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PubMed2003

Changes in cardiovascular risk by reduction of left ventricular mass in hypertension: a meta-analysis.

BACKGROUND: Some studies have suggested that serial changes in left ventricular (LV) mass in hypertensive subjects predict the subsequent risk of cardiovascular disease. The aim of this meta-analysis was to evaluate the prognostic impact of LV hypertrophy regression in hypertension. METHODS: We undertook a meta-analysis of studies that reported echocardiographic LV mass before and during antihypertensive therapy, with subsequent assessment of cardiovascular events. The aims of this meta-analysis were: 1) to compare subjects with LV hypertrophy (LVH) during treatment (persistence or new development of LVH) with those with LVH at baseline, but not during treatment (regression of LVH); and 2) to compare subjects with LVH at baseline, but not during treatment with those without LVH both before and during treatment (regression of LVH versus persistently normal LV mass). RESULTS: The four eligible studies included 1064 hypertensive subjects (41% women) aged 45 to 51 years who repeated the echocardiographic study 3 to 10 years after the initial examination. The definition of LVH was based on a LV mass corrected by body surface area >125 g/m(2) in two studies and >110 g/m(2) (for women) and 124 g/m(2) (for men) in two studies. Compared with subjects with lack of regression or new development of LVH, those with LVH regression showed a reduced risk of subsequent cardiovascular disease (odds ratio 0.41, 95% CI 0.21 to 0.78, P =.007). Compared with subjects with regression of LVH, those with persistently normal LV mass showed a similar risk of subsequent events (odds ratio 0.64, 95% CI = 0.31 to 1.30, P =.21). CONCLUSION: Compared with persistence or new development of LV hypertrophy, regression of LV hypertrophy during antihypertensive treatment is associated with a marked reduction in risk for subsequent cardiovascular disease.

Echocardiography↗

PubMed1994

Sulfasalazine and mesalazine for the maintenance therapy of Crohn's disease: a meta-analysis.

OBJECTIVE: The aim of this meta-analysis was to determine whether therapy with sulfasalazine or mesalazine is effective in the maintenance of clinical remission in patients with Crohn's disease. METHODS: Computerized searches of bibliographic databases were carried out to identify studies published up to October 1993 that were randomized controlled trials of sulfasalazine or mesalazine as single drug therapy in the prevention of symptomatic disease relapse in quiescent Crohn's disease. We extracted and statistically aggregated data from the trials, using a fixed effects model. RESULTS: A total of 10 eligible trials involving a total of 1022 patients were identified. Therapy with sulfasalazine or mesalazine reduces the risk of clinical relapse of Crohn's disease after 12 months [relative risk (RR) = 0.77, 95% confidence interval (CI) 0.64-0.92]. The benefit is less apparent at 3-6 months [RR = 0.86, 95% CI 0.67-1.09]. Subgroup analysis indicated that therapeutic benefit exists for mesalazine but not for sulfasalazine [RR for mesalazine = 0.63, 95% CI 0.50-0.79; RR for sulfasalazine = 1.08, 95% CI 0.81-1.44]. CONCLUSIONS: Maintenance therapy with mesalazine or sulfasalazine reduces the risk of clinical disease relapse in Crohn's disease after 1 yr. This benefit is seen primarily in the more recent studies that have used mesalazine as the therapeutic agent.

Aminosalicylic Acids↗

PubMed2006

The McKenzie method for low back pain: a systematic review of the literature with a meta-analysis approach.

