Corso di clinical writing

What to expect today?

Core modules

• • • • • • •

Introduction General principles Specific techniques Title/Abstract drafting Finding out relevant literature, and Introduction drafting Nuts & bolts of statistics and Methods drafting Practical session 1 – Appraisal of a published article

Which were the authors ’ goals?

The main goals in preparing a manuscript are full reporting and disclosure of relevant aspects of the study

• Is there any risk of bias?

• What are the findings?

• Do your findings apply to the my current clinical problem?

Case study

Nelson et al, NEJM 2004

Useful appraisal approaches

1.

The peer-reviewer approach 2.

The Cochrane Collaboration approach 3.

The EBM approach

-> RECOMMENDED

Focused, structured and analytic approach BMJ guidelines for peer-reviewers:

1 - What is the paper about? 2 - Why was the study done? 3 - What type of study was done? 4 - Was it primary research (RCT, cohort, case-control, cross-sectional, series)? 5 - Was it secondary research (overview, systematic review, meta-analysis, decision analysis, guidelines development, economic analysis)? 6 - Was the design appropriate (for study on treatment, diagnosis, screening, prognosis, or causation)? 7 - Was the study ethical? 8 - Is the design right? A - Does this treatment work?

→ systematic review, RCT B - How good is a diagnostic test?

→ (prospective) cohort study C - Should we screen?

→ RCT D - What causes this disease?

E - What did people think or do?

→ RCT, cohort, case/control (rare diseases) → cohort, cross-sectional survey, qualitative study

Self criticisism while “studying a study”

BMJ scoring tool for peer-reviewers

Schroter et al, JAMA 2006

Internal validity appraisal according to The Cochrane Collaboration

4 MAIN TYPES OF BIAS POTENTIALLY UNDERMINING STUDIES

•

Ascertainment bias

Non-uniform adjudication of events •

Attrition bias

Non-uniform follow-up or compliance to treatment •

Performance bias

Non-uniform performance of corollary treatments •

Selection bias

The non-random allocation of pts one of the treatment groups

http://www.cochrane.org

The EBM 3-step approach

How your article should be appraised, in three steps:

Step 1

– Are the results of the study (internally) valid?

Step 2

– What are the results?

Step 3

– How can I apply these results to patient care?

EBM: Articles about therapy

•

Are the results valid?

Did experimental and control groups begin the study with a similar

• • •

prognosis?

Were pts randomized?

Was randomization concealed?

Were pts analyzed in the groups to which they were randomized?

• Were pts in the treatment and control groups similar with respect to known prognostic factors?

Did experimental and control groups retain a similar prognosis

• • • •

after the study started?

Were pts aware of group allocation?

Were clinicians aware of group allocation?

Were outcome assessors aware of group allocation?

Was follow-up complete?

EBM: Articles about therapy

•

What are the results?

• • How large was the treatment effect?

How precise was the estimate of the treatment effect?

•

How can I apply the results to patient care?

• • • Were the study patients similar to my patient?

Were all clinically important outcomes considered?

Are the likely treatment benefits worth the potential harm and costs?

Title

Nelson et al, NEJM 2004

Abstract

Nelson et al, NEJM 2004

Introduction

OK!

Follows KUQE Brief but clear

Nelson et al, NEJM 2004

Methods

OK!

Explicit selection criteria Documentation of expertise Specific procedural protocol Centralized randomization

Nelson et al, NEJM 2004

Methods

OK!

Explicit follow-up criteria Independent adjudication Justification for sample size Clarification on non-inferiority

Nelson et al, NEJM 2004

Results

OK!

Trial profile Reasons for high drop-in (20%) BUT No details on non-enrolled pts Miss confidence intervals Lacks per protocol analysis

Nelson et al, NEJM 2004

Results

OK!

Trial profile Reasons for high drop-in (20%) BUT No details on non-enrolled pts Miss confidence intervals Lacks per protocol analysis

Nelson et al, NEJM 2004

Discussion/Conclusions

OK!

Comprehensive but concise Include disclosures of support BUT No conflicts of interest?

Nelson et al, NEJM 2004

Discussion/Conclusions

OK!

Comprehensive but concise Include disclosures of support BUT Cost implications?

External validity?

No conflicts of interest?

Nelson et al, NEJM 2004

Figures

OK!

Detailed but synthetic BUT Miss confidence intervals

Nelson et al, NEJM 2004

Questions?

Take home messages

1. Criticizing

constructively

even the apparently most rigorous study is a very useful exercise 2. As long as you apply the same

constructive

criticism to yourself, your writing skills will continue to improve

And now have a good dinner…