1

Outcome Outcome evaluation of evaluation of

health health promotion/life promotion/life style changestyle change

Wei-Chu ChieWei-Chu Chie

2

Health promotionHealth promotion• Primary prevention

– life style change– education and health behavior

3

Three elements for health Three elements for health promotionpromotion

• Experiment unit – Individual or group (cluster), usually

healthy

• Treatments– education

• Evaluation– efficacy– safety: less serious and sometimes

overlooked

4

Basic characteristicsBasic characteristics• Difficult to follow the rule of

randomized controlled double-blinded trials– placebo control with blindness: difficult

to make and keep– individual randomization not convenient

• requires a large sample size– low incidence of the disease to prevent– low incidence of adverse effects

5

Major difficulties (1)Major difficulties (1)• No blindness:

– Hawthorn effect and information bias– Rater blindness

• loyalty to the original randomization– Compliance or adherence – ‘Contamination’ of the control group:

• got the intervention content elsewhere or from the treatment group

6

Major difficulties (2)Major difficulties (2)• Randomization unit

– individual: ideal but difficult to implement

– group (cluster): easy to implement but has statistical problem

7

ethical concernsethical concerns• administered on healthy people

– autonomy emphasized: informed consent

– safety less serious than immunization and drug, sometimes overlooked

8

ExamplesExamples– Diabetes Prevention Program Research Gro

up. Reduction in the incidence or type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002;346:393-403.

– Brown KS, et al. Outcome evaluation of a high school smoking reduction intervention based on extracurricular activities. Prev Med 2002;35:506-10.

9

DM: DM: background/goal/hypothesisbackground/goal/hypothesis

• Background: – burden of type 2 DM and delayed diagnos

is– previous studies of its preventability

• Goal/hypothesis:– to determine whether ... /DM is preventa

ble by metformin and lifestyle intervention

10

DM: study designDM: study design• Randomized controlled trial

– four groups … three• two drugs (one DC due to serious AE) + lifestyle• one placebo + lifestyle• one intensive lifestyle

– randomized by individual/stratified by centers

– blinded only in the drug vs. placebo groups• primary endpoint evaluated centrally/blind• unaware of the test results in the middle

11

DM: subjectsDM: subjects• High-risk people at 27 centers four steps:

– www.bsc.gwu.edu/dpp (the U.S.)• 1996-1999, 3234 subjects (1082:1073:1079)

– inclusion: 25 years+, BMI 24 or more, fasting glucose 95-125 mg/dL, 2 hr 75-g GTT 140-199 me/dL; half from minorities

– exclusion: taking medicines, illness reducing life expectancy or ability to participate.

12

DM: DM: exposure/interventionexposure/intervention• Group 1: standard lifestyle + metformin

850 mg qd to bid (GI symptoms)• Group 2: … troglitazone … DC• Group 3: intensive lifestyle• Group 4: standard lifestyle + placebo (co

ntrol)

13

DM: standard vs. intensive DM: standard vs. intensive lifestylelifestyle

• Standard:– written form+individual session

• Intensive:– goal: weight reduction 7%– 16-lesson curriculum, one-to-one for 1st

24 wks• healthy low-calorie, low-fat diet• physical activity of moderate intensity

– subsequent sessions and group sessions

14

DM: endpointsDM: endpoints• Primary

– efficacy: DM/ safety: adverse effects

• Secondary– weight, physical activity (MET), glucose

• Follow-up– annual o-GTT, semi-annual fasting plasma

glucose/symptoms• to planned 5/2001, actually on 3/31/2001• early stop due to advice from the monitoring

board

15

DM: endpointsDM: endpoints• Definition of DM

– abnormal o-GTT tests or fasting plasma sugar

– confirmation by a second test within 6 weeks• inform the patient and physician• fasting sugar /6 months, HbA1c /year• fasting sugar <140 mg /dL … continue• fasting >= 140 mg/dL … DC and referral

16

DM: dDM: data analysisata analysis• Basic characteristics and comparison

– for confounding and possible selection bias

• Intention-to-treat analysis• primary: time-to-event, survival (life-

table)– modified product-limit … cumulative

incidence– proportional hazards regression/ subgroup– persons need to treat

• secondary: fixed-effects models

17

DM: mDM: major results/discussionajor results/discussion– Comparison: Table 1– Efficacy

• primary: Table 2, Figure 2 / subgroup analysis• cumulative incidence P>M>L• secondary: Figure 1, 3, 4• L has better weight reduction and increase in

physical activity, similar or better glucose & HbA1c to M

– Safety: Table 3• M has more GI & L has more MS symptoms

18

DM: mDM: major results/discussionajor results/discussion• Discussion

– Confounding, selection bias: randomization

– Information bias: blindness– Early termination/ ethics– differentiation of diet and physical

activity– Sample size and power of test

• Conclusion: L>=M>P

19

Smoking:background/goal/Smoking:background/goal/hypothesishypothesis

• Background: – youth smoking rate and intervention– in-class vs. extra-curricular activities

• Goal/hypothesis:– to determine whether... extra-

curricular activities can reduce teenage smoking rate

20

Smoking: study designSmoking: study design

• Randomized controlled trial– two groups

• intervention• usual care (control)

– randomized by school (cluster)– no blindness

21

Smoking: subjectsSmoking: subjects• Waterloo, Canada• Phase 1: 7 school boards/100 schools

– teachers/ nurses social influence program– self-preparation materials– high-risk schools

• phase 2: 6 boards agreed/ 35 high-schools– 30 schools agreed– matched within school board … pairs

22

Smoking: subjectsSmoking: subjects• Matching

– by size, number and proportion of cohort students

• randomized into two groups– pairs: intervention vs. control

• grade 9 cohort attending the 30 schools– 30 schools 15:15– 3028 students…2776... 1563:1465

23

Smoking: Smoking: exposure/interventionexposure/intervention

• Mobilizing staff and students/commitments• A teacher facilitated students, staff,

community participants in planning and implementing prevention and cessation activities … tailored to each school

• Role of research staff• Budgets

24

Smoking: endpointsSmoking: endpoints

• Primary– efficacy: smoking status – safety: no

• Secondary– No

• Follow-up– to grade 10

25

Smoking: endpointsSmoking: endpoints• Definition of smoking status• By questionnaire:

– never, – tried once, quit, experimental (<

once/week)– regular (weekly)

• By CO breath samples

26

Smoking: dSmoking: data analysisata analysis

• Basic characteristics and comparison– for confounding and possible

selection bias

• Intention-to-treat analysis• Primary:

– smoking status– subgroup analysis

27

Smoking: mSmoking: major ajor results/discussionresults/discussion

• Comparison: Table 1• Efficacy

– Table 2– subgroup analysis: – only effective for male non-smoker at

grade 8

• No other analyses

28

DM: mDM: major results/discussionajor results/discussion• Discussion

– Confounding, selection bias: randomization

– Information bias: blindness– Sample size and power of test– Limited to one special group– Adverse effects not analyzed– Cost?

• Conclusion: limited!