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. 2001 Jul 21;323(7305):165.
Using clinical evidence
Randomised controlled trials are not the only evidence
Editor—Randomised controlled trials—the focus of evidence based medicine—will be given more momentum by the availability of Clinical Evidence on line.1 The criteria to be used to select evidence for this journal imply that only recommendations from randomised controlled trials can be used if medicine is to be considered evidence based.
I urge the BMJ and Clinical Evidence to take a less conservative position on what can be regarded as clinical evidence. The exclusion from publication of anything other than randomised controlled trials (except where these do not exist on a particular topic) will dissuade clinicians and research workers from considering quantitative statistical analysis of sequential data from individuals as an alternative but meaningful form of clinical evidence. Statistical analyses of sequences of numerical data from individuals can provide evidence that is as robust and as statistically valid as data from the best randomised controlled trials.
The probability of a real effect from an intervention on an individual may be high when there are sufficient data points for analysis before and after the intervention. Interventions used may be a drug, a placebo, a physical treatment (for example, physiotherapy), the introduction of a “natural” therapy, or any other intervention when the effect can be determined by its impact on relevant numerical variables that are collected sequentially. The variables may be laboratory measurements, clinical measurements, or patient assessments (for example, pain scores). Reports that contain statistically valid calculations of change as a result of an intervention in an individual or in a group should have as much right to inclusion in Clinical Evidence as evidence from randomised controlled trials.
The statistical analysis of sequential information from individuals has the potential to improve clinical care for those individuals as well as providing clinical evidence for future practice. With colleagues, including clinicians and statisticians, I reported on real time monitoring applied to sequential kidney function testing in patients with renal disease2,3 and proposed its general application in both research and clinical practice.4 That has not happened.
With its influence, Clinical Evidence could encourage the use of evidence acquired from individuals with time series analysis. This is currently used extensively for quality control in laboratories, by investors in the stock market, and by biometricians, but it is not used as it could be to provide clinical evidence, both in clinics and as a research tool.
2.Knapp MS, Smith AFM, Trimble IM, Pownall R, Gordon K. Mathematical and statistical aids to evaluate data from renal patients. Kidney Int. 1983;24:474–486. doi: 10.1038/ki.1983.184. [DOI] [PubMed] [Google Scholar]
3.Trimble IM, West M, Knapp S, Pownall R, Smith AFM. Detection of renal allograft rejection by computer. BMJ. 1983;286:1695–1699. doi: 10.1136/bmj.286.6379.1695. [DOI] [PMC free article] [PubMed] [Google Scholar]
4.Knapp MS. Computing, mathematics and the nephrologist. Kidney Int. 1983;24:433–435. doi: 10.1038/ki.1983.178. [DOI] [PubMed] [Google Scholar]
BMJ. 2001 Jul 21;323(7305):165.
Clinical Evidence is one of respondents' three favourite sources of information
Editor—We agree with Barton that presenting good quality information alone is often insufficient to change practice.1-1 Because we were impressed by the content, Clinical Evidence was purchased for all consultants and general practitioners (and some pharmacists) in Northumberland and Gateshead and South Tyneside Health Authorities for a year. We undertook a survey to assess how useful it had been in clinical practice; the response was 58% (187/323) in Northumberland and 40% (202/504) in Gateshead and South Tyneside.
The table shows that the British National Formulary was the most frequently cited favourite source of information, but 95 (24%) respondents identified Clinical Evidence as one of their three favourite sources. Frequency of use of the book was reported as daily by four respondents, weekly by 109, monthly by 167, and less than monthly by 109. Most (230) used it during or after a consultation.
Table.
Favourite sources of information. Values are numbers of people citing source among their top three choices
The publication was rated as particularly useful by general practitioners, physicians, and pharmacists; surgical specialties generally gave it a lower rating. The few people who thought that it was of no use mostly did so because the subject material was not relevant to their work. Multiple format presentations were of interest to 249 respondents, although the preferred format for most (237) was the book, with 62 wanting only a paper format. Only 17 had tried the online version.
