Spine (Phila Pa 1976). 2011 (Apr 15); 36 (8): E505–512 ~ FULL TEXT
Francisco Kovacs, MD , PhD, Malén Oliver-Frontera, BS, María N. Plana, MD, Ana Royuela, MSc, Alfonso Muriel, MSc, Mario Gestoso, M.D, and the Spanish Back Pain Research Network
Palma de Mallorca. Spain.
STUDY DESIGN: Cluster randomized controlled trial.
OBJECTIVE: To evaluate the effect of a very simple education campaign among community-dwelling 8-year-old schoolchildren.
SUMMARY OF BACKGROUND DATA: Information has a positive effect on low back pain (LBP) prevention and management. There is sparse evidence on the feasibility and effectiveness of education campaigns focusing on LBP among young schoolchildren.
METHODS: A stratified random sample of 12 schools was randomized to an intervention and a control group. Eight-year-old schoolchildren from these schools were given a questionnaire on LBP prevention and management at baseline, and 15 and 98 days later. On day 8, teachers in the intervention group gave the schoolchildren a Comic Book of the Back, while no intervention was carried out in the control group. After adjusting by possible confounders, generalized estimating equations (GEE) models were developed to calculate the probability of "success" (a score over 80% of the maximum possible one).
RESULTS: Six schools (231 children, 46.5%) were assigned to the control group, and 6 (266 children, 53.5%) to the intervention one. At baseline, the percentage of correct answers was above 73% in both groups, with 8 as a median total score in the control group and 7 in the intervention group. GEE showed that the odds ratio for success in the intervention group, when compared with the control group, was 1.61 (95% CI: 1.03-2.52, P = 0.038).
CONCLUSION: The handing out of a Comic Book of the Back slightly improves children's knowledge of appropriate methods for the prevention and management of LBP, and the effect remains significant 3 months after intervention.
Key words : education campaign, low back pain, schoolchildren, cluster randomized controlled trial.
From the Full-Text Article:
Short education programs and campaigns that correct erroneous
beliefs are effective for prevention and treatment
of low back pain (LBP) among the general population,
workers, the elderly, and patients. [1–7] Current evidence-based
guidelines for prevention and treatment of LBP recommend
such programs. [8–10] The Back Book is a short booklet designed
f or this purpose. [1–3]
Suffering from back pain in childhood or adolescence
increases the risk of having it as an adult,  and some risk
factors associated with back pain in childhood have been
identifi ed. [12–17] Hence, prevention campaigns and health education
programs should include children. Since it has been
shown that from the age of 13 years, the prevalence of back
pain is similar to that of adults, [12–17] these campaigns should
be aimed at children younger than that age, [18–22] and need to
include material that is understandable at these ages. For this
purpose, a very short booklet with messages consistent with
those in the Back Book was designed in a comic book format.
Its main content included the following: back pain is usually
not due to any serious injury; physical activity and exercise
have a positive effect on back pain for both prevention and
treatment; and if back pain occurs, bed rest should be avoided
and the highest possible degree of activity should be maintained.
In addition, the comic book recommended that backpacks
should not surpass 10% of body weight [23–28] and that
children involved in competitive sports follow the advice of
their coaches and physicians strictly. [12–20] The Comic Book of
the Back is available in Spanish from the authors.
A campaign consisting of the distribution of the Comic
Book of the Back among young schoolchildren was launched
in September 2006 and endorsed by Spanish national medical,
health, and educational authorities. Within the campaign, the
Comic Book of the Back was made freely available through
the Internet and it was also distributed in the schools in the
areas where the regional authorities decided to do so.  With
slight organizational changes, the campaign was repeated at
the beginning of the academic course in September 2007.
The objective of this study was to evaluate the effect that
the handing out of the Comic Book of the Back had on the
knowledge of measures to prevent and manage LBP among
MATERIALS AND METHODS
This was a cluster randomized controlled clinical trial, with
a 3-month follow-up, in which randomization and analysis
The study population was constituted of all 8-year-old schoolchildren
in Majorca, a Spanish island in the Mediterranean
Sea with a population of approximately 850,000. An 8-year old
schoolchild was defined as one who has reached or will
reach that age throughout the school year in which the study
The study sample was composed of all 8-year-old children
attending the schools that were selected to participate. The
only exclusion criterion was not attending class on the day in
which subjects were recruited.
