Version 01/03/2017 (to be submitted to the Br Med J)
Effectiveness of DASH, a physical activity scheme, on cardiorespiratory fitness, body mass index and skinfolds in disadvantaged primary schoolchildren from Port Elizabeth, South Africa: a cluster randomised control trial
I M”ller research assistant1,2,3*, C Schindler statistician1,2, P Steinmann researcher1,2, P Yap researcher1,2,4, H Seelig statistician2,3, S Gall research assistant2,3, D Smith research assistant6, L Adams research assistant6, S Nqweniso research assistant6, N Joubert research assistant6, B P Damons research assistant5,6, K Endes researcher2,3, M Gerber assistant professor2,3, R d Randt professor6, J Utzinger professor1,2, C Walter assistant professor6 and U P”hse professor2,3
Affiliations
1 Swiss Tropical and Public Health Institute, P.O. Box, CH-4002 Basel, Switzerland
2 University of Basel, P.O. Box, CH-4003 Basel, Switzerland
3 Department of Sport, Exercise and Health, University of Basel, St. Jakobsturm, Birsstrasse 320B, CH-4056 Basel, Switzerland
4 Institute of Infectious Disease and Epidemiology, Tan Tock Seng Hospital, 308433 Singapore, Singapore
5 Faculty of Education, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031, South Africa
6 Department of Human Movement Science, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031, South Africa
*Correspondence to: ivan.mueller@unibas.ch
Email addresses:
IM: ivan.mueller@unibas.ch
CS: christian.schindler@unibas.ch
PS: peter.steinmann@unibas.ch
PY: peiling_yap@ttsh.com.sg
HS: herald.seelig@unibas.ch
SG: stefanie.gall@unibas.ch
DS: deez_cs@yahoo.com
LA: larissa.adams13@gmail.com
SN: sihlenqweniso3@gmail.com
NJ: joubertnandi@gmail.com
BPD: Bruce.Damons2@nmmu.ac.za
KE: katharina.imhof@unibas.ch
MG: markus.gerber@unibas.ch
RdR: rosa.durandt@nmmu.ac.za
JU: juerg.utzinger@unibas.ch
CW: cheryl.walter@nmmu.ac.za
UP: uwe.puehse@unibas.ch
Abstract (max. 300 words)
Objectives To evaluate the effectiveness of a one year school based physical activity intervention module on physical health in disadvantaged South African primary schoolchildren.
Design Cluster randomised controlled trial.
Setting 26 Grade 4 classes from 8 disadvantaged quintile 3 primary schools in Port Elizabeth, South Africa, from February 2015 to May 2016.
Participants 746 children with written informed consent sheets.
Intervention The multidimensional physical activity intervention module included (i) a physical activity programme, (ii) weekly dancing-to-music classes, (iii) in-class activity breaks, (iv) physical activity homework and (v) school infrastructure adaptation to promote physical activity. It lasted from February 2015 to May 2016.
Main outcome measures Primary outcomes included cardiorespiratory fitness (20 m shuttle run), body mass index (scale and stadiometer) and thickness of skinfolds (Harpenden caliper). Secondary outcomes were anaemia (HemoCue” Hb 301 system), SES index (asset ownership and housing), physical activity score (Health Behaviours in School Age Children Survey), stunting (HAZ), protozoa (Crypto-Giardia Duo-Strip”) and soil-transmitted helminth status (Kato-Katz method).
Results 579 children completed the baseline and follow-up assessments (mean age 10.0 years, SD 0.9). We noticed a significantly lowered increase in the mean BMIZ (estimate of mean change: -0.12 with 95% CI: -0.22 to -0.03; P=0.008) and reduced increase in the mean thickness of skinfolds (estimate of mean change: -1.06 with 95% CI: -1.83 to -0.29; P=0.007) from baseline to follow-up. However, children in the intervention group showed no significantly difference in mean shuttle runs and indirectly measured VO2max, established with the estimate of mean change (P>0.05).
Conclusions A multidimensional school-based physical activity intervention module reduced the increase in BMI and thickness of skinfolds, two cardiovascular risk factors, but did not affect cardiorespiratory fitness in disadvantaged Grade 4 primary schoolchildren in Port Elizabeth, South Africa.
Trial registration Current controlled trials, unique identifier: ISRCTN68411960, registration date: 1 October 2014
Keywords: Body mass index, Cardiorespiratory fitness, Disadvantaged, Intestinal protozoa, School based physical activity module, Schoolchildren, Soil-transmitted helminths, South Africa.
