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Biomedical subjects

Victor M Montori

Publications and source records attributed to Victor M Montori.

At least 19 recordsLinked to original sources
PubMed2005

Milk thistle and indinavir: a randomized controlled pharmacokinetics study and meta-analysis.

OBJECTIVES: To determine whether ingestion of milk thistle affects the pharmacokinetics of indinavir. METHODS: We conducted a three-period, randomized controlled trial with 16 healthy participants. We randomized participants to milk thistle or control. All participants received initial dosing of indinavir, and baseline indinavir levels were obtained (AUC(0-8)) (phase I). The active group were then given 450 mg milk-thistle extract capsules to be taken t.i.d. from day 2 to day 30. The control group received no plant extract. On day 29 and day 30, indinavir dosing and sampling was repeated in both groups as before (phase II). After a wash-out period of 7 days, indinavir dosing and sampling were repeated as before (phase III). RESULTS: All participants completed the trial, but two were excluded from analysis due to protocol violation. There were no significant between-group differences. Active group mean AUC(0-8) indinavir decreased by 4.4% (90% CI, -27.5% to -26%, P=0.78) from phase I to phase II in the active group, and by 17.3% (90% CI, -37.3% to +9%, P=0.25) in phase III. Control group mean AUC(0-8) decreased by 21.5% (90% CI, -43% to +8%, P=0.2) from phase I to phase II and by 38.5% (90% CI, -55.3% to -15.3%, P=0.01) of baseline at phase III. To place our findings in context, milk thistle-indinavir trials were identified through systematic searches of the literature. A meta-analysis of three milk thistle-indinavir trials revealed a non-significant pooled mean difference of 1% in AUC(0-8) (95% CI, -53% to 55%, P=0.97). CONCLUSIONS: Indinavir levels were not reduced significantly in the presence of milk thistle.

Adult↗
PubMed2004

Optimal search strategies for retrieving systematic reviews from Medline: analytical survey.

OBJECTIVE: To develop optimal search strategies in Medline for retrieving systematic reviews. DESIGN: Analytical survey. DATA SOURCES: 161 journals published in 2000 indexed in Medline. MAIN OUTCOME MEASURES: The sensitivity, specificity, and precision of retrieval of systematic reviews of 4862 unique terms in 782,485 combinations of one to five terms were determined by comparison with a hand search of all articles (the criterion standard) in 161 journals published during 2000 (49,028 articles). RESULTS: Only 753 (1.5%) of the 49,028 articles were systematic reviews. The most sensitive strategy included five terms and had a sensitivity of 99.9% (95% confidence interval 99.6% to 100%) and a specificity of 52% (51.6% to 52.5%). The strategy that best minimised the difference between sensitivity and specificity had a sensitivity of 98% (97% to 99%) and specificity of 90.8% (90.5% to 91.1%). Highest precision for multiterm strategies, 57% (54% to 60%), was achieved at a sensitivity of 71% (68% to 74%). The term "cochrane database of systematic reviews.jn." was the most precise single term search strategy (sensitivity of 56% (52% to 60%) and precision of 96% (94% to 98%)). These strategies are available through the "limit" screen of Ovid's search interface for Medline. CONCLUSIONS: Systematic reviews can be retrieved from Medline with close to perfect sensitivity or specificity, or with high precision, by using empirical search strategies.

Information Storage and Retrieval↗
PubMed2004

Interaction of St John's wort with conventional drugs: systematic review of clinical trials.

OBJECTIVE: To determine the methodological quality of clinical trials that examined possible interactions of St John's wort with conventional drugs, and to examine the results of these trials. DESIGN: Systematic review. DATA SOURCES: Electronic databases from inception to April 2004, reference lists from published reports, and experts in the field. STUDY SELECTION: Eligible studies were prospective clinical trials evaluating the pharmacokinetic effect of St John's wort on the metabolism of conventional drugs. DATA EXTRACTION: Two reviewers selected studies for inclusion and independently extracted data. DATA SYNTHESIS: 22 pharmacokinetic trials studied an average of 12 (SD 5) participants; 17 trials studied healthy volunteers and five studied patients. Most (17) studies used a "before and after" design; four studies used control groups other than the active group. Three studies randomised the sequence of administration or the participants to study arms or periods; three studies blinded participants or investigators. In 15 trials, investigators independently assayed the herb. Of 19 trials with available plasma data, three found no important interaction (change in area under the curve < 20%) and 17 found a decrease in systemic bioavailability of the conventional drug; in seven studies the 95% confidence interval excluded a decrease of < 20%. CONCLUSION: Clinicians and patients should beware of possible decreases in the systemic bioavailability of conventional drugs when taken concomitantly with St John's wort.

