Graphical method to aid design and reporting of complex intervention

trials

Pat Yudkin

Dept of Primary Health Care University of Oxford

York 16 September 2009

Examples of complex interventions

All target behaviour change

• 50 hours of group sessions to reduce incidence of HIV in rural South Africa (Jewkes 2008)

• 12-weeks of group sessions for parents, to reduce problem behaviour in children and depression and stress in parents (Hutchings 2007)

• Home visits over 2 years by nurses to prevent recurrence of physical abuse and neglect of children (MacMillan 2005)

These interventions are complex

• Complex construction

• Complex mechanism of action

Complex construction

• Many different parts (components)

• Includes personal actions and interactions, which may be repeated or difficult

• Involves flexibility in delivery, depending on characteristics of recipient and setting

Two levels of description needed

• Simple, clear description at design stage and for readers of paper

• Detailed and comprehensive description needed for those delivering the intervention to ensure reproducibility

Review of non-drug interventiontrials in UK primary care

Systematic search of randomised trials, UK primary care 1999-2003

Identified 169 non-drug trials

Many aimed to improve lifestyle (diet, exercise, smoking)

Perera et al, BMJ 2007;334:127-9

Problems identified in review

1. Descriptions of interventions long and wordy2. Components of the intervention and its

comparator not easy to identify3. Missed crucial points like timing of delivery

of some components4. Difference between trial groups not clear5. Timing of outcome not obvious

Describing the intervention

• Many ways to describe intervention - we see the delivery of a complex intervention as a set of different activities

• Some activities involve giving objects to the recipients of the intervention

Simple description of an activity

1. What form does it take?

2. What does it consist of?

3. Who delivers it?

4. Where and when does it happen?

5. How long does it take?

Can a diagram be clarifying?

Timeline Intervention Control

Pre-randomisation

Randomisation

1, 2, 3 months

6 months

Outcome, 1 year

b a

Activity Object

The DIGEM trial in Type 2 diabetes

Does blood glucose self-monitoring, alone, or with training in interpretation to guide behaviour, improve glycaemic control?

1. No monitor, HbA1c measured 3-monthly by doctor

2. Int 1: Blood glucose monitor given with advice to contact doctor if readings persistently high

3. Int 2: Blood glucose monitor given with training in interpretation of results to guide behaviour

The DIGEM trial (2)

All patients given information, education and support by trained nurses over one year. Content of nurse contacts different in each trial arm

Main outcome: blood glucose level at 12 months

a

b c

a

d

a a a

b b b

c d e

f

g

h i j

Cont Int 1 Int 2Timeline

Baseline, 2 wks after randomisation

2 wks before each visit

1, 3, 6, 9 months visits

2 wks after baseline

Before randomisation

b

RANDOMISATION

OUTCOME, 1 YEAR

b

a

a

b

c

d

DescriptionSymbol

Nurse training: 6 days, based on manual.Behaviour change techniques, theory etc

45 mins with nurse: review diet, exercise anddrugs; set goals for behaviour change

45 mins with nurse: roles of diet, exercise anddrugs discussed, glucose control emphasised

e

45 mins with nurse: instruct in using blood glucose meter; review and set goals

45 mins with nurse: instruct in using meter and interpreting results; review and set goals

Diary to record goals, strategies for achieving them, and whether achieved

Blood glucose meter

DescriptionSymbol

Diary to record blood glucose results

Phone call from nurse to reinforce use of meter and check for problems

Diary to record blood glucose results and relate them to activities and diet

Patient attends blood test at surgery to measure HbA1c

20 mins with nurse: HbA1c results reviewed

20 mins with nurse: blood glucose results reviewed to show specific relation between self-care and glycaemic control

20 mins with nurse: blood glucose results reviewed

c

d

f

g

h

i

j

a

b c

a

d

a a a

b b b

c d e

f

g

h i j

Cont Int 1 Int 2Timeline

Baseline, 2 wks after randomisation

2 wks before visits

1, 3, 6, 9 months visits

2 wks after baseline

Before randomisation

b

RANDOMISATION

OUTCOME, 1 YEAR

Advantages of diagram

• Structure of intervention easy to grasp• Structure of comparator also made clear• Timing of components clarified• Difference between interventions obvious• Timing of outcome measures clear

A diagram can’t do everything

May not be helpful for all interventions

Still need full material to describe interventions well enough for them to be reproduced

Acknowledgements

Rafael Perera

Andrew Farmer Ray Fitzpatrick Paul Glasziou Carl Heneghan David Mant Sasha Shepperd Alison Ward Sue Ziebland

http://www.cebm.net/index.aspx?o=4200

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