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D Moher

Publications and source records attributed to D Moher.

At least 73 records · Page 4Linked to original sources
PubMed1996

Completeness of reporting of trials published in languages other than English: implications for conduct and reporting of systematic reviews.

BACKGROUND: Lately, the number of systematic reviews published has increased substantially. Many systematic reviews exclude trials published in languages other than English. However, there is little empirical evidence to support this action. We looked for differences in the completeness of reporting between trials published in other languages and those published in English, to see whether the exclusion of trials published in other languages is justified. METHODS: We compared completeness of reporting, design characteristics, and analytical approaches of 133 randomised controlled trials (RCTs) published in English between 1989 and 1994 and 96 published in French, German, Italian, or Spanish during the same time. RCTs were identified by hand searching of journals (seven in English and six in the other languages). FINDINGS: We found no significant differences between trials published in English and other-language trials for any single item in the completeness of reporting scale (randomisation, double-blinding, withdrawals), or for the overall score (percentage of maximum possible score 51.0% for trials in English, 46.2% for trials in other languages; 95% CI for difference -1.1 to 10.5). Other-language trials were more likely than English-language trials to have adult participants, to use two or more interventions, and to compare two or more active treatments without an untreated control group. Trials in other languages were less likely to report a clearly prespecified primary outcome or any rationale for sample size estimation. INTERPRETATION: These results provide evidence for inclusion of all trial reports, irrespective of the language in which they are published, in systematic reviews. Their inclusion is likely to increase precision and may reduce systematic errors. We hope that our findings will prove useful to those developing guidelines and policies for the conduct of reporting of systematic reviews.

Adult↗
PubMed1996

Assessing the quality of randomized controlled trials. Current issues and future directions.

Assessing the quality of randomized controlled trials is a relatively new and important development. Three approaches have been developed: component, checklist, and scale assessment. Component approaches evaluate selected aspects of trials, such as masking. Checklists and scales involve lists of items thought to be integral to study quality. Scales, unlike the other methods, provide a summary numeric score of quality, which can be formally incorporated into a systematic review. Most scales to date have not been developed with sufficient rigor, however. Empirical evidence indicates that differences in scale development can lead to important differences in quality assessment. Several methods for including quality scores in systematic reviews have been proposed, but since little empirical evidence supports any given method, results must be interpreted cautiously. Future efforts may be best focused on gathering more empirical evidence to identify trial characteristics directly related to bias in the estimates of intervention effects and on improving the way in which trials are reported.

Data Interpretation, Statistical↗
PubMed1996

Nephrotoxicity of ioxaglate and ioversol assessed by glomerular filtration rate: a pilot study.

OBJECTIVE: To determine the effect of ioxaglate and ioversol on glomerular filtration rate (GFR) in a heterogeneous inpatient group to allow calculation of the necessary sample size for a randomized trial. PATIENTS AND METHODS: The study group consisted of 36 men and 12 women, ranging in age from 25 to 79 (mean 63) years. Fourteen of the patients, those undergoing abdominal aortography with or without renal arteriography, received ioxaglate (Hexabrix 320; 40 to 240 [mean 141] mL), and the remaining 34, those receiving intravenous injections and those undergoing computed tomography with arterioportography or carotid arteriography, received ioversol (Optiray 320; 20 to 180 [mean 87] mL). GFR was measured by determining the clearance of diethyl-enetriaminepenta-acetic acid labelled with technetium-99m up to 72 hours before and 24 hours after administration of the contrast medium. Risk factors for nephrotoxicity included diabetes (7 patients) and pre-existing renal impairment (mild in 11 and severe in 6). RESULTS: GFR decreased by 20% to 34% in six patients (13%); in only one of these was the serum level of creatinine increased at 24 hours. One of these six patients had received 120 mL of ioversol for carotid arteriography and had no risk factors for nephrotoxicity. The other five had received 40 to 187 (mean 115) mL of ioxaglate, three for abdominal aortography and two for selective renal arteriography. The risk factors in these patients included diabetes (two patients) and severe pre-existing renal impairment (two patients). Renal failure necessitating treatment did not develop in any of the patients. CONCLUSIONS: A decrease in GFR occurred more often with ioxaglate than with ioversol and usually occurred in patients with additional risk factors. Injection of contrast medium into the abdominal aorta or the renal artery may increase the risk of nephrotoxicity. Changes in serum level of creatinine at 24 hours were not reliable in identifying patients with decreased GFR. On the basis of these data, the authors estimate that a group of 194 patients would be necessary for a randomized trial comparing the nephrotoxicity of ioxaglate and ioversol for abdominal aortography.

