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Results for “Meta- analysis”

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PubMed1991

[A meta-analysis of controlled studies of the treatment of chronic hepatitis due to the hepatitis B virus].

BACKGROUND: Since the results obtained in controlled studies of antiviral treatment of chronic hepatitis by the hepatitis B virus are frequently insignificant the authors have undertaken a combined study of the different controlled trials with the meta-analysis technique. METHODS: The results of 7 controlled trials of treatment with adenosin arabinoside (AAR) and 18 published studies on therapy of a control group with interferon were studied. Meta-analysis was performed by two methods: Mantel expressing the results in odds ratio (OR) and Cochram-Dersimonian-Laird which consider the results in differences of risk (RD). RESULTS: The meta-analysis of AAR treatment shows a mean difference of response of 11% with no homogeneity among the different studies published. This lack of homogeneity may be due to the different selection criteria of the patients which determine very variable degrees of response. The controlled studies with interferon showed a mean difference of response of 20% with homogeneity of effects. No differences were observed in the degrees of response according to whether recombinant lymphoblastoid interferon was used or if the dose was of 5 or 10 megaunits per day. Non were differences observed in degrees of response with respect to the time in which the loss of viral DNA was evaluated. CONCLUSIONS: Following analysis of the results it was concluded that interferon is clearly effective in the treatment of chronic hepatitis B and based on published studies adenosin arabinoside demonstrate less efficacy.

Clinical Trials as Topic↗

PubMed1989

Meta-analysis of relation between cigarette smoking and stroke.

There is a lack of consensus among studies on the possible risks of stroke from cigarette smoking; because of this a meta-analysis was conducted. All published data on the association were sought and the relative risk for each study obtained whenever possible. The pooled relative risks were calculated by using estimates of the precision of the individual relative risks to weight their contribution to the meta-analysis. Thirty two separate studies were analysed. The overall relative risk of stroke associated with cigarette smoking was 1.5 (95% confidence interval 1.4 to 1.6). Considerable differences were seen in relative risks among the subtypes: cerebral infarction 1.9, cerebral haemorrhage 0.7, and subarachnoid haemorrhage 2.9. An effect of age on the relative risk was also noted; less than 55 years 2.9, 55-74 years 1.8, and greater than or equal to 75 years 1.1. A dose response between the number of cigarettes smoked and relative risk was noted, and there was a small increased risk in women compared with men. Ex-smokers under the age of 75 seemed to retain an appreciably increased risk of stroke (1.5); for all ages the relative risk in ex-smokers was 1.2. The meta-analysis provides strong evidence of an excess risk of stroke among cigarette smokers. Stroke should therefore be added to the list of diseases related to smoking.

Age Factors↗

PubMed2004

Meta-analysis in occupational epidemiology: a review of practice.

OBJECTIVES: To describe past practice in meta-analyses found in occupational epidemiology, identifying the major issues that should be considered by researchers planning a meta-analysis in this setting. METHODS: An electronic search of relevant online databases was undertaken. Papers were included in the review if they contained a statistical synthesis of risks in an occupational health setting. RESULTS: Sixty reports of meta-analyses were identified, mostly in cancer. The number of meta-analyses has increased consistently over the last 20 years. A majority of studies focused on a mean overall effect, although more than half of them also investigated heterogeneity of results. Both fixed effect and random effects meta-analysis models were employed, the former more often, and in eight studies used despite a statistically significant test for heterogeneity. A large proportion of the meta-analyses included different effect measures in the statistical synthesis, for example, including standardized mortality ratios (SMRs) and standardized incidence ratios. Most meta-analyses limited to a single type of effect measure focused on SMRs. The vast majority of meta-analyses combined all studies regardless of variation in the extent of information on exposures. CONCLUSIONS: Meta-analyses in occupational epidemiology should properly explore and incorporate heterogeneity among studies. The meta-SMR is an important construct in this field, evidenced by a large proportion of cohort studies in the meta-analyses we identified. Controversy remains over the definition and validity of the meta-SMR. In addition, several other issues, notably dealing with heterogeneity in exposure, warrant further consideration.

