PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Meta- analysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed2003

Perioperative outcomes of laparoscopic versus open splenectomy: a meta-analysis with an emphasis on complications.

BACKGROUND: The purpose of this study was to analyze the published perioperative results of laparoscopic splenectomy (LS) compared to open splenectomy (OS), and to determine the impact of LS on the incidence and type of splenectomy-related complications. METHODS: Perioperative results and complications were tabulated from all English-language reports of LS from 1991 through 2002, and complications were analyzed further by type. Data were taken from 26 series that compared OS to LS within an institution (paired analysis) and from an additional 25 series of only LS (unpaired analysis), and a meta-analysis was performed. RESULTS: A total of 2940 patients from 51 published series were included (LS, 2119 patients; OS, 821 patients). Age, gender, and American Society of Anesthesiologists class were similar. In the analysis of paired OS and LS studies, the mean operative time for LS was significantly longer (LS, 180 minutes; OS, 114 minutes; P<.0001,) but the postoperative hospital stay was shorter (LS, 3.6 days; OS, 7.2 days; P<.001). Accessory spleens were identified in 11% of cases in both groups. The total complication rate for LS was 15.5%, compared with 26.6% for OS (P<.0001). LS was associated with significantly fewer pulmonary, wound, and infectious complications (P<.001 for all) but with more hemorrhagic complications, when conversions for bleeding were included. Mortality rates for LS and OS were similar (OS, 1.1%; LS, 0.6%; P=not significant). Comparable results were obtained when the unpaired LS series were added to the analysis. CONCLUSIONS: Although operative times are longer for LS than OS, LS is associated with a significant reduction in splenectomy-related morbidity, primarily as a function of fewer pulmonary, wound, and infectious complications.

Adult↗
PubMed2001

Clinical outcomes in reduction mammaplasty: a systematic review and meta-analysis of published studies.

This systematic review and meta-analysis were undertaken to determine whether reduction mammaplasty improves measurable outcomes in women with breast hypertrophy. A systematic review of the literature in 5 languages from 1985 until March 1999 was performed, and data were compared for meta-analysis. Eligible studies were both experimental and observational and involved women with preoperative physical and/or psychosocial signs and symptoms who underwent reduction mammaplasty for breast hypertrophy. Outcomes assessed were postoperative physical signs and symptoms such as shoulder pain, shoulder (bra strap) grooving, and quality-of-life domains, such as physical and psychological functioning, and were expressed primarily as risk differences (RDs). Twenty-nine studies of 4173 patients met all eligibility criteria. Reduction mammaplasty was associated with a statistically significant improvement in physical signs and symptoms involving shoulder pain (RD, 0.71 [95% confidence interval (CI), 0.62-0.80]); shoulder grooving (RD, 0.69 [95% CI, 0.60-0.78]); upper/lower back pain (RD, 0.59 [95% CI, 0.48-0.70]); neck pain (RD, 0.50 [95% CI, 0.37-0.64]); intertrigo (RD, 0.44 [95% CI, 0.34-0.54]); breast pain (RD, 0.36 [95% CI, 0.17-0.55]); headache (RD, 0.28 [95% CI, 0.11-0.46]); and pain/numbness in the hands (RD, 0.11 [95% CI, 0.04-0.18]). The quality-of-life parameter of physical functioning was also statistically significant (RD, 0.58 [95% CI, 0.44-0.71]), while psychological functioning was not significant (RD, 0.46 [95% CI, 0.00-1.00]). The evidence suggests that women undergoing reduction mammaplasty for breast hypertrophy have significant postoperative improvement in preoperative signs and symptoms, quality of life, or both.

Adult↗
PubMed1996

A meta-analysis of clinical studies on the caries-inhibiting effect of chlorhexidine treatment.

