Best Evidence Topics

Randomised control trial

Moe, G; Howlett, J; Januzzi, J; et al
N-Terminal Pro-B-Type Natriuretic Peptide Testing Improves the Management of Patients With Suspected Heart Failure
2007; 115: 3103-3110
  • Submitted by:Craig Ferguson - SPR
  • Institution:Salford Royal Foundation Trust
  • Date submitted:30th November 1999
Before CA, i rated this paper: 7/10
1 Objectives and hypotheses
1.1 Are the objectives of the study clearly stated?
  Yes. States in the introduction that the objectives were to evaluate whether the testing for NT-proBNP improved clinical judgment in diagnosing heart failure and whether this knowledge would lead to cost savings.
2 Design
2.1 Is the study design suitable for the objectives
  Yes, although I'm not quite clear on how the costs were calculated.
2.2 Who / what was studied?
  500 patients with acute dyspnoea of suspected cardiac origin were recruited from 7 sites in Canada.
2.3 Was this the right sample to answer the objectives?
2.4 Is the study large enough to achieve its objectives? Have sample size estimates been performed?
  Sample size estimates were performed assuming a 20% reduction in the time spent in the Emergency department, from 9h to 7.2h. In fact the median time spent in the ED was 6.3h in the usual care group and 5.6h in the NT-proBNP group. The mean time is not provided.
2.5 Were all subjects accounted for?
  Yes. Figures given for recruitment, protocol violation, drop outs and lost to follow up patients.
2.6 Were all appropriate outcomes considered?
  Yes although it would have been interesting to compare the outcomes in the patient groups who were considered to have heart failure with the patients who were considered not to have heart failure.
2.7 Has ethical approval been obtained if appropriate?
  Yes and all patients consented.
2.8 Were the patients randomised between treatments?
2.9 How was randomisation carried out?
  Blocks of four on 1:1 basis. As well as the NT-proBNP results the attending physician was given information from the manufacturer to aid with interpretation of the result and a recent paper demonstrating the benefit of knowing NT-proBNP results in the management of a group of similar patients.
2.10 Are the outcomes clinically relevant?
  The primary outcomes of whether the diagnosis of heart failure was improved and whether this reduced the cost of management of the patient are clinically relevant.
3 Measurement and observation
3.1 Is it clear what was measured, how it was measured and what the outcomes were?
  Clinical judgment without NT-proBNP is compared to diagnosis with this test and found to be improved. The gold standard is the diagnosis made by 2 cardiologists on reviewing the notes.
I was less clear about how the costs per patient were calculated. There is mention made of a scale of intensity weight and complexity levels and I am not sure how this was applied to the patients in this study.
3.2 Are the measurements valid?
3.3 Are the measurements reliable?
  Should be.
3.4 Are the measurements reproducible?
  Should be.
3.5 Were the patients and the investigators blinded?
  Patients were blinded. Investigator not blinded but treating physician was in half of the cases.
4 Presentation of results
4.1 Are the basic data adequately described?
4.2 Were groups comparable at baseline?
4.3 Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
  Yes. It would have been nice to have been given the data on how outcomes were affected by whether or not the patient was considered to have actually had heart failure.
4.4 Are the results internally consistent, i.e. do the numbers add up properly?
4.5 Were side effects reported?
5 Analysis
5.1 Are the data suitable for analysis?
5.2 Are the methods appropriate to the data?
  median values rather than mean.
5.3 Are any statistics correctly performed and interpreted?
6 Discussion
6.1 Are the results discussed in relation to existing knowledge on the subject and study objectives?
  Yes. Expanded the outcomes to management within the ED to 60 day outcomes in terms of all cause mortality and readmissions which was not mentioned as a primary objective.
6.2 Is the discussion biased?
  not bad
7 Interpretation
7.1 Are the authors' conclusions justified by the data?
  Yes. Diplomatically worded, "provided health cost savings that are accompanied by an improvement in selected clinical outcomes.@
7.2 What level of evidence has this paper presented? (using CEBM levels)
7.3 Does this paper help me answer my problem?
  Suggests that testing NT-proBNP may aid me in diagnosing heart failure and may save the hospital, if not the ED, some money.
Suggestion in the paper the greatest benefits are seen in patients who lie in the intermediate area when the attending clinician decided whether they had heart failure or not.
Does not tell me which breathless patients would benefit from having this test done.
After CA, i rated this paper: 7/10
8 Implementation
8.1 Can any necessary change be implemented in practice?
8.2 What aids to implementation exist?
8.3 What barriers to implementation exist?