Common sense and figures: the rhetoric of validity in medicine (Bradford Hill Memorial Lecture 1999)

Horton, Richard

doi:10.1002/1097-0258(20001215)19:23<3149::aid-sim617>3.0.co;2-e

Cited by 59 publications

(29 citation statements)

References 45 publications

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“…We also ensured that communities were qualitatively independent during a rapid assessment following the match but before data collection. 6 Availability of baseline (preintervention) data. Baseline data that include key confounding covariates are used for matched sampling of communities.…”

Section: Implementation Activities Evaluation Activitiesmentioning

confidence: 99%

“…Bias from other sources can result from frequent measurement (3) or lack of blinding treatment (blinding is rarely possible for community interventions) (4,5). Even if unbiased, trials must evaluate treatments that are amenable to randomization and typically estimate the average effect of an intervention under ideal conditions (delivery and compliance) in populations most likely to benefit; it is widely acknowledged that treatment effects estimated in such trials can differ from those obtained when the intervention is deployed in the general population (6). Measuring intervention sustainability using prospective trials can also be difficult due to logistical complexity, short funding cycles, and rare sequential awards (7).…”

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confidence: 99%

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Causal inference methods to study nonrandomized, preexisting development interventions

Arnold

Khush

Padmavathi

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Empirical measurement of interventions to address significant global health and development problems is necessary to ensure that resources are applied appropriately. Such intervention programs are often deployed at the group or community level. The gold standard design to measure the effectiveness of communitylevel interventions is the community-randomized trial, but the conditions of these trials often make it difficult to assess their external validity and sustainability. The sheer number of community interventions, relative to randomized studies, speaks to a need for rigorous observational methods to measure their impact. In this article, we use the potential outcomes model for causal inference to motivate a matched cohort design to study the impact and sustainability of nonrandomized, preexisting interventions. We illustrate the method using a sanitation mobilization, water supply, and hygiene intervention in rural India. In a matched sample of 25 villages, we enrolled 1,284 children <5 y old and measured outcomes over 12 mo. Although we found a 33 percentage point difference in new toilet construction [95% confidence interval (CI) = 28%, 39%], we found no impacts on height-for-age Z scores (adjusted difference = 0.01, 95% CI = −0.15, 0.19) or diarrhea (adjusted longitudinal prevalence difference = 0.003, 95% CI = −0.001, 0.008) among children <5 y old. This study demonstrates that matched cohort designs can estimate impacts from nonrandomized, preexisting interventions that are used widely in development efforts. Interpreting the impacts as causal, however, requires stronger assumptions than prospective, randomized studies.impact evaluation | study design | propensity score matching | communityled total sanitation | open defecation

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Section: Implementation Activities Evaluation Activitiesmentioning

confidence: 99%

mentioning

confidence: 99%

Causal inference methods to study nonrandomized, preexisting development interventions

Arnold

Khush

Padmavathi

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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“…Bradford Hill encouraged randomized experimental evaluation of medical interventions over sixty years ago (as cited by Horton, 2000) and, thirty years later, Fletcher and Sackett (1979) proposed "evidence-based medicine". The difficulties in implementing experimental evaluation were well known, but now the medical profession can select interventions with the best efficacy.…”

Section: Introductionmentioning

confidence: 99%

A web-based learning tool improves student performance in statistics: A randomized masked trial

González

Jover

Cobo

et al. 2010

Computers & Education

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a b s t r a c tBackground: e-status is a web-based tool able to generate different statistical exercises and to provide immediate feedback to students' answers. Although the use of Information and Communication Technologies (ICTs) is becoming widespread in undergraduate education, there are few experimental studies evaluating its effects on learning.Method: All of the students (121) from an introductory course for statistics in dentistry were randomly assigned to use the tool with one of two 6-problem sets, known as types A and B. The primary endpoint was the grade difference obtained in the final exam, composed of two blocks of questions related to types A and B. The exam evaluator was masked to the intervention group. Results: We found that the effect of e-status on the student grade was an improvement of 0.48 points (95% CI: 0.10e0.86) on a ten-point scale. Among the 94 students who actually employed e-status, the effect size was 0.63 (95% CI: 0.17e1.10). Conclusions:It is feasible to formally assess the learning effect of an innovative tool. Providing e-status exercises to students has a direct effect on learning numerical operations related to statistics. Further effects on higher cognitive levels still have to be explored.

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“…While there is no evidence against the applicability of the results in non-eligible patients, or a pathophysiological basis to support such conclusions 18 , it seems prudent to rely on RCTs and clinical guidelines for decision making. Notwithstanding this, the increasing complexity of patients undergoing interventional procedures today often compels us to an individualised approach.…”

Section: Rct Participants N=249 Eligible Patients (Ep) N=106mentioning

confidence: 99%

External validity of a contemporaneous primary percutaneous coronary intervention trial in patients with acute ST-elevation myocardial infarction: insights from a single-centre investigation

Spitzer

Hadorn²,

Zanchin³

et al. 2016

EuroIntervention

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Aims: Randomised controlled trials (RCTs) represent the most robust source of evidence-based medicine.However, the generalisability of RCTs is limited by the inclusion of selected populations. We sought to assess the external validity of a contemporary trial including patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). Methods and results:Patients presenting to Bern University Hospital during the inclusion period of the COMFORTABLE AMI trial were divided into three groups: RCT participants (41%), eligible not included (17.5%), and excluded patients (41.5%). Major adverse cardiac events (MACE) were defined as one-year death and myocardial infarction. RCT participants compared with RCT-eligible patients had comparable baseline characteristics and outcomes; however, excluded patients differed in risk and had higher rates of MACE (HR 3.63, 95% CI: 2.03-6.48, p<0.001), death (HR 6.23, 95% CI: 2.93-13.24, p<0,001) and definite/probable stent thrombosis (HR 3.63, 95% CI: 1.79-7.36, p<0.001). Inability to provide consent was the most frequent exclusion criterion and was independently associated with an increased risk for MACE (HR 6.85, 95% CI: 3.97-11.81, p<0.001).Conclusions: In this single-centre investigation, results from the COMFORTABLE AMI trial appeared applicable to a broad representation of RCT-eligible patients. However, patients excluded from the trial represented a higher-risk population with impaired clinical outcomes and a lower adherence to cardiovascular medication. KEYWORDS• clinical research • clinical trial • death • drug-eluting stent • STEMI

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Common sense and figures: the rhetoric of validity in medicine (Bradford Hill Memorial Lecture 1999)

Cited by 59 publications

References 45 publications

Causal inference methods to study nonrandomized, preexisting development interventions

Causal inference methods to study nonrandomized, preexisting development interventions

A web-based learning tool improves student performance in statistics: A randomized masked trial

External validity of a contemporaneous primary percutaneous coronary intervention trial in patients with acute ST-elevation myocardial infarction: insights from a single-centre investigation

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