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PubMed2001

Meta-analysis: a tool for evidence-based practice.

Evidence-based practice rests on the knowledge generated from sound empirical research combined with clinical expertise. However, many clinicians lack the time to evaluate multiple studies. Meta-analysis is a statistical procedure for combining the results of multiple studies investigating a common problem or issue to produce a pooled effect size, and to evaluate the efficacy of interventions across studies. Meta-analysis can thus be used to synthesize and integrate empirical research to provide important evidence for best-practice decisions. This article examines the meta-analysis process and its links to evidence-based practice.

Evidence-Based Medicine↗

PubMed1998

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

A meta-analysis was performed on published data on the caries-inhibiting effect of fluoride gel treatment in 6- to 15-year-old children. The purposes of this meta-analysis were: (1) to calculate the overall caries-inhibiting effect of clinical fluoride gel treatment studies, based on explicit selection criteria, and (2) to explore factors potentially modifying the effect of fluoride gel treatment in caries prevention, concerning the baseline caries prevalence of the target population, the general fluoride regimen, and application features. The caries-inhibiting effect of fluoride gel application was assessed by the prevented fraction and the 'number needed to treat'. The overall prevented fraction of the fluoride gel treatment studies, indicating the reduction of caries incidence by fluoride gel treatment relative to the incidence in the control group, was 22% (95% CI = 18-25%). Multiple regression analysis showed no significant influence on the prevented fractions for the variables 'baseline caries prevalence', 'general fluoride regimen', 'application method', and 'application frequency'. The 'number needed to treat' (NNT), indicating the number of patients that need to be treated in order to prevent 1 DMFS, estimated the efficiency of fluoride gel treatment according to the caries incidence of the target population, including cost/effect relations. It was found that the NNT = 18 in a population with caries incidence 0.25 DMFS per year, and NNT = 3 in a population with caries incidence = 1.5 DMFS per year (treatment duration 1 year). From the standpoint of cost-effectiveness, the additional effect of fluoride gel treatment in current low and even moderate caries incidence child populations must be questioned.

Adolescent↗

PubMed1998

Preoperative radiotherapy in esophageal carcinoma: a meta-analysis using individual patient data (Oesophageal Cancer Collaborative Group).

PURPOSE: The existing randomized evidence has failed to conclusively demonstrate the benefit or otherwise of preoperative radiotherapy in treating patients with potentially resectable esophageal carcinoma. This meta-analysis aimed to assess whether there is benefit from adding radiotherapy prior to surgery. METHODS AND MATERIALS: This quantitative meta-analysis included updated individual patient data from all properly randomized trials (published or unpublished) comprising 1147 patients (971 deaths) from five randomized trials. RESULTS: With a median follow-up of 9 years, the hazard ratio (HR) of 0.89 (95% CI 0.78-1.01) suggests an overall reduction in the risk of death of 11% and an absolute survival benefit of 3% at 2 years and 4% at 5 years. This result is not conventionally statistically significant (p = 0.062). No clear differences in the size of the effect by sex, age, or tumor location were apparent. CONCLUSION: Based on existing trials, there was no clear evidence that preoperative radiotherapy improves the survival of patients with potentially resectable esophageal cancer. These results indicate that if such preoperative radiotherapy regimens do improve survival, then the effect is likely to be modest with an absolute improvement in survival of around 3 to 4%. Trials or a meta-analysis of around 2000 patients would be needed to reliably detect such an improvement (15-->20%).

Carcinoma↗

PubMed2002

Lactobacillus therapy for acute infectious diarrhea in children: a meta-analysis.

