a Departamento de Ortopedia, Santa Casa de São Paulo, São Paulo, SP, Brasil
b Serviço de Ortopedia e Traumatologia, Hospital Israelita Albert Einstein, Universidade Federal de São Paulo (Unifesp), São Paulo, SP,Brasil
c Instituto de Ortopedia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (USP), São Paulo, SP, Brasil
d Escola Paulista de Medicina, Universidade Federal de São Paulo (Unifesp), São Paulo, SP, Brasil
Nonspecific lumbar pain is considered to be one of themain health problems in industrialized countries1and ithas increased considerably over recent decades amongadolescents.2The earliest cases of nonspecific lumbar painoccur in the age group from 11 to 12 years, with a gradualincrease of approximately 10% per year, until reaching around50% of adolescents at the age of 18 years.3This problem iseven more significant when it is perpetuated into adulthood.
It is difficult to identify the etiology of lumbar pain becauseit is manifested under various conditions5and is often ofmultifactorial nature.6Among other causes, lumbar painpresents an association with individuals' lifestyles, such thatoverweight,7-9sedentarism8,9and remaining in certain posi-tions for long periods of time7,10are triggering factors for thisproblem.
In this context, a study conducted among school children inFlorianópolis, state of Santa Catarina, showed that 25.5% of theindividuals who feel lumbar pain indicate that the triggeringfactor for their painful state consists of situations in whichthey remain in a seated position for long periods.10In addition,adolescents who occupy their time doing activities that allowdiversity of posture present a chance of developing lumbarpain that is 2.3 times lower than the rate presented by theirsedentary peers.
On the other hand, high levels of physical activity arepositively associated with the appearance of nonspecific lum-bar pain.3,4,7However, this association needs to be analyzedcautiously, since continuous well-guided physical activitypractices contribute toward better posture and lower inci-dence of lumbar pain.
It is important to emphasize that lumbar pain is not a spe-cific pathological condition but, rather, a symptom that maybe related to a disease12and which, with the passage of time,may result in a degenerative musculoskeletal disorder2,7withthe capacity to reduce the individual's fitness for work.13 Thus, knowledge of the etiology of lumbar pain and the associatedfactors in adolescents may help to prevent and understandthe problem in adults.
The present study had the objective of analyzing the preva-lence of nonspecific lumbar pain and the associated factorsamong adolescents in Uruguaiana, state of Rio Grande do Sul(RS).
Method
This was a school-based cross-sectional study conductedamong adolescents aged 10-17 years who were enrolled inthe daytime shift of the municipal and state school networkof Uruguaiana, RS. This study formed part of a larger projectdeveloped in 2011, under the title "Habitual physical activityand associated factors among school children in Uruguaiana,RS", which was approved by our institution's research ethicscommittee (protocol 042/2010) and followed the guidance ofResolution 196/96 of the National Health Council.
According to information from the elementary schoolcensus of 2010,15the study population comprised 15,210 ado-lescents in the age group determined. To make the samplecalculation, the following procedures were used: prevalenceof 50%, since the larger project addressed multiple outcomes;95% confidence interval (95% CI); sample error of 3%; designeffect (deff) of 1.5; and an additional amount of 15% to makeup for possible losses and refusals. Through using these crite-ria, it was estimated that it would be necessary to assess 1398school children. The sampling criterion used was probabilisticin clusters, in which each school was considered to be a clus-ter. All the public schools in the municipality participated inthe draw and had the same chances of participating, accord-ing to the number of students enrolled in the age group from10 to 17 years. To reach the estimated number of adolescents,it was necessary to draw 10 schools: nine in the urban area(seven state schools and two municipal schools) and one inthe rural area. All the school children between the ages of 10 and 17 years at the 10 schools that were drawn were invited toparticipate. Only students who presented a free and informedconsent statement signed by an adult responsible for themand who expressed willingness to participate were includedin the sample composition.
The data-gathering procedure comprised two stages.Firstly, a questionnaire structured into sections was appliedto all the individuals who made up the sample. The question-naire contained questions relating to: (a) sociodemographicindicators; (b) behavior and habits of the daily routine (includ-ing physical activity); and (c) history of nonspecific lumbarpain. In the second stage, anthropometric and motor mea-surements were made. The data were gathered by a groupof trained evaluators (teachers and students/bursary-holdersat the institution where the study was conducted). The data-gathering period was from May to November 2011.
