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PubMed2000

Bleeding and pneumonia in intensive care patients given ranitidine and sucralfate for prevention of stress ulcer: meta-analysis of randomised controlled trials.

OBJECTIVES: To determine the effectiveness of ranitidine and sucralfate in the prevention of stress ulcer in critical patients and to assess if these treatments affect the risk of nosocomial pneumonia. DESIGN: Published studies retrieved through Medline and other databases. Five meta-analyses evaluated effectiveness in terms of bleeding rates (A: ranitidine v placebo; B: sucralfate v placebo) and infectious complications in terms of incidence of nosocomial pneumonia (C: ranitidine v placebo; D: sucralfate v placebo; E: ranitidine v sucralfate). Trial quality was determined with an empirical ad hoc procedure. MAIN OUTCOME MEASURES: Rates of clinically important gastrointestinal bleeding and nosocomial pneumonia (compared between the two study arms and expressed with odds ratios specific for individual studies and meta-analytic summary odds ratios). RESULTS: Meta-analysis A (five studies) comprised 398 patients; meta-analysis C (three studies) comprised 311 patients; meta-analysis D (two studies) comprised 226 patients: and meta-analysis E (eight studies) comprised 1825 patients. Meta-analysis B was not carried out as the literature search selected only one clinical trial. In meta-analysis A ranitidine was found to have the same effectiveness as placebo (odds ratio of bleeding 0.72, 95% confidence interval 0.30 to 1.70, P=0.46). In placebo controlled studies (meta-analyses C and D) ranitidine and sucralfate had no influence on the incidence of nosocomial pneumonia. In comparison with sucralfate, ranitidine significantly increased the incidence of nosocomial pneumonia (meta-analysis E: 1.35, 1.07 to 1.70, P=0.012). The mean quality score in the four analyses (on a 0 to 10 scale) ranged from 5.6 in meta-analysis E to 6.6 in meta-analysis A. CONCLUSIONS: Ranitidine is ineffective in the prevention of gastrointestinal bleeding in patients in intensive care and might increase the risk of pneumonia. Studies on sucralfate do not provide conclusive results. These findings are based on small numbers of patients, and firm conclusions cannot presently be proposed.

Anti-Ulcer Agents↗

PubMed1998

Overcoming the limitations of current meta-analysis of randomised controlled trials.

For a meta-analysis to give definitive information, it should meet at least the minimum standards that would be expected of a well-designed, adequately powered, and carefully conducted randomised controlled trial. These minimum standards include both qualitative characteristics--a prospective protocol, comparable definitions of key outcomes, quality control of data, and inclusion of all patients from all trials in the final analysis--and quantitative standards--an assessment of whether the total sample is large enough to provide reliable results and the use of appropriate statistical monitoring guidelines to indicate when the results of the accumulating data of a meta-analysis are conclusive. We believe that rigorous meta-analyses undertaken according to these principles will lead to more reliable evidence about the efficacy and safety of interventions than either retrospective meta-analysis or individual trials.

Humans↗

PubMed2001

[Meta-analysis of pharmacotherapies for allergic rhinitis].

We performed meta-analysis using the data in literatures of the clinical study related to pharmacotherapies for allergic rhinitis in Japan as evidences. We extracted double-blind studies which used first-generation antihistamines, early-stage second-generation antihistamines, late-stage second-generation antihistamines and arachidonic acid metabolite-receptor antagonists as investigational drugs. In meta-analysis of first-generation antihistamines and early-stage second-generation antihistamines, significant differences between them were detected in final overall improvement and usefulness. In meta-analysis of early-stage second-generation antihistamines and late-stage second-generation antihistamines, significant differences between them were detected in usefulness and sleepiness as an adverse effect. In meta-analysis of late-stage second-generation antihistamines and arachidonic acid metabolite-receptor antagonists, significant differences between them were detected in final overall improvement and usefulness. These results indicate a historical trend in the development of drugs including measures to deal with sleepiness as an adverse effect. The arachidonic acid metabolite antagonists appeared to be promising among the oral drugs for allergic rhinitis, although data related to the arachidonic acid metabolite antagonists are still few and further collection of them is necessary.

Arachidonic Acids↗

PubMed2002

A Bayesian fixed effects analysis of the Mantel-Haenszel model applied to meta-analysis.