OBJECTIVE: Childhood diarrhea accounts for substantial morbidity and mortality worldwide. Multiple studies in children have shown that Lactobacillus, administered orally, may have antidiarrheal properties. We conducted a meta-analysis of randomized, controlled studies to assess whether treatment with Lactobacillus improves clinical outcomes in children with acute infectious diarrhea. METHODS: Studies were sought in bibliographic databases of traditional biomedical as well as complementary and alternative medicine literature published from 1966 to 2000. Search terms were "competitive inhibition," "diarrhea," "gastroenteritis," "Lactobacillus," "probiotic," "rotavirus," and "yog(h)urt." We included studies that were adequately randomized, blinded, controlled trials in which the treatment group received Lactobacillus and the control group received an adequate placebo and that reported clinical outcome measures of diarrhea intensity. These inclusion criteria were applied by blind review and consensus. The original search yielded 26 studies, 9 of which met the criteria. Multiple observers independently extracted study characteristics and clinical outcomes. Data sufficient to perform meta-analysis of the effect of Lactobacillus on diarrhea duration and diarrhea frequency on day 2 were contained in 7 and 3 of the included studies, respectively. RESULTS: Summary point estimates indicate a reduction in diarrhea duration of 0.7 days (95% confidence interval: 0.3-1.2 days) and a reduction in diarrhea frequency of 1.6 stools on day 2 of treatment (95% confidence interval: 0.7-2.6 fewer stools) in the participants who received Lactobacillus compared with those who received placebo. Details of treatment protocols varied among the studies. A preplanned subanalysis suggests a dose-effect relationship. CONCLUSION: The results of this meta-analysis suggest that Lactobacillus is safe and effective as a treatment for children with acute infectious diarrhea.

Administration, Oral↗

PubMed1991

Impact of glycine-containing ORS solutions on stool output and duration of diarrhoea: a meta-analysis of seven clinical trials. The International Study Group on Improved ORS.

The results are described of a meta-analysis of seven randomized trials that compared the clinical effects of the standard solution of WHO oral rehydration salts (ORS), containing 20 milligrams of glucose, and experimental ORS solutions, containing glycine, on 643 children with acute noncholera diarrhoea. The availability of data on individual patients in each trial permitted the scope of the meta-analysis to be enhanced because the data could be pooled after adjusting for differences in baseline patient characteristics; also, the statistical strategy in terms of data quality, post-randomization exclusion of patients, and regression modelling could be standardized for all trials. The results of the analysis showed that neither stool output nor duration of diarrhoea was reduced by the experimental formulations. Only for weight gain was there a statistically significant difference between the treatment groups (those given the WHO-ORS solution gained less weight). This probably reflects transient excess fluid retention within the gut lumen or tissues of the patients who received the glycine-containing solutions. ORS formulations that contain glycine are therefore not clinically superior to the WHO-ORS solution.

Body Weight↗

PubMed1999

Residential exposure to electromagnetic fields and childhood leukaemia: a meta-analysis.

Although individual epidemiological investigations have suggested associations between residential exposure to electromagnetic fields (EMFs) and childhood leukaemia, overall the findings have been inconclusive. Several of these studies do, however, lend themselves to application of the meta-analysis technique. For this purpose we carried out searches using MEDLINE and other sources, and 14 case-control studies and one cohort study were identified and evaluated for epidemiological quality and included in the meta-analysis. Relative risk estimates were extracted from each of the studies and pooled. Separate meta-analyses were performed on the basis of the assessed EMF exposure (wiring configuration codes, distance to power distribution equipment, spot and 24-h measures of magnetic field strength (magnetic flux density) and calculated magnetic field). The meta-analysis based on wiring configuration codes yielded a pooled relative risk estimate of 1.46 (95% confidence interval (CI) = 1.05-2.04, P = 0.024) and for that for exposure to 24-h measurements of magnetic fields, 1.59 (95% CI = 1.14-2.22, P = 0.006), indicating a potential effect of residential EMF exposure on childhood leukaemia. In most cases, lower risk estimates were obtained by pooling high-quality studies than pooling low-quality studies. There appears to be a clear trend for more recent studies to be of higher quality. Enough evidence exists to conclude that dismissing concerns about residential EMFs and childhood leukaemia is unwarranted. Additional high-quality epidemiological studies incorporating comparable measures for both exposure and outcomes are, however, needed to confirm these findings and, should they prove to be true, the case options for minimizing exposure should be thoroughly investigated to provide definitive answers for policy-makers.

Child↗

PubMed1992

Lactitol or lactulose in the treatment of chronic hepatic encephalopathy: results of a meta-analysis.

