Biomedical subjects

Ben Vandermeer

Publications and source records attributed to Ben Vandermeer.

9 recordsLinked to original sources

PubMed2006

Transition from meeting abstract to full-length journal article for randomized controlled trials.

CONTEXT: Not all research presented at scientific meetings is subsequently published and, even when it is, there may be inconsistencies between these results and what is ultimately printed. Although late-breaking trials sessions are now integrated into several major scientific meetings and the results are often promptly and prominently communicated, no studies have examined the publication fate and degree of consistency between meeting abstracts or presentations and subsequent full-length article publications for randomized controlled trials (RCTs) presented at these sessions. OBJECTIVE: To compare RCT abstracts presented in the late-breaking trials session vs other sessions at a major scientific meeting and subsequent full-length publications. DESIGN: RCTs were identified by hand searching abstract proceedings booklets and related Web sites for the American College of Cardiology scientific meetings (1999-2002). Subsequent full-length articles were identified via electronic databases. MAIN OUTCOME MEASURES: Publication fate and degree of consistency between meeting abstract results and subsequent full-length publication results. RESULTS: The 86 late-breaking RCTs were significantly larger (median, 2737 patients vs 896; P<.001), were more likely to be preceded by a published design paper (27 [31%] vs 13 [13%]; P = .002), had higher quality scores when eventually published (mean Jadad score 2.69 vs 2.19; P = .01), and were less likely to report favorable results for the intervention than the 100 randomly chosen comparison RCTs presented in other sessions (50 [58%] vs 75 [75%]; P = .01; odds ratio 0.46; 95% confidence interval, 0.24-0.90). RCTs presented at the late-breaking trials sessions were significantly more likely to be published (79 [92%] vs 69 [69%]; P<.001) and appeared earlier after presentation (median 11.5 months vs 22.0 months; P<.001) than RCTs presented in other sessions, an association that persisted even after adjusting for sample size, conclusion of study, and RCT design: adjusted hazard ratio, 1.80 (95% confidence interval, 1.24-2.61). Sixty (41%) of the 148 RCTs that were subsequently published exhibited discrepancies between the efficacy estimate reported in the meeting abstract vs the one reported in the full-length article for the primary outcome. The mean change in effect was 0.44 SDs and in 20 cases (14%), the point estimate was statistically significant in only 1 member of the pair. The discrepancy rate was the same for late-breaking RCTs as for RCTs presented in other American College of Cardiology sessions (P = .92). CONCLUSIONS: Late-breaking trials were larger, more likely to be preceded by a design paper, and less likely to report positive results than RCTs presented at other sessions, but discrepancies between the meeting abstract results and subsequent full-length publication results were common even for late-breaking trials.

Abstracting and Indexing↗

PubMed2006

Single data extraction generated more errors than double data extraction in systematic reviews.

BACKGROUND AND OBJECTIVE: To conduct a pilot study to compare the frequency of errors that accompany single vs. double data extraction, compare the estimate of treatment effect derived from these methods, and compare the time requirements for these methods. METHODS: Reviewers were randomized to the role of data extractor or data verifier, and were blind to the study hypothesis. The frequency of errors associated with each method of data extraction was compared using the McNemar test. The data set for each method was used to calculate an efficacy estimate by each method, using standard meta-analytic techniques. The time requirement for each method was compared using a paired t-test. RESULTS: Single data extraction resulted in more errors than double data extraction (relative difference: 21.7%, P = .019). There was no substantial difference between methods in effect estimates for most outcomes. The average time spent for single data extraction was less than the average time for double data extraction (relative difference: 36.1%, P = .003). CONCLUSION: In the case that single data extraction is used in systematic reviews, reviewers and readers need to be mindful of the possibility for more errors and the potential impact these errors may have on effect estimates.

Data Interpretation, Statistical↗

PubMed2006

Efficacy and safety of exogenous melatonin for secondary sleep disorders and sleep disorders accompanying sleep restriction: meta-analysis.

OBJECTIVE: To conduct a systematic review of the efficacy and safety of exogenous melatonin in managing secondary sleep disorders and sleep disorders accompanying sleep restriction, such as jet lag and shiftwork disorder. DATA SOURCES: 13 electronic databases and reference lists of relevant reviews and included studies; Associated Professional Sleep Society abstracts (1999 to 2003). STUDY SELECTION: The efficacy review included randomised controlled trials; the safety review included randomised and non-randomised controlled trials. QUALITY ASSESSMENT: Randomised controlled trials were assessed by using the Jadad Scale and criteria by Schulz et al, and non-randomised controlled trials by the Downs and Black checklist. DATA EXTRACTION AND SYNTHESIS: One reviewer extracted data and another reviewer verified the data extracted. The inverse variance method was used to weight studies and the random effects model was used to analyse data. MAIN RESULTS: Six randomised controlled trials with 97 participants showed no evidence that melatonin had an effect on sleep onset latency in people with secondary sleep disorders (weighted mean difference -13.2 (95% confidence interval -27.3 to 0.9) min). Nine randomised controlled trials with 427 participants showed no evidence that melatonin had an effect on sleep onset latency in people who had sleep disorders accompanying sleep restriction (-1.0 (-2.3 to 0.3) min). 17 randomised controlled trials with 651 participants showed no evidence of adverse effects of melatonin with short term use (three months or less). CONCLUSIONS: There is no evidence that melatonin is effective in treating secondary sleep disorders or sleep disorders accompanying sleep restriction, such as jet lag and shiftwork disorder. There is evidence that melatonin is safe with short term use.