STUDY DESIGN AND OBJECTIVES: Meta-analysis of randomized controlled trials to evaluate the effectiveness of the McKenzie method for low back pain (LBP). SUMMARY OF BACKGROUND DATA: The McKenzie method is a popular classification-based treatment for LBP. The faulty equation of McKenzie to extension exercises (generic McKenzie) is common in randomized trials. METHODS: MEDLINE, EMBASE, PEDro, and LILACS were searched up to August 2003. Two independent reviewers extracted the data and assessed methodologic quality. Pooled effects were calculated among homogeneous trials using the random effects model. A sensitivity analysis excluded trials reporting on generic McKenzie. RESULTS: Eleven trials of mostly high quality were included. McKenzie reduced pain (weighted mean difference [WMD] on a 0- to 100-point scale, -4.16 points; 95% confidence interval, -7.12 to -1.20) and disability (WMD on a 0- to 100-point scale, -5.22 points; 95% confidence interval, -8.28 to -2.16) at 1 week follow-up when compared with passive therapy for acute LBP. When McKenzie was compared with advice to stay active, a reduction in disability favored advice (WMD on a 0- to 100-point scale, 3.85 points; 95% confidence interval, 0.30 to 7.39) at 12 weeks of follow-up. Heterogeneity prevented pooling of studies on chronic LBP as well as pooling of studies included in the sensitivity analysis. CONCLUSIONS: There is some evidence that the McKenzie method is more effective than passive therapy for acute LBP; however, the magnitude of the difference suggests the absence of clinically worthwhile effects. There is limited evidence for the use of McKenzie method in chronic LBP. The effectiveness of classification-based McKenzie is yet to be established.

Acute Disease↗

PubMed1990

Marital discord and child behavior problems: a meta-analysis.

The relation of marital discord to the behavior problems of children was examined through a meta-analysis of the results of prior research. The sample comprised all published studies through 1988 that met criteria for the meta-analysis and that could be located through a combined computer and hand search of the literature. Marital discord included conflict, disharmony, and lack of agreement between currently married parents. Child behavior problems were defined as conduct problems, excluding internalized difficulties, such as anxiety. Four hypotheses were drawn from recent reviews of studies on this topic: The relation between marital conflict and child behavior problems will be (1) positive overall and will be stronger (2) for boys than for girls, (3) for cases based entirely on parent self-report data than for cases involving external sources of data, (4) for clinic than for nonclinic families. Results supported the first three hypotheses. Little evidence was found for an association between marital conflict and the behavior problems of girls. Findings are discussed in terms of their methodological and theoretical implications and in relation to a recent review of research on sex differences in children's reactions to divorce.

Child↗

PubMedDate not supplied

Breastfeeding and the risk of childhood leukemia: a meta-analysis.

OBJECTIVE: The authors used a meta-analytic technique to (1) quantify the evidence of an association between duration of breastfeeding and risk of childhood acute lymphoblastic leukemia (ALL) or acute myeloblastic leukemia (AML), (2) assess the influence of socioeconomic status (SES) on any such associations, and (3) discuss the implications of these findings for the evaluation of whether breastfeeding reduces the risk of childhood leukemia. METHODS: A fixed effects model was employed to systematically combine the results of 14 case-control studies addressing the effect of short-term (< or = 6 months) and long-term (>6 months) breastfeeding on the risk of childhood ALL and/or AML. Subgroup analyses of studies that did and did not adjust for SES were also performed. RESULTS: A significant, negative association was observed between long-term breastfeeding and both ALL risk (odds ratio [OR]=0.76; 95% confidence interval [CI] 0.68, 0.84) and AML risk (OR=0.85; 95% CI 0.73, 0.98). Short-term breastfeeding was similarly protective for ALL and AML. Results for studies that adjusted and did not adjust for SES were not significantly different from the results for the 14 studies combined. CONCLUSIONS: This meta-analysis showed that both short-term and long-term breastfeeding reduced the risk of childhood ALL and AML, suggesting that the protective effect of breastfeeding might not be limited to ALL as earlier hypothesized. Potential bias introduced by different participation rates for case and control samples that differed in SES can be minimized by implementing larger case-control studies with SES-matched, population-based controls.

Breast Feeding↗

PubMed1996

The role of meta-analysis in monitoring clinical trials.