When performing a meta analysis, it is often necessary to combine results from several 2 x 2 contingency tables. The Mantel-Haenszel model assumes a common measure of association between the treatment and outcome variables across the tables. A Bayesian method is described for drawing inferences regarding the measure of association, for checking the plausibility of the Mantel-Haenszel model, and for drawing inferences regarding the success rates for the individual studies. While the methodology is readily extendable to random effects models, a fixed effects approach avoids the complex statistical modelling of a mixture distribution which is required for the good application of random effects models.

Anti-Bacterial Agents↗

PubMed1999

Wound infection in open versus laparoscopic appendectomy. A meta-analysis.

The authors performed a meta-analysis to determine whether open or laparoscopic appendectomy would reduce wound infection incidence in adult patients with acute appendicitis. The meta-analysis included nine of seven patients from eight randomized controlled trials. Data were analyzed using the fixed effect-model method of Mantel-Haenszel. Wound infection incidence was lower in the laparoscopic group.

Acute Disease↗

PubMed1993

Meta-analysis: strategies to strengthen postanesthesia care unit study results.

Meta-analysis is a research method used to synthesize findings across multiple studies that tested similar variables on similar subjects. An overview of meta-analysis is presented and defined in an eight-step approach. A meta-analysis of the effect of preoperative instruction on postoperative outcomes is applied to the eight defined steps. Implications for postanesthesia nurses include the usefulness of meta-analysis as a method of building knowledge by examining findings and drawing conclusions from multiple, single-institution studies conducted with small sample sizes.

Meta-Analysis as Topic↗

PubMed1994

Meta-analysis in dental research: a paradigm for performance and interpretation.

Applications of meta-analysis have begun to appear with some regularity in the dental research literature. Recently, a meta-analysis played a high-profile role in the ongoing academic debate concerning the relative anticaries efficacy of dentifrices containing fluoride as sodium fluoride and as sodium monofluorophosphate, engendering a controversy concerning the methodology employed. This has given rise to the need for a careful consideration of the principles involved in the meta-analytic process to provide a basis of understanding upon which such controversies may be resolved. The present report endeavors to meet this need by enumerating the steps involved in a meta-analysis, and contrasting them with the analogous steps in the more widely-understood "usual" inferential process, bringing to light both the similarities and differences between these two types of analyses. Within this context, the conflicting meta-analyses associated with the current controversy are discussed and compared, and the source of the difference between them is readily identified. This process reaffirms the need for close collaboration between statisticians and other scientists in the performance of a meta-analysis, and the value of such close collaboration in the evaluation and interpretation of a meta-analysis performed by others, as well.

Dental Caries↗

PubMed1991

A practitioner's guide to meta-analysis.

Describes the application to community issues of the meta-analytic research strategies increasingly used in many field of psychology. First, we highlight the potential value of meta-analysis to community research. Second, we describe six major steps involved in conducting an effective meta-analysis. These steps include formulating the initial research question(s), locating relevant studies, abstracting critical information from each study, and presenting, analyzing, and interpreting the resultant data. In this guide, the major aspects of meta-analysis are discussed with particular emphasis on the procedures that are most critical to the validity of its conclusions. Greater familiarity with the techniques, issues, and potential of meta-analysis may stimulate investigators to make more effective use of this powerful approach to integrating research in community psychology.

Community Mental Health Services↗

PubMed2001

Meta-analysis of thalamic size in schizophrenia.

BACKGROUND: This article presents a meta-analysis of thalamic size reduction in schizophrenia. METHODS: Reviewed studies were based on magnetic resonance imaging or postmortem material and included measures of thalamic volume or thalamic area in schizophrenic patients and comparison subjects. Meta-analysis I was based on absolute thalamic values (not controlled for overall brain size), and Meta-analysis II evaluated thalamic size adjusted for brain size. RESULTS: Meta-analysis I included data from 15 studies (485 schizophrenic subjects and 500 control subjects). Twelve (80%) of the studies had negative effect sizes, which is consistent with the hypothesis that thalamic size is smaller in schizophrenic subjects compared to control subjects. The composite effect size was -0.29 (p <.0001; without outliers: -0.41, p <.0001). Meta-analysis II included data from 11 studies (313 schizophrenic patients and 434 control subjects). Ten (91%) of the studies had negative effect sizes. The composite effect size was -0.35 (p <.0001; without outlier: -0.30, p <.0001). CONCLUSIONS: Both meta-analyses indicate a statistically significant, small-to-moderate effect size for thalamic size reduction in schizophrenia; however, the effect size for thalamic size reduction is modest in comparison to that of other structural abnormalities noted in schizophrenia.

