H571 Week 3 - Carpenter-HBM - Natalie

Report
“A meta-analysis of the
effectiveness of health
belief model variables in
predicting behavior”
Carpenter, 2010
Natalie Linton
Oregon State University
October 9, 2014
What is the Health Beliefs Model (HBM)?
 Developed by the U.S.
Public Health Service in the
1950s
 Based in value-expectancy
theory
measles
http://xkcd.com/51/
What is a meta-analysis?
 Statistical methods for
contrasting and combining
results from different studies
 Meta-analyses can identify:
 patterns
 sources of disagreement
Previous HBM meta-analyses:
 Janz & Becker 1984
 barriers, benefits, susceptibility
 did not estimate mean effect sizes
 Harrison et. al. 1992
 retrospective studies = larger effect
sizes than prospective
 did not correct effect size estimates
 Zimmerman & Vernberg 1994
 HBM prediction weak compared to
Social Cognitive Theory and TRA
 did not examine the effects of each
variable on behavior
Why did Carpenter conduct
a meta-analysis of the HBM?
 Determine whether measures of HBM
concepts could longitudinally predict
behavior
 Which elements are strong predictors?
 What are the moderators?
 Moderators found:
 Time between variable measurement (Time 1)
and outcome behavior measurement (Time 2)
 Type of outcome behavior:
 Prevention or treatment
 Drug-taking or not drug-related
Methodology
 18 studies (2,702 subjects); published 1982-2007
 Looked at only the first 4 concepts of HBM:
 Susceptibility (18), severity (17), barriers (17), benefits (15)
 Studies had to include at least 2 of the 4
 Studies had to be longitudinal
 Time 1: measure HBM variables
 Time 2: measure health-related behavior outcome
 Outcome dichotomized as treatment (8 studies) or prevention
behavior (10 studies)
 Outcome also dichotomized as drug-taking behavior (5
studies) or other behavior (13 studies)
Results
Results
Perceived susceptibility
 Usually not correlated with health behavior (weakest
predictor)
 Estimates mostly homogenous
 Subset of drug-taking studies only set for which
susceptibility was positively correlated with behavior
 Moderator: length of time
 Longer periods of time between Time 1 and Time 2
associated with weaker effects
 r = -0.50
Perceived severity
 “There is something about about considering complying
with a prescription to take drugs that causes people to
consider the severity of the consequences for not
taking the drugs more so than for other health
behaviors”
 Moderator: length of time
 Severity ratings more likely to be positively correlated to
behavior if the behavior is measured shortly after Time 1
 r = -0.37
Perceived benefits and barriers
 Strongest predictors of
behaviors
 Stronger when dealing with
preventive behavior
 Findings mostly consistent
with previous literature
 Moderator for perceived
benefits: length of time
 Longer periods of time
between Time 1 and Time 2
associated with weaker effects
r = -0.59
http://xkcd.com/388/
Limitations
 Small number of studies
 Not enough articles providing effect sizes
 Variety and varying quality of measures used
 16 (of 18) articles relied on convenience samples
 Did not test more complex models that are possible
and would be better to test (studies would have needed
to report full correlation matrices)
Levels of
Causation
Intrapersonal Stream
Biological/Nature
BIOLOGY/
PERSONALITY
Ultimate
Causes
1
Social/
Personal
Nexus
2
Sense of
Self/Control
Distal
Influences
7
13
8
h
Skills:
Social+General
14
Proximal
Predictors
b
c
B
C
Others’
Beh & Atts
9
i
k
j
l m
u
d
e
n
16
SOCIAL
NORMATIVE
BELIEFS
o
11
w
20
q
Values/
Evaluations
x
v
6
Interactions w/
Social Instit’s
p
Perceived
Norms
15
5
f
10
Motivation
to Comply
s
CULTURAL
ENVIRONMENT
4
Interpersonal
Bonding
19
A
Nurture/Cultural
3
SELF-EFFICACY t
BEHAVIORAL
CONTROL
Affect and
Cognitions
Cultural/Attitudinal Stream
SOCIAL
SITUATION
a
Social
Competence
g
Self
Determination
Expectancies
& Evaluations
Decisions
Social/Normative Stream
Information/
Opportunities
Knowledge/
Expectancies
17
F
21
I
22
Trial Behavior
EXPERIENCES: Expectancies -- Social Reinforcements -- Psychological/Physiological
Experiences
18
ATTITUDES
TOWARD THE
BEHAVIOR
DECISIONS/INTENTIONS
D E
12
r
23
J
K
Related Behaviors
H
G
Discussion
 Why do you think Carpenter found perceived
susceptibility to have almost no relationship to health
behavior?
 Why do you think time between measures worked as a
moderator for susceptibility, severity, and benefits?
 Why was time between measurements not a moderator
for barriers?
References
 Christopher J. Carpenter (2010): A Meta-Analysis of the
Effectiveness of Health Belief Model Variables in Predicting
Behavior, Health Communication, 25:8, 661-669.
 DiClemente, R.J., Salazar, L.F., & Crosby, R.A. (2013). Health
Behavior Theory for Public Health: Principles, Foundations and
Applications. Jones and Bartlett, Boston, MA.
 TTI slides provided to H 571 class at Oregon State University.

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