Lactitol (beta-galactosido-sorbitol) has been recently compared with lactulose for the treatment of chronic hepatic encephalopathy in a few studies, each comprising a small number of patients. The results are controversial. We studied the efficiency and tolerance of both compounds by using a meta-analysis on the basis of published controlled trials. Our study only included controlled or randomized trials comprising cirrhotic patients with chronic hepatic encephalopathy. Analyzed parameters were the portosystemic encephalopathy index of Conn after treatment, the percentage of improved patients and the percentage of patients who had ill effects related to the treatment (flatulence, diarrhea). Bibliographical screening revealed five studies comparing the effects of lactitol and lactulose in chronic hepatic encephalopathy. Four crossover studies were done that included 48 patients and one parallel study that included 29 patients. The duration of the treatment ranged from 3 to 6 mo. All studies found a similar efficiency with both drugs. However, they exhibited some discrepancies in the relative frequency of adverse reactions (flatulence). Meta-analysis showed no statistical differences in the portosystemic encephalopathy index after lactitol or lactulose treatment. The percentage of improved patients after lactitol or lactulose was similar. In contrast, the analysis revealed a higher frequency (p less than 0.01) of flatulence in patients treated with lactulose compared with those treated with lactitol. In conclusion, this meta-analysis shows no statistical difference between therapeutic effects of lactitol and lactulose, but it does show a higher frequency of flatulence with lactulose. This suggests that lactitol should be preferred to lactulose for the treatment of chronic hepatic encephalopathy.

Chronic Disease↗

PubMed2005

Magnetic resonance colonography versus colonoscopy as a diagnostic investigation for colorectal cancer: a meta-analysis.

AIMS: Magnetic resonance colonography (MRC) is emerging as a potential complementary investigation for the diagnosis of colorectal cancer (CRC) and also for benign pathology such as diverticular disease. A meta-analysis reporting the use of MRC is yet to be performed. The aim of this study was to evaluate the diagnostic accuracy of MRC compared with the gold-standard investigation, conventional colonoscopy (CC). METHODS: A literature search was carried out to identify studies containing comparative data between MRC findings and CC findings. Quantitative meta-analysis for diagnostic tests was performed, which included the calculation of independent sensitivities, specificities, diagnostic odds ratios, the construction of summary receiver operating characteristic (SROC) curves, pooled analysis and sensitivity analysis. The study heterogeneity was evaluated by the Q-test using a random-effect model to accommodate the cluster of outcomes between individual studies. RESULTS: In all, 8 comparative studies were identified, involving 563 patients. The calculated pooled sensitivity for all lesions was 75% (95% CI: 47% to 91%), the specificity was 96% (95% CI: 86% to 98%) and the area under the ROC curve was 90% (weighted). On sensitivity analysis, MRC had a better diagnostic accuracy for CRC than for polyps, with a sensitivity of 91% (95% CI: 97% to 91%), a specificity of 98% (95% CI: 66% to 99%) and an area under the ROC curve of 92%. There was no significant heterogeneity between the studies with regard to the diagnostic accuracy of MRC for CRC. CONCLUSION: This meta-analysis suggests that MRC is an imaging technique with high discrimination for cases presenting with colorectal cancer. The exact diagnostic role of MRC needs to be clarified (e.g. suitable for an elderly person with suspected CRC). Further evaluation is necessary to refine its applicability and diagnostic accuracy in comparison with other imaging methods such as computed tomography colonography.

Adenocarcinoma↗

PubMed2005

A meta-analysis of outcomes of conventional IVF in women with polycystic ovary syndrome.