A meta-analysis was performed on published data on the caries-inhibiting effect of chlorhexidine treatment. The results of the various studies are difficult to evaluate because of various treatment procedures, dissimilar features of participants, and different presentations of study results. A meta-analysis provides a more structured approach than the traditional review, due to systematic analysis and numerical processing of the available information. The objectives of this meta-analysis were: (1) to assess a more accurate estimate of the caries-inhibiting effect of chlorhexidine treatment than provided by individual studies, and (2) to explore factors potentially modifying the effect of chlorhexidine treatment in caries prevention, i.e., the application method, application frequency, target population, the fluoride regime, and caries criteria. Caries reduction was expressed by the prevented fraction, indicating the percentage reduction of caries incidence in the chlorhexidine group. For all prevented fractions, 95% confidence intervals were calculated. The overall caries-inhibiting effect of the chlorhexidine treatment studies was 46% (95% CI = 35% - 57%). Multiple-regression analysis showed no significant influence on the prevented fractions for the variables "application method", "application frequency", "caries risk", "fluoride regime", "caries diagnosis", and "tooth surface".

Adolescent↗
PubMed2000

A meta-analysis of methylprednisolone in recovery from multiple sclerosis exacerbations.

Despite recent advances in multiple sclerosis treatment, patients experience relapses for which standard treatment remains glucocorticosteroids (GCS). However, there is limited information comparing doses or routes of administration for different GCS types or the benefit of GCS compared to natural recovery. Currently, high dose (HD) methylprednisolone (MP) is the preferred therapy. We conducted meta-analyses of published studies assessing MP at different doses and in comparison to other steroid products or no treatment. Relevant studies were identified through predetermined processes and five articles met the inclusion criteria. Three studies compared HD MP to placebo; two studies compared the effect of HD MP and low dose (LD) MP; only one accepted report compared HD MP to another GCS. This report could not be included in a meta-analysis. The meta-analysis of HD MP vsplacebo studies indicated a mean treatment difference of 0.76 in Expanded Disability Status Score (EDSS) changes from baseline. The meta-analysis of HD and LD MP demonstrated no difference in EDSS change. Despite these rather obvious findings, these meta-analyses have been valuable in identifying further research questions. We recommend studies to determine optimum benefit related to dosage, timing for starting therapy and the most appropriate GCS type. Given the advances in MS therapeutics, these studies will have to include patients on additional disease modifying therapy. Multiple Sclerosis (2000) 6 267 - 273

Disability Evaluation↗
PubMed1995

A meta-analysis of selective versus routine nasogastric decompression after elective laparotomy.

OBJECTIVE: A meta-analysis of all published clinical trials comparing selective versus routine nasogastric decompression was performed in an attempt to evaluate the need for nasogastric decompression after elective laparotomy. BACKGROUND: Many studies have suggested that routine nasogastric decompression is unnecessary after elective laparotomy and may be associated with an increased incidence of complications. Despite these reports, many surgeons continue to practice routine nasogastric decompression, believing that its use significantly decreases the risk of postoperative nausea, vomiting, aspiration, wound dehiscence, and anastomotic leak. METHODS: A comprehensive search of the English language medical literature was performed to identify all published clinical trials evaluating nasogastric decompression. Twenty-six trials (3964 patients) met inclusion criteria. The outcome data extracted from each trial were subsequently "pooled" and analyzed for significant differences using the Mantel-Haenszel estimation of combined relative risk. RESULTS: Fever, atelectasis, and pneumonia were significantly less common and days to first oral intake were significantly fewer in patients managed without nasogastric tubes. Meta-analysis based on study quality revealed significantly fewer pulmonary complications, but significantly greater abdominal distension and vomiting in patients managed without nasogastric tubes. Routine nasogastric decompression did not decrease the incidence of any other complication. CONCLUSIONS: Although patients may develop abdominal distension or vomiting without a nasogastric tube, this is not associated with an increase in complications or length of stay. For every patient requiring insertion of a nasogastric tube in the postoperative period, at least 20 patients will not require nasogastric decompression. Routine nasogastric decompression is not supported by meta-analysis of the literature.

Elective Surgical Procedures↗
PubMed2003

Chromium picolinate for reducing body weight: meta-analysis of randomized trials.