Adult↗
PubMed1995

Assessing the quality of randomized controlled trials: an annotated bibliography of scales and checklists.

Assessing the quality of randomized controlled trials (RCTs) is important and relatively new. Quality gives us an estimate of the likelihood that the results are a valid estimate of the truth. We present an annotated bibliography of scales and checklists developed to assess quality. Twenty-five scales and nine checklists have been developed to assess quality. The checklists are most useful in providing investigators with guidelines as to what information should be included in reporting RCTs. The scales give readers a quantitative index of the likelihood that the reported methodology and results are free of bias. There are several shortcomings with these scales. Future scale development is likely to be most beneficial if questions common to all trials are assessed, if the scale is easy to use, and if it is developed with sufficient rigor.

Bias↗
PubMed1994

Statistical power, sample size, and their reporting in randomized controlled trials.

OBJECTIVE: To describe the pattern over time in the level of statistical power and the reporting of sample size calculations in published randomized controlled trials (RCTs) with negative results. DESIGN: Our study was a descriptive survey. Power to detect 25% and 50% relative differences was calculated for the subset of trials with negative results in which a simple two-group parallel design was used. Criteria were developed both to classify trial results as positive or negative and to identify the primary outcomes. Power calculations were based on results from the primary outcomes reported in the trials. POPULATION: We reviewed all 383 RCTs published in JAMA, Lancet, and the New England Journal of Medicine in 1975, 1980, 1985, and 1990. RESULTS: Twenty-seven percent of the 383 RCTs (n = 102) were classified as having negative results. The number of published RCTs more than doubled from 1975 to 1990, with the proportion of trials with negative results remaining fairly stable. Of the simple two-group parallel design trials having negative results with dichotomous or continuous primary outcomes (n = 70), only 16% and 36% had sufficient statistical power (80%) to detect a 25% or 50% relative difference, respectively. These percentages did not consistently increase over time. Overall, only 32% of the trials with negative results reported sample size calculations, but the percentage doing so has improved over time from 0% in 1975 to 43% in 1990. Only 20 of the 102 reports made any statement related to the clinical significance of the observed differences. CONCLUSIONS: Most trials with negative results did not have large enough sample sizes to detect a 25% or a 50% relative difference. This result has not changed over time. Few trials discussed whether the observed differences were clinically important. There are important reasons to change this practice. The reporting of statistical power and sample size also needs to be improved.

Publishing↗
PubMed1994

Definition and management of abdominal aortic aneurysms: results from a Canadian survey.

OBJECTIVE: To assess how vascular surgeons define and manage asymptomatic abdominal aortic aneurysms (AAAs) 5.4 cm in diameter or smaller. DESIGN: Descriptive survey. SETTING: All provinces and territories of Canada. PARTICIPANTS: One hundred and ninety-one vascular surgeons. INTERVENTIONS: A 12-item questionnaire sent in two mailings to all vascular surgeons who were members of the Canadian Society for Vascular Surgery. MAIN OUTCOME MEASURES: Definition and routine management of asymptomatic AAAs assessment of aneurysm size before elective surgery and basic personal data. RESULTS: One hundred and sixty-seven (87%) vascular surgeons responded to the mailings; 149 (78%) completed the questionnaire. The majority of respondents were experienced (78%), academic (70%) vascular surgeons. AAAs were defined in any one of four ways. There was notable consistency regarding the size range in which vascular surgeons seriously considered elective surgical repair of small aneurysms. CONCLUSION: Standards need to be developed to define what constitutes a small AAA if meaningful research on small aneurysms is to be conducted.