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Background (max. 4’000 words, without references)
Non-communicable diseases, such as diabetes, cardiovascular diseases or obesity-related conditions, meanwhile, impose a growing burden on low and middle income countries (1). Beyond, physical inactivity and inappropriate diet, most importantly low fruit intake and excess salt consumption, have emerged as new leading risk factors, accounting for 10% of the global burden of disease, as expressed in disability-adjusted life years (DALYs). Nowadays, the World Health Organization (WHO) is strongly involved in the new pandemic of adiposity and related non-communicable diseases. Overweight has replaced under-nutrition as a risk factor for the first time (2-4) and as a constantly and rapidly growing epidemic reached all socioeconomic levels and ethnicities (5). Amongst others, one of the main environmental factor attributed to the abnormal increase in body fat in the last few decades are an increase in energy intake through fast food and a decrease in energy expenditure or physical activity and/or increase in sedentary behaviour (6). A decisive contributor to sedentary behaviour is media use (e.g. TV consumption) which is in turn related to energy intake (7).
Previous surveys revealed that the South African population has moved towards a disease profile similar to Western countries, where in average one in three to five children is overweight or obese (8), with increasing proportions of deaths attributed to chronic diseases of lifestyle (9). South Africa’s 2014 Report Card on Physical Activity for Children and Youth (10) highlights the current concerns for the health and well-being of children and youth in relation to declining physical activity levels and increasing rates of consumption of soft-drink and fast food. Soft-drinks are drunk in South Africa about three times the global average and fast food consumed at least three times a week by over two-third of the adolescents. However, it must be noted, that these global or national averages hide important information, and hence, what is happening locally is more crucial for research.
The ‘Disease, Activity and Schoolchildren’s Health’ (DASH) study in Port Elizabeth, South Africa, aims to investigate this dual disease burden (i.e. non-communicable chronic conditions and infectious diseases) among children in selected primary schools located in disadvantaged neighbourhoods (11). Here, we report the findings of the effectiveness of DASH, a physical activity module, on cardiorespiratory fitness, body mass index (BMI) and thickness of skinfolds from a cluster randomized controlled trial among 9 to 14-year-old children. The objectives of this longitudinal survey were (i) to increase cardiorespiratory fitness and (ii) to reduce BMI in disadvantaged primary schoolchildren (intervention vs. control group) and (iii) and to stratify for possible covariates.
Methods
Study site and school selection
Recruitment started from September 2014, and the practical intervention study took place between February 2015 and May 2016. 103 quintiles 3 primary schools were invited to be considered to participate in the study (Figure 1). Due to non-secure functioning of school-telephone and -fax, the project information were delivered by hand. We received 25 written responses from interested schools. 15 schools were selected based on (i) large Grade 4 classes (n > 100); (ii) geographical location; (iii) representation of the various target communities; and (iv) commitment to support the project activities. Out of these 15 schools, 4 intervention and 4 control schools have been randomly selected.
Figure 1
The study was carried out at eight primary schools in socioeconomically disadvantaged neighbourhoods of Port Elizabeth, in the Eastern Cape province of South Africa (geographical coordinates: 34”07’54” S to 33”57’29” S latitude and 25”36’00” E to 25”55’49” E longitude, altitude extending from 0 m to approx. 100 m above sea level) and fieldwork started in February 2015 and ended in May 2016. The study population consisted of coloured children, generally Afrikaans speaking, and black African children, largely Xhosa speaking. The people living in these areas are still detrimentally affected by the legacy of Apartheid (12, 13). Colloquially, these respective areas are referred to as the northern areas and townships.
Study design
The DASH study is a cohort study with a physical activity intervention component to determine whether a physical activity education programme can improve cardiorespiratory fitness levels among 9 to 14-year-old children (11). Trained examiners or nurses assessed anthropometric indicators (i.e. height and weight) and measured haemoglobin (Hb) concentrations. In addition, this study also measured the prevalence of intestinal parasites. We collected a single stool sample for parasitological work-up to diagnose helminth and intestinal protozoa infections by using light microscopy. We determined cardiorespiratory fitness by measuring the participants’ performance in a 20 m shuttle run test for cardiorespiratory endurance.
Intervention
We developed the physical activity intervention module in cooperation with various members of school principals, primary school teachers, students from the participating Universities and Institutes and various stakeholders. The physical activity intervention module focused on four topics: (i) Regular physical activity opportunities including two physical education (PE) lessons a week, (ii) one weekly dancing-to-music classes, (iii) in-class activity breaks incorporated into the main school curriculum, (iv) physical activity homework and (v) the adaptation to a more physical activity friendly school environment (Figure 2).
