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Abstract
Background Childhood obesity is associated with self-reported musculoskeletal complaints, injuries and fractures. In the current study, we investigated the association between weight status of children and the frequency and type of musculoskeletal consultations at the general practitioner (GP) during a 2-year follow-up.
Methods Data from a prospective longitudinal cohort study including children aged 2–18 years presenting in general practices in the Netherlands were used. Height and weight were measured at baseline, at 6-month, 1-year and 2-year follow-ups. Electronic medical files were used to collect information on the frequency and type of consultations at the GP during the 2-year follow-up period. Associations between weight status and frequency and type of GP consultations were calculated.
Results Of the 617 included children, 111 (18%) were overweight or obese and 506 (82%) were non-overweight. Overweight children were significantly older (mean age in years (SD): 9.8 (3.6)vs7.8 (4.0), p=0.004). Overweight children consulted the GP in general significantly more frequent during the 2-year follow-up than non-overweight children (mean (SD): 7.3 (5.7)vs6.7 (5.4), OR 1.09, 95% CI 1.01 to 1.18). No significant difference was seen in the number of overweight and non-overweight children consulting their GP for musculoskeletal complaints (OR 1.20 (0.86 to 1.68)). Additionally, no significant difference between overweight and non-overweight children was seen for the number of consultations for further specified musculoskeletal disorders.
Conclusion No association was seen between childhood weight status and the frequency and type of musculoskeletal consultations at the GP during a 2-year follow-up.
- obesity
- musculo-skeletal
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What is already known on this topic?
Childhood obesity leads to many diseases like diabetes, cardiovascular issues and musculoskeletal complaints.
Childhood overweight and obesity are associated with, in questionnaires reported, musculoskeletal complaints, injuries, and fractures as early as childhood.
What this study adds?
This is the first prospective cohort study comparing overweight and non-overweight children in general practice with a 2-year follow-up.
Overweight and obese children do not consult their GP more often for musculoskeletal complaints than normal weight children.
Overweight and obese children do consult the GP in general more often than normal weight children.
Introduction
Childhood obesity is a worldwide health issue, especially in western countries.1 Previous studies, mostly carried out on population basis and in secondary healthcare settings, have shown that childhood overweight and obesity are associated with (in questionnaires reported) musculoskeletal complaints, injuries and fractures as early as childhood.2 3 The prevalence of musculoskeletal pain is 26% higher in overweight children compared with normal weight children, and the prevalence of injuries and fractures is 8% higher.2 In contrast with these findings, it has also been found that overweight children do not have an increased injury risk compared with normal weight sports participants.4 The mechanisms behind the suggested higher frequency of musculoskeletal complaints, and increased risk of injuries and fractures in overweight and obese children is frequently discussed.5 One mechanism is based on altered loading of the joints, causing knee and/or hip pain and related pathologies.6–8 Altered loading of the joints and excessive weight put on the joints seen in obesity also increases the risk on later life osteoarthritis (OA).8 9 Other factors are also thought to play a role in the development of musculoskeletal pain. One of these include disturbed hormone and lipid levels found in overweight and obese adult and children.10–13 These are known to play a role in the pathogenesis of OA in older adults, but it is unknown whether this mechanism already starts during childhood.
In daily practice, obese children are more likely to present to a paediatric emergency department with injuries and pain of the lower extremities compared with normal weight children.3 14 However, in the Netherlands, the general practitioner is the first point of care for non-emergency complaints, as in many other countries. Since previous literature suggests that overweight and obese children report more musculoskeletal problems than normal weight children, the current study will investigate whether these differences influence the frequency of consultations for musculoskeletal complaints at the general practitioner during a follow-up of 2 years.
Methods
Study design
This study is a prospective longitudinal cohort study using data from the DOERAK cohort. The DOERAK (‘Determinants of (sustained) Overweight and complaints; Epidemiological Research among Adolescents and Kids in general practice’) cohort was set up to gain knowledge on the differences between overweight and normal weight children in general practice. The study protocol has previously been published.15 The study has been approved by the Institutional Review Board of the Erasmus University Medical Center, Erasmus MC.