Bias↗

PubMed2006

Bilateral movement training and stroke rehabilitation: a systematic review and meta-analysis.

OBJECTIVE AND DESIGN: Bilateral movement training is being increasingly used as a post-stroke motor rehabilitation protocol. The contemporary emphasis on evidence-based medicine warrants a prospective meta-analysis to determine the overall effectiveness of rehabilitating with bilateral movements. METHODS: After searching reference lists of bilateral motor recovery articles as well as PubMed and Cochrane databases, 11 stroke rehabilitation studies qualified for this systematic review. An essential requirement for inclusion was that the bilateral training protocols involved either functional tasks or repetitive arm movements. Each study had one of three common arm and hand functional outcome measures: Fugl-Meyer, Box and Block, and kinematic performance. RESULTS: The fixed effects model primary meta-analysis revealed an overall effect size (ES=0.732, S.D.=0.13). These findings indicate that bilateral movement training was beneficial for improving motor recovery post-stroke. Moreover, a fail-safe analysis indicated that 48 null effects would be necessary to lower the mean effect size to an insignificant level. CONCLUSION: These meta-analysis findings indicate that bilateral movements alone or in combination with auxiliary sensory feedback are effective stroke rehabilitation protocols during the sub-acute and chronic phases of recovery.

Arm↗

PubMed2006

Meta-analysis of vesicoureteral reflux and urinary tract infection in children.

OBJECTIVE: We evaluated the efficacy of medical and surgical treatment of vesicoureteral reflux (VUR) in children by means of a meta-analysis, using the recurrence of urinary tract infections (UTIs), renal growth and renal scarring as endpoints. MATERIAL AND METHODS: We performed a MEDLINE search for articles published in the English language between 1966 and 2002. Of 639 relevant articles found, 139 were chosen for a close review and the main database was supplemented with some additional articles derived from the references of these reviewed articles. Five studies were found acceptable for a meta-analysis. We reviewed all articles independently. All reviewers had to approve the accepted articles and data that were used in this meta-analysis. RESULTS: Operative treatment of VUR was better than medical treatment in terms of abolishing reflux (OR = 0.033; 95% CI 0.010-0.107). We found no statistically significant differences between surgically and medically treated patients in terms of kidney growth (OR = 2.46; 95% CI 0.74-8.16), scarring (OR = 1.05; 95% CI 0.71-1.55) or recurrence of UTIs (OR = 0.80; 95% CI 0.49-1.29). We could not evaluate possible differences in the parameters monitored between boys and girls because of a lack of data. CONCLUSIONS: Although surgical treatment of VUR is a common pediatric urologic procedure, the data relating to it are scanty. We found no clinically significant differences between surgical and medical treatment for VUR other than in the resolution of VUR itself. On the basis of present evidence we suggest that a child with UTI and significant VUR should be treated conservatively at first and that surgical treatment should be reserved for children who experience problems with antimicrobials or persistent clinically significant VUR after several years of follow-up.

Child↗

PubMed1992

Antidepressant-induced analgesia in chronic non-malignant pain: a meta-analysis of 39 placebo-controlled studies.

For 39 controlled studies on the analgesic effect of antidepressants, a meta-analysis was conducted to get an estimation of the effect size, and to obtain a sight on the possible modes of action and the methodology used. The mean size of the analgesic effect was 0.64. It means that the average chronic pain patient who received an antidepressant treatment had less pain than 74% of the chronic pain patients who received a placebo. This quantification, however, is only as good as the studies on which it is based, and it could be differentiated for each of the pain syndromes and antidepressants examined. Real analgesic qualities of antidepressive agents seemed to offer the most plausible and economical explanation for the effect, but the predominant importance of serotonin reuptake blocking was not confirmed. Finally, the meta-analysis appeared to be fruitful for the generation of new hypotheses, for making some recommendations for future research, and for proposing some provisional guidelines for the clinical use of antidepressants in chronic non-malignant pain.

Analgesia↗

PubMed2004

Ginkgo biloba does not benefit patients with tinnitus: a randomized placebo-controlled double-blind trial and meta-analysis of randomized trials.