The randomized clinical trial is the gold standard methodology for evaluating treatment interventions. The randomized trial is a prospective experimental study, the embodiment of the scientific method applied to the clinic. Both organizational and ethical considerations encourage the use of formal criteria for termination. Such criteria, typically based on an overall 5 per cent significance test, are frequently portrayed as guidelines, but none the less usually succeed in focusing the debate on termination decisions and thus facilitate decision making. The use of the 5 per cent criterion is entirely arbitrary and is not based in any way on optimality considerations. No credible model for optimizing the decision to terminate trials has been developed. Meta-analysis is an evolving technique for evaluating the totality of the evidence on general treatment strategies. It has enjoyed considerable success in influencing medical opinion and treatment practice in selected areas. Its role is in establishing proof of concept of general treatment strategies, and is thus a consensus builder, making use of data from trials which may be heterogeneous in the details of treatment administration and patient selection, but similar in conceptual intent. The level of evidence required for consensus is not well understood and cannot be defined precisely. The retrospective nature of meta-analysis and the risks of biased data acquisition mandate a conservative approach to data analysis and interpretation. Randomized trials and meta-analyses have distinct but complementary goals. Meta-analysis can be used productively in planning new clinical trials, and in supplying updated information to study monitors in the course of a trial. However, it is not advisable to employ meta-analysis in formal statistical procedures for terminating clinical trials.

Bias↗

PubMed2005

Impact of hepatitis C virus on immune restoration in HIV-infected patients who start highly active antiretroviral therapy: a meta-analysis.

BACKGROUND: There are conflicting data in the medical literature regarding the degree of immune restoration (as measured by CD4 cell count) in patients who commence highly active antiretroviral therapy (HAART) when coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV), compared with those with HIV infection alone. METHODS: We performed a meta-analysis that compared CD4 cell count increases after HAART initiation in HCV-negative and HCV-positive patients who were infected with HIV. Published studies in the English-language medical literature that involved cohorts of HCV-negative and HCV-positive patients who were coinfected with HIV were obtained by searching the Medline, Embase Drugs and Pharmacology, and EBM Review-Cochrane Central Register of Controlled Trials databases. Data were extracted independently from relevant studies by 3 investigators and were used in a fixed-effects meta-analysis to determine the mean difference in the expected CD4 count change in the 2 groups. RESULTS: Eight trials involving 6216 patients were analyzed. Patients with HIV-HCV coinfection had a mean increase in the CD4 cell count that was 33.4 cells/mm3 (95% CI, 23.5-43.3 cells/mm3) less than that for HIV-infected patients without HCV infection. The results of the meta-analysis were independent of any one study and were not influenced by the year in which HAART was started. CONCLUSIONS: This meta-analysis shows that patients with HIV-HCV coinfection do, in fact, have less immune reconstitution, as determined by CD4 cell count after 48 weeks of HAART, than do patients with HCV infection alone. Future research should examine whether an impaired immunologic response corresponds with meaningful virologic and clinical outcomes.

Anti-HIV Agents↗

PubMed1997

Sinonasal melanoma. A clinicopathologic study of 25 cases and literature meta-analysis.