Humans↗

PubMed1995

The relationships between left ventricular mass and daytime and night-time blood pressures: a meta-analysis of comparative studies.

OBJECTIVE: To review the literature to examine critically the assertion that night-time blood pressure is a better predictor of echocardiographic left ventricular mass than daytime blood pressure, and that left ventricular mass is inversely related to the day-night blood pressure difference. STUDY SELECTION: Published studies in which left ventricular mass (index) of normotensive or hypertensive individuals, or both, was related to automated blood pressure measurement during the day and night, or their difference, or both. RESULTS OF DATA ANALYSIS: The meta-analysis of 19 comparative studies, involving 1223 participants, indicates that the weighted correlation coefficient for the relationship between left ventricular mass (index) and systolic night-time blood pressure (0.44; 95% confidence limit 0.39-0.48) is not significantly different from the correlation with systolic daytime blood pressure (0.48; 95% confidence limit 0.44-0.52; P > 0.2). The corresponding correlation coefficients for diastolic blood pressure both average 0.37. In half of the eight studies in which the association between left ventricular mass (index) and the day-night difference in blood pressure was analysed, investigators found no significant relationship between those variables; in the others, the variance of the mass (index) that can be explained by the blood pressure difference is 15% at the most. CONCLUSION: The overall analysis suggests that night-time blood pressure is not a significantly better predictor of left ventricular mass than daytime blood pressure is, and that the relationship to the day-night blood pressure difference is not a unanimous finding and is only ever weakly significant.

Blood Pressure↗

PubMed2002

The nature and dimensionality of organizational citizenship behavior: a critical review and meta-analysis.

This article reviews the literature on organizational citizenship behavior (OCB) and its dimensions as proposed by D. W. Organ (1988) and other scholars. Although it is assumed that the behavioral dimensions of OCB are distinct from one another, past research has not assessed this assumption beyond factor analysis. Using meta-analysis, the authors demonstrate that there are strong relationships among most of the dimensions and that the dimensions have equivalent relationships with the predictors (job satisfaction, organizational commitment, fairness, trait conscientiousness, and leader support) most often considered by OCB scholars. Implications of these results are discussed with respect to how the OCB construct should be conceptualized and measured in the future.

Humanism↗

PubMed2006

Cardiac effects of growth hormone treatment in chronic heart failure: A meta-analysis.

CONTEXT: Experimental studies suggest that GH treatment may improve cardiovascular parameters in chronic heart failure (CHF). However, clinical trials involved small numbers of patients and did not allow a conclusion to be drawn on the effect of this treatment in humans. OBJECTIVE: We systematically reviewed and analyzed all randomized controlled trials and open studies of sustained GH treatment in CHF. STUDY SELECTION: Twelve trials were identified in three databases. We conducted a combined analysis of GH effects on cardiovascular parameters using the overall effect size to evaluate significance and computing the weighted mean differences with and without treatment to assess effect size. DATA SYNTHESIS: GH treatment significantly modified morphological cardiovascular parameters [interventricular septum thickness, +0.55 (sd, 0.43) mm (P < 0.001); posterior wall thickness, +1.01 (0.44) mm (P < 0.01); left ventricle (LV) end-diastolic diameter, -2.02 (1.22) mm (P < 0.01); and LV end-systolic diameter, -5.30 (2.33) mm (P < 0.05)]; LV and systemic hemodynamics [LV end-systolic wall stress, -38.9 (13.3) dynes/cm(2) (P < 0.001); LV ejection fraction, +5.10 (1.74)% (P < 0.05); and systemic vascular resistance, +195.0 (204.5) dyn x sec(-1) x cm(-5) (P < 0.01)]; and functional parameters [New York Heart Association class, -0.97 (0.23) (P < 0.01); exercise duration, +103.7 (37.6) sec (P < 0.001); and maximal oxygen uptake, +2.48 (1.76) ml/kg x min (P < 0.01)]. Subgroup analysis and meta-regression showed significant relationships between the IGF-I response and GH treatment effects. CONCLUSION: Our meta-analysis suggests that GH treatment improves several relevant cardiovascular parameters in patients with CHF. However, these results must be confirmed by a large randomized placebo-controlled trial on hemodynamic, morphological, and functional parameters during long-term high-dose GH treatment of patients with CHF.