The aim of this meta-analysis was to assess the evidence of chromium picolinate for reducing body weight. Literature searches were conducted on Medline, Embase, The Cochrane Library, Amed and Ciscom. Nine experts and four manufacturers of commercial preparations containing chromium picolinate were asked to contribute published and unpublished studies. There were no restrictions regarding the language of publication. The screening of studies, selection, data extraction, validation and the assessment of methodological quality were performed independently by two reviewers. To be included, studies were required to state that they were randomized, double-blind and placebo-controlled, and report on body weight. Ten trials met all inclusion criteria and provided data, which were suitable for statistical pooling. For body weight a significant differential effect was found in favour of chromium picolinate (weighted mean difference: -1.1 kg; 95% confidence interval (CI): -1.8 to -0.4 kg, n=489). Sensitivity analysis suggests that this effect is largely dependent on the results of a single trial (weighted mean difference: -0.9 kg; 95% CI: -2.0 to 0.2 kg, n=335). Three of the reviewed trials reported on adverse events, indicating their absence in the treatment groups. In conclusion, our meta-analysis suggests a relatively small effect of chromium picolinate compared with placebo for reducing body weight. The clinical relevance of the effect is debatable and the lack of robustness means that the result has to be interpreted with caution.

Dietary Supplements↗
PubMed2001

Meta-analysis of ordinal outcomes using individual patient data.

Meta-analyses are being undertaken in an increasing diversity of diseases and conditions, some of which involve outcomes measured on an ordered categorical scale. We consider methodology for undertaking a meta-analysis on individual patient data for an ordinal response. The approach is based on the proportional odds model, in which the treatment effect is represented by the log-odds ratio. A general framework is proposed for fixed and random effect models. Tests of the validity of the various assumptions made in the meta-analysis models, such as a global test of the assumption of proportional odds between treatments, are presented. The combination of studies with different definitions or numbers of response categories is discussed. The methods are illustrated on two data sets, in a classical framework using SAS and MLn and in a Bayesian framework using BUGS. The relative merits of the three software packages for such meta-analyses are discussed.

Alzheimer Disease↗
PubMed2004

Relevance of methodological design for the interpretation of efficacy of drug treatment of premature ejaculation: a systematic review and meta-analysis.

The aim of this systematic review and meta-analysis is to evaluate whether the design and methodology of drug-treatment studies of premature ejaculation affect the efficacy outcome differently. Therefore, methodological, design and efficacy data from 79 studies (3034 males), published between 1943 and 2003, are reviewed. A meta-analysis is performed on 43 selective serotonin reuptake inhibitors (SSRIs) and clomipramine studies (1514 males), published between 1973 and 2003; these studies were pooled to provide a summary variance-weighted effect size. The antidepressant-induced percentage increase of the intravaginal ejaculation latency time (IELT) was calculated and examined against various methodological items. A significant difference in efficacy between SSRIs was observed. Using daily treatment, paroxetine appeared more effective than the other SSRIs. Retrospective use of a questionnaire, subjective reports, single-blind and open study designs generate far greater variability of ejaculation time both at baseline and during active drug treatment than real time assessment by stopwatch. In conclusion, at daily treatment, the overall efficacy of paroxetine, clomipramine, sertraline and fluoxetine is comparable, but paroxetine exerts the strongest ejaculation delay. Only eight (18.5%) studies on antidepressant treatment fulfilled all criteria used in evidence-based medicine, for example, randomised, double-blind studies with prospective real time (stopwatch) assessment of the IELT at each intercourse. Single-blind studies, open designs, retrospective reporting, or the use of a questionnaire to assess ejaculation time should be avoided.

Adult↗
PubMedDate not supplied

Meta-analysis and the synthesis of evidence.

Use of meta-analytical (quantitative overview) techniques is now commonplace in a large range of medical-research contexts, with a rapid rise in its frequency of use being particularly apparent in the last decade. Many methods of meta-analysis have been proposed and used, from crude 'vote-counting' of studies showing significant or nonsignificant results, through methods for combination of effect-size estimates based on fixed- or random-effects models, to general, linear, mixed models and Bayesian methods. The history of meta-analysis and the advantages and disadvantages of various approaches to it are briefly reviewed in this paper, with reference to its application in health-services research and related fields. Broader approaches to the synthesis of evidence in these contexts using conventional multilevel modelling and hierarchical Bayesian models to address the combination of evidence from disparate types of study are then outlined.