Figure 2
These aforementioned interventions were primarily applied at the level of schools within school time and school environment to the intervention schools (and after the study also being provided to the control schools). The physical education lessons were given by professional physical education teachers and the dancing lessons by talented Honours students from the Nelson Mandela Metropolitan University (NMMU). The control group continued to follow their usual school curriculum. However, to our knowledge, practical physical education lessons are almost not practiced at disadvantaged schools, even though three weekly lessons are written in the curriculum. Schoolchildren, volunteers of the schools and teachers were informed that the intervention could promote children’s health.
At the beginning of the study prior to the physical activity intervention, all the principals, teachers and representatives of the parents took part in several afternoon workshops explaining all the study procedures including planned physical activity intervention. During the intervention phase of the study, regular informal exchanges in close collaboration between teachers and research assistants took place.
Aiming for a smooth integration into the regular school curriculum, physical education lessons were given three times a week over twice a ten-week period (September 2015 and February 2016). From the first ten-week intervention block to the second ten-week intervention block, the research team adapted the interventions and arranged them more efficient targeting to increase the intensity. Further, the class teachers with our support, taught one of the three weekly lessons. The lessons included 40 min, starting with 5 min of warming up and cooling down at the end of each lesson. As a matter of fact gymnastic halls were missing. All the classes were taught outside on either grass or pavement and participants were wearing an official school uniform. Partially, the children had no and did not wear sports shoes. All physical education lessons were prepared by professional physical education teachers from the NMMU and wer held together with the class teachers. Additional sports equipment for the lessons, such as various balls and skipping ropes was donated to the schools. Adherence to the physical education lessons was assessed by the class teachers in regular school lessons.
Study procedures
Baseline (February 2015) and follow-up (May 2016) measurements took place at disadvantaged quintile 3 primary schools (quintile 1 being the poorest and quintile 5 being the ‘least poor’ schools) and the latter directly followed to the physical activity intervention module. The measurements and intervention phases (two times each ten week) were planned in the course of the year in collaboration with the representatives of the schools targeting for a smooth integration into the regular school curriculum. All researchers and field workers were trained in a multi-day workshop prior to the DASH baseline measurement. Primary outcome measures included anthropometric indicators, such as height, weight, sex and skinfolds (triceps and subscapular) and cardiorespiratory fitness, whereas secondary outcomes were haemoglobin (Hb), socioeconomic status (SES), self-perceived physical activity (PA), stunting and soil-transmitted helminth- and intestinal protozoa-infection status.
For the anthropometric measurements, we asked each child to remove the shoes and sweater before standing on a digital weighting scale (Micro T7E electronic platform scale, Optima Electronics; Georg, South Africa). We measured body weight once to the nearest 0.1 kg. The height of each child we assessed with a Seca stadiometer (Surgical SA; Johannesburg, South Africa) whereby the child was standing with the back erect and shoulders relaxed to the nearest 0.1 cm. The thickness of the skinfold we measured at two sites, namely triceps and subscapular (14, 15) 3 times each, with the Harpenden skinfold caliper.
We measured the children’s endurance with the 20 m shuttle run test (16), using the test protocol from L”ger et al. (1984) (17) which was also used in other studies in other settings (18, 19). The majority of the schoolchildren wore school or street shoes. However, a minority ran barefoot. Shortly before test start, we asked the children if anyone did not feel well or was sick. Due to serious health problems, we excluded children prior to the maximum performance test. The pre-recorded sound signals was played and the children did a trial run of two intervals (40 m). Once they were familiar with the test procedures, we asked them to run in groups, back and forth on the 20 m flat course, following the pace of the signals. Starting with a running speed of 8.5 km h-1, the frequency of the signal increased gradually such that every min, the pace increased by 0.5 km h-1. In case a child failed to follow the pace in two consecutive intervals, we asked to stop. We noted as the final score the number of fully run and completed 20 m laps.
We measured the Hb concentration once to the nearest 0.1 g l-1 with the HemoCue” Hb 301 system (HemoCue”AB; ”ngelholm, Sweden). In brief, after swabbing the child’s fingertip with alcohol, a field worker pricked the fingertip with a safety lancet and squeezed gently to obtain two drops of blood. The first drop we wiped away with the alcohol swab and the second drop we took up with the microcuvette.