Growth Hormone↗

PubMed2002

Selective dorsal rhizotomy: meta-analysis of three randomized controlled trials.

This study is a comparative analysis and meta-analysis of three randomized clinical trials. Children with spastic diplegia received either 'selective' dorsal rhizotomy (SDR) plus physiotherapy (SDR+PT) or PT without SDR (PT-only). Common outcome measures were used for spasticity (Ashworth scale) and function (Gross Motor Function Measure [GMFM]). Baseline and 9- to 12-month outcome data were pooled (n=90). At baseline, 82 children were under 8 years old and 65 had Gross Motor Function Classification System level II or III disability. Pooled Ashworth data analysis confirmed a reduction of spasticity with SDR+PT (mean change score difference -1.2; Wilcoxonp<0.001). Pooled GMFM data revealed greater functional improvement with SDR+PT (difference in change score +4.0, p=0.008). Multivariate analysis in the SDR+PT group revealed a direct relationship between percentage of dorsal root tissue transected and functional improvement. SDR+PT is efficacious in reducing spasticity in children with spastic diplegia and has a small positive effect on gross motor function.

Cerebral Palsy↗

PubMed2004

What to add to nothing? Use and avoidance of continuity corrections in meta-analysis of sparse data.

OBJECTIVES: To compare the performance of different meta-analysis methods for pooling odds ratios when applied to sparse event data with emphasis on the use of continuity corrections. BACKGROUND: Meta-analysis of side effects from RCTs or risk factors for rare diseases in epidemiological studies frequently requires the synthesis of data with sparse event rates. Combining such data can be problematic when zero events exist in one or both arms of a study as continuity corrections are often needed, but, these can influence results and conclusions. METHODS: A simulation study was undertaken comparing several meta-analysis methods for combining odds ratios (using various classical and Bayesian methods of estimation) on sparse event data. Where required, the routine use of a constant and two alternative continuity corrections; one based on a function of the reciprocal of the opposite group arm size; and the other an empirical estimate of the pooled effect size from the remaining studies in the meta-analysis, were also compared. A number of meta-analysis scenarios were simulated and replicated 1000 times, varying the ratio of the study arm sizes. RESULTS: Mantel-Haenszel summary estimates using the alternative continuity correction factors gave the least biased results for all group size imbalances. Logistic regression was virtually unbiased for all scenarios and gave good coverage properties. The Peto method provided unbiased results for balanced treatment groups but bias increased with the ratio of the study arm sizes. The Bayesian fixed effect model provided good coverage for all group size imbalances. The two alternative continuity corrections outperformed the constant correction factor in nearly all situations. The inverse variance method performed consistently badly, irrespective of the continuity correction used. CONCLUSIONS: Many routinely used summary methods provide widely ranging estimates when applied to sparse data with high imbalance between the size of the studies' arms. A sensitivity analysis using several methods and continuity correction factors is advocated for routine practice.

Bayes Theorem↗

PubMed1992

Meta-analysis of cisplatin, doxorubicin, and cyclophosphamide versus cisplatin and cyclophosphamide chemotherapy of ovarian carcinoma.

OBJECTIVE: To compare the survival with cisplatin, doxorubicin (Adriamycin), and cyclophosphamide versus that of cisplatin and cyclophosphamide in women with advanced epithelial ovarian cancer, to evaluate the effect of dose intensity, and to evaluate meta-analysis methodology. METHODS: Meta-analysis was done on 30 studies of 2060 women with stages III and IV epithelial ovarian cancer. All had 3-year survival data, adequate follow-up, no other chemotherapy, no radiation therapy, and had information for various prognostic variables (age, stage, grade, and residual disease). We used four different methods of meta-analysis: pooled published data and modified effect-size analyses of the entire group (30 studies), and pooled published data and effect-size analyses of the subset of five prospective randomized studies. RESULTS: Three-year survival for the entire group was 43% for cisplatin, doxorubicin, and cyclophosphamide versus 36% for cisplatin and cyclophosphamide; for the five prospective randomized studies, the rates were 46 and 35%, respectively. The survival advantage of cisplatin, doxorubicin, and cyclophosphamide was statistically significant when analyzed by the pooled published data and modified effect-size meta-analysis of the entire group and the pooled published data meta-analysis of the five prospective randomized studies. The effect-size meta-analysis of the five prospective studies did not reach statistical significance. Total dose intensity and doxorubicin dose intensity were not significantly associated with survival advantage in cisplatin, doxorubicin, and cyclophosphamide use. CONCLUSIONS: There seems to be a survival advantage to treatment with cisplatin, doxorubicin, and cyclophosphamide versus treatment with cisplatin and cyclophosphamide. We believe this to be due to the properties of multiagent chemotherapy (the addition of doxorubicin) rather than to increased dose intensity. In addition, we believe that physicians need to familiarize themselves with meta-analysis methodology.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2006

Meta-analysis of coefficient alpha.