Bayes Theorem↗
PubMed2005

A meta-analysis of time-series studies of ozone and mortality with comparison to the national morbidity, mortality, and air pollution study.

BACKGROUND: Although many time-series studies of ozone and mortality have identified positive associations, others have yielded null or inconclusive results, making the results of these studies difficult to interpret. METHODS: We performed a meta-analysis of 144 effect estimates from 39 time-series studies, and estimated pooled effects by lags, age groups, cause-specific mortality, and concentration metrics. We compared results with pooled estimates from the National Morbidity, Mortality, and Air Pollution Study (NMMAPS), a time-series study of 95 large U.S. urban centers from 1987 to 2000. RESULTS: Both meta-analysis and NMMAPS results provided strong evidence of a short-term association between ozone and mortality, with larger effects for cardiovascular and respiratory mortality, the elderly, and current-day ozone exposure. In both analyses, results were insensitive to adjustment for particulate matter and model specifications. In the meta-analysis, a 10-ppb increase in daily ozone at single-day or 2-day average of lags 0, 1, or 2 days was associated with an 0.87% increase in total mortality (95% posterior interval = 0.55% to 1.18%), whereas the lag 0 NMMAPS estimate is 0.25% (0.12% to 0.39%). Several findings indicate possible publication bias: meta-analysis results were consistently larger than those from NMMAPS; meta-analysis pooled estimates at lags 0 or 1 were larger when only a single lag was reported than when estimates for multiple lags were reported; and heterogeneity of city-specific estimates in the meta-analysis were larger than with NMMAPS. CONCLUSIONS: This study provides evidence of short-term associations between ozone and mortality as well as evidence of publication bias.

Age Factors↗
PubMed2003

Effects of psychosocial interventions on quality of life in adult cancer patients: meta analysis of 37 published controlled outcome studies.

The present meta analysis summarized the results of 37 published, controlled studies that investigated the effectiveness of psychosocial interventions on quality of life (QoL) in adult cancer patients. The overall effect size of psychosocial interventions and the effect of potential moderating variables such as type and duration of intervention, sociodemographic and clinical parameters, characteristics of QoL measurement, and methodological quality of the selected studies were calculated using a meta analysis model suggested by Hunter and Schmidt. The overall effect size was 0.31 (correlation equivalent delta) which corresponds to a standardized mean difference of d=0.65 (N=3120 cancer patients). The most important moderating variable was duration of psychosocial intervention with durations of more than 12 weeks being significantly more effective than interventions of shorter duration. The meta analytical findings support the usefulness of psychosocial interventions for improving QoL in adult cancer patients.

Adaptation, Psychological↗
PubMed1998

Single agent versus combination chemotherapy in patients with advanced nonsmall cell lung carcinoma: a meta-analysis of response, toxicity, and survival.

BACKGROUND: This meta-analysis was conducted to compare the effects of single agent versus combination chemotherapy on response rate, toxicity, and survival of patients with advanced nonsmall cell lung carcinoma (NSCLC). METHODS: The authors reviewed randomized clinical trials published in the medical literature and the reference lists of relevant articles. Objective response rate, survival at 6 and 12 months, and the incidence of treatment-related death were compared among all patients receiving single agent chemotherapy and those receiving combination chemotherapy. A subgroup analysis for all outcomes was conducted for 10 trials published between 1989 and 1996 that used a platinum analogue or vinorelbine as the single agent arm. RESULTS: The authors identified 38 potentially eligible trials, 25 of which (with a total of 5156 patients) were included in the meta-analysis. Overall, combination chemotherapy produced a nearly 2-fold increase in response rate compared with single agent chemotherapy (response rate [RR], 1.93; 95% confidence interval [CI], 1.54-2.42). However, combination chemotherapy also increased toxicity significantly, including a 3.6-fold increase in the risk of treatment-related death (RR, 3.5; 95% CI, 1.8-6.7). Survival at 6 months (RR, 1.10; 95% CI, 1.02-1.19) and 12 months (RR, 1.22; 95% CI, 1.03-1.45) was modestly superior with combination chemotherapy when all trials are included. However, when a platinum analogue or vinorelbine are used as single agents, this difference was no longer statistically significant at 6 months (RR, 1.03; 95% CI, 0.92-1.15) or at 12 months (RR, 1.10; 95% CI, 0.94-1.43). CONCLUSIONS: Combination chemotherapy increased objective response and toxicity rates compared with single-agent chemotherapy. Survival was prolonged only modestly with combination chemotherapy but not significantly so when more active single agents were used.

