R. Brian Haynes

The North American Symptomatic Carotid Endarterectomy Trial: Surgical Results in 1415 Patients

BACKGROUND AND PURPOSE This study reports the surgical results in those patients who underwent carotid endarterectomy in the North American Symptomatic Carotid Endarterectomy Trial (NASCET). METHODS The rates of perioperative stroke and death at 30 days and the final assessment of stroke severity at 90 days were calculated. Regression modeling was used to identify variables that increased or decreased perioperative risk. Nonoutcome surgical complications were summarized. The durability of carotid endarterectomy was examined. RESULTS In 1415 patients there were 92 perioperative outcome events, for an overall rate of 6.5%. At 30 days the results were as follows: death, 1.1%; disabling stroke, 1.8%; and nondisabling stroke, 3.7%. At 90 days, because of improvement in the neurological status of patients judged to have been disabled at 30 days, the results were as follows: death, 1.1%; disabling stroke, 0.9%; and nondisabling stroke, 4.5%. Thirty events occurred intraoperatively; 62 were delayed. Most strokes resulted from thromboembolism. Five baseline variables were predictive of increased surgical risk: hemispheric versus retinal transient ischemic attack as the qualifying event, left-sided procedure, contralateral carotid occlusion, ipsilateral ischemic lesion on CT scan, and irregular or ulcerated ipsilateral plaque. History of coronary artery disease with prior cardiac procedure was associated with reduced risk. The risk of perioperative wound complications was 9.3%, and that of cranial nerve injuries was 8.6%; most were of mild severity. At 8 years, the risk of disabling ipsilateral stroke was 5.7%, and that of any ipsilateral stroke was 17.1%. CONCLUSIONS The overall rate of perioperative stroke and death was 6.5%, but the rate of permanently disabling stroke and death was only 2.0%. Other surgical complications were rarely clinically important. Carotid endarterectomy is a durable procedure.

Optimal search strategies for retrieving scientifically strong studies of diagnosis from Medline: analytical survey

Abstract Objective To develop and test optimal Medline search strategies for retrieving sound clinical studies on prevention or treatment of health disorders. Design Analytical survey. Data sources 161 clinical journals indexed in Medline for the year 2000. Main outcome measures Sensitivity, specificity, precision, and accuracy of 4862 unique terms in 18 404 combinations. Results Only 1587 (24.2%) of 6568 articles on treatment met criteria for testing clinical interventions. Combinations of search terms reached peak sensitivities of 99.3% (95% confidence interval 98.7% to 99.8%) at a specificity of 70.4% (69.8% to 70.9%). Compared with best single terms, best multiple terms increased sensitivity for sound studies by 4.1% (absolute increase), but with substantial loss of specificity (absolute difference 23.7%) when sensitivity was maximised. When terms were combined to maximise specificity, 97.4% (97.3% to 97.6%) was achieved, about the same as that achieved by the best single term (97.6%, 97.4% to 97.7%). The strategies newly reported in this paper outperformed other validated search strategies except for two strategies that had slightly higher specificity (98.1% and 97.6% v 97.4%) but lower sensitivity (42.0% and 92.8% v 93.1%). Conclusion New empirical search strategies have been validated to optimise retrieval from Medline of articles reporting high quality clinical studies on prevention or treatment of health disorders.

Low-dose and high-dose acetylsalicylic acid for patients undergoing carotid endarterectomy: a randomised controlled trial *

