Outcome evaluation of health promotion/life style change
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Outcome Outcome evaluation of evaluation of
health health promotion/life promotion/life style changestyle change
Wei-Chu ChieWei-Chu Chie
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Health promotionHealth promotion• Primary prevention
– life style change– education and health behavior
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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
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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
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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
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Major difficulties (2)Major difficulties (2)• Randomization unit
– individual: ideal but difficult to implement
– group (cluster): easy to implement but has statistical problem
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ethical concernsethical concerns• administered on healthy people
– autonomy emphasized: informed consent
– safety less serious than immunization and drug, sometimes overlooked
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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.
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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
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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
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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.
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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)
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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
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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
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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
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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
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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
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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
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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
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Smoking: study designSmoking: study design
• Randomized controlled trial– two groups
• intervention• usual care (control)
– randomized by school (cluster)– no blindness
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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
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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
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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
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Smoking: endpointsSmoking: endpoints
• Primary– efficacy: smoking status – safety: no
• Secondary– No
• Follow-up– to grade 10
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Smoking: endpointsSmoking: endpoints• Definition of smoking status• By questionnaire:
– never, – tried once, quit, experimental (<
once/week)– regular (weekly)
• By CO breath samples
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Smoking: dSmoking: data analysisata analysis
• Basic characteristics and comparison– for confounding and possible
selection bias
• Intention-to-treat analysis• Primary:
– smoking status– subgroup analysis
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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
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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!