Antineoplastic Agents↗
PubMed1999

Meta-analysis of resting metabolic rate in formerly obese subjects.

BACKGROUND: A low resting metabolic rate (RMR) for a given body size and composition is partly genetically determined and has been suggested to be a risk factor for weight gain. Moreover, a low relative RMR has been reported in some, but not all, studies of formerly obese persons. The inconsistent reports may be due to a lack of statistical power to detect small differences in RMR and improper adjustment for body size and composition. OBJECTIVE: We conducted a meta-analysis based on published studies of RMR in formerly obese persons [body mass index (in kg/m2) < or = 27] and matched control subjects who had never been obese. DESIGN: We performed both an individual subject data meta-analysis and a traditional meta-analysis. RESULTS: The individual subject data meta-analysis included 124 formerly obese and 121 control subjects. RMR adjusted for differences in fat-free mass and fat mass was 2.9% lower in formerly obese subjects than in control subjects (P = 0.09). A low relative RMR (> 1 SD below the mean of the control group) was found in 3.3% of the control subjects and in 15.3% of the formerly obese subjects [difference: 12% (95% CI: 4.7%, 19.3%); P < 0.003]. The traditional meta-analysis was based on 12 studies (including 94 formerly obese and 99 control subjects) and included 3 studies not represented in the individual subject data analysis. In this analysis, relative RMR was lower in the formerly obese group than in the control group by 5.1% (95% CI: 1.7%, 8.6%). CONCLUSIONS: Formerly obese subjects had a 3-5% lower mean relative RMR than control subjects; the difference could be explained by a low RMR being more frequent among the formerly obese subjects than among the control subjects. Whether the cause of the low RMR is genetic or acquired, the existence of a low RMR is likely to contribute to the high rate of weight regain in formerly obese persons.

Basal Metabolism↗
PubMed1994

Issues in meta-analysis: an overview.

A summary is provided for the relevant issues that investigators must address when wishing to synthesize data via a meta-analysis. The analogy is made to conducting a clinical trial and its components. Both design and statistical issues are discussed with the goal of assuring that the proper elements are included in the meta-analysis. Further, global concerns are presented so that the researcher is aware of the clinical controversies faced when conducting a meta-analysis. Finally a comparison is made of the advantages and disadvantages of a large-scale clinical trial versus a meta-analysis.

Clinical Trials as Topic↗
PubMed2000

Helicobacter pylori eradication: proton pump inhibitor vs. ranitidine bismuth citrate plus two antibiotics for 1 week-a meta-analysis of efficacy.

OBJECTIVE: To compare the efficacy of proton pump inhibitor vs. ranitidine bismuth citrate (RBC) with two antibiotics for 1 week in Helicobacter pylori eradication. METHODS: Randomized trials comparing 1-week regimens with (i) proton pump inhibitor plus two antibiotics [clarithromycin (C) and amoxycillin (A) or a nitroimidazole (N)]; or (ii) RBC plus the same antibiotics. Eradication was confirmed by histology or 13C-urea breath test at least 4 weeks after therapy. Data sources included PubMed database and abstracts from congresses until October 1999. Statistical analysis was by meta-analysis combining the odds ratios (OR) of the individual studies in a global OR (Peto method). RESULTS: Twelve studies met the selection criteria. Nine compared proton pump inhibitor vs. RBC plus C and A, and five compared proton pump inhibitor vs. RBC plus C and N. With RBC, C and A, mean H. pylori eradication efficacy by intention-to-treat analysis (pooled data) was 76.6% (95% CI: 72-81%) and 73.7% (95% CI: 69-78%) with proton pump inhibitor, C and A. The OR for the effect of RBC vs. proton pump inhibitor (plus C and A) on H. pylori eradication was 1.15 (95% CI: 0.8-1.64%). Mean H. pylori eradication with RBC, C and N was 87. 2% (95% CI: 83-91%), and 74.9% (95% CI: 74-84%) with proton pump inhibitor plus these two antibiotics. The OR for the effect of RBC vs. proton pump inhibitor (plus C and N) on H. pylori eradication was 1.76 (95% CI: 1.08-2.85%). CONCLUSION: RBC and proton pump inhibitor have similar efficacy for H. pylori eradication when given with C and A for 1 week, but RBC seems to have a higher efficacy than proton pump inhibitor when C and N are the co-prescribed antibiotics.