All schools in the island of Majorca were listed and classified in six strata, according to the type of school (public, private
or concerted—the latter, run with public funds and managed
according to government-issued criteria, but privately owned)
and their location (urban, rural, the latter defined as located in
cities with ≤10,000 inhabitants). There was no school in the
“private, rural” stratum. A stratified random sample of the
schools was selected, and confi rmation of their agreement to
participate in the study was taken from all the schools.
Sample size was established at 12 schools (6 public,
4 concerted, and 2 private), assuming that at the end of the
follow-up, the proportion of schoolchildren with an appropriate
knowledge of the prevention and management of back
pain would be 80% in the control group and 90% in the
intervention group, with a median cluster size of 38 children
per school (i.e., a total number of 456 schoolchildren), an intraclass
correlation coefficient of 0.10, a type I error of 0.05
and a type II of 0.20. “Appropriate” knowledge was defined
as having a score higher than or equal to 80% of the maximum
possible score in the questionnaire that was answered
on day 98.
The study was supported by the regional education authorities
and was approved by the institutional review board
of the Majorcan Health Authorities and the District Attorney’s
offi ce for children’s affairs. According to the Spanish
laws, the characteristics of this study made it unnecessary to
ask for parental written informed consent.
Randomization was performed at the cluster level, with the
unit of randomization and analysis being the school.
Randomization was performed according to the table of
random numbers of Moses and Oakford.  Sealed opaque
envelopes were prepared. In the front, Arabic co rrelative
numbers were indicated, and each envelope contained the
number in the corresponding order in the table of random
numbers. The starting point where the tables began to be
read was randomly determined just before the process
Once a school in a given stratum accepted to participate in
the study, the envelope corresponding to the order in which
its acceptance had been received was opened by a member of
the administrative staff who was unaware of the number it
contained. Assignment to control or intervention groups was
determined by the number from the table of random numbers
contained in the envelope.
No intervention was undertaken in the control group, in
which only assessments were carried out. In the intervention
group, the intervention consisted of the teacher handing out a
Comic Book of the Back to each pupil in the class. Teachers
were not asked to discuss the content of the comic book in
class. Intervention took place in the different schools between
October 20, 2008, and November 7, 2008.
Each school was supplied with the Comic Book of the
Back in the language(s) in which it provided education: Spanish,
English, or Majorcan (a variation of Catalan, a regional
language used in some areas in Northeast Spain).
For ethical reasons, the children in schools from the control
group were given the Comic Book of the Back at the end
of the study, after having completed their participation in it.
Outcome was assessed through a questionnaire, which was
handed out 1 week before, 1 week after, and 90 days after the
One week before the Comic Book of the Back was given to
the children in the intervention group, teachers handed out a
questionnaire that the children filled out, and retrieved it. The
questionnaire was written in the language(s) the school used,
and contained 10 statements focusing on ways to prevent or
manage back pain (Tables 1 and 2). The children were asked
to indicate which statements were true and which were false.
For ethical and legal reasons, students were identified by numeric
codes instead of their names.
At follow-ups that took place 7 and 90 days after intervention
(i.e., 15 and 98 days after the first assessment), children
were given the same questionnaire. On days 1 and 15, the
children were unaware that they would be given the same
The children were not aware of the existence of other
groups (control or intervention) in other schools. The teachers
could obviously not be blinded with respect to whether the
children were or were not given the comic book. They were
instructed not to give away the correct answers, not to help the
children answer the questionnaire, and not to interfere with
the children’s responses in any way, but to simply hand out the
questionnaires on the appropriate days, ensure that the children
answered all of the questions, and place them in a special
container which one of the assistants from the study’s coordination
offi ce retrieved no later than an hour after completion.
Data were entered in a database at a coordination-centralized
offi ce by two administrative assistants who double-checked
that the data entered coincided with the questionnaire
scores. Those administrative assistants were blinded to
the school’s assignment to the intervention or control group.