This meta-analysis was conducted to compare outcomes of conventional IVF in women presenting with polycystic ovary syndrome (PCOS) and non-PCOS patients. Studies in which PCOS patients undergoing IVF were compared with a matched--no male factor--control group were considered for this review. A definition consistent with the Rotterdam consensus criteria of PCOS was required, and all patients within a given study had to be treated with the same ovarian stimulation protocol. Information regarding patient characteristics and pregnancy outcome was also required. Nine out of 290 identified studies reporting data on 458 PCOS patients (793 cycles) and 694 matched controls (1116 cycles) fulfilled these inclusion criteria. PCOS patients demonstrated a significantly reduced chance of oocyte retrieval per started cycle, odds ratio (OR) = 0.5 [95% confidence interval (CI) = 0.2-1.0]. However, no difference was observed in chance of embryo transfer per oocyte retrieval between the groups (OR = 0.7, 95% CI = 0.4-1.3). Significantly more oocytes per retrieval were obtained in PCOS patients compared with controls [random effects estimate 3.4 [95% (CI) = 1.7-5.1)]. The number of oocytes fertilized did not differ significantly between PCOS patients and controls, weighted mean difference (WMD) 0.1 oocytes (95% CI = 21.4-1.6). No significant difference was observed in the clinical pregnancy rates per started cycle, OR = 1.0 (95% CI = 0.8-1.3). The incidence of ovarian hyperstimulation syndrome (OHSS) after oocyte retrieval was rarely reported. This meta-analysis demonstrates an increased cancellation rate, but more oocytes retrieved per retrieval and a lower fertilization rate in PCOS undergoing IVF. Overall, PCOS and control patients achieved similar pregnancy and live birth rates per cycle.

Female↗

PubMed2004

Meta-analysis of the efficacy of methylphenidate for treating adult attention-deficit/hyperactivity disorder.

This article reviews the efficacy of methylphenidate (MPH) for adult attention-deficit/hyperactivity disorder (ADHD). A literature search identified double-blind placebo-controlled MPH treatment studies of ADHD adults. Meta-analysis estimated the pooled effect size for MPH treatment and tested for publication bias. Meta-analysis regression assessed the influence of study design features on medication effects. Six trials met criteria and were included in this meta-analysis. These studies included a total of 140 MPH-treated ADHD adults and 113 placebo-treated ADHD adults. The mean effect size of 0.9 was statistically significant and there was no evidence of publication bias. Larger MPH effect sizes were associated with physician ratings of outcome and use of higher doses. When treatment is optimized to high doses, the effect size for MPH in adults was 1.3. We found strong support for the assertion that MPH is efficacious for treating adult ADHD. Because the degree of efficacy of MPH in treating ADHD adults is similar to what has been reported from meta-analyses of the child and adolescent literature, our work provides further assurance to clinicians that the diagnosis of ADHD can be validly applied in adulthood.

Adult↗

PubMedDate not supplied

Human corneal thickness and its impact on intraocular pressure measures: a review and meta-analysis approach.