The meta-analysis of coefficient alpha across many studies is becoming more common in psychology by a methodology labeled reliability generalization. Existing reliability generalization studies have not used the sampling distribution of coefficient alpha for precision weighting and other common meta-analytic procedures. A framework is provided for a statistically grounded meta-analysis of coefficient alpha using its sampling distribution. Two empirical examples are offered to illustrate these methods, and limitations of reliability generalization are described.

Humans↗

PubMed2006

Diagnostic value of multislice computed tomography angiography in coronary artery disease: a meta-analysis.

PURPOSE: To perform a meta-analysis of the diagnostic value of multislice CT (MSCT) angiography in the detection of coronary artery disease (CAD) when compared to conventional coronary angiography. MATERIALS AND METHODS: A search of PubMed and MEDLINE databases for English literature was performed. Only studies with at least 10 patients comparing MSCT angiography with conventional coronary angiography in the detection of CAD were included. Diagnostic value of MSCT angiography compared to coronary angiography was compared and analyzed at segment-, vessel- and patient-based assessment. RESULTS: 47 studies (67 comparisons) met the criteria and were included in our study. Pooled overall sensitivity, specificity and 95% confidence interval for MSCT angiography in the detection of CAD were 83% (79%, 89%), 93% (91%, 96%) at segment-based analysis; 90% (87%, 94%), 87% (80%, 93%) at vessel-based analysis; and 91% (88%, 95%), 86% (81%, 92%) at patient-based analysis, respectively. Diagnostic accuracy of MSCT angiography in evaluating assessable segments was significantly improved with 64-slice scanners when compared to that with 4- and 16-slice scanners (p<0.05). CONCLUSION: Our meta-analysis showed that MSCT angiography has potential diagnostic accuracy in the detection of CAD. Diagnostic performance of MSCT angiography has been significantly improved with the latest 64-slice CT, with resultant high qualitative and quantitative diagnostic accuracy. 16-slice CT was limited in spatial resolution which makes it difficult to perform quantitative assessment of coronary artery stenoses.

Clinical Trials as Topic↗

PubMed2005

Bacteriophage-based assays for the rapid detection of rifampicin resistance in Mycobacterium tuberculosis: a meta-analysis.

OBJECTIVE: To summarize, using meta-analysis, the accuracy of bacteriophage-based assays for the detection of rifampicin resistance in Mycobacterium tuberculosis. METHODS: By searching multiple databases and sources we identified a total of 21 studies eligible for meta-analysis. Of these, 14 studies used phage amplification assays (including eight studies on the commercial FASTPlaque-TB kits), and seven used luciferase reporter phage (LRP) assays. Sensitivity, specificity, and agreement between phage assay and reference standard (e.g. agar proportion method or BACTEC 460) results were the main outcomes of interest. RESULTS: When performed on culture isolates (N=19 studies), phage assays appear to have relatively high sensitivity and specificity. Eleven of 19 (58%) studies reported sensitivity and specificity estimates > or =95%, and 13 of 19 (68%) studies reported > or =95% agreement with reference standard results. Specificity estimates were slightly lower and more variable than sensitivity; 5 of 19 (26%) studies reported specificity <90%. Only two studies performed phage assays directly on sputum specimens; although one study reported sensitivity and specificity of 100 and 99%, respectively, another reported sensitivity of 86% and specificity of 73%. CONCLUSIONS: Current evidence is largely restricted to the use of phage assays for the detection of rifampicin resistance in culture isolates. When used on culture isolates, these assays appear to have high sensitivity, but variable and slightly lower specificity. In contrast, evidence is lacking on the accuracy of these assays when they are directly applied to sputum specimens. If phage-based assays can be directly used on clinical specimens and if they are shown to have high accuracy, they have the potential to improve the diagnosis of MDR-TB. However, before phage assays can be successfully used in routine practice, several concerns have to be addressed, including unexplained false positives in some studies, potential for contamination and indeterminate results.

Antibiotics, Antitubercular↗