BACKGROUND Endarterectomy benefits certain patients with carotid stenosis, but benefits are lessened by perioperative surgical risk. Acetylsalicylic acid lowers the risk of stroke in patients who have experienced transient ischaemic attack and stroke. We investigated appropriate doses and the role of acetylsalicylic acid in patients undergoing carotid endarterectomy. METHODS In a randomised, double-blind, controlled trial, 2849 patients scheduled for endarterectomy were randomly assigned 81 mg (n=709), 325 mg (n=708), 650 mg (n=715), or 1300 mg (n=717) acetylsalicylic acid daily, started before surgery and continued for 3 months. We recorded occurrences of stroke, myocardial infarction, and death. We compared patients on the two higher doses of acetylsalicylic acid with patients on the two lower doses. FINDINGS Surgery was cancelled in 45 patients, none were lost to follow-up by 30 days, and two were lost by 3 months. The combined rate of stroke, myocardial infarction, and death was lower in the low-dose groups than in the high-dose groups at 30 days (5.4 vs 7.0%, p=0.07) and at 3 months (6.2 vs 8.4%, p=0.03). In an efficacy analysis, which excluded patients taking 650 mg or more acetylsalicylic acid before randomisation, and patients randomised within 1 day of surgery, combined rates were 3.7% and 8.2%, respectively, at 30 days (p=0.002) and 4.2% and 10.0% at 3 months (p=0.0002). INTERPRETATION The risk of stroke, myocardial infarction, and death within 30 days and 3 months of endarterectomy is lower for patients taking 81 mg or 325 mg acetylsalicylic acid daily than for those taking 650 mg or 1300 mg.

IMPROVEMENT OF MEDICATION COMPLIANCE IN UNCONTROLLED HYPERTENSION

38 hypertensive Canadian steelworkers who were neither compliant with medications nor at goal diastolic blood-pressure six months after starting treatment were allocated either to a control group or to an experimental group who were taught how to measure their own blood-pressures, asked to chart their home blood-pressures and pill taking, and taught how to tailor pill taking to their daily habits and rituals; these men were also seen fortnightly by a highschool graduate with no formal health professional training who reinforced the experimental manoeuvres and rewarded improvements in compliance and blood-pressure. Six months later, average compliance had fallen by 1.5% in the control group but rose 21.3% in the experimental group. Blood-pressures fell in 17 of 20 experimental patients (to goal in 6) and in 10 of 18 control patients (to goal in 2).

Increased Absenteeism from Work after Detection and Labeling of Hypertensive Patients

A study of hypertension in an industrial setting allowed us to confirm and explore an earlier retrospective finding that the labeling of patients as hypertensive resulted in increased absenteeism from work. After screening and referral, we found that absenteeism rose (mean +/- 1 S.E.) 5.2 +/- 2.3 days per year (P less than 0.025); this 80 per cent increase greatly exceeded the 9 per cent rise in absenteeism in the general employee population during this period. The main factors associated with increased absenteeism were becoming aware of the condition (P less than 0.01) and low compliance with treatment (P less than 0.001). Subsequent absenteeism among patients unaware of their hypertension before screening was not related to the degree of hypertension, whether the worker was started on therapy, the degree of blood-pressure control achieved or exposure to attempts to promote compliance. These results have major implications for hypertension screening programs, especially since absenteeism rose among those previously unaware of their condition, regardless of whether antihypertensive therapy was begun.

Randomised clinical trial of strategies for improving medication compliance in primary hypertension.

230 Canadian steelworkers with hypertension took part in a randomised trial to see if compliance with antihypertensive drug regimens could be improved. For care and follow-up these men were randomly allocated to see either their own family doctors outside working-hours or industrial physicians during work shifts; the same men were randomly allocated to receive or not receive an educational programme aimed at instructing them about hypertension and its treatment. Surprisingly, the convenience of follow-up at work had no effect upon these mens compliance with antihypertensive drug regimens. Similarly, although men receiving health education learned a lot about hypertension, they were not more likely to take their medicine.

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

Abstract 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 Ovids 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.

