Acta Prediatr 81: 1035-9. 1992
Low back pain and disability in 14-year-old schoolchildren JJ Salminen’, J Pentti2 and P Terho3 Department of Physical Medicine and Rehabilitation‘. University of Turku, Turku Regional Institute of Occupational Health2 and Public Health Care of Turku’, Finland
Salminen JJ, Pentti J, Terho P. Low back pain and disability in 14-year-old schoolchildren. Acta Prediatr 1992;81:1035-9. Stockholm. ISSN 0803-5253 In this cross-sectional prevalence study in 1503 14-year-old Finnish schoolchildren (n = 1503) low back pain was found to be the third most common form of pain interfering with schoolwork or leisure time during the past 12 months. The lifetime cumulative incidence of low back pain was 30% and that of sciatica 1.8%. Of the 417 pupils who had experienced low back pain at some time, 39% had suffered during the past month; 65% recovered in one month from the last pain episode, while 35.2% of those reporting disabling low back pain during the past year were aware of recurrent or continual pain. Thus, 7.8% ( n = 107) of the whole population could be classified as “low back pain chronics”: 86% of the low back pain chronics had trouble with at least one of the daily activities listed, most commonly with sitting at school. Excluding pain in the extremities or sciatica, girls reported various pains more commonly than boys. Moreover, girls reporting recurrent low back pain had more trouble with their daily activities due to pain than boys ( p < 0.001), even though the recovery from the last pain episode took the same time in boys and girls. The pupils who had had sciatica at some time, in addition to recurrent low back pain, had more trouble with the 10 daily activities than others with recurrent low back pain ( p =0.014). 0 Adolescence, disability, epidemiology, low back pain, schoolchildren JJ Salminen. University Central Hospital of Turku. Department of Physical Medicine and Rehabilitation, Kiinamyllynkatu 4-8, SF-20520 Turku, Finland
In the working population, recurrent low back pain (LBP) which limits activity is at present a significant and poorly understood and controlled health problem (1). On the basis of cases presenting to pediatric orthopedic clinics, LBP in a young patient has been considered rare and has often been referred to a serious back disorder or to a disorder causing symptoms in the back (2). On the other hand, the few studies carried out in the growing age population indicate that LBP is common in this age group (3-5). The first pain episodes often occur at 13- 14 years of age (4) and the prevalence increases with age (3-5). Various characteristics, such as increased trunk length (4), decreased elasticity of the hamstring muscles (6) and decreased strength of the abdominal muscles ( 5 ) have been found to be associated with LBP in adolescence. The purpose of the first phase of the study was to discover the prevalence and disabling effect of LBP in a group of schoolchildren, in relation to time and localization (1, 7) of LBP. This was achieved by investigating pupils with a questionnaire-based history of recurrent or continuous LBP. In the second phase of the study, we compared spinal mobility and trunk muscle strength and investigated the occurrence of lumbar disc degeneration (DD) and associated factors in matched pairs of pupils with recurrent LBP and pupils without LBP. The results of the second phase of the study have been
published previously (8). We found a subgroup of schoolchildren with recurrent or continuous LBP, with a different mobility pattern and decreased trunk muscle strength. In a magnetic resonance imaging study, disc protrusion and atrophied back muscles in girls were more common in the LBP group. Also, DD was more common in the LBP group but the difference was not significant (9). Our results indicate that the questionnaire used in this study has some validity in identifying cases with structural changes and decreased spinal function related to recurrent or continuous LBP in the young. This paper focuses on the questionnaire results of the first phase of the study. The more specific aims were: to investigate the prevalence of disabling LBP in the past 12 months in comparison to other pain states; to determine the lifetime cumulative incidence of LBP; to discover the occurrence of traumas leading to LBP; to study the recovery from the last LBP episode; and to investigate the prevalence of recurrent or continuous LBP and the possible interference with daily activities.
Subjects and methods The population consisted of all eighth grade comprehensive school pupils in the municipality of Turku with 170000 inhabitants (n= 1503), 778 of whom were boys
I036
ACTA PRDIATR 81 (1992)
JJ Salminen el al.
1 DESCRIPTIVE QUESTIONNAIRE DATA
TARGET POPULATION N= t503
.................................................................................................. :................ ADEQUATE RESPONSE N=1377 (91.6 % )
’ I
i I
I
................................
....................................
................................
.......................