OBJECTIVES: To report on 25 cases of sinonasal melanoma at our institution during 1977 to 1995 and to perform a literature meta-analysis on sinonasal melanoma and study survival statistics. DATA SOURCES: A retrospective search of pathology and clinical records at our institution to identify patients with sinonasal melanoma; a retrospective search of the English-language literature for cases of documented sinonasal melanoma. STUDY SELECTION: Cases from our institution were included if there was adequate pathologic material confirming the pathologic diagnosis. For the meta-analysis, cases were accepted if they included convincing histologic illustrations or documentation of melanin by Fontana-Masson staining or ultrastructural examination or had an acceptable immunohistochemical profile with some documented clinical follow-up on individual patients. DATA EXTRACTION: The following parameters were monitored for patients from our institution: age, sex, possible exposure histories, tumor site, tumor size, type of therapy, clinical outcome, cytochemistry (Fontana-Masson stain), and immunohistochemical profile (S-100, HMB-45, vimentin, cytokeratin). The parameters of the meta-analysis were age, sex, tumor site, and survival data. DATA SYNTHESIS: Our patient population included 10 men and 15 women aged 23 to 83 years (mean, 65 years). Tumor sites included inferior turbinate, superior nasal cavity, nasal cavity floor/palate, ethmoid sinuses, and maxillary sinus. The immunohistochemical profile was as follows (positive cases): S-100 (14 of .14), HMB-45 (12 of 14), vimentin (9 of 10), cytokeratin (0 of 9). Melanin was demonstrated by Fontana-Masson stain (8 of 8 cases). Follow-up information was available in 25 cases, with follow-up ranging from 1 to 217 months (mean, 39 months). Eleven patients were disease free at 1 to 217 months (mean, 59 months) after excision. Local single recurrences developed in 6 patients at 3 to 84 months (mean, 14 months), and were treated with surgery. Multiple local recurrences were seen in 2 patients. One of them died of disseminated disease, after 2 local recurrences, 60 months after original diagnosis. The other was disease free after 38 months. Ten patients ultimately died of disease within 2 to 60 months after diagnosis (mean, 21 months). Only 2 patients may have developed metastatic disease in the absence of local recurrence. A total of 163 cases were identified from the literature: 53 women, 54 men (56 gender unknown). Stratification by era (pre-1980 vs post-1980) did not reveal any gender differences (pre-1980: 34 women [48%], 37 men [52%]; post-1980: 34 women [55%], 27 men [44%]). However, stratification by era did reveal an age shift toward older patients in the 1980-1995 era. The 5-year median survival for all patients was 36 months. Stratification by era of treatment revealed a long-term survival trend: patients treated before 1980 had somewhat better survival at 60 and 100 months (40% and 36%, respectively) than patients diagnosed and treated between 1980 and 1995 (30% and 23%, respectively), although statistical significance was not reached. CONCLUSION: It is unclear why the long-term survival for patients with sinonasal melanoma seems to be decreasing. Despite advances in imaging techniques, which would potentially allow for earlier tumor discovery, and advances in surgical techniques and adjuvant therapeutics, the mean survival for patients with sinonasal melanoma has not improved during the past 15 years.

Aged↗

PubMed1993

The logic and role of meta-analysis in clinical research.

The term meta-analysis refers to the quantitative combination of data from independent trials. Where the result of such combination is a descriptive summary of the weight of the available evidence, the exercise is of undoubted value. Attempts to apply inferential methods, however, are subject to considerable methodological and logical difficulties. The selection and quality of the trials included, population bias, and the specification of the population to which inference may properly be made are problems to which no satisfactory solutions have been proposed. Insightful quantitative description ought not to differ materially from inferential conclusions; where discrepancies exist the inferential techniques should be regarded with extreme caution.

Bias↗

PubMed1999

Generalized linear mixed models for meta-analysis.

We examine two strategies for meta-analysis of a series of 2 x 2 tables with the odds ratio modelled as a linear combination of study level covariates and random effects representing between-study variation. Penalized quasi-likelihood (PQL), an approximate inference technique for generalized linear mixed models, and a linear model fitted by weighted least squares to the observed log-odds ratios are used to estimate regression coefficients and dispersion parameters. Simulation results demonstrate that both methods perform adequate approximate inference under many conditions, but that neither method works well in the presence of highly sparse data. Under certain conditions with small cell frequencies the PQL method provides better inference.

Humans↗

PubMed1995

Comparison of the results of cemented, porous-ingrowth, and threaded acetabular cup fixation. A meta-analysis of the orthopaedic literature.