We determined the "normal" central corneal thickness (CCT) value in human corneas based on reported literature values for within-study average CCT values, and used this as a reference to assess the reported impact of physiological variables (especially age and diurnal effects), contact lens wear, pharmaceuticals, ocular disease, and ophthalmic surgery on CCT. With the expected CCT and its variance defined, it should be possible to determine the potential impact of differences in CCT in intraocular pressure (IOP) assessments, especially by applanation tonometry, using a meta-analysis approach. Some 600 sets of CCT data were identified from the worldwide literature over the period of 1968 through mid-1999, of which 134 included IOP measures as well. The within-study average CCT values and reported variance (SD) was noted along with the number of eyes and any special characteristics, including probable ethnic origin of the study subjects. Various sets of data were subjected to statistical analyses. From 300 data sets from eyes designated as normal, the group-averaged CCT was 0.534 mm. From 230 data sets where interindividual variance was reported, the group-averaged CCT was 0.536 mm (median 0.536 mm; average SD of 0. 031 mm, average coefficient of variation = 5.8%). Overall, studies using slit-lamp-based pachometry have reported marginally lower CCT values (average 0.530 mm, average SD 0.029 mm) compared to ultrasound-based studies (average 0.544, average SD 0.034 mm), which perhaps reflects the type of individual studied (non-surgical vs. pre-surgical patients) rather than the technique itself. A slight chronological increase in reported average CCT values (approximately 0.006 mm/decade) was evident, but a substantial chronological increase was evident for ultrasound pachometry studies (approximately 0.015 mm/decade). Within the meta-analysis-generated average and variance, age had no obvious impact on CCT measures for *whites, although an age-related decline in CCT is evident for non-whites. Any diurnal effects are likely concealed within the expected variance in CCT. Contact lens wear and pharmaceuticals generally produced changes in CCT that were well within the expected variance in CCT. Of the ocular diseases, only those associated with collagen disorders (including keratoconus) or endothelial-based corneal dystrophies (e.g., Fuchs) were likely to result in decreases or increases, respectively, of CCT beyond the normal variance. Routine contact lens wear and diseases such as diabetes seem unlikely to produce changes in CCT of a magnitude that would justify pachometry as a monitoring method beyond routine slit-lamp evaluation. Increases in CCT beyond the expected variance were reported after a range of intraocular surgeries (cataract operations, penetrating keratoplasty), whereas photorefractive surgery produces a measurable decrease in CCT. A meta-analysis of possible association between CCT and IOP measures of 133 data sets, regardless of the type of eyes assessed, revealed a statistically significant correlation; a 10% difference in CCT would result in a 3. 4 +/- 0.9 mm Hg difference in IOP (P </= 0.001, r = 0.419). The observed phenomenon was much smaller for eyes designated as healthy (1.1 +/- 0.6 mm Hg for a 10% difference in CCT, P = 0.023, r = 0. 331). For eyes with chronic diseases, the change was 2.5 +/- 1.1 mm Hg for a 10% difference in CCT (P = 0.005, r = 0.450), whereas a substantial but highly variable association was seen for eyes with acute onset disease (approximately 10.0 +/- 3.1 mm Hg for a 10% difference in CCT, P = 0.004, r = 0.623). Based on the meta-analysis, normal CCT in white adults would be expected to be within +/-11.6% (+/-2 SD) of 0.535 mm, i.e., 0.473-0.597 mm (95% CI, 0.474-0.596). The impact of CCT on applanation tonometry of healthy eyes is unlikely to achieve clinical significance, but for corneas of eyes with chronic disease, pachometry should be performed if the tonometry reveals IOP readi

Aging↗

PubMed2004

Evaluation of the association between hereditary thrombophilias and recurrent pregnancy loss: a meta-analysis.

BACKGROUND: Recurrent pregnancy loss (RPL) is a significant clinical problem. Recently, thrombophilias have been implicated as a possible cause. Factor V Leiden (FVL) and prothrombin gene (G20210A) mutations are the most common types of hereditary thrombophilias, but are usually undiagnosed because most carriers are asymptomatic. The relationship between FVL, G20210A, and RPL has been investigated with conflicting results. This study analyzed existing data to determine whether an association exists. METHODS: A systematic review of the literature was performed. Only case-control studies that defined RPL as 2 or more pregnancy losses in the first or second trimester and that confirmed mutations by DNA analysis were included. Sixteen studies were selected for the FVL meta-analysis and 7 for the G20210A analysis. Stratified and multivariate logistic regression analyses were performed with the use of aggregate data. Results were confirmed by means of fixed- and random-effects meta-analyses models. RESULTS: The combined odds ratios for the association between RPL and FVL and between RPL and G20210A were 2.0 (95% confidence interval, 1.5-2.7; P<.001) and 2.0 (95% confidence interval, 1.0-4.0; P =.03), respectively. Similar results were produced by the logistic regression and both fixed- and random-effects meta-analysis models. CONCLUSIONS: Carriers of FVL or prothrombin gene mutations have double the risk of experiencing 2 or more miscarriages compared with women without thrombophilias. Hereditary thrombophilias may be an unrecognized cause of RPL. We recommend testing for these mutations in women with RPL.

Abortion, Habitual↗

PubMed2004

Breastfeeding and risk of inflammatory bowel disease: a systematic review with meta-analysis.