I
RECURRENTOR CONTINUAL LBP n= 107 ( 7.8 % )
MATCHED CASE-CONTROLLED STUDY
4
j
RANDOM SAMPLE OF RECURRENTLBP+CASES
n=38
I
PAIN
4
AGE. SEXSCHOOL MATCHED LBP-CONTROLS
7 1 7 SCIATICA
+ CASES
1
SPINAL MOBILITY AND TRUNK MUSCLE STRENGTH (
11 TESTS 1
ULTRALOW FIELD MRI
Fig. 1 . Study outline.
and 725 girls (Fig. 1). The eighth grade pupils were or had turned 14 years of age during the year of the study. The questionnaire data were collected in connection with a general health inspection, regularly carried out in this age group by school doctors, which now includes a short standardized physical examination of the back. About two weeks before the examination, the school health nurse gave the pupils a short questionnaire consisting of eight questions, to answer, if necessary, with the parents’ assistance. A letter explaining the background of the study together with instructions was enclosed. Where necessary, the school health nurse gave further information, when the pupils returned the questionnaire before the physical examination. The task of the school health nurse was to inform, not to interview. In addition to LBP, the first question dealt also with other types of pain limiting schoolwork or leisure time activities in the past 12 months (full details of the questionnaire can be obtained from the author). The second question, concerning the lifetime cumulative incidence of LBP, defined LBP as a pain, ache or uncomfortable feeling at a location demonstrated by a drawing. In addition, the pupils were asked about the occurrence of low back and leg pain below the knee (sciatica). Other questions dealt with accidents causing LBP (including minor traumas), last pain episode interfering with schoolwork or leisure time, and the disabling effect of recurrent of continuous pain on 10 daily activities. T o minimize the classification problems (1,7) LBP
LOW BACK PAIN
NECK I SHOlADER PUN
................................
LEG PAIN
k UPPER BAa(
PAIN
ARM PAIN
Fig. 2. Pain episodes interfering with schoolwork or leisure time in boys and girls in the past 12 months.
was defined exactly in relation to time and localization and the low-back area was demonstrated by a drawing. T o validate the questionnaire data in the second phase before the tests and MRI study, the pupils were asked, in a short interview, about any occurrence of LBP or other pains in the past seven days. Of the recurrent or continuous LBP cases versus controls, 36.8% versus 28.9% reported headache, 28.9% versus 7.9% neck and shoulder pain, and 44.7% versus 15.8% LBP. The prevalence of leg pain in the past seven days (15.8%) was equal in the two groups. Neither cases nor controls had experienced arm pain. The interview-based pain data were collected without awareness of the child’s pain history in the questionnaire to avoid observation bias. Over 97% of the questionnaires were returned: 1377 pupils (91.6% of the target population) answered the question on lifetime cumulative incidence and responded adequately to the other questions. If the answer was negative, the pupil was to answer no further questions. The questions about limitation to daily activities concerned only those who reported recurrent or continuous pain. Before analysis, all answers were checked by the second author and the answers concerning sciatica by the first author. Statistical analysis
Associations between two categorical variables were analyzed using the chi-square test. Fisher’s exact probability test was used in cases with few observations. Associations between more than two categorical variables were examined by using log-linear models. Matched sets of proportions were tested with Cochran’s Q-test and in paired comparisons NcNemar’s test was used.
Results Pain in the past 12 months limiting schoolwork or leisure time
Nearly one-fifth (1 7.6%) of children reported LBP with
Low back pain and disability
ACTA PEDIATR 81 (1992)
IN ME PAsr
WEEK
IN ME PAST M o m
IN ME PAST YEAR
.....................
.......................
.....................
......................
.....................
.......................
.....................
GIRLS
was significant only as to the occurrence of abdominal pain in girls with LBP (girls 43% versus 21 %, boys 21 YO versus 15%, log-linear model p = 0.037).
A r n W
.......................
Lifetime cumulative incidence of LBP Four hundred and seventeen (30.3%) subjects reported having suffered from LBP at some time. Also, girls reported symptoms more often than boys (33.9%versus 27.0%, chi-square (1)=7.71, p=0.005): 25 (1.8%) pupils reported sciatica, 14 of whom were boys. A total of 46.2% of pupils with LBP considered it to be due to some accident. Most of these (84.5%) had occurred during school sports or gymnastics or during leisure time sport activities.
BOYS
Fig. 3. Occurrence of the last disabling LBP episode in pupils reporting
LBP by sex.