A meta-analysis of the orthopaedic literature was performed to evaluate the clinical performance of cementless, threaded acetabular cups. The hypothesis for the study was that the clinical performance of the cementless, threaded acetabular cup is equivalent to that of the cemented and porous-ingrowth acetabular cups. Ninety-five articles were included in the study. There were 1,269 cases in the threaded cup group, 1,979 in the porous control group, and 10,230 in the cemented control group. The primary outcome variable tested was the rate of aseptic loosening of the acetabular components as measured by the revision rates following the index total hip arthroplasty procedure. Other measures of acetabular component loosening that were analyzed included clinical rating scores, pain scores, frequency of radiolucencies according to location and size, frequency of radiolucencies as a separately defined outcome variable, progressive radiolucencies, and component migration. The threaded cup group was found to have a significantly higher rate of revision, clinical and pain score failures, progressive radiolucencies and migrations when compared with the cemented and porous control groups (P < .05). Despite the many limitations of meta-analyses and the poor state of the orthopaedic literature database, this study provides a reasonable comparison of the clinical performance of threaded acetabular cups with that of cemented and porous-ingrowth acetabular cups.

Acetabulum↗

PubMed1997

Comparing medical knowledge of osteopathic medical trainees in DO and MD programs: a random effect meta-analysis.

The authors used random effect meta-analysis to synthesize eight mean score differences of the Part III/Level 3 examinations of the national Board of Osteopathic Medical Examiners (NBOME) between osteopathic medical trainees in DO residency programs and osteopathic medical trainees in MD programs. The analysis involved 6001 trainees and all Part III or Level 3 examinations since 1992. The average mean score difference was not significantly different from zero; however, the estimates of true effect sizes of each examination varied substantially. The findings indicate that, overall, medical knowledge of osteopathic trainees in MD and DO residency programs is compatible at the time they took the examinations. However, a large variation of effect size suggests the need for further investigation of the factors other than difference between osteopathic and allopathic training programs.

Clinical Competence↗

PubMed1988

What patients like about their medical care and how often they are asked: a meta-analysis of the satisfaction literature.

A meta-analysis of studies on consumer satisfaction with medical care yielded 221 studies that reported relations between satisfaction and other variables, of which 107 reported satisfaction levels for two or more aspects of medical care. A method was developed to derive the relative levels of patient satisfaction with 11 aspects of care across these 107 studies. Humaneness and technical quality of medical care were ranked near the top, while the bottom five ranks were occupied by aspects of care that reflected the provider's attention to other patient needs and the patient's relation to the system as a whole. In addition, it was demonstrated that different aspects of medical care are measured with extremely uneven frequencies in satisfaction instruments.

Consumer Behavior↗

PubMed1996

Gamma versus DHS nailing for extracapsular femoral fractures. Meta-analysis of ten randomised trials.

A meta-analysis has been carried out of all published randomised trials which compare the gamma with the DHS nail, giving in a total of 1794 patients with extracapsular femoral fractures. Results showed that the Gamma nail had a significantly increased risk of fracture of the femoral shaft and an increased reoperation rate. There was no difference in the lag screw cut-out rates, incidence of wound infection or length of stay in hospital. The gamma nail cannot be recommended for routine use in trochanteric fractures until the problem of femoral shaft fracture is resolved.

Aged↗

PubMed2003

The efficacy of motivational interviewing: a meta-analysis of controlled clinical trials.

A meta-analysis was conducted on controlled clinical trials investigating adaptations of motivational interviewing (AMIs), a promising approach to treating problem behaviors. AMIs were equivalent to other active treatments and yielded moderate effects (from .25 to .57) compared with no treatment and/or placebo for problems involving alcohol, drugs, and diet and exercise. Results did not support the efficacy of AMIs for smoking or HIV-risk behaviors. AMIs showed clinical impact, with 51% improvement rates, a 56% reduction in client drinking, and moderate effect sizes on social impact measures (d=0.47). Potential moderators (comparative dose, AMI format, and problem area) were identified using both homogeneity analyses and exploratory multiple regression. Results are compared with other review results and suggestions for future research are offered.

Controlled Clinical Trials as Topic↗

PubMed2006

Differential effectiveness of behavioral parent-training and cognitive-behavioral therapy for antisocial youth: a meta-analysis.

