In praise of cows

Farrell, Liam

doi:10.1136/bmj.c410

Cited by 3 publications

(2 citation statements)

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“…If, however, the existing primary studies identified are essentially exploratory in nature, a prospective protocol driven hypothesis-testing study may be required before a change in clinical practice could be justified [33-36]. The results of the proposed review would greatly facilitate the design of such a study.…”

Section: Discussionmentioning

confidence: 99%

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Protocol for a systematic review of the diagnostic and prognostic utility of tests currently available for the detection of aspirin resistance in patients with established cardiovascular or cerebrovascular disease

et al. 2013

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BackgroundThe benefits of aspirin as an anti-platelet agent are well established; however, there has been much debate about the lack of uniformity in the efficacy of aspirin to inhibit platelet function. In some patients, aspirin fails to inhibit platelets even where compliance has been verified, a phenomenon which has been termed “aspirin resistance”. These patients may in turn be at a higher risk of future vascular events. The proportion of “resistant” patients identified depends on the type of platelet function test. Therefore, the aim of this systematic review is to determine which, if any, platelet function test has utility in terms of identifying patients with a high risk of vascular events. The review has been registered with PROSPERO (CRD42012002151).MethodsRelevant studies will be sought from bibliographic databases. Trials registers will be searched for ongoing studies. Reference lists will be checked and subject experts contacted. There will be no date or language restrictions. Standard reviewing methodology to minimise bias will be employed. Any prospective studies in patients on aspirin therapy and assessing platelet function in relation to relevant clinical outcomes will be included, as will studies reporting prognostic models. Risk of bias assessment will be based on the Quality Assessment of Diagnostic Accuracy Studies guidelines, and suitable criteria for assessing quality of prognostic studies. Data on test accuracy measures, relative risks, odds or hazard ratios will be extracted and meta-analysed, where possible, using a random-effects model to account for between-study heterogeneity. Where appropriate, the causes of heterogeneity will be explored through meta-regression and sub-group or sensitivity analyses. If platelet function testing is demonstrated to have diagnostic/predictive utility in a specific population, the potential for a cost-effectiveness analysis will be considered and, if possible, an economic model constructed. This will be supported by a systematic review of existing economic evaluation studies.DiscussionThe results of the review could indicate if platelet function test(s) could lead to a reliable prediction of the risk of clinically important events in a defined population, and thus support investigations into adjustments to therapy in order to compensate for a predicted poor response to standard aspirin.

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Section: Discussionmentioning

confidence: 99%

“…We do not seek individual participant data in this review [33,37]. The decision to collate individual patient data (IPD) is premature until a systematic review has established the current reported evidence regarding the individual prognostic and diagnostic accuracy of existing tests, as described above.…”

Section: Discussionmentioning

confidence: 99%

Protocol for a systematic review of the diagnostic and prognostic utility of tests currently available for the detection of aspirin resistance in patients with established cardiovascular or cerebrovascular disease

et al. 2013

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Retrospective cohort study evaluating clinical, biochemical and pharmacological prognostic factors for prostate cancer progression using primary care data

et al. 2021

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ObjectivesTo confirm the association of previously reported prognostic factors with future progression of localised prostate cancer using primary care data and identify new potential prognostic factors for further assessment in prognostic model development and validation.DesignRetrospective cohort study, employing Cox proportional hazards regression controlling for age, prostate specific antigen (PSA), and Gleason score, was stratified by diagnostic stage.SettingPrimary care in England.ParticipantsMales with localised prostate cancer diagnosedbetween 01/01/1987 and 31/12/2016 within the Clinical Practice ResearchDatalink database, with linked data from the National Cancer Registration andAnalysis Service and Office for National Statistics.Primary and secondary outcomesPrimary outcome measure was prostate cancer mortality. Secondary outcome measures were all-cause mortality and commencing systemic therapy. Up-staging after diagnosis was not used as a secondary outcome owing to significant missing data.Results10 901 men (mean age 74.38±9.03 years) with localised prostate cancer were followed up for a mean of 14.12 (±6.36) years. 2331 (21.38%) men underwent systemic therapy and 3450 (31.65%) died, including 1250 (11.47%) from prostate cancer. Factors associated with an increased risk of prostate cancer mortality included age; high PSA; current or ex-smoker; ischaemic heart disease; high C reactive protein; high ferritin; low haemoglobin; high blood glucose and low albumin.ConclusionsThis study identified several new potential prognostic factors for prostate cancer progression, as well as confirming some known prognostic factors, in an independent primary care data set. Further research is needed to develop and validate a prognostic model for prostate cancer progression.

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EBM round-up: February 2011

Saitz

2011

Evid Based Med

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Commentary on: Bassler D, Briel M, Montori VM, et al. Stopping randomized trials early for benefit and estimation of treatment effects. Systematic review and meta-regression analysis. JAMA 2010;303:1180-7.Richard Saitz published elsewhere in the peer-reviewed medical literature. The primary criterion for selection is relevance to EBM. Articles are selected by scanning selected journal tables of contents for reports of potential relevance. The round-up writer (an EBM editor) comments on each summary.1. Merriam-Webster's Online Dictionary. http://www. merriam-webster.com/dictionary/roundup (accessed 2 August 2010). EBM round-up: February 2011Noun (\ˈraund-ˌəp\) 1) the act or process of collecting animals by riding around them and driving them in; 2) a summary of information.Transitive verb 1) to collect (as cattle) by means of a roundup; 2) to gather in or bring together from various quarters. 1 In this occasional feature we gather and summarise articles relevant to the practice, research and teaching of evidence-based medicine (EBM) that have been Trials stopped early for benefit overestimate treatment effects Data safety monitoring committees are often charged with stopping controlled studies when data suggest a benefi t is very likely. Such committees often base decisions on statistical signifi cance using calculations designed specifi cally for this purpose. But the results of studies stopped early might not be what they would have been had the trial continued. To determine whether treatment effects differed, investigators systematically reviewed the literature to compare outcomes of treatment studies stopped earlier than initially planned due to interim results favouring the intervention, to those in meta-analyses of studies addressing the same question that were not truncated.Investigators included 91 truncated randomised controlled trials (RCTs) and 424 non-truncated trials of the same question identifi ed in systematic reviews addressing 63 questions. They calculated the ratio of relative risks (RRs) (in other words, the RR of bad outcome in the treatment group compared with control in truncated studies over the RR in non-truncated trials). The ratio was <1 in 55 of 63 comparisons, and the (weighted) average of the ratios was 0.71 (95% CI 0.65 to 0.77). RCTs were more likely to be published in high-impact journals (30% vs 68%). Differences between truncated and non-truncated study results were larger when truncated studies had fewer than 500 outcome events. CommentaryWhether studies missed by this systematic review would change the conclusions is not clear. But it does appear that studies stopped early overestimate treatment effects. That is important information for clinicians. The authors suggest that in addition to statistical signifi cance, researchers may want to take number of events into account when deciding on whether to stop a trial. Ethicists will no doubt need to wrestle with the implications.

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In praise of cows

Cited by 3 publications

References 0 publications

Protocol for a systematic review of the diagnostic and prognostic utility of tests currently available for the detection of aspirin resistance in patients with established cardiovascular or cerebrovascular disease

Protocol for a systematic review of the diagnostic and prognostic utility of tests currently available for the detection of aspirin resistance in patients with established cardiovascular or cerebrovascular disease

Retrospective cohort study evaluating clinical, biochemical and pharmacological prognostic factors for prostate cancer progression using primary care data

EBM round-up: February 2011

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