% I
I
GIRLS
1037
I
I
1
BOYS
Fig. 4. Number of daily activities limited by pain in pupils reporting recurrent or continuous LBP (n= 107) by sex.
Recovery from the last LBP episode, limitation to activity due to recurrent or continuous LBP Of those reporting LBP, 38.770 had suffered from if during the past month (Fig. 3). No difference was found between boys and girls. In 64.8%of those with disabling LBP during the past year, the recovery from the last LBP episode took less than a month whereas in 35.2% the pain was recurrent or continuous: 7.8% (107) of the whole population were classified as “LBP chronics”. Recovery took as long in boys as in girls. Of those reporting recurrent or continous LBP, 86% had trouble in at least one of the daily activities listed in the questionnaire. Girls had difficulties in several situations more often than boys (Fig. 4, chi-square (2) = 16.78, p < 0.001). Of the pupils reporting sciatica, 8 (32%)had recurrent pain as well as difficulties in daily activities; they had trouble in several daily activities more often than others with LBP (Fisher’s exact test (two-tailed, p=0.014). Of those reporting recurrent or continuous LBP and limitation to daily activities, 38.9% found sitting for over 30 min at school troublesome. The proportion of pupils reporting LBP with limitation to daily activities varied significantly from one activity to another (Fig. 5, Cochran’s Q-test: Q(9)= 57.74,p < 0.001). In the paired comparison, the proportion of pupils finding sitting at school difficult did not differ significantly from the proportion of those experiencing difficulty in school sports or gymnastics or standing for over 10 min. By McNemar’s test, a significant difference was found between situation 1 and situations 4-7 (McNemar’s test: chi-square (1) = 6.7-8.6, p < 0.01) and situations 8-10 (McNemar’s test: chi-square (1) = 18.2-20, p < 0.001): 84.5%of those finding sitting at school troublesome felt that their LBP was due, at least partly, to an unsuitable school desk.
limitation to activity in the past year. LBP was the third most common pain after headache and abdominal pain (Fig. 2). Girls suffered from LBP more often than boys (chi-square (1) = 10.04,p = 0.002) but girls also reported other pains, with the exception of pain in the extremities, significantly more often than boys. Pupils with LBP reported other pains in the past year more frequently than the symptomless: neck and shoulder pain 26.6% versus 1 1.3% (chi-square (1)=41.63, p
Low back pain and disability in 14-year-old schoolchildren JJ Salminen’, J Pentti2 and P Terho3 Department of Physical Medicine and Rehabilitation‘. University of Turku, Turku Regional Institute of Occupational Health2 and Public Health Care of Turku’, Finland
Salminen JJ, Pentti J, Terho P. Low back pain and disability in 14-year-old schoolchildren. Acta Prediatr 1992;81:1035-9. Stockholm. ISSN 0803-5253 In this cross-sectional prevalence study in 1503 14-year-old Finnish schoolchildren (n = 1503) low back pain was found to be the third most common form of pain interfering with schoolwork or leisure time during the past 12 months. The lifetime cumulative incidence of low back pain was 30% and that of sciatica 1.8%. Of the 417 pupils who had experienced low back pain at some time, 39% had suffered during the past month; 65% recovered in one month from the last pain episode, while 35.2% of those reporting disabling low back pain during the past year were aware of recurrent or continual pain. Thus, 7.8% ( n = 107) of the whole population could be classified as “low back pain chronics”: 86% of the low back pain chronics had trouble with at least one of the daily activities listed, most commonly with sitting at school. Excluding pain in the extremities or sciatica, girls reported various pains more commonly than boys. Moreover, girls reporting recurrent low back pain had more trouble with their daily activities due to pain than boys ( p < 0.001), even though the recovery from the last pain episode took the same time in boys and girls. The pupils who had had sciatica at some time, in addition to recurrent low back pain, had more trouble with the 10 daily activities than others with recurrent low back pain ( p =0.014). 0 Adolescence, disability, epidemiology, low back pain, schoolchildren JJ Salminen. University Central Hospital of Turku. Department of Physical Medicine and Rehabilitation, Kiinamyllynkatu 4-8, SF-20520 Turku, Finland