Participant selection
Between December 2010 and April 2013, children were recruited from 73 general practices. All children visiting their GP or GP trainee (from here on both defined as GP) in this time frame were asked to participate in the study. In order to be eligible, children had to be between 2 and 18 years of age and they/their parents had to have a basic understanding of the Dutch language to be able to give informed consent and fill out Dutch questionnaires. Children having a mental or physical disability, children with comorbidities affecting weight and children consulting their GP with emergency problems were not eligible to participate.
All children and parents who were approached during consultation received verbal information about the study by their GP during this regular consultation. If child and parent were interested in participation, height, weight and waist circumference of the child were measured, and contact information was sent to the researcher. Written study information and informed consent forms were then sent to the participant by the research team (children of age 12 and older also received an informed assent form), where after the researcher contacted the family to answer any questions about the study and to investigate if they were willing to participate. The child was formally included in the study when the informed consent (and informed assent form when needed) was received. While participating in the study, children received usual care from their GP.
Data collection
At baseline, after formal inclusion, a questionnaire was sent to the GP to collect data on the child’s height, weight and waist circumference and to collect the reason for consultation at baseline. The parents of the included children also received a questionnaire at baseline to collect data on demographics of parent and child. After inclusion, the participants were asked to fill out a questionnaire at 6, 12 and 24 months. If one of these questionnaires was not completed after 1 week, a reminder was sent, which was repeated for 8 weeks. If after these 8 weeks the questionnaire was still unanswered, the research assistant contacted the participant to remind him or her. After a 2-year follow-up, the research assistant retrieved the medical file records of all children who completed the 2-year follow-up (as covered by informed consent) or who gave permission to search their file even after dropout. For every consultation during the 2 year-follow-up period, the GP recorded reason for consultation by the International Classification of Primary Care (ICPC coding)16 (see online supplementary appendix 1), and the corresponding explanatory text was extracted. Any correspondence between the GP and other health professionals during the 2-year follow-up was also extracted.
Supplementary file 1
Measures
For the present study, the GP questionnaire was used to extract the child’s age and gender. Height and weight were measured by the GP or the research assistant, who received the same instructions and followed an identical protocol.15 From height and weight measures taken after formal inclusion, baseline body mass index (BMI) z-scores were calculated, and weight status was determined using the international age-specific and gender-specific cut-off points.17 18 Since only a small percentage of the included children was obese, overweight and obese children were combined into one category called the ‘overweight’ category. Parent’s questionnaires were used to extract general information. Ethnicity (both parents born in the Netherlands, at least one parent born in another country), socioeconomic status (SES) based on net household income using monthly general labour income of 2014 as cut-off point19 (<2000 euros/month and ≥2000 euros/month) and marital status reported by parents (parents living together and parents separated) were dichotomised. Highest level of education in the household was categorised into three levels (up to lower secondary level, upper secondary level and at least bachelor level), based on the international standard classification of education.20
Medical files were used to determine the frequency of all consultations. The ICPC letter ‘L’ (corresponding to musculoskeletal complaints) and the explanatory text were used to determine the frequencies of musculoskeletal complaints. To further specify musculoskeletal complaints, the accompanying numbers were used and categorised into lower extremities, upper extremities and others (eg, back, neck and thorax) (see online supplementary appendix 2). Consultations with code L that could not be categorised, due to missing information on location, were defined as ‘unclear’.
Supplementary file 2
Primary outcome measures
The primary outcome measures of this study were the frequency and type of musculoskeletal consultations during the 2-year follow-up. Secondary outcomes included the overall number of consultations.
Statistical analyses
Baseline demographics, frequencies of complaints and type of complaints among overweight and non-overweight children were described using means (SD) for continuous variables and frequencies (%) for dichotomous or categorical variables. To test whether weight status was associated with the frequency of musculoskeletal consultations and the frequency of consultations in general, Poisson regression was used. Logistic regression analysis was used to assess the association between weight status and the presence of musculoskeletal consultations during 2-year follow-up time. Furthermore, the association between weight status and further specified musculoskeletal conditions denoting to specific body parts were tested separately using logistic regression analysis. Multivariable analysis was used to test for different predictors for musculoskeletal consultations during the 2-year follow-up. Complete case analysis was used.