Area Under Curve↗
PubMed2004

Author self-citation in the diabetes literature.

BACKGROUND: Author self-citation is the practice of citing one's previous publications in a new publication. Its extent is unknown. We studied author self-citation, choosing the major clinical field of diabetes mellitus to represent the general medical literature. METHODS: We identified every article about diabetes mellitus in 170 hand-searched clinical journals published in 2000. For every article, we recorded the bibliographic citation and publication type (original or review article) and assessed the methodologic rigour. Citation information was obtained from the ISI Web of Knowledge in April 2003. RESULTS: Of 49,028 articles, 289 were about diabetes mellitus and had citation information. Citation counts ranged from 0 to 347 (median 6, interquartile range [IQR] 2-12). Author self-citation counts ranged from 0 to 16 (median 1, IQR 0-2). Author self-citations accounted for an average of 18% (95% confidence interval [CI] 15%-21%) and a median of 7% (95% CI 5%- 11%) of all citations of each publication that was cited at least once (n = 266). Original articles had double the mean proportion of author self-citations compared with review articles (19% v. 9%; median 7% v. 0%, difference 7%, 95% CI 0- 10%). Methodologic rigour and review type were not significantly associated with subsequent author self-citation. INTERPRETATION: Nearly one-fifth of all citations to articles about diabetes mellitus in clinical journals in the year 2000 were author self-citations. The frequency of self-citation was not associated with the quality of publications. These findings are likely applicable to the general clinical medicine literature and may have important implications for the assessment of journal or publication importance and the process of scientific discovery.

Authorship↗
PubMed2004

Association between industry funding and statistically significant pro-industry findings in medical and surgical randomized trials.

BACKGROUND: Conflicting reports exist in the medical literature regarding the association between industry funding and published research findings. In this study, we examine the association between industry funding and the statistical significance of results in recently published medical and surgical trials. METHODS: We examined a consecutive series of 332 randomized trials published between January 1999 and June 2001 in 8 leading surgical journals and 5 medical journals. Each eligible study was independently reviewed for methodological quality using a 21-point index with 5 domains: randomization, outcomes, eligibility criteria, interventions and statistical issues. Our primary analysis included studies that explicitly identified the primary outcome and reported it as statistically significant. For studies that did not explicitly identify a primary outcome, we defined a "positive" study as one with at least 1 statistically significant outcome measure. We used multivariable regression analysis to determine whether there was an association between reported industry funding and trial results, while controlling for study quality and sample size. RESULTS: Among the 332 randomized trials, there were 158 drug trials, 87 surgical trials and 87 trials of other therapies. In 122 (37%) of the trials, authors declared industry funding. An unadjusted analysis of this sample of trials revealed that industry funding was associated with a statistically significant result in favour of the new industry product (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.3-3.5). The association remained significant after adjustment for study quality and sample size (adjusted OR 1.8, 95% CI 1.1-3.0). There was a nonsignificant difference between surgical trials (OR 8.0, 95% CI 1.1-53.2) and drug trials (OR 1.6, 95% CI 1.1-2.8), both of which were likely to have a pro-industry result (relative OR 5.0, 95% CI 0.7-37.5, p = 0.14). INTERPRETATION: Industry-funded trials are more likely to be associated with statistically significant pro-industry findings, both in medical trials and surgical interventions.

Conflict of Interest↗
PubMed2004

An observational study found that authors of randomized controlled trials frequently use concealment of randomization and blinding, despite the failure to report these methods.

BACKGROUND AND OBJECTIVE: Readers of randomized controlled trials (RCTs) commonly assume that what was not reported did not occur. We undertook an observational study to determine whether concealment of randomization or blinding was used in RCTs that failed to report these bias-reducing strategies. METHODS: We recorded the reporting of concealment of randomization and blinding in 105 RCTs. We subsequently contacted the authors and determined if they had used these methodological safeguards. RESULTS: We successfully obtained data from 98 authors. The authors in the full-text publications of these 98 RCTs failed to report the presence or absence of concealment of randomization in 55%, and the blinding status of participants in 26%, health care providers in 64%, data collectors in 84%, outcome assessors in 83%, and data analysts in 96%. In direct contact, authors frequently reported concealing randomization (96%; 95% confidence interval CI=87-100%), blinding participants (20%; 95% CI=7-41%), blinding health care providers (65%; 95% CI=52-77%), blinding data collectors (65%; 95% CI=53-75%), blinding outcome assessors (79%; 95% CI=69-87%), and blinding data analysts (50%; 95% CI=40-60%), despite not reporting the use of these methodological safeguards in their publications. CONCLUSIONS: Readers should not assume that bias-reducing procedures not reported in an RCT did not occur.

Bias↗
PubMed2004

Measurement of agreement on health-related quality of life changes in response to respiratory rehabilitation by patients and physicians--a prospective study.