Adolescent↗

PubMed2006

A systematic review identifies a lack of standardization in methods for handling missing variance data.

BACKGROUND AND OBJECTIVES: To describe and critically appraise available methods for handling missing variance data in meta-analysis (MA). METHODS: Systematic review. MEDLINE, EMBASE, Web of Science, MathSciNet, Current Index to Statistics, BMJ SearchAll, The Cochrane Library and Cochrance Colloquium proceedings, MA texts and references were searched. Any form of text was included: MA, method chapter, or otherwise. Descriptions of how to implement each method, the theoretic basis and/or ad hoc motivation(s), and the input and output variable(s) were extracted and assessed. Methods may be: true imputations, methods that obviate the need for a standard deviation (SD), or methods that recalculate the SD. RESULTS: Eight classes of methods were identified: algebraic recalculations, approximate algebraic recalculations, imputed study-level SDs, imputed study-level SDs from nonparametric summaries, imputed study-level correlations (e.g., for change-from-baseline SD), imputed MA-level effect sizes, MA-level tests, and no-impute methods. CONCLUSION: This work aggregates the ideas of many investigators. The abundance of methods suggests a lack of consistency within the systematic review community. Appropriate use of methods is sometimes suspect; consulting a statistician, early in the review process, is recommended. Further work is required to optimize method choice to alleviate any potential for bias and improve accuracy. Improved reporting is also encouraged.

Data Interpretation, Statistical↗

PubMed2006

A systematic review of intentional delivery in women with preterm prelabor rupture of membranes.

OBJECTIVE: To evaluate the effect of intentional delivery versus expectant management in women with preterm prelabor rupture of membranes (PPROM). METHODS: We searched electronic databases and trials registries, contacted experts, and checked reference lists of relevant studies. Studies were included if they were randomized controlled trials comparing intentional delivery versus expectant management after PPROM, the gestational age of participants was between 30 and 36 weeks, and the study reported one of several pre-determined outcomes. RESULTS: Four studies were included in the meta-analysis. No difference was found between intentional delivery and expectant management in neonatal intensive care unit (NICU) length of stay (LOS) (weighted mean difference (WMD) -0.81 day, 95% confidence interval (CI) -1.66, 0.04), respiratory distress syndrome (risk difference (RD) -0.01, 95% CI -0.07, 0.06), and confirmed neonatal sepsis (RD -0.01, 95% CI -0.05, 0.04). One study found a significantly lower incidence of suspected neonatal sepsis among the intentional delivery group (RD -0.31, 95% CI -0.50, -0.12; number needed to treat (NNT) 3, 95% CI 2, 8). Maternal LOS was significantly shorter for the intentional delivery group (WMD -1.39 day, 95% CI -2.03, -0.75). There was a significant difference in the incidence of clinical chorioamnionitis favoring intentional delivery (RD -0.16, 95% CI -0.23, -0.10; NNT 6, 95% CI 5, 11). There was no significant difference in the incidence of other maternal outcomes, including cesarean section (RD 0.05, 95% CI -0.01, 0.11). CONCLUSIONS: Intentional delivery may be favorable to expectant management for some maternal outcomes (chorioamnionitis and LOS). There is insufficient evidence to suggest that either strategy is beneficial or harmful for the baby. Large multicenter trials with primary neonatal outcomes are required to assess whether intentional delivery is associated with less neonatal morbidity.

Cesarean Section↗

PubMed2006

Bacterial contamination of health care workers' pagers and the efficacy of various disinfecting agents.

Health care workers in our facility were surveyed, and their pagers were cultured before and after disinfection with various agents. All pagers were contaminated with bacteria, including the pathogens Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella spp. and methicillin-resistant S. aureus. Disinfection reduced bacterial contamination. No risk factors for pager contamination with pathogens were identified.

Bacteria↗

PubMed2005

Meta-analysis: secondary prevention programs for patients with coronary artery disease.