Aortic Aneurysm, Abdominal↗
PubMed1993

Publication bias.

Explore the source record for details and available documents.

Clinical Trials as Topic↗
PubMed1993

Cigarette smoking and peripheral arterial occlusive disease.

BACKGROUND: The importance of cigarette smoking in the etiology of peripheral arterial occlusive disease is well known, but there have been few studies that have quantified this relationship. METHODS: A case-control study design was used in which the case subjects were men with a history of claudication for at least 1 year and abnormal findings on noninvasive blood flow studies or on arteriography; control subjects were men attending the same hospital for conditions other than cancer, with no history of cancer or vascular disease and with a normal ankle-brachial index. Case and control subjects were interviewed by a trained nurse interviewer using a pilot-tested questionnaire. Current smoking status was confirmed by serum cotinine level estimation. Univariate odds ratios for smoking and other potential risk factors were calculated, and their significance was tested by comparison with the chi-squared distribution. Logistic regression analysis was used to adjust the effect of smoking for confounding variables, and the regression equation was used to estimate the proportion of disease attributable to smoking. RESULTS: Of the patients approached, 94% of the eligible case subjects and 93% of the eligible control subjects agreed to participate. Recruitment ended with 102 cases of peripheral arterial occlusive disease and 99 controls. Most of the control subjects were attending clinics for other surgical specialties. Compared with men who had never smoked the relative risk was 7 for exsmokers and 16 for current smokers (p < 0.001). The relative risk increased directly with the lifetime number of cigarettes smoked, the chi-squared test for trend being highly significant (p < 0.001). Age, lipoprotein concentration, body mass index, and history of hypertension or heart disease were also significant risk factors. CONCLUSIONS: After adjustment for confounding variables the estimate of the fraction of disease attributable to smoking was 76%.

Arterial Occlusive Diseases↗
PubMed1993

A prospective comparison of abdominal hysterectomy using absorbable staples.

Forty-eight abdominal hysterectomies performed using Polysorb (United States Surgical Corporation) [corrected] absorbable staples were compared prospectively with 46 hysterectomies performed using a regular suture technique. The two groups were demographically similar and it was found that the time of operation (p = 0.001) and the amount of blood loss at operation was significantly reduced (p = 0.03). The incidence of granulations at the vaginal vault at six weeks was significantly reduced (p = 0.001) and return to activity (p = 0.02) and work (p = 0.01) were also significantly reduced for the patients who had a hysterectomy performed using Polysorb staples. There was no statistical difference in morbidity, complications, use of analgesics and period of hospitalization. The continued use of absorbable staples in abdominal hysterectomy is supported, related to the advantages that were statistically significant.

Adult↗
PubMed1993

A comparison between expanded polytetrafluoroethylene and plasma tetrafluoroethylene grafts for hemodialysis access.

Animal studies have indicated that plasma tetrafluoroethylene (TFE) may be a better prosthetic material than expanded polytetrafluoroethylene (ePTFE) for arteriovenous access in patients who require hemodialysis because it combines the advantages of both Dacron and Teflon. A randomized clinical trial to compare the two materials was conducted between May 1987 and January 1989. Forty-four patients were enrolled, 22 in each group. The status of the grafts was monitored for at least 18 months. The patency rate for plasma TFE was 59% and for ePTFE was 64%. Kaplan-Meier analysis and Wilcoxon testing revealed no statistical differences between the two groups. Four grafts became infected, two in each group, and one aneurysm developed. Despite its theoretical advantages, plasma TFE was found to be similar to ePTFE as a graft material for hemodialysis.

Aged↗