freshfruits, vegetables, and antioxidant vitamins may reduce the risk of gastric cancer[10– 13]. Overall, the results of relevant studies on the effects of dietary factors on gastric cancer are inconsistent and need further investigation.
Introduction: Since dysphagia may be one of the brain post-stroke consequences, the objective of this study was to analyze the average recovery time of patients with cerebrovascular accident and dysphagia subjected to speech therapy in a hospital bed. Material and Methods: Systematic review performed following the ‘Preferred Reporting Items is Systematic Reviews and Meta- Analyses’ instructions. The search was performed in different electronic databases, without restriction of time and language. The studies were evaluated regarding their methodological quality.
resumO: Objetivo: Realizar uma revisão sistemática sobre o uso da Classiicação Internacional de Funcionalidade, Incapacidade e Saúde (CIF) em estudos observacionais. Metodologia: Trata-se de uma revisão sistemática de artigos que utilizaram a CIF em estudos observacionais. Foram incluídos artigos com desenho de estudo observacional disponíveis nas bases de dados do PubMed, Lilacs e SciELO, publicados em inglês e português no período de janeiro a junho de 2011. Foram excluídos aqueles em que a amostra não era composta por indivíduos, os que tratavam sobre crianças e adolescentes, e artigos com metodologia qualitativa. Apos a leitura de 265 resumos identiicados, 65 preencheram os critérios de inclusão. Desses, 18 foram excluídos. Nos 47 artigos incluídos foi aplicado o checklist adaptado do Strengthening the Reporting of ObservationalStudies in Epidemiology (STROBE) que contém 15 itens necessários para estudos observacionais. Artigos que preencheram 12 desses critérios foram incluídos na revisão sistemática. Resultados: Foram incluídos 29 artigos. Em relação à metodologia de aplicação da CIF, o checklist foi utilizado em 31%, o core set em 31%, as categorias da CIF em 31% e em 7% não foi possível deinir a metodologia. Para o uso dos qualiicadores, a aplicação na forma original foi a mais frequente (41%). Analisando os estudos por área de conhecimento, a maioria deles era referente às áreas de Reumatologia (24%) e Ortopedia (21%). Analisando o desenho de estudo, observou-se que 83% dos artigos eram estudos seccionais. Conclusão: Os resultados indicam um aumento da produção cientiica relacionada à CIF nos últimos 10 anos. Diferentes áreas de conhecimento estão envolvidas no debate sobre a melhoria das informações relacionadas à morbidade. No entanto, apenas um pequeno número de estudos epidemiológicos quantitativos utilizou a CIF. Futuros estudos são necessários para a melhoria dos dados relacionados à funcionalidade e incapacidade.
Freqüentemente, a descrição de pesquisas de natureza observacional é inadequada, diﬁ cultando a avaliação de seus pontos fracos e fortes e, em conseqüência, a generalização de seus resultados. A iniciativa denominada Strengthening the Reporting of ObservationalStudies in Epidemiology (STROBE), formulou uma lista de veriﬁ cação que contém 22 itens, denominada STROBE Statement (“Declaração STROBE”), com recomendações sobre o que deveria ser incluído em uma descrição mais precisa e completa de estudos observacionais. Entre junho e dezembro de 2008, um grupo de pesquisadores brasileiros dedicou-se à tradução e adaptação da “Declaração STROBE” para o português. O objetivo do estudo foi apresentar a tradução para o português, bem como introduzir a discussão sobre o contexto de utilização, as potencialidades e limitações da Iniciativa STROBE.
Our definition of pneumonia was intended to balance sensitivity and specificity and excluded terms that may include exacerbations (e.g., lower respiratory tract infections), which have been shown to be reduced by ICS in COPD . Interestingly, though our definition contained numerous codes (see Methods, Table S1 and S2), most were not used. Additionally, evidence suggests that ICS use may be associated with increased risk of other respiratory infections, such as non-tuberculosis mycobacterium  and tuberculosis, but not significantly associated with influenza . Therefore, the terms used to define pneumonia and validation of recorded pneumonia diagnoses are important considerations in observationalstudies. Our hospitalized pneumonia codes included those that performed well in identifying acute hospitalized pneumonia episodes according to validation , and the differences in applied definitions may relate to some variation in effect measures observed across studies.
The results of our study show a strong evidence on the subject. Furthermore, it should be pointed out that this is the first study review of the literature and meta-analysis about this topic involving corneal hysteresis in glaucoma. However, we recognize that our study has some limitations. We highlighted the fact that we include several glaucoma diagnosis [POAG, normal tension glaucoma (NTG), pre-perimetric POAG, pseudoexfoliative glaucoma (PEXG) and exfoliative glaucoma (EXG)], which can also bias the results, once the different physiopathology of each type of glaucoma may have a different impact on the cornea. Additionally, our study only considered articles from 2008 through 2016, based on a strict criteria. Furthermore, the ORA device was only introduced in 2005. So, these two factors resulted in a relatively short period under review in our study. Finally, we also recognise some other limitations, namely, the fact that it is not a systematic review, that it has not a risk of bias evaluation and that we have only included observationalstudies with the purpose to eliminate the risk of bias from interventions in the groups.
Study eligibility criteria: clinical trials and observationalstudies were considered eligible if they assessed pharmacological treatment using the main drugs used in the treatment of ATL (meglumine antimoniate, amphotericin, pentamidine isethionate and miltefosine) in one of the following patient populations: pregnant women, nursing mothers, children (individuals under 16 years of age), the elderly (individuals over 60 years or age) and individuals with renal disease, heart disease, liver disease or suppressed immune systems (e.g., individuals with human immunodeﬁ ciency virus (HIV) infection or individuals receiving therapy with immunosuppressive drugs or bone marrow or solid organ transplantation). For renal, heart and liver disease, we considered the same deﬁ nition that the included papers employed.