BACKGROUND: It has long been believed that breastfeeding provides protection against ulcerative colitis and Crohn disease. Studies designated to test this hypothesis were conducted without reaching conclusive results. OBJECTIVE: The aim of this meta-analysis was to examine the role of breastfeeding in preventing inflammatory bowel disease and to summarize the evidence gathered about this subject. DESIGN: A meta-analysis was performed on 17 relevant articles that were found by using MEDLINE, EMBASE, the Internet, and articles' references. The publications were fully reviewed and divided, on the basis of their quality, into 3 groups. RESULTS: Studies showed heterogeneous results. The pooled odds ratios of all the 17 reviewed studies, calculated according to the random-effects model, were 0.67 (95% CI: 0.52, 0.86) for Crohn disease and 0.77 (0.61, 0.96) for ulcerative colitis. However, only 4 studies for Crohn disease and 4 for ulcerative colitis were eventually included in the highest quality group. In this group, the pooled odds ratio was 0.45 (0.26, 0.79) for Crohn disease and 0.56 (0.38, 0.81) for ulcerative colitis. CONCLUSIONS: The results of this meta-analysis support the hypothesis that breastfeeding is associated with lower risks of Crohn disease and ulcerative colitis. However, because only a few studies were graded to be of high quality, we suggest that further research, conducted with good methodology and large sample sizes, should be carried out to strengthen the validity of these observations.

Breast Feeding↗

PubMed1994

A meta-analysis of colorectal cancer and asbestos exposure.

A meta-analysis of the relation between asbestos exposure and colorectal cancer mortality was conducted, using published reports of 20 asbestos-exposed cohorts. Summary standardized mortality ratios (SMRs) for colorectal cancer were examined in relation to asbestos type and estimates of dust exposure (as direct estimators of asbestos exposure) and in relation to lung cancer SMR and the proportion of all deaths due to mesothelioma (as proxy estimators of asbestos exposure). An elevated summary SMR was observed in cohorts exposed to amphibole asbestos (summary SMR = 1.47; 95% confidence interval (CI) 1.09-2.00), but not in cohorts exposed to serpentine asbestos (summary SMR = 1.04; 95% CI 0.81-1.33) or in cohorts exposed to both serpentine and amphibole asbestos (summary SMR = 1.03; 95% CI 0.74-1.42). Cohorts having a lung cancer SMR greater than 2.00 had a summary SMR of 1.51 (95% CI 1.29-1.76), and cohorts in which more than 1% of all deaths were attributed to mesothelioma had a summary SMR of 1.24 (95% CI 0.94-1.64). After stratifying the cohorts based on mortality due to all cancers excluding those known or suspected to be associated with asbestos exposure, lung cancer mortality was not clearly associated with colorectal cancer mortality, suggesting that the crude association between these factors may be due to misdiagnosis of lung cancer as other types of cancer in the reported causes of death. These results suggest that exposure to amphibole asbestos may be associated with colorectal cancer, but these findings may reflect an artifact of miscertification of cause of death. The results also suggest that serpentine asbestos is not associated with colorectal cancer.

Asbestos↗

PubMed2005

Meta-analysis and structured literature review in radiology.

The overall goal of a systematic review or meta-analysis is to combine results of previous studies to arrive at summary conclusions about a body of research. In radiology, systematic reviews or meta-analyses can be used to calculate a summary estimate of effect size of a treatment that used imaging data to assess outcomes in observational or randomized controlled clinical trials, estimate the clinical effectiveness of an imaging-guided therapy procedure, evaluate the summary diagnostic accuracy of an imaging test, or synthesize results of economic evaluations that used imaging data. This article outlines the general concepts of structured literature reviews and discusses the approaches for conducting a meta-analysis in radiology, emphasizing the methods available for data synthesis and handling heterogeneity between and among studies.

Humans↗

PubMed2005

Multivariate meta-analysis of pharmacokinetic studies of ampicillin trihydrate in cattle.

OBJECTIVE: To investigate the feasibility of using multivariate cluster analysis to meta-analyze pharmacokinetic data obtained from studies of pharmacokinetics of ampicillin trihydrate in cattle and identify factors that could account for variability in pharmacokinetic parameters among studies. SAMPLE POPULATION: Data from original studies of the pharmacokinetics of ampicillin trihydrate in cattle in the database of the Food Animal Residue Avoidance Databank. PROCEDURE: Mean plasma or serum ampicillin concentration versus time data and potential factors that may have affected the pharmacokinetics of ampicillin trihydrate were obtained from each study. Noncompartmental pharmacokinetic analyses were performed, and values of pharmacokinetic parameters were clustered by use of multivariate cluster analysis. Practical importance of the clusters was evaluated by comparing the frequency of factors that may have affected the pharmacokinetics of ampicillin trihydrate among clusters. RESULTS: A single cluster with lower mean values for clearance and volume of distribution of ampicillin trihydrate administered PO, compared with other clusters, was identified. This cluster included studies that used preruminant calves in which feeding was withheld overnight and calves to which probenecid had been administered concurrently. CONCLUSIONS AND CLINICAL RELEVANCE: Meta-analysis was successful in detecting a potential subpopulation of cattle for which factors that explained differences in pharmacokinetic parameters could be identified. Accurate estimates of pharmacokinetic parameters are important for the calculation of dosages and extended withdrawal intervals after extralabel drug administration.