All analyses were adjusted for potential confounders (age, gender, SES and marital status), which were considered a confounder if the regression coefficient of the overweight status changed more than 10% after adding it to the model. We did not adjust for ethnicity and education level due to collinearity with SES. p Values <0.05 were considered statistically significant. The strength of associations were determined using ORs and incidence rate ratios with 95% CIs. IBM SPSS statistics V.12.0 was used for statistical analyses.
Results
General characteristics
Of the 1109 children that showed interest to their GP to participate, 733 gave written consent and were included. Baseline weight status was missing for 18 children due to missing weight and/or height measures at baseline. At 2-year follow-up, medical records were not searched for 98 children due to dropout and/or no permission. A total of 28 children gave permission to search their medical file after dropout. Therefore, a total of 617 children were included in the present study (figure 1). Children excluded from analysis were significantly older (mean age in years (SD): 9.4 (4.4) vs 8.0 (3.9), p=0.001) and had a higher BMI z-score at baseline (mean 0.50 (1.3) vs 0.06 (1.344), p=0.003).
Flow chart of inclusion.
At baseline, a total of 18% (n=111) was overweight, of which 24 children (4% of total population) were obese and 82% (n=506) was non-overweight (table 1). Overweight children were significantly older (mean age in years (SD): 9.8 (3.6) vs 7.8 (4.0), p=0.004) and had significantly higher baseline BMI z-score values (2.0 (0.7) vs −0.4 (1.1)). Most children came from families with a middle or high SES (78.6%) and high education level (83.5%), with both parents born in the Netherlands (84.8%) and with parents living together (84.0%).
Baseline characteristics
Consultations during 2-year follow-up
Overall, there was a mean of 6.8 (5.43) consultations during the 2-year follow-up. Overweight children consulted the GP in general significantly more frequent than non-overweight children (mean 7.3 (5.7), and 6.7 (5.4) OR 1.09, 95% CI 1.01 to 1.18, adjusted p value 0.03).
A total of 377 (61%) children went to see their GP at least once during follow-up, and 260 (42.1%) children went for a musculoskeletal consultation (table 2). After specifying into the different categories, 164 (26.6%) children consulted their GP for a lower extremity condition, 104 (16.9%) for an upper extremity condition, 65 (10.5%) for other body parts and in 42 (6.8%) the musculoskeletal localization was not registered. Since some children visited the GP for multiple musculoskeletal complaints of different categories, the sum of children with further specified consultations is greater than the number of children with consultations in the category ‘any musculoskeletal consultation’. No significant difference was seen in the number of overweight and non-overweight children consulting their GP for any musculoskeletal complaints (56 (50.5%) vs 204 (40.3%), OR 1.36 (0.87 to 2.16)). After further specifying the musculoskeletal conditions into consultations for lower extremities, upper extremities, other body part and miscellaneous, no significant differences in frequencies of visits were seen between overweight and non-overweight children.
Number of patients with musculoskeletal consultations during 2-year follow-up
Number of musculoskeletal consultations (table 3)
During 2-year follow-up, a child had a mean of 0.4 (SD 0.5) musculoskeletal consultations with the GP, which is equal to one musculoskeletal consult per 5 years. No significant difference was seen in the number of musculoskeletal consultations during 2-year follow-up between overweight (mean 0.5 (SD 0.5)) and non-overweight (0.4 (0.5)) children (OR 1.20, 95% CI 0.86 to 1.68). Additionally, no significant difference between overweight and non-overweight children was seen for the number of consultations for any of the further specified musculoskeletal conditions.
Number of musculoskeletal consultations during 2-year follow-up
Finally, a multivariable regression was performed to test for predictors (besides overweight and/or obesity) for musculoskeletal consultations during 2-year follow-up (table 4). (Higher) Age was significantly associated with a higher number of consultations for musculoskeletal complaints (OR 1.07 (95% C.I. 1.02 to 1.13)).