Nonspecific lumbar pain (dependent variable) was esti-mated using an adaptation of the instrument proposed bySjoile et al.16The adolescents gave responses to the follow-ing question: "Have you ever had pain or discomfort in yourback, in the lumbar region?" There was a drawing beside thequestion that indicated the location of the lumbar region.The responses possible were: never; only a few times; often;and all the time. For the analyses, the categories of "never"and "only a few times" were grouped and considered to be"without lumbar pain" and the categories of "often" and "allthe time" were grouped and considered to be "with lumbarpain".
The variables that formed the sociodemographic indica-tors were: (a) sociodemographic level (in conformity withthe Brazilian economic classification criteria divided into fivelevels from A to E)17; (b) sex (male or female); and (c) age (com-pleted years).
The indicators of behavior and daily routine habits were:(a) time spent doing sedentary activities, involving use of tele-visions, electronic games and computers (=3 h or >3 h); and(b) habitual physical activity level, using a questionnaire forphysical activities among children and adolescents: PhysicalActivity Questionnaire for Older Children (PAQ-C)18and Ado-lescents (PAQ-A).19The PAQ-C/PAQ-A contains nine questionswith five possible responses. Each response is scored from 1 to5, thus producing the final score for each questionnaire. Theindividuals were classified into terciles with regard to theirphysical activity levels: "least active" (tercile 1), "intermediate"(tercile 2) and "most active" (tercile 3).
The anthropometric and motor activities evaluatedwere: height, body mass, flexibility and abdominalstrength/resistance. Body mass measurements were madewith the aid of a Plenna®digital balance (Plenna, São Paulo,Brazil) with a capacity of 150 kg and precision of 100 g. Heightwas measured in centimeters, with one decimal place, withthe aid of a measuring stick fixed to the wall. The individualswere positioned in accordance with the Frankfurt plane,using a setsquare on the head. Both of these anthropometricmeasurements were made in accordance with standardprocedures.20The body mass index (BMI) was obtained bydividing the body mass in kilograms by the height in meterssquared and was categorized as "normal weight" or "over-weight" (the overweight and obese categories were grouped),in conformity with the proposal of Cole et al. and abdominal strength/resistance were mea-sured using the sit-and-reach test and according to thenumber of sit-ups that could be done in one minute,respectively. The measurement procedure followed the rec-ommendations of the Brazilian sports project (Proesp).22Through using specific cutoff points according to sex and age,flexibility and abdominal strength/resistance were classifiedas "less than recommended" or "recommended".
To analyze the data, univariate, bivariate and multivariablemethods were used. In the univariate analysis, the abso-lute and relative frequencies (proportions) were used for eachof the variables studied, followed by calculation of the 95%confidence interval (95% CI). For the bivariate analysis, the chi-squared test for heterogeneity and chi-square test for lineartrend were used. In this analysis, each independent vari-able was correlated with the dichotomized dependent variable("without lumbar pain" or "with lumbar pain"). Also for thebivariate analysis, Student's t-test for independent sampleswas used to test the difference between the mean ages of thegroups with and without lumbar pain.
In the multivariable analysis, binary logistic regressionwas used. Nonspecific lumbar pain was dichotomized as anoutcome. Each of the independent variables in this analysiswas entered in conformity with the hierarchical theoreticalmodel that was constructed (Fig. 1). The theoretical modelused three causal determination levels (proximal, intermedi-ate and distal). The first level (sociodemographic indicators)included the socioeconomic level, age and sex. The interme-diate level (lifestyle indicators) included sedentary behaviorand physical activity. The last level (anthropometric and motorindicators) included the body mass index, flexibility and mus-cle strength/resistance. The final multivariable model took theindependent variables that presented p-values < 0.05 into con-sideration as factors associated with nonspecific lumbar pain.
Results
For the analyses, data on 1455 adolescents were gathered. Tocalculate the prevalences of lumbar pain, 1377 individuals whofilled out all the information needed were taken into consid-eration.