The objective was to ascertain if Ginkgo biloba benefits patients with tinnitus. The study design was: 1. Randomized double blind trial of Ginkgo biloba versus placebo; 2. A meta-analysis of randomized placebo controlled double blind trials. Participants included 66 adult patients with tinnitus and six (including our study) randomized placebo controlled double blind trials were meta-analysed. The main outcome measures were the Tinnitus Handicap Inventory (THI), Glasgow Health Status Inventory (GHSI) and average of hearing threshold at 0.5, 1, 2, 4 kHz. In the meta-analysis the proportion of patients gaining benefit and an overall odds ratio were determined. The results showed the mean difference in change of the THI, GHSI and hearing between Ginkgo biloba (n = 31) and placebo group (n = 29) was 2.51 (CI -10.1, 5.1, P = 0.51), 0.58 (CI-4.8, 3.6, P = 0.38) and 0.68 db (CI -4.13, 2.8, P = 0.69). Meta-analysis revealed 21.6% of Ginkgo biloba treated patients (n = 107/552) gained benefit versus 18.4% (n = 87/504) of placebo treated patients with an odds ratio of 1.24 (CI 0.89, 1.71). In conclusion, Ginkgo biloba does not benefit patients with tinnitus.

Adult↗

PubMed2026

The Impact of Hemoglobin Concentration on Prognosis in Patients With Diabetic Foot: A Systematic Review and Meta-Analysis of Risk Factors for Adverse Outcomes and Clinical Management.

BackgroundDiabetic foot (DF) complications, including diabetic foot ulcers (DFUs), lead to significant morbidity, disability, and economic burden. Hemoglobin (Hb) levels may influence the prognosis of DF patients, but their relationship with adverse clinical outcomes remains unclear. This systematic review and meta-analysis aimed to assess the association between hemoglobin concentration and the risk of adverse outcomes in diabetic foot patients, including amputation and mortality.MethodsWe followed PRISMA guidelines to conduct a systematic literature review. A meta-analysis was performed on observational studies assessing the impact of hemoglobin levels on amputation, mortality, and ulcer incidence. A random-effects model was applied, and risk bias was evaluated using the Newcastle-Ottawa Scale.ResultsA total of 22 observational studies involving 10,984 patients were included. Our meta-analysis revealed that lower hemoglobin levels were significantly associated with a higher risk of amputation (OR = 0.97, 95% CI: 0.94-0.99, P < .001), and lower hemoglobin concentrations were found in amputation cases compared to non-amputation cases (SMD = -0.14, 95% CI: -0.24 to -0.04, P < .01). However, no significant association was found between hemoglobin levels and mortality (OR = 0.99, 95% CI: 0.33-2.89, P > .05). Sensitivity and publication bias analyses indicated robust results.ConclusionLower hemoglobin levels were associated with higher odds of amputation in patients with diabetic foot. However, pooled effects were small and heterogeneity was substantial across studies; therefore, hemoglobin likely functions primarily as a marker of overall disease burden and perioperative risk rather than a proven modifiable target. Prospective interventional studies are needed to determine whether correcting anemia improves limb outcomes and survival.

Humans↗

PubMed2005

Use of benchmark dose and meta-analysis to determine the most sensitive endpoint for risk assessment for dimethoate.