We handed out stool containers with unique identifiers to schoolchildren together with the instruction to return them with a small portion (at least 15 g) of their own next morning stool. We collected between 9 and 10 a.m. and transferred them to a laboratory of the NMMU in Port Elizabeth for diagnostic work-up on the same day. Stool samples, were first visually examined for the presence of Taenia proglottids, signs of blood, mucus and diarrhoea. We prepared duplicate 41.7 mg Kato-Katz thick smears from each stool sample (20). Experienced laboratory technicians read the slides under a microscope and counted the number of eggs of each helminth species. Different technicians read the two slides, compared the results for quality control and, in case of inconsistencies (i.e. positive versus negative or egg counts differing by more than 20%), re-read the slides. We multiplied the helminth egg counts by a factor of 24 to obtain a proxy for infection intensity, as expressed by the number of eggs per 1 g of stool (EPG) (21). Finally, we performed on the stool samples a Crypto-Giardia Duo-Strip” rapid diagnostic test (RDT) (CORIS, BioConcept; Gembloux, Belgium) for the detection of C. parvum and G. intestinalis.
Statistical analysis
Data were double-entered, validated using EpiData version 3.1 (EpiData Association; Odense, Denmark) and merged into a single database. Statistical analysis was performed using STATA version 13.0 (STATA Corp.; College Station, TX, USA).
The sample size for the study was calculated based on achieving sufficient precision in assessing the prevalence of soil-transmitted helminth infections at baseline and estimated clusters and loss to follow-up (11). We defined statistical significance as P<0.05. The SES index was based on asset ownership and housing and was calculated using the principal component analysis (PCA) (Table S1 in supplemental file). To describe the anthropometry of the children, we used body weight and height values to calculate the BMI, defined as weight (in kg)/height2 (in m2), the sex-adjusted BMI-for-age Z-score (BMIZ) and the sex-adjusted height-for-age Z-score (HAZ) as an indicator for stunting (22). For the data analysis of the skinfold thickness at triceps and subscapular, we formed the average of all six measurements. Anthropometric indicators, Hb concentrations and fitness performance scores were assessed as means and standard deviations (SD). We used mixed linear and mixed logistic regression models with random intercepts for schools and classes to analyse quantitative and binary data, respectively. These analyses included group comparisons with and without adjustment for covariates. We used the likelihood-ratio test to compare models. The intraclass correlation coefficient (ICC) was utilized for estimating clusters within classes and schools. To perform a secondary analysis upon the interaction of the intervention with secondary outcome measures, we dichotomized the respective variables at the median (23).
Results
Characteristics of the baseline data
At baseline, 1,009 Grade 4 primary schoolchildren with written informed consent sheets of eight selected schools, situated in the northern part of Port Elizabeth, were recruited to participate. As illustrated in Figure 3, complete baseline data were available from 746 children. Reasons for exclusion were absent at baseline or withdrawal or not complete baseline data (e.g. reported health problems precluding participation in the cardiorespiratory fitness test such as chronic asthma). Children infected with either C. parvum or G. intestinalis and those who reported abdominal pain, blood in the stool or diarrhoea, those with special lung sounds (e.g. chest wheezing or creeping), ringworm infection or showed signs of tachycardia, were referred to the local clinic (data not shown). All subsequent analyses refer to the final cohort of 746 children, which included 372 girls (49.9%) and show a mean age of 10.0 years. Table 1 presents the baseline characteristics of the study participants, stratified by intervention and control group. We discovered no differences in the baseline characteristics and outcome variables when comparing the intervention with the control group (t-tests, all P’0.2).
Figure 3
Cardiorespiratory fitness, body mass index and skinfolds
Cardiorespiratory fitness and body composition outcome measures from 746 primary schoolchildren at baseline and follow-up are presented in Table 2, as well as estimates of adjusted mean difference. Furthermore, stratified and adjusted estimates of mean changes are presented in Figure 4. We noticed a significantly lowered increase in the mean BMIZ (estimate of mean change: -0.12 with 95% CI: -0.22 to -0.03; P=0.008) and reduced increase in the mean thickness of skinfolds (estimate of mean change: -1.06 with 95% CI: -1.83 to -0.29; P=0.007) from baseline to follow-up, when comparing children from the intervention with the control group. However, study participants in the intervention group showed no significantly difference in mean shuttle runs, established with the estimate of mean change and P>0.05, and indirectly calculated mean VO2max. The prevalence of overweight and obese children both increased from baseline (overweight: 13.7%, obese: 5.3% out of 746 children) to follow-up (overweight: 14.9%, obese: 7.7% out of 683). The ICC were all <0.1, showing a low level of clustering within schools and classes, whereas additional cluster adjustment did not revise the results.