Ampicillin↗

PubMed2001

Routine perioperative pulmonary artery catheterization has no effect on rate of complications in vascular surgery: a meta-analysis.

Despite widespread use pulmonary artery catheterization has not been proven to reduce complications or mortality. One study supported the use of routine preoperative pulmonary artery catheterization in moderate-risk vascular surgery patients; several other studies have reported that pulmonary artery catheterization is not efficacious. Our goal was to scrutinize the data using meta-analysis. This is a systematic review of the literature. MEDLINE was searched for all articles on pulmonary artery catheterization, optimization, oxygen delivery, and preoperative preparation of vascular surgery patients. Data from papers judged appropriate for inclusion were analyzed using a computer program, Easy MA. Complications were defined as only those that could have reasonably have been prevented by or resulted from pulmonary artery catheterization. Of hundreds of possible papers only four were found to be adequate randomized prospective studies with similar exclusions, therapeutic endpoints, and interpretable complication and mortality rates. Controls included 174 patients versus 211 in the protocol group. Power analysis showed that the combined sample sizes were adequate. The meta-analysis demonstrates that the studies are homogeneous. The use of a pulmonary artery catheter does not prevent morbidity or mortality. Of the studies providing data on the amount of intravenous fluid administered three reported that statistically significantly more fluid was given to patients who underwent pulmonary artery catheterization. Meta-analysis indicates that in moderate-risk vascular surgery patients routine preoperative pulmonary artery catheterization is not associated with improved outcomes.

Catheterization, Swan-Ganz↗

PubMed2006

A meta-analysis of diabetes mellitus and the risk of prostate cancer.

BACKGROUND: Studies investigating the association between diabetes mellitus and prostate cancer have reported inconsistent findings. We examined this association by conducting a detailed meta-analysis of the studies published on the subject. METHODS: MEDLINE and EMBASE databases and bibliographies of retrieved articles were searched. Studies investigating the relationship between diabetes mellitus and prostate cancer were included in the meta-analysis. Potential sources of heterogeneity between studies were explored and publication bias was evaluated. Pooled relative risk (RR) was calculated using the random-effects model. Numerous relevant subgroup analyses were also done. RESULTS: We included 19 studies, published between 1971 and 2005, in the meta-analysis and found an inverse association between diabetes mellitus and prostate cancer [RR, 0.84, 95% confidence interval (CI), 0.76-0.93, P for heterogeneity <or= 0.01]. For cohort studies alone, the RR was 0.81 (95% CI, 0.71-0.92, P for heterogeneity <or= 0.01) and for case-control studies alone, the RR was 0.89 (95% CI, 0.72-1.11, P for heterogeneity = 0.02). The significant heterogeneity was mitigated in some of the subgroup analyses. For studies conducted before prostate-specific antigen screening was introduced as a common procedure, the RR was 0.94 (95% CI, 0.85-1.03, P for heterogeneity = 0.15), and for studies conducted after this time, the RR was 0.73 (95% CI, 0.64-0.83, P for heterogeneity = 0.10). For studies that adjusted for three or more potential confounders, the RR was 0.74 (95% CI, 0.65-0.85, P for heterogeneity = 0.06) and for studies that adjusted for less than three potential confounders, the RR was 0.93 (95% CI, 0.86-1.02, P for heterogeneity = 0.18). CONCLUSION: This study suggests an inverse relationship between diabetes and prostate cancer. Potential biological mechanisms underlying this association, as well as possible biases, are discussed.

Cohort Studies↗