Identifying cognitively healthy people at high risk of developing dementia is an ever-increas- ing focus. These individuals are essential for inclusion in observationalstudies into the natu- ral history of the prodromal and early disease stages and for interventional studies aimed at prevention or disease modification. The success of this research is dependent on having access to a well characterised, representative and sufficiently large population of individu- als. Access to such a population remains challenging as clinical research has, historically, focussed on patients with dementia referred to secondary and tertiary services. The primary care system in the United Kingdom allows access to a true prodromal population prior to symptoms emerging and specialist referral. We report the development and recruitment rates of the CHARIOT register, a primary care-based recruitment register for research into the prevention of dementia. The CHARIOT register was designed specifically to support recruitment into observational natural history studies of pre-symptomatic or prodromal dementia stages, and primary or secondary prevention pharmaceutical trials or other pre- vention strategies for dementia and other cognitive problems associated with ageing.
In this meta-analysis of 37 observationalstudies comparing antiplatelets with anticoagulants in 1991 patients with cervical artery dissection, we found evidence to suggest a clinically relevant advantage of antiplatelets over anticoagulants on the primary outcome (composite of ischaemic stroke, intracranial haemorrhage or death), and 4 out of 7 secondary outcomes. When we stratified according to components of study quality, we found the benefit of antiplatelets considerably less pronounced in studies of higher methodological quality. Tests for interaction between estimated relative risks and study characteristics formally reached statistical significance for prospective study design and balanced group size, and showed a statistical trend for consecutive recruitment of patients and analysis in accordance with the intention-to-treat principle. In an analysis restricted to studies, which satisfied all pre-specified methodological criteria, credibility intervals were wide for all outcomes, except for intracranial haemorrhage, and were compatible with both, a substantial advantage or disadvan- tage of antiplatelets over anticoagulants. Furthermore, we stratified analyses according to the site of dissection, i.e. carotid or vertebral artery. This analysis showed similar results in the two groups, even though tests for interaction between the site of dissection and the estimated treatment effect were positive for ischaemic stroke and the composite of ischaemic stroke or intracranial haemorrhage. None of the numerous analyses provided robust evidence that anticoagulants are more beneficial than antiplatelets in patients with cervical artery dissection. The risk of intracranial hemorrhage was lower in the antiplatelet group and may be considered to contradict contemporary trials, which found aspirin in patients with atrial fibrillation not safer than warfarin [62,63]. This apparent contradiction may be explained by the characteristics of included patients (age, comorbidity and severity of stroke) and timing of treatment initiation (immediate versus delayed): patients with cervical artery dissection are typically younger and have less comorbid conditions than patients with atrial fibrillation at risk of stroke considered for antiplatelet treatment, but typically experience severe strokes with large brain tissue infarction. If treatment is initiated immediately, these patients may be more likely to suffer intracranial haemorrhage with anticoagulation as compared to antiplatelet treatment . This notion is in accordance with current guidelines, which recommend against full-dose anticoagulation in patients with acute ischaemic stroke [64,65].
As a meta-analysis of observationalstudies, this current meta- analysis was conducted according to the PRISMA guidelines and MOOSE guidelines [6,7]. A systematic search of Pubmed and Embase databases was conducted for relevant literature published up to Oct. 2013 with the key words ‘‘esophag*’’, ‘‘adenocarcino- ma’’, ‘‘carcinoma’’, ‘‘cancer’’ in combine with ‘‘Barrett’s esoph- agus’’ and ‘‘alcohol’’, ‘‘drink’’ or ‘‘wine’’ or ‘‘beer’’. No language or any other restrictions were set in the search strategy. In addition, we also manually searched the reference lists to detect additional eligible studies. When different articles from the same dataset were obtained, only the most recent study with available data was included in the meta-analysis. The contact with the corresponding author of certain article was conducted when more data was required.
This kind of indirect comparison, when clinicians must choose between interventions that have not been tested in head-to-head comparisons, requires considering quality and the methods of the studies of the candidate interventions . To rate overall quality of evidence, review authors and guideline developers must consider and summarize study limitations considering all the evidence from multiple studies focusing on benefit and harm . GRADE’s approach to rating quality of evidence consider observationalstudies as low initial quality of the evidence, but increase strength of recommendation when there is large effect . The strength of a recommendation reflects the extent to which we can be confident that the composite desirable effects of a management strategy outweigh the composite undesirable effects . Values and preferences includes patients' perspectives, beliefs, expectations, and goals for health and life. Also, they refer to the processes that individuals use in considering the potential benefits, harms, costs, limitations, and inconvenience of the management options in relation to one another . Mortality related to surgery in patients with PVT is high, counterbalancing embolic rate of thrombolytic therapy. In the case of small embolic events following thrombolytic therapy, they are much more likely to be appreciated as transient ischemic attacks in these conscious patients than similar small events in surgical patients who are sedated, ventilated and in whom some post-operative confusion might be expected to mask such events. In the case of success, valve functioning was better verificated in thrombolytic therapy studies than in surgical treatment studies.
Despite an absence of level I data suggesting a survival benefit, interest in radical prostatectomy (RP) for patients with metastatic prostate cancer (PC) is rising (1). Tradi- tionally, RP has been reserved for clinically localized PC, and good outcomes have been demonstrated in this population (2). While both retrospective and observationalstudies have reported improved survival outcomes for patients with metastatic (M1) disease who undergo primary tumor treatment relative to androgen deprivation therapy alone (1, 3), prospective data – particularly for surgery – is sparse. It would be unwise, then, to pre- maturely extrapolate these results to patients with metastatic disease until the merits of such an approach are carefully considered.