The effects of screening on health behaviour: a summary of the results of randomized controlled trials
Journal of Public Health |
The effects of screening on health behaviour: a summary of the results of randomized controlled trials
Marije Deutekom 1 2 3
Fleur Vansenne 1 2
Kirsten McCaffery 0 2
Marie-Louise Essink-Bot 2 3
Karien Stronks 2 3
Patrick M.M. Bossuyt 1 2
0 Screening and Test Evaluation Program, School of Public Health, University of Sydney , Sydney , Australia
1 Department of Clinical Epidemiology and Biostatistics from the Academic Medical Centre , Amsterdam , The Netherlands
2 Marije Deutekom , Senior Researcher, Public Health Fleur Vansenne , Researcher , Clinical Epidemiology Kirsten McCaffery, Assistant Professor, Public Health Marie-Louise Essink-Bot , Assistant Professor, Public Health Karien Stronks , Professor, Public Health Patrick M.M. Bossuyt , Professor , Clinical Epidemiology
3 Department of Public Health , Room K2-207, Meibergdreef 9, 1105 AZ Amsterdam , The Netherlands
A B S T R AC T Background Screening aims to improve health by early detection of disease or risk factors for disease. It may also influence health behaviour, either by intention or as a side effect. The aim of this review was to summarize evidence of the effects of screening, either risk factor screening or screening for early detection of disease, on health behaviour: smoking habits, diet, exercise, alcohol consumption and adherence to guidelines for healthy living. Methods This review included randomized controlled trials (RCTs) comparing the effects of screening on health behaviour in a screened group and an unscreened group. Systematic searches of Medline, CCTR and Embase between 1970 and May 2008 were conducted. Results Seven trials were included, five on screening for risk factors (four cardiovascular; one ALDH2) and two on screening for early detection of disease (colorectal cancer and hearing loss). In trials of screening for risk factors, health behaviour was on average significantly more favourable in screened individuals. The number of trials on screening for early detection of disease was too small to allow for conclusions on effects on health behaviour. Conclusion The number of trials studying the effect of population-based screening programmes on health behaviour is limited. The trials on screening for risk factors suggest a positive effect on health behaviour, while the number of trials on screening for early detection of disease was too low to draw conclusions on subsequent health behaviour. Future RCTs of screening interventions should systematically include health behaviour effects in their study design.
exercise; health behaviour; risk factors; screening; smoking
This review included RCTs studying the effects of screening
on health behaviour in a screened group and an unscreened
group. Systematic searches of electronic databases were
conducted, including National Library of Medicine (Medline;
1966 onwards), Cochrane Controlled Trial Register (CCTR)
and Embase (1980 onwards). The searches were conducted
in May 2008.
The following search strategies were used: (health AND
behaviour) OR lifestyle OR diet OR exercise OR smoking
OR life style mesh OR risk reduction behaviour mesh OR
health behaviour mesh AND mass screening mesh AND
(Clinical trialpt OR randomizedtiab OR placebotiab OR
clinical trialsmh OR randomlytiab OR trialti) NOT
(animalsmh NOT (animalsmh AND humansmh)) (Medline)
(diet or smoking or exercise or (health and behaviour) or
lifestyle).mp AND mass screening/AND (Clinical tria$ or
randomized or randomized or placebo or control or
randomly or trial).mp (Embase) and (health AND behaviour)
OR lifestyle OR diet OR exercise OR smoking OR life style
OR risk reduction behaviour) AND mass screening mesh in
Clinical Trials (CCTR). No language restrictions were used.
The reference sections of the obtained articles were also
studied and requests for unpublished studies were circulated
among colleagues. A methodological filter to identify RCTs
Possibly eligible papers were downloaded into Reference
Inclusion criteria were: randomized study on screening in
healthy adults (aged 18 and above), measurement of health
behaviour. Health behaviour was defined as any data on
smoking habits, diet, exercise, alcohol consumption or
adherence to guidelines of healthy living.
Studies were not included when they investigated health
intentions only, when they focused solely on improving the
uptake of screening, or reattendance at screening when next
invited, or when they investigated the effect on families
(significant others) and social environment.