A meta-analysis of several rat toxicity studies for dimethoate was conducted to determine the most sensitive endpoint for use in risk assessment. The analysis was motivated by a recent developmental neurotoxicity (DNT) study, which identified the same no observed adverse effect level (NOAEL) for pup mortality and cholinesterase inhibition. The pup mortality NOAEL was lower than that determined in a range-finding study for the DNT and other reproduction studies, and was highly influenced by a single total litter loss in the middle dose group, which made interpretation difficult. First, a meta-analysis was conducted of four recent studies by gavage dosing with very similar designs, including the DNT. Benchmark dose (BMD) modeling was used to determine the appropriate point of departure for regulatory purposes, the lower limit of the BMD for a 5% incidence for pup mortality (BMDL(5)) and the lower limit of a 10% inhibition of brain cholinesterase (BMDL(10)*), the asterisk denotes that the BMD is based on continuous response variable as opposed to an incidence level. For pup mortality, the BMDL(5) for post-natal days (PND) 1-4 was 0.64 mg/kg/day. For cholinesterase inhibition, the lowest BMDL(10)* was 0.19 mg/kg/day for the dams at gestation day 20. These results show that the regulatory point-of-departure for cholinesterase inhibition is more than threefold lower than pup mortality. Thus, risk assessments protecting against cholinesterase inhibition are likely to also be protective of pup mortality. In addition, cholinesterase inhibition and pup mortality were evaluated in two 2-generation reproduction studies by dietary exposure. Also, cholinesterase inhibition was evaluated in a 28-day dietary study. Dietary exposure is more relevant than gavage exposures for many human risk assessment scenarios. There was no consistent pup mortality at the highest doses of the two 2-generation dietary studies (6.0 and 6.5mg/kg/day). The average BMD(10)s for brain cholinesterase inhibition for the 2-generation studies was 0.65 mg/kg/day, with a range of 0.49--0.96 mg/kg/day. This suggests that cholinesterase inhibition is at least a 10-fold more sensitive endpoint than pup mortality for dietary exposures. For the 28-day dietary study, the BMD(10) for brain cholinesterase inhibition was 1.1mg/kg/day for males and 0.70 mg/kg/day for females. The exposure duration in the 28-day dietary study is closest to the durations in the gavage studies. Compared to the dams in the gavage studies, which had a BMDL(10) of 0.19 mg/kg/day, the animals were more than threefold more sensitive to cholinesterase inhibition by gavage compared to dietary exposure.

Age Factors↗

PubMed2002

Five-factor model of personality and job satisfaction: a meta-analysis.

This study reports results of a meta-analysis linking traits from the 5-factor model of personality to overall job satisfaction. Using the model as an organizing framework, 334 correlations from 163 independent samples were classified according to the model. The estimated true score correlations with job satisfaction were -.29 for Neuroticism, .25 for Extraversion, .02 for Openness to Experience, .17 for Agreeableness, and .26 for Conscientiousness. Results further indicated that only the relations of Neuroticism and Extraversion with job satisfaction generalized across studies. As a set, the Big Five traits had a multiple correlation of .41 with job satisfaction, indicating support for the validity of the dispositional source of job satisfaction when traits are organized according to the 5-factor model.

Factor Analysis, Statistical↗

PubMed2000

A meta-analysis of the interrelationships between the modes in Roy's adaptation model.

A meta-analysis of nine empirical studies based on Roy's adaptation model was conducted to determine the magnitudes of the interrelationships of the four modes: physiological, self-concept, role function, and interdependence. Small to medium effect sizes between each two modes do support the proposition of Roy's model that the four modes are interrelated. The only exception is the relationship between interdependence and physiological modes, as shown by the non-significant effect size of .04. The present study also discusses several limitations that should be considered when interpreting the findings of this meta-analysis. This study does provide a useful compilation of the Roy model's credible studies and proposes a direction for further research. The results indicate a need for further study to explore the relationship in all response modes to have a clearer understanding of the credibility of Roy's model.

Adaptation, Psychological↗

PubMed2005

Bayesian implementation of a genetic model-free approach to the meta-analysis of genetic association studies.

A genetic model-free method for the meta-analysis of genetic association studies is described that estimates the mode of inheritance from the data rather than assuming that it is known. For a bi-allelic polymorphism, with G as risk allele and g as wild-type, the genetic model depends on the ratio of the two log odds ratios, lambda = log OR(Gg)/log OR(GG), where OR(GG) compares GG with gg and OR(Gg) compares Gg with gg. Modelling log OR(GG) as a random effect creates a hierarchical model that can be implemented within a Bayesian framework. In Bayesian modelling, vague prior distributions have to be specified for all unknown parameters when no external information is available. When the data are sparse even supposedly vague prior distributions may have an influence on the posterior estimates. We investigate the impact of different vague prior distributions for the between-study standard deviation of log OR(GG) and for lambda, by considering three published meta-analyses and associated simulations. Our results show that depending on the characteristics of the meta-analysis the results may indeed be sensitive to the choice of vague prior distribution for either parameter. Genetic association studies usually use a case-control design that should be analysed by the corresponding retrospective likelihood. However, under some circumstances the prospective likelihood has been shown to produce identical results and it is usually preferred for its simplicity. In our meta-analyses the two likelihoods give very similar results.