Figure 4
Self-perceived physical activity (PA), stunting, anaemia, intestinal protozoa- and soil-transmitted helminth-infection
Baseline and follow-up data of covariates affecting cardiorespiratory fitness or body composition, including corresponding estimate of mean change, are presented in Table 3. However, no interaction showed statistical significance (all P-values >0.05). At baseline (n=746), stunted children, anaemic or infected with either Protozoa or STH, were present at 11.5%, 18.5%, 16.1% and 31.5%, respectively, while at follow-up the prevalences shifted to 14.0% (ouf of 681 children), 12.8% (ouf of 678), 14.4% (ouf of 638) and 24.9% (ouf of 639), respectively. To our knowledge, no injuries or other adverse events occurred during physical activity lessons. Teacher focus group discussions and written evaluation yielded in a mark of 4.2 (on a 5 point scale, 1 being poor and 5 excellent) and the teachers wished to continue with the physical activity module and integration into the regular school curriculum.
Discussion
Main findings
A multidimensional physical activity intervention module in disadvantaged South African primary schools has contributed beneficial to a lower increase of BMI and thickness of skinfolds, but not to cardiorespiratory fitness. The interventions included physical education lessons, dancing-to-music classes, in-class activity breaks, physical activity homework and construction of a physical activity friendly school environment.
Study results in context with other studies
Little research has been devoted to primary schoolchildren in low income settings in South Africa to further provide insights regarding the effectiveness of school-based initiatives to promote physical activity and the potential of strengthening schoolchildren’s health. Low quality and often inaccessible sport and recreation facilities, a lack of qualified teachers and an irregular physical education schedule complicate the promotion of age-appropriate physical activity, especially in disadvantaged schools. This also applies to our study schools, built in areas in the 1950s to accommodate 6,000 predominantly coloured people, but where a recent survey estimated that more than 30,000 people are living in the area (24). Our study neighbourhood is characterised by unhygienic living conditions, poor sanitation, litter, high unemployment and gangsterism.
Another study, such as the HealthKick study, conducted in primary schools in low-income settings in the Western Cape (WC), focused more on healthy nutrition (25). Overall, studies of school-based interventions promoting a healthy lifestyle have shown disappointing results and the implementation of successful projects is even more difficult in children with lower SES (26). However, primary prevention against overweight in this child age is essential. Previous investigations of physical activity patterns of primary schoolchildren attending schools in disadvantaged neighbourhoods have confirmed insufficient physical activity (27). Kimani-Murage et al. (28) reported that in a low-income South African setting, the co-prevalence of early stunting and adolescent obesity in girls is a result of increasing physical inactivity. This observation was particularly prevalent among black girls, who were found to have the highest rates of physical inactivity (29). As physical inactivity during childhood can lead to poor health outcomes in adulthood (30), promotion of physical activity among school-aged children in disadvantaged communities is meaningful in order to prevent obesity-related conditions and related increased morbidity later in life. In addition in the face of weak health systems, infectious diseases that are intimately connected with poverty may also occur in disadvantaged South African schools (25) and create a dual burden and a challenge for the health system. Such infections might have a negative impact on children’s nutritional status and cardiorespiratory fitness (31, 32).
Comparing our study results, the mean number of completed levels/stages of the 20 m shuttle run test corresponds closely to the mean results reported from other intervention studies in differing settings, e.g. the KISS- or the SPORTCHECK study with Swiss primary schoolchildren of slightly younger age (33-35). Yap et al. reported slightly lower VO2 max results, 45.6 ml kg’1 min’1 for 9 to 12-year-old boys and 44.7 ml kg’1 min’1 for girls from south-west Yunnan province, People’s Republic of China (32).
Strengths and limitations
Firstly, a novelty of our study was the focus on young schoolchildren attending school in disadvantaged primary schools in South Africa, a social community with low SES at high risk for development of obesity (10). Secondly, we have succeeded in installing a successful physical activity intervention programme with favourable effects on body composition in young children, which is of public health relevance. Only few physical activity intervention programmes were considered being effective and successful in lowering the increase of BMI and body fat in schoolchildren (36).
Our study has several limitations. Firstly, although the physical education intervention module was liked by especially the schoolchildren but also the teachers, the level of teachers’ compliance and adherence towards a high intervention quality was insufficient. The teachers themselves often suffered from overweight and were partially not interested in self-physical movement. It must be a key feature of future projects to noticeably increase teachers’ intrinsic motivation towards a playful movement. Secondly, it is possible that the length and intensity of the intervention was somewhat limited (37). However, the implementation of a comprehensive and intensive physical activity intervention in such a difficult study setting/environment is a complex undertaking. A more extensive involvement of the school communities, school volunteer, parents and policies could be favorable (26). Thirdly, only self-perceived physical activity was measured. As PA is an important cardiovascular risk factor, in a next step, an objective measurement with GT3x accelerometers (ActiGraph, Shalimar, FL, USA) should be included by calibrating for children (38). Fourth, only single stool samples were collected. Hence, some infections, particularly those of light intensity, were possibly missed, as seen in other studies where multiple biological samples and a combination of diagnostic methods were employed (21, 39). Despite these limitations, the study confirms the practicability of the employed methods, as suggested by previous experiences in differing African and Asian settings (40-42).