Extended the findings from previous meta-analytic work by comparing the effectiveness of behavioral parent-training (BPT) and cognitive-behavioral therapy (CBT) for youth with antisocial behavior problems. Youth demographic variables were also examined as potential moderators of the effectiveness of these 2 types of interventions. Thirty BPT studies and 41 CBT studies met inclusion criteria for this meta-analysis. The weighted mean effect size (ES) for all interventions was 0.40. Youth age was found to moderate the outcome of the 2 interventions, with BPT having a stronger effect for preschool and school-aged youth and CBT having a stronger effect for adolescents. The results also indicate that there may be systematic differences in the outcomes associated with BPT and CBT when the setting of the intervention is considered, suggesting the need to carefully consider the effect of setting in future research. This study also highlights the need for outcome research dealing with more diverse populations and the better classification of research participants on different developmental trajectories of antisocial behavior.

Adolescent↗

PubMed1997

Does pancreatic enzyme supplementation reduce pain in patients with chronic pancreatitis: a meta-analysis.

OBJECTIVE: Pancreatic enzyme therapy is widely used in the treatment of pain in chronic pancreatitis. The aim of our study was to perform a meta-analysis to determine whether pancreatic enzyme supplementation significantly decreases abdominal pain in patients with chronic pancreatitis. METHODS: From a MEDLINE search, we identified, evaluated, and subjected to a meta-analysis, six randomized, double-blind, placebo-controlled trials. Important features of data extraction included the method of subject inclusion, definition of disease, enzyme preparation, response to pancreatic enzyme therapy versus placebo, and modality for measuring response. RESULTS: In the meta-analysis, the pooled estimate of the percentage of patients per study who preferred enzymes relative to placebo was 52% (95% confidence interval, 45-60%). A test of homogeneity indicated that there was no statistically significant heterogeneity across studies in the percentage of patients preferring enzymes. CONCLUSION: Statistical analysis demonstrates no significant benefit of supplemental pancreatic enzyme therapy to relieve pain associated with chronic pancreatitis.

Chronic Disease↗

PubMed1994

Meta-analysis of controlled trials of drug therapy in mild chronic asthma: the role of inhaled corticosteroids.

OBJECTIVE: To determine the role of inhaled corticosteroids in the treatment of mild chronic asthma. SOURCE OF STUDIES: Searches of MEDLINE and Index Medicus for English language literature dealing with asthma and inhaled corticosteroids. DESIGN: All retrieved articles were subjected to predetermined criteria for inclusion in the meta-analysis. Inclusion criteria centered around randomized, double-blind studies reporting objective clinical endpoint(s) for subjects with mild chronic asthma who were treated for more than seven days. Studies that were included were not allowed to have any predetermined exclusion criteria. RESULTS: The literature search identified 129 articles, of which 41 satisfied some but not all of the criteria for inclusion. Five articles met all the criteria and were subjected to meta-analysis. The total number of subjects was 141. Peak expiratory flow rate (PEFR) was used as the objective endpoint for effect size calculation. Subjecting these five studies to quality review revealed a range of 0.607-0.741, with 1 as the highest attainable quality and 0 the lowest. Reported results for the different studies were found to be homogenous, thus allowing for the calculation of overall effect size. Inclusion of children in some of the studies added variance to the reported studies, but not to the point at which studies would be considered heterogenous. Effect sizes ranged between 0.41 and 0.89, and the overall weighted average effect size for PEFR was 0.59, with the calculated 95 percent confidence interval at 0.32 to 0.84. A tabulated display of binomial effect size for included trials provided ranges of success rates for treatment versus control values. Results of the studies were judged robust, as 92 studies reporting no significant effects are needed to turn the finding of the meta-analysis insignificant. CONCLUSIONS: Based on the results of the meta-analysis, the existing literature suggests a role for inhaled corticosteroids in the treatment of mild chronic asthma.

Administration, Inhalation↗