The prevalence of lumbar pain among the adolescents eval-uated was 16.1%. Divided according to sex, the male grouppresented prevalence of 10.5% (n = 71) and the female group,21.6% (n = 151).
The frequency distribution of the variables analyzed is pre-sented in Table 1. From this, it can be seen that 26.7% of theindividuals evaluated were overweight and that 64.2% werespending more than three hours a day doing sedentary activ-ities.
The results from the chi-square test indicated that onlythe variables of sex, BMI, abdominal strength/resistance andphysical activity level presented statistically significant asso-ciations with nonspecific lumbar pain (p < 0.05), as shown in
Table 2. In relation to age, the t-test indicated that adoles-cents who reported having lumbar pain had a higher meanage than those who reported that they did not feel any lumbarpain (t = -3.61; p < 0.05).
The crude odds ratio (OR) values from the binary logisticregression analyses confirmed the results from the analyseson the chi-square test. From combined analysis (adjusted OR),sex, age and BMI maintained their significance in the model. Itis worth emphasizing that the results from the adjusted binarylogistic regression analysis indicated that female adolescentspresented approximately a 2.3-fold greater chance of havinglumbar pain than their peers. In relation to age, it could beseen that with each year that passed, the chance of lumbarpain increased by 14% (Table 3).
Discussion
Nonspecific lumbar pain in adolescents has been the focusof several studies because of the high prevalences found inthe literature and because of the multifactorial nature of itsetiology
In this context, the results showed that the preva-lence of nonspecific lumbar pain among the adolescentsin Uruguaiana (16.1%) was lower than the rates presentedin the literature, which have ranged from 20% to 60%,approximately
However, this result needs to be analyzed attentively,because sociocultural, environmental and genetic aspectsof the reality analyzed should be taken into consideration,which adds difficulty to extrapolating the results to differ-ent contexts.30Moreover, Masiero et al.25commented thatthe different conclusions regarding the prevalence of lumbarpain may be related to the study design, sample selection,instrument used for measurements and the geographical area,among other factors.
Sex has been indicated as one of the factors associatedwith nonspecific lumbar pain,25,28,29,31,32which is in line withthe findings from the present study, which showed thatfemales were more affected by painful conditions and pre-sented around a 2.4-fold greater chances of presenting lumbarpain than shown by males.
The fact that females presented greater prevalence of paincan be explained by cultural issues, in that women maydemonstrate their feeling more,28along with their specificanatomofunctional characteristics, such as less adaptation tosustained physical effort and joints that are more fragile.33It needs to be emphasized that the differences between thesexes may be linked to endogenous pain modulation sys-tems that contribute toward greater sensitivity to and greaterprevalence of a variety of painful conditions among women.34Moreover, perceptions of pain may be affected by hormonalalterations induced by puberty.
The association between age and lumbar pain hasbeen shown to be positive, with increasing prevalence asage increases. This makes it possible to speculate thatlumbar pain during childhood is predictive of lumbar pain inadulthood.
In this regard, a study conducted among school children inBauru, state of São Paulo, also found an association between
lumbar pain and age,28thereby strengthening the findingsfrom the present study, in which a significant increase inprevalence relating to advancing age was highlighted.
The increase in prevalence according to age may resultfrom accumulated overload on the spine caused, amongother factors, by carrying backpacks and other heavyobjects and by remaining in a seated position for longperiods.
The variable of socioeconomic level was not found topresent any association with lumbar pain. This variable needs
to be analyzed cautiously in this regard, given that socioe-conomic level is related to several other factors and mayserve as a confounding variable in cases of significant asso-ciations with lumbar pain.35Nonetheless, a study conductedamong the population of Salvador, state of Bahia, also didnot find any significant association between lumbar painand socioeconomic level among the subjects evaluated.36Likewise, among students in Londrina, state of Paraná, noassociation was found between back pain and socioeconomicclass.
BMI also presented a significant association with condi-tions of lumbar pain among the adolescents evaluated hereand corroborated the results from the meta-analysis pre-sented by Shiri et al.38regarding the association betweenlumbar pain and obesity. They concluded that both overweightand obesity increased the risk of lumbar pain and also sug-gested that the association between overweight or obesity andthe prevalence of lumbar pain was stronger among womenthan among men.