Locally we have decided to continue with a print subscription for some clinicians to complement the online access and print editions issued through the NHS. Although we cannot show that the publication has had a positive impact on clinical care, we at least show that some people are reading it. Most use related to time around the consultation, which indicates a potential link between an episode of clinical care and a desire to check the evidence. We view this as a positive development.
References
1-1.Barton S. Using clinical evidence. BMJ. 2001;322:503–504. doi: 10.1136/bmj.322.7285.503. . (3 March.) [DOI] [PMC free article] [PubMed] [Google Scholar]
BMJ. 2001 Jul 21;323(7305):165.
Obstetricians seem to be overstating the evidence in major placenta praevia
Editor—Barton is correct in saying that the pressures of clinical medicine mean that the incorporation of evidence based practice into everyday clinical practice has become almost impossible.2-1 This makes busy clinicians vulnerable to expert committees that purport to produce evidenced based guidelines for them.
We were recently dismayed by a guideline on the diagnosis and management of placenta praevia published by the Royal College of Obstetricians and Gynaecologists.2-2 The authors state, among other recommendations, that women with major placenta praevia should be managed as inpatients in the third trimester. The evidence for this was one small randomised controlled trial, which was underpowered but showed no difference between women managed as outpatients and those managed as inpatients, and a series of retrospective reviews that showed no difference in clinical outcome. The authors base their recommendation on the belief that inpatient care is the current standard management.
We sent questionnaires to the 220 clinical tutors of the Royal College of Obstetricians and Gynaecologists in England and Wales to survey the antenatal management of asymptomatic placenta praevia. Altogether we received 149 responses (response rate 68%). Eighty five obstetric units had a guideline for management of placenta praevia and 59 did not; seven were not sure. The table summarises the results.
Table.
Responses to questionnaire sent to obstetric units to survey antenatal management of asymptomatic placenta praevia
Our practice at this hospital has been not to admit women routinely with asymptomatic major placenta praevia; this practice seems to be shared by 42% of other maternity units. Elective admission from 34.5 weeks' gestation represents a huge investment by the NHS for an unproved intervention. We hope that Clinical Evidence, which we understand is produced by the NHS, will not overstate its remit of just presenting the evidence for what does and does not work in health care.
References
2-1.Barton S. Using clinical evidence. BMJ. 2001;322:503–504. doi: 10.1136/bmj.322.7285.503. . (3 March.) [DOI] [PMC free article] [PubMed] [Google Scholar]
2-2.Royal College of Obstetricians and Gynaecologists. Placenta praevia: diagnosis and management. London: RCOG; 2000. . (Green-top guideline No 27.) [Google Scholar]
Editor—Knapp is right in arguing that randomised controlled trials are not the only form of good evidence. Clinical Evidence includes evidence that doesn't come from randomised controlled trials when such trials are not feasible or are unethical, and when confirmation is needed that the effects seen in randomised controlled trials (“efficacy”) are deliverable in the real world (“effectiveness”).
The typical problem with observational studies is not their ability to detect significant changes, it is their difficulty in excluding systematic biases that could also explain those changes. Randomised controlled trials rarely provide all the evidence needed to answer clinical questions. Few randomised controlled trials are designed to provide good evidence about harms, and good quality observational studies are likely to remain essential in any thorough review of the adverse effects of treatments.
I am encouraged by the early evaluation by Gordon and Lambert, particularly the proportion of doctors who said that they used the book during or soon after a consultation. The next steps are to ensure that Clinical Evidence covers most questions being asked by people who turn to it, and that the evidence is provided in the most useful form.
Ghaem-Maghami et al indicate their dismay with a stipulation made by a guideline. Their reaction reinforces the approach taken in Clinical Evidence—to avoid making recommendations. Instead, evidence about the effects (benefits and harms) of treatments is presented in a clear way, so that it can be weighed by all those involved (the person with the problem and his or her advisers) at the appropriate time.
Clinical Evidence is not produced by the NHS. It was first suggested by Tom Mann (who worked for the NHS), but the authors are drawn from around the world, and Clinical Evidence is published independently by the BMJ Publishing Group. The NHS plays a major part, making Clinical Evidence available to carers and by supporting high quality research and systematic reviews (for example, by the Cochrane Collaboration and the NHS Centre for Reviews and Dissemination), which underpin Clinical Evidence.