Generalisability and implications
The dissemination of non-communicable diseases affects humans and societies, especially from lower SES, and constitutes meanwhile a global burden (43). All our quintile 3 study intervention schools were located in neighbourhoods affected with poverty and included compulsory physical activity modules in their regular school curriculum (44). However, differences in SES and between different school and educational systems might limit the generalisability of our findings transnationally. Though, due to the negative potential in such disadvantaged settings/environments, the future need for action is given.
Conclusions
Summarising, this longitudinal cluster randomised controlled trial of the DASH study provides new insights into the reduction of the increase of BMI and thickness of skinfolds, both significant risk factors for development of health in adulthood (45), in Grade 4 schoolchildren from disadvantaged communities in Port Elizabeth, South Africa. Currently, officials in Port Elizabeth, in collaboration with the Department of Education, are implementing modules from the DASH intervention programme into the regular school curriculum. Further dissemination of this school based activity program may help to reduce the burden of cardiovascular diseases, resulting from social health inequalities.
What is already known in this research area
The public health concern of overweight related with physical inactivity and low cardiorespiratory fitness in children is growing in low and middle income countries, which results in increased cardiovascular risk factors
Pre- and intervention programmes are scarce in disadvantaged primary schools in South Africa
Only little is known about the effects of school based physical activity intervention studies in disadvantaged and spars equipped primary schools in South Africa to effectively prevent overweight and influence cardiorespiratory fitness in disadvantaged children
What this study adds
A multidimensional school based physical activity intervention module (DASH) reduced the increase in BMI and lowered the increase in thickness of skinfolds, but did not affect cardiorespiratory fitness in disadvantaged Grade 4 primary schoolchildren in Port Elizabeth, South Africa
List of abbreviations
BMI Body mass index
BMIZ BMI-for-age Z-score
DALY Disability-adjusted life year
DASH Disease, Activity and Schoolchildren’s Health
EKNZ Ethics committees of Northwest and Central Switzerland
EPG Eggs per gram (of stool)
HAZ Height-for-age Z-score
Hb Haemoglobin
ISRCTN International Standard Randomised Controlled Trial Number
NMMU Nelson Mandela Metropolitan University
NRF National Research Foundation
RDT Rapid diagnostic test
SD Standard deviation
SES Socioeconomic status
SNSF Swiss National Science Foundation
SSAJRP Swiss-South African Joint Research Programme
STH Soil-transmitted helminth
VO2 max Maximal oxygen uptake
WC Western Cape
WHO World Health Organization
Declarations
Acknowledgements
The authors are grateful to the children and parents/guardians for their willingness to participate in the study. Special thanks are addressed to the education authorities of the school, including the indispensable support and collaboration of the teaching staff and the respective school health services. We are grateful to Mrs. Leyli Zondie and Mrs. Lindsey Beyleveld and her team of the Department of Medical Laboratory Sciences at the NMMU for providing diagnostic support in the laboratory. Moreover, we thank all the participating Master- and Honours-students for their dedicated contribution to the long and intensive data collection.
Authors’ contributions
PY, IM, PS, CS, HS, KE, MG, RdR, UP, CW and JU designed the study, established the methods and wrote the original study protocol. All other authors contributed to the development of the study protocol. IM, SG, DS, LA, SN, NJ, PY, BPD, MG, RdR, UP and CW conducted the fieldwork of the study. IM, SG, DS, LA, SN and NJ managed data entry, cleaning and preparation of the database for statistical analysis, supported by CS and HS. IM wrote the first draft of the manuscript with support of CS. All authors provided comments on the drafts and have read and approved the final version of the paper prior to submission. IM and UP are the guarantors.
Funding
This study was conducted within the scope of the Swiss-South African Joint Research Programme (SSAJRP), financially supported by the Swiss National Science Foundation (SNSF, project no. IZLSZ3 149015) and the National Research Foundation (NRF, project no. 87397) in South Africa. The funders had no role in the study design, data collection and analysis, preparation of the manuscript or decision to publish.