Data on sex, type of school (public, private, or concerted),
location (urban or rural), and language(s) used in the school
were collected. Since subjects could not be identifi ed by their
name, data on history of previous LBP episodes could not be
gathered from their families. No data were found on the reliability
of 8-year-old subjects’ report on history of LBP. Therefore,
history of LBP was not gathered.
Analysis was done by a group of statisticians who were not
involved in the conduct of the study and worked in a different
region of Spain. They were given the codes to identify schools
from each group but were blinded as to which group corresponded
to control or intervention.
Data were analyzed at the individual and cluster levels. At the
individual level, absolute and relative frequencies were used for
categorical variables. Medians and interquartile ranges (IQR)
were used for “global score” because it was not normally distributed. At the cluster level, medians and interquartile ranges of
the statistics used at the individual level were calculated.
The primary outcome of the study was the “success” variable,
defined as having a score higher than or equal to 80% of
the maximum possible score in the questionnaire that was answered
at the last follow-up assessment, on day 98. The intraclass
correlation coefficient was estimated by 1-way ANOVA
for the difference between scores at baseline and 98 days. 
At the individual level, the Mann-Whitney U test was used
to compare the evolution of the global score between groups.
Because of the cluster design, to estimate the effect of the
dependent variable, generalized estimating equation (GEE)
models were used to adjust for possible confounding factors.
The maximal model included the following variables:
sex, type of school, language (Catalonian, Catalonian and
Spanish, English and Spanish), location of the school (urban/
rural), and baseline score. A backward strategy was used so
that a variable was considered to be a confounder when its
removal from the model resulted in a change in the effect size
of 10% or more.  The variable “language” was eliminated
from the maximal model due to problems with collinearity.
SPSS (v. 17.0) and STATA (v. 10.0; Stata corp., College
Station, TX) statistical programs were used for the analysis.
Twelve schools were randomly selected and agreed to participate.
They schooled 587 eight-year-olds, 574 (97.8%) of
whom attended class on the day in which recruitment took
place and were included in the study. Thirty-two children
(5.6% of those included) missed the 15-day follow-up, and
other 45 (7.8%) the 98-day follow-up assessment. Among
the 497 children who completed follow-up (86.6% of those
included), 231 (46.5%) were studying in schools allocated
to the control group and 266 (53.5%) to the intervention
group (Figure 1). Tables 1 and 2 show the baseline characteristics
of the schoolchildren, at both the individual and
For both groups, the percentage of correct answers to the
questionnaire before the intervention (baseline) was above
73%, with 8 as a median total score for the control group
and 7 for the intervention group (Table 2).
At the individual level, the median (IQR) increases in score,
within the control and intervention groups, were, respectively,
on day 15: 0 (–1;1) versus 1 (0;2) (P < 0.001). On day 98: 1
(0;2) versus 1 (0;3) (P < 0.001) (Figure 2).
Table 3 shows the evolution of the median global scores
for each group, at both the individual and cluster levels. The
cluster effect estimated by the intraclass correlation coefficient
Results from the GEEs had to be adjusted for baseline score
and type of school, whereas sex, language, and school location
did not influence results. Results from GEE showed that
the odds of “success” for the intervention group was 1.61
(95% CI: 1.03–2.52) times higher than that for the control
group (P = 0.038) (Table 4). Questions responsible for the
better evolution of the score in the intervention group were
N° 1, 3, 4, and 9, which relate to the effect of bed rest, sitting,
physical activities and sport, on back’s pain prevention and
management (Tables 1 and 2).
In this study, the intervention consisted in handing out comic
books in the classrooms of 8-year-old schoolchildren. This
simple education program had a positive effect that lasted for
at least 3 months.
Baseline score in both groups was high (Table 1), probably
because of previous campaigns in the geographic setting where
it was conducted. Should that be the case, the intervention used
in this study might have a greater impact in settings where previous
campaigns have not been undertaken. The high baseline
score in both groups did not leave much room for improvement
in the intervention group. This may account for the improvement
in the intervention group being small (OR = 1.61,
but in terms of risk ratio, according to a baseline probability of
50%, it is equal to 1.25 [95% CI: 1.01–1.43]). However, this
improvement is statistically significant and, in the context of a
public campaign, small effects deriving from cheap and easyto-
generalize interventions, are valuable.