BACKGROUND: Although supervised exercise programs reduce mortality in survivors of myocardial infarction, the effects of other types of cardiac secondary prevention programs are unknown. PURPOSE: To determine the effectiveness of secondary cardiac prevention programs with and without exercise components. DATA SOURCES: The authors searched MEDLINE (1966-2004), the Cochrane Central Register of Controlled Trials, EMBASE, CINAHL, SIGLE, and the Cochrane Effective Practice and Organization of Care Study Registry. They also contacted primary study authors and hand-searched bibliographies provided by the Centers for Medicare & Medicaid Services. STUDY SELECTION: Randomized clinical trials. DATA EXTRACTION: Two reviewers chose studies and extracted data independently; random-effects summary risk ratios were calculated. DATA SYNTHESIS: The authors identified 63 randomized trials (21 295 patients with coronary disease). The summary risk ratio was 0.85 (95% CI, 0.77 to 0.94) for all-cause mortality, but this result differed over time with a risk ratio of 0.97 (CI, 0.82 to 1.14) at 12 months and 0.53 (CI, 0.35 to 0.81) at 24 months. The summary risk ratio was 0.83 (CI, 0.74 to 0.94) for recurrent myocardial infarction over a median follow-up of 12 months. Effects were similar for programs that included risk factor education or counseling with a structured exercise component (risk ratio, 0.88 [CI, 0.74 to 1.04] for mortality and 0.62 [CI, 0.44 to 0.87] for myocardial infarction), for programs that included risk factor education or counseling without an exercise component (risk ratio, 0.87 [CI, 0.76 to 0.99] for mortality and 0.86 [CI, 0.72 to 1.03] for myocardial infarction), and for programs that were solely exercise-based (risk ratio, 0.72 [CI, 0.54 to 0.95] for mortality and 0.76 [CI, 0.57 to 1.01] for myocardial infarction). Most of these programs improved quality of life or functional status, but effect sizes were small. LIMITATIONS: Although these programs may reduce total health care costs, published data on the costs of the programs are inadequate to conclusively comment on their cost-effectiveness. CONCLUSIONS: A wide variety of secondary prevention programs improve health outcomes in patients with coronary disease.

Cause of Death↗

PubMed2005

A systematic review of intravenous gamma globulin for therapy of acute myocarditis.

BACKGROUND: Intravenous gamma globulin (IVGG) is commonly used in the management of acute myocarditis. The objective of this study was to systematically review the literature evaluating this practice. METHODS: We conducted a comprehensive search (electronic databases, trials registries, conference proceedings, reference lists, contact with authors) to identify studies evaluating the use of IVGG in adults and children with a clinical or histologically proven diagnosis of myocarditis of possible viral etiology and symptoms of less than six months duration. Two reviewers independently screened the searches, applied inclusion criteria, and graded the evidence. RESULTS: Results were described qualitatively; data were not pooled because only one randomized controlled trial (RCT) with 62 patients was identified. The RCT showed no benefit with respect to cardiac function, functional outcome, or event-free survival. A small, uncontrolled trial (n = 10) showed significant improvement in LVEF from a mean of 24% to 41% 12 months after IVGG in nine survivors. A retrospective cohort study of pediatric patients showed improvement in cardiac function and a trend towards improved survival in patients receiving IVGG (n = 21) versus historic controls (n = 25). Ten case reports and two case series (total n = 21) described improvement in cardiac function after administration of IVGG; two case reports showed no benefit of IVGG. One case of hemolytic anemia was attributed to IVGG. CONCLUSION: There is insufficient data from methodologically strong studies to recommend routine use of IVGG for acute myocarditis. Future randomized studies that take into account the etiology of acute myocarditis will be required to determine the efficacy of IVGG.

Acute Disease↗

PubMed2005

The efficacy and safety of exogenous melatonin for primary sleep disorders. A meta-analysis.

BACKGROUND: Exogenous melatonin has been increasingly used in the management of sleep disorders. PURPOSE: To conduct a systematic review of the efficacy and safety of exogenous melatonin in the management of primary sleep disorders. DATA SOURCES: A number of electronic databases were searched. We reviewed the bibliographies of included studies and relevant reviews and conducted hand-searching. STUDY SELECTION: Randomized controlled trials (RCTs) were eligible for the efficacy review, and controlled trials were eligible for the safety review. DATA EXTRACTION: One reviewer extracted data, while the other verified data extracted. The Random Effects Model was used to analyze data. DATA SYNTHESIS: Melatonin decreased sleep onset latency (weighted mean difference [WMD]: -11.7 minutes; 95% confidence interval [CI]: -18.2, -5.2)); it was decreased to a greater extent in people with delayed sleep phase syndrome (WMD: -38.8 minutes; 95% CI: -50.3, -27.3; n=2) compared with people with insomnia (WMD: -7.2 minutes; 95% CI: -12.0, -2.4; n=12). The former result appears to be clinically important. There was no evidence of adverse effects of melatonin. CONCLUSIONS: There is evidence to suggest that melatonin is not effective in treating most primary sleep disorders with short-term use (4 weeks or less); however, additional large-scale RCTs are needed before firm conclusions can be drawn. There is some evidence to suggest that melatonin is effective in treating delayed sleep phase syndrome with short-term use. There is evidence to suggest that melatonin is safe with short-term use (3 months or less).

Humans↗