Conflicting interests
All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethics statement
This study was cleared by the ethics committees of Northwest and Central Switzerland (EKNZ; reference no. 2014-179, approval date: 17 June 2014), the Nelson Mandela Metropolitan University (NMMU; study number H14-HEA-HMS-002, approval date: 4 July 2014), the Eastern Cape Department of Education (approval date: 3 August 2014) and the Eastern Cape Department of Health (approval date: 7 November 2014). The study is registered at ISRCTN registry under controlled-trials.com (unique identifier: ISRCTN68411960, registration date: 1 October 2014).
The school principals, teaching staff and potential study participants were briefed on the purpose, procedures, potential risks and benefits of the study. Oral assent from each participating child was sought and individual written informed consent was obtained from parents/guardians. For illiterate parents/guardians, the information sheet, available in English, Xhosa and Afrikaans, was read aloud in the appropriate language. Participation was voluntary, and hence, children could withdraw from the study at any time without further obligations. Children with serious health problems were referred to the local clinic and STH infections were managed free of charge according to WHO and national treatment guidelines.
Availability of data and material
The raw datasets are available from the corresponding author on request.
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Figure captions
Fig. 1 Flow of schools, study clusters, of the DASH study
Fig. 2 Timetable and content of the DASH physical education module intervention
Fig. 3 Flow chart of the study participants, including outcome measures
Fig. 4 Stratified estimates of mean changes in VO2max, BMIZ and thickness of skinfolds from baseline to follow-up for children with and without physical activity intervention, adjusted for baseline characteristics
Table 1 Baseline characteristics of 746 disadvantaged primary schoolchildren in Port Elizabeth, South Africa, with a physical activity intervention or without (control). Values are either numbers (percentages) or means (standard deviations; SD)
Total (n=746) Intervention group (n=300) Control group (n=446)
In numbers (percentages)
Girls 372 (49.9) 150 (50) 222 (49.8)
Overweighta 102 (13.7) 38 (12.7) 64 (14.3)
Obeseb 39 (5.3) 15 (5) 24 (5.4)
Stuntedc 86 (11.5) 46 (15.3) 40 (9.0)
Anaemicd 138 (18.5) 67 (22.3) 71 (15.9)
Infected with Protozoae 120 (16.1) 61 (20.3) 59 (13.2)
Infected with STHf 235 (31.5) 132 (44) 103 (23.1)
In means (SD)
Age in years 10.0 (0.03) 10.1 (0.05) 9.9 (0.05)
Height in cm 133.3 (0.26) 132.6 (0.41) 133.8 (0.33)
Overall SES indexg -0.04 (0.10) -0.12 (0.16) 0.01 (0.13)
SES index of the poorest -4.77 (0.18) -4.48 (0.31) -4.98 (0.21)
SES index of the second -0.29 (0.05) -0.21 (0.07) -0.36 (0.07)
SES index of the middle 1.01 (0.02) 1.00 (0.03) 1.02 (0.03)
SES index of the fourth 1.71 (0.01) 1.70 (0.03) 1.72 (0.02)
SES index of the richest 2.28 (0.01) 2.25 (0.02) 2.29 (0.02)
Score of self-perceived PA 8.35 (0.14) 9.11 (0.22) 7.83 (0.18)
a Overweight: >+1SD (equivalent to BMI 25 kg/m2 at 19 years)
b Obesity: >+2SD (equivalent to BMI 30 kg/m2 at 19 years)
c Stunting is defined as ‘-2 HAZ score
d Anaemic is defined as haemoglobin concentration in blood ‘114g/l
e Infected with one or two intestinal parasite species (Cryptosporidium spp. and/or Giardia intestinalis)
f Infected with one or two soil-transmitted helminth species (Ascaris lumbricoides and/or Trichuris trichiura)
g Socio-economic status (SES) was formed using principal component analysis (PCA)
‘
Table 2 Cardiorespiratory fitness and adiposity outcome measures from 746 disadvantaged primary schoolchildren in Port Elizabeth, South Africa, before and after a physical activity intervention and control group. Values are unadjusted means (standard deviations) unless specified otherwise
Variables Intervention Control Estimate of mean changea
Baseline (n=300) Follow-Up (n=272) Baseline (n=446) Follow-Up (n=397) Estimate (95% CI) P-value ICCb