Multivariable logistic regression for the presence of musculoskeletal consultations during 2-year follow-up
Discussion
Main findings
Children with overweight or obesity consulted their GP more often than non-overweight children during a 2-year follow-up period but not for musculoskeletal problems. When further specifying the musculoskeletal consultations into lower and upper extremities, other body parts and a miscellaneous group, still no significant difference was seen for any of these subgroups in frequency of consultations between overweight and non-overweight children.
Our findings seem to be in contrast with published literature2 3 21 showing more musculoskeletal complaints in overweight and obese children. These complaints were however mainly self-reported by means of questionnaires.8 10 These children may report complaints on questionnaires but may not find the complaints serious enough to consult the GP for. This could explain why we found no difference in frequency of musculoskeletal consultations between normal weight and overweight children. Though, an earlier study performed in primary care did find a difference between overweight and obese children and normal weight children in experiencing musculoskeletal problems.21 However, the authors did not adjust the analyses for important confounders including SES and ethnicity, while these factors are known confounders for the frequency of GP consultations.22 23 This is confirmed by the current study where the positive trend between overweight/obesity and musculoskeletal consultations (p=0.05) changes to being not significant (p=0.19) after adjusting for confounders (table 2). Furthermore, our study population is relatively young compared with other literature. It is known that the frequency of musculoskeletal complaints seen in primary care especially increases around the age of 10 years.24 This is strengthened by the fact that we found a positive association between age and musculoskeletal consultations during follow-up. This might explain that studies with an older age group will find more musculoskeletal complaints.
Strengths and limitations
This is, to our knowledge, the first prospective cohort study comparing overweight and non-overweight children in general practice with a 2-year follow-up. Calibrated scales were used to measure height and weight for BMI calculation, consultations were recorded from medical files and GP trainees were trained on the reliability of measurement. This all implies that the main outcomes of this paper are based on valid data.
By instructing the GP trainees to invite every child visiting the GP to participate in the study, we tried to minimise selection bias. However, when we compare our study population to the overall Dutch population, parents from children in our cohort were more often both born in the Netherlands (84% vs 79%) and highly educated (43% vs 32%). Therefore, our cohort might not be completely representative of all children in general practices, which could lead to an underestimation of the percentage overweight and obese. Furthermore, since we recruited our patients at the GP, our study population only reflects a sample of all children living in the Netherlands. However, since in the current study we are primarily interested in children visiting the GP, we believe this did not impact our results.
Children who completed the 2-year follow-up or who gave permission for their medical files to be used were included in the analyses. Children excluded from analysis were significantly older and had a higher BMI z-score at baseline. Therefore, an underestimation of the percentage overweight could be the result of this selection bias.
The size of our study sample was smaller than intended.15 The smaller sample size may have introduced a power problem. We were able to show a significant difference in visits to the GP in general, indicating that this difference could be even more profound if more children were included.
Furthermore, there was a significant difference in age and BMI between the included and excluded children, which could bias the results. Excluded children were significantly older and had a significantly higher BMI. Since an earlier study found that overweight children of older age had more consultations at the GP than overweight children of younger age,25 the exclusion of these children could have led to an underestimation of the amount of GP consultations.
Finally, we did not take possible changes in weight status during the 2-year follow-up into consideration that may have had impact on the consultations during the 2-year follow-up.
Conclusion
Overweight and obese children visited the GP significantly more often than normal weight children during a 2-year follow-up. However, no association was seen between childhood overweight and obesity and the frequency and type of musculoskeletal consultations at the GP.
References
Footnotes
Contributors BWK, WDP and MvM conceived and designed the study, WDP collected data, JvL analysed and interpreted the data and wrote the manuscript.
Competing interests None declared.
Ethics approval The Institutional Review Board of the Erasmus University Medical Center, Erasmus MC.
Provenance and peer review Not commissioned; externally peer reviewed.