In this context, obesity has a negative impact on children'sosteoarticular health, because it promotes biomechanicalalterations in the lumbar spine and triggers significantlygreater frequency of lumbar pain among obese individuals.
39However, in an analysis by Jannini et al.32on muscu-loskeletal pain among adolescents, the prevalence of lumbarpain was not found to be greater among obese individualsthan among normal-weight individuals. Even so, back pain isthe most frequent painful manifestation among obese chil-dren and adolescents and affects approximately 39% of theseindividuals.
Review studies have indicated that back pain in childrenand adolescents may be associated with seated positions, pos-tural deviations and also weakness of the abdominal muscles,among other factors.7,41In the present study, lumbar pain wascorrelated with abdominal strength/resistance, which corrob-orates this information.
Jones et al.6also found significant differences in abdominalresistance among adolescents with lumbar pain, in com-parison with adolescents without pain. However, Balagué,Troussier and Salminen7showed that lumbar pain at schoolage cannot simply be attributed to muscle weakness. This isbecause there seems to be a correlation between shorteningof the posterior muscles of the thigh and lumbar pain. Thisinformation is reinforced by the study by Feldman et al.,35whoassessed adolescents and found an association between lum-bar pain and shortening in the hamstring muscles and in thefemoral quadriceps.
In the present study, no association was identified betweenlumbar flexibility and occurrences of lumbar pain. This resultmay be associated with the fact that there is no consensusregarding what the appropriate values for protection againstcases of lumbar pain would be.7,41In this regard, one studyfound that only intermediate trunk flexibility values providedprotection against the appearance of lumbar pain, since valuesindicating hypomobility and hypermobility were predictive ofthe appearance of the problem.
However, this lack of consonance in the informa-tion may be related to the group studied, since themorphological differences between the sexes may affectthe results. Thus, the fact that women present greater flexibility and lower abdominal resistance values maygive rise to higher prevalence of lumbar pain amongwomen.
The time spent doing sedentary activities did not presentany relationship with the states of lumbar pain presented bythe individuals evaluated. This result differed from what wasfound in a study among school children in Bauru, state ofSão Paulo, in which it was shown that individuals who spentmore than two hours watching television presented an 86%greater chance of having lumbar pain.28However, it has to beborne in mind that the association between the time spentdoing sedentary activities and the presence of lumbar painis not well defined among students, which shows the lack ofstudies.
A study conducted in Italy by Masiero et al.25amongadolescents aged 13-15 years found an association betweennonspecific lumbar pain and female sex, family history andsedentarism. A similar result was found by Noll et al.,29inanalyzing factors associated with back pain among adoles-cents.
Regarding the association between the physical activitylevel and lumbar pain, the crude analysis showed that adoles-cents who were less active had higher chances of presentinglumbar pain. However, when the analysis was adjusted for thesociodemographic variables, the association ceased to presentstatistical significance.
These results are in line with information available inthe literature that indicates that there is no consistencyin the results regarding the association between physicalactivity and lumbar pain. Results stating that lower lev-els of physical activity are associated with lumbar pain inadolescents11,24and that vigorous physical activity practicesalso may increase the chance of lumbar pain in adolescents31are available in the literature and indicate that further studieson the association between these variables need to be con-ducted.
The results from the present study provide evidence thatcontributes toward better comprehension of lumbar painamong adolescents. However, certain limitations need to betaken into consideration. Since this was a school-based study,the results cannot be generalized to all of the adolescents inthe city. Although significant associations were found betweenlumbar pain and some independent variables, it was notpossible to establish the causality because this was a cross-sectional study.
Conclusions
In relation to the factors associated with lumbar pain,the adjusted model indicated that sex, age and BMI werethe factors that predicted cases of lumbar pain. Femalesex, greater age and overweight or obesity increasedthe chance of presenting nonspecific lumbar pain amongthe adolescents in Uruguaiana, state of Rio Grande doSul.