INTRODUCTION: To provide optimal care for patients with chronic obstructive pulmonary disease physicians need to understand if their patients benefit from an intervention. The objective of this study was to assess agreement between patients and physicians on health-related quality of life (HRQL) changes in response to respiratory rehabilitation and to explore sources for disagreement. METHODS: Sixty-one patients rated their health states on a validated preference-based instrument, the feeling thermometer (FT). In an analogous manner, the eight treating physicians rated the patients' health states on the FT. Patients and physicians were blinded to each other's ratings. We calculated intraclass correlation coefficients (ICC) to assess agreement between patients and physicians and used HRQL instruments and the 6-min walking test to assess the evaluative properties of the FT. RESULTS: We found moderate agreement at baseline (ICC 0.40, P = 0.018) and follow-up (ICC 0.49, P = 0.008) but large disagreement about change scores (ICC 0.02, P = 0.46). Patients' FTchange scores correlated well with change scores of the Chronic Respiratory Questionnaire, SF-36 and the Borg scale for dyspnoea whereas physicians' FT change scores correlated significantly with the change score of the 6- min walking test (r = 0.33). Physicians' ratings showed an inconsistent pattern for correlations with HRQL measures. CONCLUSIONS: There is large disagreement between patients and physicians on HRQL changes in response to respiratory rehabilitation. Investigators should assess whether the introduction of HRQL instruments into clinical practice raises the awareness of physicians towards HRQL and improves agreement with their patients.

Adult↗
PubMed2004

Determining the reporting quality of RCTs in clinical pharmacology.

BACKGROUND: The Consolidated Standards for Reporting Trials (CONSORT) are recommendations for improving the quality of reports of randomized controlled trials (RCTs). OBJECTIVE: To determine the extent to which clinical pharmacology journals implement specific CONSORT recommendations. DESIGN AND SETTING: Analysis of RCTs published between May 2002 and May 2003 in four clinical pharmacology journals. MAIN OUTCOME MEASURES: Proportion of RCTs that published a participant flow diagram and that reported on randomization and restriction methods, allocation concealment, blinding, intention-to-treat analysis, ethical considerations, adverse events and source of funding. RESULTS: Of 482 clinical trials, 193 were RCTs. Healthy participants were involved in 129 [66.8%, 95% confidence interval (CI) 59.9, 73.1] trials, patients who required treatment in 61 (31.6%, 95% CI 25.4, 38.4) trials and both in three (1.6%, 95% CI 0.5, 4.4) trials. The following items were infrequently reported: sequence generation (17%), allocation concealment (3%), use of restriction (16%), description of blinding (26%), and flow diagrams of study participants (2%). In contrast, the following areas were often reported: use of intention-to-treat analysis (79%), description of withdrawals (92.2%) and description of adverse events (71%), ethics review (94%) and informed consent (95%). Sources of funding were reported in 56% of studies. CONCLUSION: The use of the selected CONSORT items is limited in these journals, possibly as many items may not be relevant to the types of studies published in clinical pharmacology journals. Further efforts are required to determine the applicability of CONSORT to RCTs in clinical pharmacology.

Humans↗
PubMed2004

Telecare for patients with type 1 diabetes and inadequate glycemic control: a randomized controlled trial and meta-analysis.

OBJECTIVE: To determine the efficacy of telecare (modem transmission of glucometer data and clinician feedback) to support intensive insulin therapy in patients with type 1 diabetes and inadequate glycemic control. RESEARCH DESIGN AND METHODS: Thirty-one patients with type 1 diabetes on intensive insulin therapy and with HbA1c >7.8% were randomized to telecare (glucometer transmission with feedback) or control (glucometer transmission without feedback) for 6 months. The primary end point was 6-month HbA1c. To place our findings in context, we pooled HbA1c change from baseline reported in randomized trials of telecare identified in a systematic review of the literature. RESULTS: Compared with the control group, telecare patients had a significantly lower 6-month HbA1c (8.2 vs. 7.8%, P = 0.03, after accounting for HbA1c at baseline) and a nonsignificant fourfold greater chance of achieving 6-month HbA1c < or =7% (29 vs. 7%; risk difference 21.9%, 95% CI -4.7 to 50.5). Nurses spent 50 more min/patient giving feedback on the phone with telecare patients than with control patients. Meta-analysis of seven randomized trials of adult patients with type 1 diabetes found a 0.4% difference (95% CI 0-0.8) in HbA1c mean change from baseline between the telecare and control groups. CONCLUSIONS: Telecare is associated with small effects on glycemic control in patients with type 1 diabetes on intensive insulin therapy but with inadequate glycemic control.