Bayes Theorem↗

PubMed2000

[Effect of alendronate on bone mineral density and incidence of fractures in postmenopausal women with osteoporosis. A meta-analysis of published studies].

BACKGROUND: To perform a systematic review, completed with a meta-analysis, of the published evidences about the effect of oral alendronate on bone mineral density and the incidence of fractures in postmenopausal women with low bone mass. METHODS: We search for all alendronate clinical trials in postmenopausal women with low bone mass which were randomized, double blind, placebo controlled, with a duration of one year or more and with bone mineral density measurement and/or fractures as outcomes. We used the weighted average of individual study results as an estimation of the global effect. RESULTS: Seven studies meet all the inclusion criteria. Relative Risks (RR) with 95% Confidence Intervals (CI 95%) for the combined effect under fixed effects model were: RR 0.54 (CI 95%: 0.45 to 0.66) for vertebral fractures, RR 0.81 (CI 95%: 0.72 to 0.92) for non vertebral fractures and RR 0.64 (CI 95%: 0.40 to 1.01) for hip fractures. CONCLUSIONS: Our results demonstrate that alendronate reduces the risk of vertebral, non vertebral and hip fractures in postmenopausal women with low bone mass. This meta-analysis allows the classification of alendronate anti-fracture evidences in the highest level.

Alendronate↗

PubMed2005

Lack of association of the COMT (Val158/108 Met) gene and schizophrenia: a meta-analysis of case-control studies.

There is strong evidence for a genetic contribution to schizophrenia, but the contribution of individual candidate genes remains uncertain. We attempted to replicate a recent meta-analysis that reported an association of the catechol O-methyltransferase (COMT) Val allele with schizophrenia, and suggested that this effect may be moderated by ancestry. We included reports published subsequent to the original meta-analysis, and included a formal test of the moderating effect of ancestry in order to test whether the association operates differently in populations of European ancestry compared to populations of Asian ancestry. A corrected P-value for the 5% significance threshold was employed where appropriate, using Bonferroni's method, and studies that demonstrated departure from Hardy-Weinberg equilibrium among controls were excluded. When all studies were included in a meta-regression, there was evidence for a significant association of COMT Val allele frequency with schizophrenia case status and a significant main effect of ancestry. The interaction of COMT Val allele frequency and ancestry was also significant. However, when only studies that reported allele frequencies that did not depart significantly from Hardy-Weinberg equilibrium among controls were included, these effects were no longer significant. The results of our meta-analysis do not support an association between the COMT Val allele and schizophrenia case status, and do not support recent claims that this association may be moderated by ancestry.

Amino Acid Substitution↗

PubMed2006

Risk of cardiovascular events and celecoxib: a systematic review and meta-analysis.

OBJECTIVES: To examine whether the increased risk of cardiovascular events with rofecoxib represents a class effect of cyclooxygenase-2 (COX-2) specific inhibitors. DESIGN: Systematic review and meta-analysis of randomized double-blind clinical trials of celecoxib of at least 6 weeks' duration and presented data on serious cardiovascular thromboembolic events. Data sources included six bibliographic databases, the relevant files of the United States Food and Drug Administration, and pharmaceutical company websites. MAIN OUTCOME MEASURES: Pooled fixed effects estimates of the odds ratios for risk of cardiovascular events with celecoxib compared with comparator treatment were calculated using the inverse variance weight method. The main outcome measure was myocardial infarction. RESULTS: Four placebo-controlled trials with 4422 patients were included in the primary meta-analysis comparing celecoxib with placebo. The odds ratio of myocardial infarction with celecoxib compared to placebo was 2.26 (95%confidence interval 1.0 to 5.1). For composite cardiovascular events [odd ratio 1.38 (95% CI 0.91 to 2.10)], cardiovascular deaths [OR 1.06 (95% CI 0.38 to 2.95)] and stroke [OR 1.0(95% CI 0.51 to 1.84)] there was no significant increase in risk with celecoxib. The secondary meta-analysis which included a total of six studies (with placebo, diclofenac, ibuprofen, and paracetamol as comparators) of 12 780 patients, showed similar findings with a significant increased risk with celecoxib for myocardial infarction [OR 1.88 (95% CI 1.15 to 3.08)] but not other outcome measures. CONCLUSION: The available data indicate an increased risk of myocardial infarction with celecoxib therapy, consistent with a class effect for COX-2 specific inhibitors.