Conflicts of interest
The authors declare no conflicts of interest.
s1. Maciel SC, Jennings F, Jones A, Natour J. The development andvalidation of a low back pain knowledge questionnaire - LKQ.Clinics. 2009;64(12):1167-75.2. Hakala P, Rimpelä A, Salminen JJ, Virtanen SM, Rimpelä M.Back, neck, and shoulder pain in Finnish adolescents:national cross sectional surveys. BMJ. 2002;325(7367):743.3. Phélip X. Why the back of the child? Eur Spine J.1999;8(6):426-8.4. Harreby M, Nygaard B, Jessen T, Larsen E, Storr-Paulsen A,Lindahl A, et al. Risk factors for low back pain in a cohort of1389 Danish school children: an epidemiologic study. EurSpine J. 1999;8(6):444-50.5. Polito MD, Maranhão Neto GA, Lira VA. Componentes daaptidão física e sua influência sobre a prevalência delombalgia. Rev Bras Ciênc Mov. 2003;11(2):35-40.6. Jones MA, Stratton G, Reilly T, Unnithan VB. Biological riskindicators for recurrent non-specific low back pain inadolescents. Br J Sports Med. 2007;39(3):137-40.7. Balagué F, Troussier B, Salminen JJ. Non-specific low back painin children and adolescents: risk factors. Eur Spine J.1999;8(6):429-38.8. Hestbaek L, Korsholm L, Leboeuf-Yde C, Kyvik KO. Doessocioeconomic status in adolescence predict low back pain inadulthood? A repeated cross-sectional study of 4771 Danishadolescents. Eur Spine J. 2008;17(12):1727-34.9. Sato T, Hirano T, Morita O, Kikuchi R, Endo N, Tanabe N. Lowback pain in childhood and adolescence: a cross-sectionalstudy in Niigata City. Eur Spine J. 2008;17(11):1441-7.10. Graup S, Santos SG, Moro AR. Estudo descritivo de alterac¸õesposturais sagitais da coluna lombar em escolares da redefederal de ensino de Florianópolis. Rev Bras Ortop.2010;45(5):453-9.11. Alpalhão V, Robalo L. Algias vertebrais nos adolescentes:associac¸ão com as atividades de tempos livresautorreportadas. Essfisi on line. 2005;2(1):3-15.12. Ehrlich GE. Low back pain. Bull World Health Organ.2003;81(3):671-6.13. Salminen JJ, Erkintalo MO, Pentti J, Oksanen A, Kormano MJ.Recurrent low back pain and early disc degeneration in theyoung. Spine (Phila PA 1976). 1999;24(13):1316-21.14. Merlijn VP, Hunfeld JA, Van Der Wouden JC,Hazebroek-Kampschreur AA, Koes BW, Passchier J.Psychosocial factors associated with chronic pain inadolescents. Pain. 2003;101(1):33-43.15. Inep. Instituto Nacional de Estudos e Pesquisas EducacionaisAnísio Teixeira. Censo Escolar da Educac¸ão Básica. Availablefrom: http://portal.inep.gov.br/basica-censo [accessed on10.10.10].16. Sjölie AN. Low-back pain in adolescents is associated withpoor hip mobility and high body mass index. Scand J Med SciSports. 2004;14(3):168-75.17. Anep. Associac¸ão Nacional de Empresas de Pesquisa. Critériode classificac¸ão econômica Brasil. São Paulo: Associac¸ãoNacional de Empresas de Pesquisa (dados com base nolevantamento socioeconômico 2009); 2011.18. Crocker PR, Bailey DA, Faulkner RA, Kowalski KC, Mcgrath R.Measuring general levels of physical activity: preliminaryevidence for the Physical Activity Questionnaire for OlderChildren. Med Sci Sports Exer. 1997;29(10):1344-9.19. Kowalski K, Crocker P, Faulkner R. Validation of the physicalactivity questionnaire for older children. Pediatr Exerc Sci.1997;9(2):174-86.20. Lohman TG. Applicability of body composition techniquesand constants for children and youths. Exerc Sport Sci Rev.1986;14:325-57.21. Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing astandard definition of child overweight and obesityworldwide: international survey. BMJ. 2000;320(7244):1240-3.22. Proesp. Projeto Esporte Brasil. Available from:www.proesp.ufrgs.br/proesp/ [accessed on 15.03.11].23. Cardoso-Monterrubio A, Balmaceda-Calderón C. Lumbalgiaen ni~nos y adolescentes. Revisión etiológica. Rev Mex OrtopTraum. 2000;14(5):402-7.24. Coelho L, Almeida V, Oliveira R. Lombalgia nos adolescentes:identificac¸ão de fatores de risco psicossociais. Estudoepidemiológico na Região da Grande Lisboa. Rev Port SaúdePública. 2005;2(1):81-90.25. Masiero S, Carraro E, Celia A, Sarto D, Ermani S. Prevalence ofnonspecific low back pain in school children aged between 13and 15 years. Acta Pædiatr. 2008;97(2):212-6.26. Pelisse F, Balagué F, Rajmil L, Cedraschi C, Aguirre M,Fontecha CG, et al. Prevalence of low back pain and its effecton health-related quality of life in adolescents. Arch PediatrAdolesc Med. 2009;163(1):65-71.27. Ayanniyi O, Mbada CE, Muolokwu CA. Prevalence and profileof back pain nigerian adolescents. Med Princ Pract.2011;20(4):368-73.28. De Vitta AL, Martinez MG, Piza NT, Simeão SF, Ferreira NP.Prevalência e fatores associados à dor lombar em escolares.Cad Saúde Pública. 2011;27(8):1520-8.29. Noll M, Candotti CT, Tiggemann CL, Schoenell MCW, Vieira A.Prevalência de dor nas costas e fatores associados emescolares do ensino fundamental do município de Teutônia.Rio Grande do Sul. Rev Bras Saúde Matern Infant.2012;12(4):395-402.30. Paananen MV, Taimela SP, Auvinen JP, Tammelin TH,Kantomaa MT, Ebeling HE, et al. Risk factors for persistence ofmultiple musculoskeletal pains in adolescence: a 2-yearfollow-up study. Eur J Pain. 2010;14(10):1026-32.31. Shehab DK, Jarallah KF. Nonspecific low-back pain in Kuwaitichildren and adolescents: associated factors. J Adoles Health.2005;36(1):32-5.32. Jannini SN, Dória-Filho U, Damianis D, Silva CA.Musculoskeletal pain in obese adolescents. J Pediatr (Rio J).2011;87(4):329-35.33. Silva MC, Fassa AG, Valle NC. Dor lombar crônica em umapopulac¸ão adulta do Sul do Brasil: prevalência e fatoresassociados. Cad Saúde Pública. 2004;20(2):377-85.34. Quiton RL, Greenspan JD. Sex differences in endogenous painmodulation by distracting and painful conditioningstimulation. Pain. 2007;132 Suppl. 1:S134-49.35. Feldman DE, Shrier I, Rossignol M, Abenhaim L. Risk factorsfor the development of low back pain in adolescence. Am JEpidemiol. 2001;154(1):30-6.36. Almeida IC, Sá KN, Silva M, Baptista A, Matos MA, Lessa I.Prevalência de dor lombar crônica na populac¸ão da cidade deSalvador. Rev Bras Ortop. 2008;43(3):96-102.37. Rosseto EG, Pimenta CA. Prevalência e caracterizac¸ão da dorrecorrente em escolares na cidade de londrina. Ciênc CuidSaúde. 2012;11 Suppl.:211-9.38. Shiri R, Karppinen J, Leino-Arjas P, Solovieva S, Viikari-JunturaE. The association between obesity and low back pain: ameta-analysis. Am J Epidemiol. 2010;171(2):135-54.39. De Sá Pinto AL, de Barros Holanda PM, Radu AS, Villares SM,Lima FR. Musculoskeletal findings in obese children. JPaediatr Child Health. 2006;42(6):341-4.40. Stovitz SD, Pardee PE, Vazquez G, Duval S, Schwimmer JB.Musculoskeletal pain in obese children and adolescents. ActaPaediatr. 2008;97(4):489-93.41. Cardon G, Balague F. Low back pain prevention's effects inschool children. What is the evidence? Eur Spine J.2004;13(8):663-79.