Amoxicillin↗
PubMed2000

The incidence of major morbidity in critically ill patients managed with pulmonary artery catheters: a meta-analysis.

INTRODUCTION: The impact of pulmonary artery (PA) catheters on patient outcome has been questioned and their usage has become controversial. Meta-analysis on mortality has shown a trend for improved survival with PA catheter-guided therapy. We now perform a meta-analysis on morbidity from PA catheters in the published literature. METHODS: We did a search of the medical database (Medline) from 1970 through 1996, using the headings "pulmonary artery catheterization," "Swan-Ganz catheterization" and "right heart catheterization," and restricting the results to "effectiveness" and "usefulness." We also consulted with other experts regarding published randomized controlled trials (RCTs). This yielded 16 RCTs addressing the question of effectiveness of PA catheter-guided treatment. Of these, 12 were found to include data on morbidity. Major morbidity, defined as organ failures as per the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference criteria, from these trials was entered into a formal meta-analysis. RESULTS: A total of 1,610 patients from the 12 trials were analyzed. Morbidity events were observed in 62.77% of the PA catheter treatment group, and in 74.34% of the control group. A relative risk ratio of 0.78074 was obtained, with a 95% confidence interval of 0.6459-0.94374 and a corresponding p of .0168, a lower morbidity in the PA catheter treatment group. Those with PA catheter-guided treatment had a mean protective effect of 21.9% for risk of morbidity. Other important covariates such as acuity of illness, quality score of trials, year of publication, type of PA catheter-guided treatment used (PA catheter vs. no PA catheter, or PA catheter vs. PA catheter for supranormal hemodynamic values), and surgical or mixed patient population, all increased variability and were not statistically significant predictors for risk ratio of morbidity. CONCLUSIONS: Meta-analysis of RCTs included in this study shows that there is a statistically significant reduction in morbidity using PA catheter-guided strategies.

Catheterization, Swan-Ganz↗
PubMed1998

Meta-analysis methodology for combining non-parametric sibpair linkage results: genetic homogeneity and identical markers.

Meta-analysis methodology is developed for combining sibpair linkage results across multiple studies employing different study designs, some employing quantitative traits (e.g., blood pressure) and some employing qualitative traits (e.g., clinical hypertension), under the assumption that the underlying (disease) trait loci are the same. Pooling results based on three commonly used sibpair methods is considered: the affected sibpair method for dichotomous traits and, for quantitative traits, the Haseman-Elston regression method and the Risch-Zhang extremely discordant sibpair method. The proportion of genes shared identical by descent (IBD) by a sibpair of certain trait outcomes is chosen as a common effect to be pooled across studies. Variation in the observed IBD proportions among individual studies is modeled using a random effects model. A heterogeneity test is provided to assess the variability among individual studies. When results from all three types of studies are available, we derive pooled estimates of IBD proportions both for sibpairs with extremely concordant trait values and for sibpairs with extremely discordant trait values, and construct a combined test of linkage based on the difference of the two estimates. Simulation studies demonstrate the need for and the advantage of meta-analysis of linkage results. We also present some guidelines for reporting linkage studies bearing potential future meta-analysis in mind.

Chromosome Mapping↗