When RCTs were found compared screened and
unscreened individuals on clinical variables but did not
mention any health behaviour variables, the corresponding
author was contacted and asked whether he and his
colleagues had collected such data. If so, these unpublished
data were also included in the review.
potentially eligible trial were then obtained for further
assessment of eligibility by two authors (M.D. and F.V.). Any
disagreements were resolved by discussion.
Data regarding inclusion criteria, study characteristics and
results (study design, participants, interventions and
outcomes) were extracted.
Due to the small number of included studies and marked
heterogeneity in the type of screening, study population,
length of follow-up and outcome assessment measures, we
made no attempts at statistically pooling the data in a
meta-analysis. Instead a qualitative synthesis of the results is
presented. All dichotomous variables were analyzed, if
possible, with Chi-square statistics to compare differences
between the screened and unscreened groups. For all
statistical tests P-values ,0.05 were considered to represent
Retrieval of papers
In total 1953 manuscripts were retrieved, of which 621 were
duplicates. The remaining 1332 manuscripts were assessed
for eligibility by reading title and abstract. This resulted in
107 potentially eligible trials. Based on the complete
manuscripts 100 of these studies could not be included. In total,
seven trials13 – 19 met our inclusion criteria (see Fig. 1).
(n = 1128)
(n = 438)
(n = 360)
Cinahl (n = 0) Retrieved papers (n = 1953)
(n = 1332)
(n = 107)
(n = 7)
Duplicates (n = 621) Exclusion (n = 1225)
(n = 100)
Fig. 1 Search strategy.
place,14,16 in one study14 individuals were randomly drawn
from the population registry. The follow-up length varied
from 3 months19 to 5 years.15
Different forms of health behaviour were studied:
smoking in three studies,13,17,18 diet in three studies,13,16,18
exercise in two studies,13,18 alcohol consumption in two
studies,14,18 and adherence to given advice (testing for
cholesterol and avoidance of noise) in two studies.15,19
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Effects of early detection of disease screening
Only two studies dealt with screening for early detection of
disease.13,15 The study of Larsen et al.13 investigated the
effects of screening for colorectal cancer on smoking, diet
and exercise. The study of Karlsmose et al.15 investigated the
effects of screening for hearing loss on exposure to noise.
In the trial of colorectal cancer smoking,13 and diet were
measured on a scale from 1 (never) to 6. For smoking
‘6’indicated ‘.20 cigarettes per day’ and for diet
‘consumption .3 times per day’. Exercise was measured on a scale
from 2 to 12.
Unscreened individuals showed a decline in smoking of
0.14 points (baseline score: 2.49) versus 0.11 in the screened
group (baseline score: 2.56) (P ¼ 0.013; P-value from
original article and derived from linear regression analyses).
Diet was measured with various variables: servings of fruit,
berries and vegetables, consumption of boiled potatoes,
poultry, meat, fatty fish and chocolate. The screened group
lowered their consumption of fruit, berries and vegetables
with 0.13 points (baseline score: 2.28), whereas the unscreened
group increased their intake with 0.04 points (baseline score:
2.15; difference between screened and unscreened group: 0.17:
P ¼ 0.001; derived from linear regression analyses). No
difference in intake was detected between the screen negatives and
the screen positives (P ¼ .346).
The improvement in the amount of exercise in the
screened group was significantly lower (P , 0.001) than in
the unscreened group (þ0.01 (baseline: 6.09) versus þ 0.21
The study of screening for hearing loss found that after
screening15 there was a significant change in exposure to
leisure noise between screened and unscreened individuals (42
and 49%, respectively; P ¼ 0.045) after 5 years. However, no
differences were detected for exposure to occupational noise
(screened: 46%; unscreened: 50%: 95% CI of difference:
210.6 to 2.6) and to the use of hearing protection (screened:
42%; unscreened: 47%: 95% CI of difference: 24.0 to 14.7).
Summary of the results
In table 2 a summary of the results is shown. For all five
health behaviour variables (smoking, diet, exercise, alcohol
consumption and adherence) we list whether the outcome
was better, equal or worse in the screened group compared
with the unscreened group.
Table 2 Summary of results per outcome variable
Alcohol consumption Adherence Risk factor screening
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