Adult↗
PubMed2004

Doubling the impact: publication of systematic review articles in orthopaedic journals.

BACKGROUND: Investigators aim to publish their research papers in top journals to disseminate their findings to the widest possible audience. Systematic reviews of the literature occupy the highest position in currently proposed hierarchies of evidence. We hypothesized that the number of citations (a measure of scholarly interest) for systematic reviews (or meta-analyses) published in leading orthopaedic journals would be greater than the number of citations for narrative reviews published in the same journals. METHODS: We identified fifteen journals that had high Science Citation Index impact factors for the orthopaedic subspecialty and were believed to have a higher yield of studies and reviews of scientific merit and clinical relevance. For the year 2000, six research associates applied methodological criteria to each article in each issue of the fifteen journals to determine whether the article was scientifically sound (rigorous versus nonrigorous). Of the 3916 articles identified, 2331 were original or review articles. We queried the ISI (Institute for Scientific Information) Web of Science database to ascertain, as of March 2003, the number of subsequent citations to each one of the reviews after its original publication in all journals that published both narrative and systematic reviews. RESULTS: Of the 2331 articles published across the fifteen journals in the year 2000, 110 were review articles. Only seventeen (15%) of the 110 reviews met our criteria for systematic reviews with rigor. Rigorous systematic reviews received more than twice the mean number of citations compared with other systematic or narrative reviews (13.8 compared with 6.0, p = 0.008). The rigor of a review was a significant predictor of the number of citations in other orthopaedic journals (p = 0.01). In addition, rigor was significantly associated with the number of citations in nonorthopaedic journals (p = 0.03). CONCLUSIONS: Our findings suggest that journal editors and authors can improve the relevance and scholarly interest in their reviews (as shown by the number of citations) by meeting standard guidelines for methodological rigor.

Humans↗
PubMed2003

Systematic reviews: a cross-sectional study of location and citation counts.

BACKGROUND: Systematic reviews summarize all pertinent evidence on a defined health question. They help clinical scientists to direct their research and clinicians to keep updated. Our objective was to determine the extent to which systematic reviews are clustered in a large collection of clinical journals and whether review type (narrative or systematic) affects citation counts. METHODS: We used hand searches of 170 clinical journals in the fields of general internal medicine, primary medical care, nursing, and mental health to identify review articles (year 2000). We defined 'review' as any full text article that was bannered as a review, overview, or meta-analysis in the title or in a section heading, or that indicated in the text that the intention of the authors was to review or summarize the literature on a particular topic. We obtained citation counts for review articles in the five journals that published the most systematic reviews. RESULTS: 11% of the journals concentrated 80% of all systematic reviews. Impact factors were weakly correlated with the publication of systematic reviews (R2 = 0.075, P = 0.0035). There were more citations for systematic reviews (median 26.5, IQR 12 - 56.5) than for narrative reviews (8, 20, P <.0001 for the difference). Systematic reviews had twice as many citations as narrative reviews published in the same journal (95% confidence interval 1.5 - 2.7). CONCLUSIONS: A few clinical journals published most systematic reviews. Authors cited systematic reviews more often than narrative reviews, an indirect endorsement of the 'hierarchy of evidence'.

Bibliometrics↗
PubMed2003

The safety of over-the-counter niacin. A randomized placebo-controlled trial [ISRCTN18054903].

BACKGROUND: Niacin is widely available over the counter (OTC). We sought to determine the safety of 500 mg immediate release niacin, when healthy individuals use them as directed. METHODS: 51 female and 17 male healthy volunteers (mean age 27 years SD 4.4) participated in a randomized placebo-controlled blinded trial of a single dose of an OTC, immediate-release niacin 500 mg (n = 33), or a single dose of placebo (n = 35) on an empty stomach. The outcomes measured were self-reported incidence of flushing and other adverse effects. RESULTS: 33 volunteers on niacin (100%) and 1 volunteer on placebo (3%) flushed (relative risk 35, 95% confidence interval (CI) 6.8-194.7). Mean time to flushing on niacin was 18.2 min (95% CI: 12.7-23.6); mean duration of flushing was 75.4 min (95% CI: 62.5-88.2). Other adverse effects occurred commonly in the niacin group: chills (51.5% vs. 0%, P <.0001), generalized pruritus (75% vs. 0%, P = <.001), gastrointestinal upset (30% vs. 3%, P =.005), and cutaneous tingling (30% vs. 0%, P = <.001). Six participants did not tolerate the adverse effects of niacin and 3 required medical attention. CONCLUSION: Clinicians counseling patients about niacin should alert patients not only about flushing but also about gastrointestinal symptoms, the most severe in this study. They should not trust that patients would receive information about these side effects or their prevention (with aspirin) from the OTC packet insert.

Adult↗