In the working population, recurrent low back pain (LBP) which limits activity is at present a significant and poorly understood and controlled health problem (1). On the basis of cases presenting to pediatric orthopedic clinics, LBP in a young patient has been considered rare and has often been referred to a serious back disorder or to a disorder causing symptoms in the back (2). On the other hand, the few studies carried out in the growing age population indicate that LBP is common in this age group (3-5). The first pain episodes often occur at 13- 14 years of age (4) and the prevalence increases with age (3-5). Various characteristics, such as increased trunk length (4), decreased elasticity of the hamstring muscles (6) and decreased strength of the abdominal muscles ( 5 ) have been found to be associated with LBP in adolescence. The purpose of the first phase of the study was to discover the prevalence and disabling effect of LBP in a group of schoolchildren, in relation to time and localization (1, 7) of LBP. This was achieved by investigating pupils with a questionnaire-based history of recurrent or continuous LBP. In the second phase of the study, we compared spinal mobility and trunk muscle strength and investigated the occurrence of lumbar disc degeneration (DD) and associated factors in matched pairs of pupils with recurrent LBP and pupils without LBP. The results of the second phase of the study have been
published previously (8). We found a subgroup of schoolchildren with recurrent or continuous LBP, with a different mobility pattern and decreased trunk muscle strength. In a magnetic resonance imaging study, disc protrusion and atrophied back muscles in girls were more common in the LBP group. Also, DD was more common in the LBP group but the difference was not significant (9). Our results indicate that the questionnaire used in this study has some validity in identifying cases with structural changes and decreased spinal function related to recurrent or continuous LBP in the young. This paper focuses on the questionnaire results of the first phase of the study. The more specific aims were: to investigate the prevalence of disabling LBP in the past 12 months in comparison to other pain states; to determine the lifetime cumulative incidence of LBP; to discover the occurrence of traumas leading to LBP; to study the recovery from the last LBP episode; and to investigate the prevalence of recurrent or continuous LBP and the possible interference with daily activities.
Subjects and methods The population consisted of all eighth grade comprehensive school pupils in the municipality of Turku with 170000 inhabitants (n= 1503), 778 of whom were boys
I036
ACTA PRDIATR 81 (1992)
JJ Salminen el al.
1 DESCRIPTIVE QUESTIONNAIRE DATA
TARGET POPULATION N= t503
.................................................................................................. :................ ADEQUATE RESPONSE N=1377 (91.6 % )
’ I
i I
I
................................
....................................
................................
.......................
I
RECURRENTOR CONTINUAL LBP n= 107 ( 7.8 % )
MATCHED CASE-CONTROLLED STUDY
4
j
RANDOM SAMPLE OF RECURRENTLBP+CASES
n=38
I
PAIN
4
AGE. SEXSCHOOL MATCHED LBP-CONTROLS
7 1 7 SCIATICA
+ CASES
1
SPINAL MOBILITY AND TRUNK MUSCLE STRENGTH (
11 TESTS 1
ULTRALOW FIELD MRI
Fig. 1 . Study outline.
and 725 girls (Fig. 1). The eighth grade pupils were or had turned 14 years of age during the year of the study. The questionnaire data were collected in connection with a general health inspection, regularly carried out in this age group by school doctors, which now includes a short standardized physical examination of the back. About two weeks before the examination, the school health nurse gave the pupils a short questionnaire consisting of eight questions, to answer, if necessary, with the parents’ assistance. A letter explaining the background of the study together with instructions was enclosed. Where necessary, the school health nurse gave further information, when the pupils returned the questionnaire before the physical examination. The task of the school health nurse was to inform, not to interview. In addition to LBP, the first question dealt also with other types of pain limiting schoolwork or leisure time activities in the past 12 months (full details of the questionnaire can be obtained from the author). The second question, concerning the lifetime cumulative incidence of LBP, defined LBP as a pain, ache or uncomfortable feeling at a location demonstrated by a drawing. In addition, the pupils were asked about the occurrence of low back and leg pain below the knee (sciatica). Other questions dealt with accidents causing LBP (including minor traumas), last pain episode interfering with schoolwork or leisure time, and the disabling effect of recurrent of continuous pain on 10 daily activities. T o minimize the classification problems (1,7) LBP
LOW BACK PAIN
NECK I SHOlADER PUN
................................