Approximately 98% of the children who were eligible to
participate in this study were included, and approximately 87%
of those included completed follow-up (Figure 1). This suggests
that generalizability of these results to the schoolchildren
in Spain is not a concern. However, this study has a number
of limitations. Follow-up could not be longer because Spanish
laws on privacy make it virtually impossible to gather the names
of the minors. Therefore, a number code was used to identify
each subject. Since that code was valid only during the current
academic year, follow-up had to be completed during that period, which in fact lasts 9 months. Taking into account the time
needed to randomize schools, ensure that they were willing to
participate, and distribute the booklets, 3 months was the maximum
feasible follow-up period. Previous studies on health education
programs for prevention of back pain among elementary
schoolchildren have shown that their effects last up to 1 year. [19, 21]
However, further studies should assess the duration of the effect
of the intervention implemented in this study. If the effects
of this campaign were short-lived, its simplicity and low cost
would make it feasible to repeat it periodically.
Legal limitations made it unfeasible to gather subjects’
history of LBP from their family and associate it with the
corresponding subject, since it was impossible to identify
their names. Therefore, in order to prevent bias from advice
received during potential previous LBP episodes, it was decided
to recruit 8-year-old subjects, who were likely to have
not suffered from LBP. [11–22, 28] As a consequence, the intervention,
the outcomes, and the follow-up period were designed
for subjects of that age. Since self-reports on LBP at that age
were considered to be potentially unreliable, no data on LBP
history were gathered. Further studies should assess if previous
history of LBP influences the effect of the intervention
tested in this study, either because of the experience itself or
as a proxy for having received advice and treatment.
Another consequence of having recruited very young subjects
is that only knowledge could be assessed, as opposed to
its actual impact on LBP prevention or management. However,
most of the increase in knowledge was in the area of active
management, which among adults leads to a clinically relevant
effect. [1–7] Therefore, it is possible that it also has a positive effect
in children, and further studies should assess this.
In this study, teachers were only asked to hand out the
comic book and not to discuss it in class. Nevertheless, it is
possible that some did so, which would be a “cointervention”
increasing the effect of the intervention. However, this would
probably also occur in practice if this measure were to be generalized
in the academic environment and can be seen as inherent
to the intervention itself. Further studies might assess
the effect of this intervention outside this environment. However,
the school may be a suitable place to implement cheap
interventions aiming at young schoolchildren for the prevention
of prevalent health conditions, especially when they can
be implemented without any significant loss of academic time.
Previous randomized clinical trials have shown that an educational
program similar to the one implemented in this study
improves LBP, LBP-related disability, and quality of life, and
that these effects are not mediated by the improvement in psychological
variables, [2, 3] which in fact have shown to have no relevant
influence on LBP, LBP-related disability, or quality of life
in Spanish subjects. [2, 3, 33–35] In these trials, the positive effects of
education were attributed to direct promotion of physical activity
and increased knowledge of evidence-based methods to prevent
and manage LBP. [2, 3] Therefore, it is likely that this increased
knowledge has positive effects also in young schoolchildren,
most of whom had not undergone LBP and were likely not to
have strong previous beliefs on how to prevent or manage it.
Positive results from this study suggest that it may be advisable
to generalize this campaign to larger populations of
that age, and that for very young children, a “comic book”
format, in which messages are conveyed in simple terms and
with drawings that catch the children’s attention, is probably
an appropriate way to educate children at such an early age
on preventive mechanisms.
This cluster randomized controlled trial was
conducted to assess the effect of handing out the
Comic Book of the Back to community-dwelling
8-year-old schoolchildren. The “comic book of the
back” is a very simple booklet promoting active
management and prevention for low back pain (LBP).
Six schools (231 children) were randomly assigned
to the control group and another 6 (266 children)
to the intervention one. No intervention was carried
out in the control group, while the Comic Book of
the Back was handed out to the children in the
The handing out of the Comic Book of the Back
increased the children’s knowledge of methods
for the prevention and management of LBP. This
effect was small but significant, and it remained
3 months later.
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