Of studies, syntheses, synopses, summaries, and systems: the “5S” evolution of information services for evidence-based healthcare decisions

M ost of the articles we pick for EBM stand the test of time, and conclusions are rarely changed by subsequent research. However, John Ioannidis has published a fascinating study of this issue by looking at 49 highly cited articles (.1000 citations) from 1990–2003 (JAMA 2005;294:218–28). Of these, 7 were contradicted by subsequent research, but 5 of these were non-randomised studies (including vitamin E and hormone therapy), and 2 were surrogate endpoints. And none of these was selected for the EBM journal. Having said that, this issue does contain a minor update. We had previously published a trial showing no benefit of antibiotics in conjunctivitis, but the metaanalysis in this issue shows a small benefit. For those keen on teaching evidence-based medicine, one of the premier events on the international calendar is the biennial meeting in Sicily. So you might like to mark in your diaries that the 4th International Conference of EvidenceBased Health Care Teachers & Developers will be in Sicily, 31 October to 4 November, 2007. You will find more details at www.ebhc.org/2007.htm. For folk from developing countries interested in learning about teaching EBM, we have 6 bursaries each year to attend the annual 5 day residential Teaching & Learning EBM course in Oxford. Details and contacts can be found at the Centre for Evidence-Based Medicine website (www.cebm. net).

Features of effective computerised clinical decision support systems: meta-regression of 162 randomised trials

Objectives To identify factors that differentiate between effective and ineffective computerised clinical decision support systems in terms of improvements in the process of care or in patient outcomes. Design Meta-regression analysis of randomised controlled trials. Data sources A database of features and effects of these support systems derived from 162 randomised controlled trials identified in a recent systematic review. Trialists were contacted to confirm the accuracy of data and to help prioritise features for testing. Main outcome measures “Effective” systems were defined as those systems that improved primary (or 50% of secondary) reported outcomes of process of care or patient health. Simple and multiple logistic regression models were used to test characteristics for association with system effectiveness with several sensitivity analyses. Results Systems that presented advice in electronic charting or order entry system interfaces were less likely to be effective (odds ratio 0.37, 95% confidence interval 0.17 to 0.80). Systems more likely to succeed provided advice for patients in addition to practitioners (2.77, 1.07 to 7.17), required practitioners to supply a reason for over-riding advice (11.23, 1.98 to 63.72), or were evaluated by their developers (4.35, 1.66 to 11.44). These findings were robust across different statistical methods, in internal validation, and after adjustment for other potentially important factors. Conclusions We identified several factors that could partially explain why some systems succeed and others fail. Presenting decision support within electronic charting or order entry systems are associated with failure compared with other ways of delivering advice. Odds of success were greater for systems that required practitioners to provide reasons when over-riding advice than for systems that did not. Odds of success were also better for systems that provided advice concurrently to patients and practitioners. Finally, most systems were evaluated by their own developers and such evaluations were more likely to show benefit than those conducted by a third party.

Online Access to MEDLINE in Clinical Settings: A Study of Use and Usefulness

STUDY OBJECTIVE We introduced self-service access to the medical literature database, MEDLINE, into clinical settings to assess the frequency, patterns, purposes, and success of use. DESIGN Longitudinal descriptive study. SETTING Inpatient and outpatient services of a university medical center. PARTICIPANTS All trainees and attending staff working at the service sites were invited to participate; 158 (84%) did so. INTERVENTIONS Free online access was provided to MEDLINE through GRATEFUL MED software. Participants were offered a 2-hour introduction to online searching and 2 hours of free search time. MEASUREMENTS AND MAIN RESULTS For each search, a computer program requested identification of the user and the question to be addressed. Search transactions were recorded automatically. Interviews were conducted after a random sample of searches, and search questions were given to more expert searchers to run for comparison with the original. Eighty-one percent of participants did searches on study computers, at a mean rate of 2.7 searches per month. On comparison searches, participants retrieved 55% of the number of relevant articles retrieved by reference librarians (P = 0.024) and 50% more irrelevant articles (P less than 0.001). Forty-seven percent of searches on patient problems affected clinical decisions, but often on scanty information. CONCLUSIONS MEDLINE searching from clinical settings is feasible with brief training and affects clinical decisions. However, inexperienced searchers miss many relevant citations and search inefficiently. Further studies are needed to assess the impact of searching on physician performance and patient care.