LEG PAIN
k UPPER BAa(
PAIN
ARM PAIN
Fig. 2. Pain episodes interfering with schoolwork or leisure time in boys and girls in the past 12 months.
was defined exactly in relation to time and localization and the low-back area was demonstrated by a drawing. T o validate the questionnaire data in the second phase before the tests and MRI study, the pupils were asked, in a short interview, about any occurrence of LBP or other pains in the past seven days. Of the recurrent or continuous LBP cases versus controls, 36.8% versus 28.9% reported headache, 28.9% versus 7.9% neck and shoulder pain, and 44.7% versus 15.8% LBP. The prevalence of leg pain in the past seven days (15.8%) was equal in the two groups. Neither cases nor controls had experienced arm pain. The interview-based pain data were collected without awareness of the child’s pain history in the questionnaire to avoid observation bias. Over 97% of the questionnaires were returned: 1377 pupils (91.6% of the target population) answered the question on lifetime cumulative incidence and responded adequately to the other questions. If the answer was negative, the pupil was to answer no further questions. The questions about limitation to daily activities concerned only those who reported recurrent or continuous pain. Before analysis, all answers were checked by the second author and the answers concerning sciatica by the first author. Statistical analysis
Associations between two categorical variables were analyzed using the chi-square test. Fisher’s exact probability test was used in cases with few observations. Associations between more than two categorical variables were examined by using log-linear models. Matched sets of proportions were tested with Cochran’s Q-test and in paired comparisons NcNemar’s test was used.
Results Pain in the past 12 months limiting schoolwork or leisure time
Nearly one-fifth (1 7.6%) of children reported LBP with
Low back pain and disability
ACTA PEDIATR 81 (1992)
IN ME PAsr
WEEK
IN ME PAST M o m
IN ME PAST YEAR
.....................
.......................
.....................
......................
.....................
.......................
.....................
GIRLS
was significant only as to the occurrence of abdominal pain in girls with LBP (girls 43% versus 21 %, boys 21 YO versus 15%, log-linear model p = 0.037).
A r n W
.......................
Lifetime cumulative incidence of LBP Four hundred and seventeen (30.3%) subjects reported having suffered from LBP at some time. Also, girls reported symptoms more often than boys (33.9%versus 27.0%, chi-square (1)=7.71, p=0.005): 25 (1.8%) pupils reported sciatica, 14 of whom were boys. A total of 46.2% of pupils with LBP considered it to be due to some accident. Most of these (84.5%) had occurred during school sports or gymnastics or during leisure time sport activities.
BOYS
Fig. 3. Occurrence of the last disabling LBP episode in pupils reporting
LBP by sex.
% I
I
GIRLS
1037
I
I
1
BOYS
Fig. 4. Number of daily activities limited by pain in pupils reporting recurrent or continuous LBP (n= 107) by sex.
Recovery from the last LBP episode, limitation to activity due to recurrent or continuous LBP Of those reporting LBP, 38.770 had suffered from if during the past month (Fig. 3). No difference was found between boys and girls. In 64.8%of those with disabling LBP during the past year, the recovery from the last LBP episode took less than a month whereas in 35.2% the pain was recurrent or continuous: 7.8% (107) of the whole population were classified as “LBP chronics”. Recovery took as long in boys as in girls. Of those reporting recurrent or continous LBP, 86% had trouble in at least one of the daily activities listed in the questionnaire. Girls had difficulties in several situations more often than boys (Fig. 4, chi-square (2) = 16.78, p < 0.001). Of the pupils reporting sciatica, 8 (32%)had recurrent pain as well as difficulties in daily activities; they had trouble in several daily activities more often than others with LBP (Fisher’s exact test (two-tailed, p=0.014). Of those reporting recurrent or continuous LBP and limitation to daily activities, 38.9% found sitting for over 30 min at school troublesome. The proportion of pupils reporting LBP with limitation to daily activities varied significantly from one activity to another (Fig. 5, Cochran’s Q-test: Q(9)= 57.74,p < 0.001). In the paired comparison, the proportion of pupils finding sitting at school difficult did not differ significantly from the proportion of those experiencing difficulty in school sports or gymnastics or standing for over 10 min. By McNemar’s test, a significant difference was found between situation 1 and situations 4-7 (McNemar’s test: chi-square (1) = 6.7-8.6, p < 0.01) and situations 8-10 (McNemar’s test: chi-square (1) = 18.2-20, p < 0.001): 84.5%of those finding sitting at school troublesome felt that their LBP was due, at least partly, to an unsuitable school desk.
limitation to activity in the past year. LBP was the third most common pain after headache and abdominal pain (Fig. 2). Girls suffered from LBP more often than boys (chi-square (1) = 10.04,p = 0.002) but girls also reported other pains, with the exception of pain in the extremities, significantly more often than boys. Pupils with LBP reported other pains in the past year more frequently than the symptomless: neck and shoulder pain 26.6% versus 1 1.3% (chi-square (1)=41.63, p