Cardiovascular Diseases↗

PubMed2004

Meta-analysis for trend estimation.

Grouped dose measures, heterogeneity and publication bias are three major problems for meta-analysis in trend estimation. In this paper, we propose a model that allows for arbitrarily aggregated dose levels, and show that the resulting estimates and standard errors can be quite different from those given by the usual assigned value method. Based on fitting a model to the funnel plot, we discuss a method for random-effects sensitivity analysis that deals with the problems of heterogeneity and publication bias. A meta-analysis of epidemiological studies on the effect of alcohol on the risk of breast cancer is used to illustrate the method. Our analysis suggests that the rate of increase in risk with alcohol consumption is substantially less than has been previously suggested.

Alcohol Drinking↗

PubMed2006

A review and meta-analysis of prospective trials comparing different catheters used for embryo transfer.

OBJECTIVE: To determine the relative efficacy of different types of embryo transfer (ET) catheters. DESIGN: Systematic review and meta-analysis of prospective randomized, controlled trials comparing at least two different ET catheters. SETTING: Infertility centers providing treatment with in vitro fertilization/embryo transfer (IVF-ET). PATIENT(S): Women undergoing ET. INTERVENTION(S): Embryo transfer with soft or hard catheters. MAIN OUTCOME MEASURE(S): Clinical pregnancy rate. RESULT(S): A total of seven prospective trials were identified that compared soft (Cook or Wallace) catheters with hard (TDT, Frydman, Tomcat, Rocket) catheters. The meta-analysis demonstrated an increased chance of clinical pregnancy when soft ET catheters were used. The TDT catheter was compared against both soft catheters and other hard catheters, showing decreased chance of clinical pregnancy when the TDT catheter was used. Six more prospective trials were identified comparing the Cook and Wallace soft catheters, and the meta-analysis of these data showed no demonstrable difference in clinical pregnancy rates. CONCLUSION(S): An increased chance of clinical pregnancy is achieved when soft ET catheters are used. There appears to be little difference between the Cook and Wallace soft catheters.

Catheterization↗

PubMed2005

Meta-analysis comparing drug-eluting stents with bare metal stents.

We performed a meta-analysis of 10 randomized trials of 5,066 patients with 6 to 12 months of follow-up. The summary risk differences excluded any major differences between the 2 types of stents for death (0.12%, 95% confidence interval [CI] -0.34% to 0.58%, p = 0.60) and overall myocardial infarction (0.04%, 95% CI -0.72% to 0.81%, p = 0.91). There was a modest increase in the risk of Q-wave myocardial infarction with drug-eluting stents (0.36%, 95% CI -0.04% to 0.77%, p = 0.080) but no difference in non-Q-wave myocardial infarction (-0.26%, 95% CI -0.95% to 0.43%, p = 0.47). The trend for increased risk of Q-wave myocardial infarction was seen for paclitaxel and sirolimus stents (risk differences 0.28% and 0.58%, respectively). Drug-eluting stents also had a nonsignificant trend for higher risk of thrombosis (0.29%, 95% CI -0.08% to 0.66%, p = 0.13). We conclude that sirolimus- and paclitaxel-eluting stents are equivalent to bare-metal stents in terms of mortality and overall myocardial infarction risk for the first year of follow-up; the meta-analysis excludes with considerable confidence the presence of large, clinically relevant differences for these outcomes.

Chi-Square Distribution↗