Musculoskeletal Complaints Among 11-Year-Old Children and Associated Factors

The PIAMA Birth Cohort Study

Gerben Hulsegge; Sandra H. van Oostrom; H. Susan J. Picavet; Jos W. R. Twisk; Dirkje S. Postma; Marjan Kerkhof; Henriëtte A. Smit; Alet H. Wijga

Disclosures

Am J Epidemiol. 2011;174(8):877-884. 

In This Article

Discussion

The present study shows that at age 11 years, the prevalence of any MSC is 16%. Of a number of factors assessed, only poorer mental health was consistently associated with MSC at the different anatomic sites.

To our knowledge, this the first time that such a large variety of factors in relation to MSC among young children has been explored both cross-sectionally and longitudinally (i.e., physical activity, weight, and height). Since PIAMA was not originally designed to study MSC, there are some limitations as well. Firstly, we had no information on MSC before the age of 11 years, which prevented us from studying patterns of MSC early in the life course. However, accurate measurement of MSC earlier in children's lives is not possible, because younger children are unable to fill out questionnaires[10] and parents may not be a reliable source of information on their children's pain.[27] Secondly, the results of our study relate to complaints that had lasted for at least 1 month in the past 12 months. An emphasis on long-lasting complaints can ensure that only the more severe cases are identified,[28] but no information regarding intensity and frequency of the complaints was available. We were not able to conduct stratified analyses for children who visited a physician for their complaints, because of statistical power issues.

Thirdly, some associated factors were measured only at age 11 years, allowing for cross-sectional analyses only. Thus, it is difficult to distinguish between causes and consequences of MSC. Furthermore, obtaining accurate and reliable self-reported measures of physical activity among children is difficult, because their physical activity is characterized by frequent short bursts of activity[29] and children have poor recall of activity intensity and duration.[30] In addition, children's physical activity levels at ages 5, 7, and 8 years were reported by the parents, which may not be an accurate measure of physical activity at those ages.[31]

A fourth limitation is that we had a relatively high number of children with higher socioeconomic status, but socioeconomic status does not appear to affect MSC.[32] At 11 years of follow-up, response rates were still acceptably high, with 67% of children responding. According to stratified analyses (results not presented), differences in socioeconomic status between dropouts and responders would not be expected to have changed the results.

In addition to the multivariable logistic regression analyses based on forward stepwise selection, we also analyzed the data by adjusting all associations for the 7 most relevant confounders—that is, variables that changed the beta coefficient of at least one of the univariable associations by 10% or more. These variables were MHI-5 score, daytime tiredness, pubertal status, height or height gain, weight or weight gain, sex, and physical activity at age 11 years (results not presented). These 2 different methods of selecting variables to be included in the regression models did not lead to different results.

The prevalence of MSC in our study was relatively low in comparison with other studies. Mikkelsson et al.,[1] who included children of almost the same age as those participating in our study, found a prevalence of 32% for MSC among Finnish children. The difference in prevalence can be explained by selection of the more severe MSC cases (complaints lasting for more than 1 month) in our study as compared with Mikkelsson et al.'s case definition (at least once a week). In line with our results, Leboeuf-Yde and Kyvik[33] found a low 1-year prevalence of 1% for back pain that lasted for at least 1 month in 12-year-old children.

The literature on determinants of MSC among children is limited. Some cross-sectional studies among adolescents have also shown associations between poorer mental health and back (12, 34, 35) and upper extremity (14, 34, 35) complaints. However, it is unclear whether mental health problems are a cause or a consequence of MSC, and the same holds for tiredness and MSC. One explanation might be that children with daytime tiredness are exhausted and fatigued, leading to an increased risk of sports injuries of the lower extremities.[36] In the only longitudinal study to have investigated these associations prospectively, El-Metwally et al.[11] showed that when children felt sad or down or experienced daytime tiredness at baseline, more MSC were found after 1 year of follow-up, but the association with feeling down disappeared after adjustment for confounders. In adults, mental health and a large variety of related psychosocial issues are strongly associated with MSC,[9] and therefore psychosocial factors are an important component of both prevention and treatment programs. Our data showed that when MSC were present in more than one body area, the relation with mental health is even stronger (OR = 0.64, 95% CI: 0.52, 0.79). It may be impossible to fully disentangle mental health, tiredness, and MSC, but at the least, this shows that treatment and prevention of MSC at a young age should take mental health and tiredness into account.

Earlier studies found that physical activity is associated with traumatic lower extremity complaints and any MSC but not with nontraumatic complaints among children[11,36] Our results showed that physical activity was associated with lower extremity complaints. It is likely that sports injuries partly explain this association, but we had no information about the causes of the complaints or the types of sports children were involved in. Physical activity was associated with a reduced risk of back complaints among 9-year-old children in one study,[13] but not in our study. In line with our study, numerous studies among adolescents have indicated that there is no association between television/computer use and MSC (12, 34, 35, 37, 38).

Anthropometric measures were not associated with MSC among adolescents in most earlier studies (12, 14, 37, 38). However, our results are in line with those of Bell et al.,[17] who showed an association between MSC and body mass index z score in 177 children aged 6–13 years. Our study also suggests that children with a relatively high weight gain are more likely to have lower extremity complaints, which was not studied before. Since it is well established in adults that overweight and obesity increase the amount of force on weight-bearing joints and result in damage like osteoarthritis in the knee joints,[39] our data may point to a similar mechanism among children. Weight gain has several detrimental effects in childhood, with long-lasting consequences. The prevention of overweight might be an important component of the prevention of musculoskeletal pain, but first the association between weight gain and MSC should be confirmed in other prospective studies.

Pubertal status has rarely been examined in relation to MSC. A study in participants aged 11–21 years showed that those with early pubertal development were more likely to experience MSC.[40] In our study, pubertal stage was independently associated with lower and upper extremity complaints, and in the multivariate analyses it seemed relevant for any MSC. More research is needed.

Previous studies among adolescents found that the prevalence of neck/shoulder and back complaints was higher in girls than in boys.[15,34,35,37,38] A higher prevalence in girls may be due to differences in sex-linked biologic factors (hormones or physiology) and different pain sensitivity, or it might be more socially acceptable for girls to complain about pain than boys.

One study of adolescents aged 12–16 years found no associations between ethnic background or maternal educational level and back, arm, and neck complaints.[35] Thus, socioeconomic status seems irrelevant regarding MSC at young ages. Our study showed significantly more upper extremity complaints among children of non-Western origin, but no increased risk for other anatomic sites. The question of whether migrant children are at higher risk of developing MSC should be investigated in future studies.

MSC in adulthood represent a large health and economic problem[7,8] Since MSC have a recurrent and persistent nature and might originate in childhood, MSC research among children needs further attention.[3–5] The importance of some factors in childhood, especially the importance of mental health problems in relation to MSC, is emphasized by the results of this study. Additional large-scale longitudinal studies are needed to shed further light on the early-life determinants of MSC. Continuation of PIAMA data collection—with the children now becoming adolescents aged 14 years—will allow further analysis of determinants of developing MSC.

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