Cardiorespiratory fitness
Shuttle run
(stages) 35.55 (0.98) 34.50 (1.09) 36.79 (0.83) 35.34
(0.94) -0.56 (-4.67 to 3.56) 0.79 0.04
VO2maxc
(ml kg-1 min-1) 45.83 (0.24) 43.50 (0.28) 46.30 (0.21) 44.03 (0.24) -0.14 (-1.17 to 0.88) 0.78 0.03
Adiposity
BMIZd -0.08 (0.07) -0.06
(0.08) 0.01 (0.06) 0.15 (0.06) -0.12 (-0.22 to -0.03) 0.008 <0.01
Skinfoldse
(mm) 8.98 (0.26) 9.58
(0.27) 9.03 (0.21) 10.11 (0.29) -1.06 (-1.83 to -0.29) 0.007 0.02
a Estimate of adjusted difference of the respective outcome at follow-up between intervention and control group (95% confidence interval), P-value and ICC; adjusted for baseline values of age, sex, SES index and Protozoa- and STH-infection status in mixed linear model with random effect for class and school
b Intraclass correlation coefficient (ICC) for class and school
c Using age-adjusted test protocol from L”ger et al. (1984) (17)
d Sex-adjusted BMI-for-age Z-score (BMIZ)
e Average of six measurements (triceps and subscapular 3 times each)
‘
Table 3 Outcome measures in self-perceived physical activity (PA), stunting, anaemia or intestinal parasite- or soil-transmitted helminth-infection from 746 disadvantaged primary schoolchildren in Port Elizabeth, South Africa, before and after a physical activity intervention and control group. Values are numbers (percentages) unless specified otherwise
Variables Intervention Control Estimate of mean changea
Baseline (n=300) Follow-Up (n=264) Baseline (n=446) Follow-Up (n=374) Estimate (95% CI) P-value ICCb
Unadjusted mean in self-perceived PAc (SD) 9.11
(0.22) 8.98
(0.19) 7.83
(0.18) 9.85
(0.16) -1.08 (-2.36 to 0.18) 0.09 0.04
Stuntedd 46 (15.3) 47 (17.8) 40 (9) 48 (12.8) -0.35 (-1.39 to 0.68) 0.50 <0.01
Anaemice 67 (22.3) 37 (14) 71 (15.9) 50 (13.4) 0.16 (-0.71 to 1.02) 0.72 0.05
Infected with Protozoaf 61 (20.3) 54 (20.5) 59 (13.2) 38 (10.2) 0.35 (-0.33 to 1.04) 0.32 <0.01
Infected with STHg 132 (44) 108 (40.9) 103 (23.1) 51 (13.6) 0.97 (-3.59 to 5.53) 0.68 0.60
a Estimate of adjusted difference of the respective outcome at follow-up between intervention and control group (95% confidence interval), P-value and ICC; adjusted for baseline values of age, sex, SES index and Protozoa- and STH-infection status in mixed linear model with random effect for class and school; for binary outcome variables, estimates obtained from logistic regression models with same adjustments
b Intraclass correlation coefficient (ICC) for class and school
c Score of self-perceived PA generated out of the physical activity from the past 7 days and intense exercises outside school hours (range: from 1 to 14 with 14 being the most active)
d Stunting is defined as ‘-2 HAZ score
e Anaemic is defined as haemoglobin concentration in blood ‘114g/l
f Infected with one or two intestinal parasite species (Cryptosporidium spp. and/or Giardia intestinalis)
g Infected with one or two soil-transmitted helminth species (Ascaris lumbricoides and/or Trichuris trichiura)
‘
Figure 1
‘
Figure 2
‘
Figure 3
‘
Figure 4
Stratification after:
a) Younger
b) Older
c) Lower SES index
d) Higher SES index
e) Lower BMIZ
f) Higher BMIZ
g) Lower self-perceived PA
h) Higher self-perceived PA
i) Stunted
j) Not stunted
k) Anaemic
l) Not anaemic
m) Infected with Protozoa
n) Not infected with Protozoa
o) Infected with STH
p) Not infected with STH’
Supplemental file
Table S1 Socio-economic-status (SES) index among 9 to 14-year-old schoolchildren in Port Elizabeth, South Africa, in February 2015: Interim results from the principal component analysis (PCA)
Variable description Mean SDa Eigenvectorb
Asset ownership
Washing machine for clothes 0.71 0.02 0.13
Fridge 0.91 0.01 0.19
Freezer for food 0.80 0.01 0.17
Radio 0.80 0.01 0.07
Land line phone 0.31 0.02 0.07
Television 0.97 0.01 0.10
Cell phone 0.97 0.01 0.10
Car 0.61 0.02 0.14
Computer 0.61 0.02 0.16
Electricity 0.97 0.01 0.18
Housing
Shack in informal settlement 0.12 0.01 -0.25
Backyard shack 0.05 0.01 -0.06
Privately built house 0.07 0.01 0.06
RDP housec 0.40 0.02 0.11
Council house 0.37 0.02 0.05
House of zinc 0.11 0.01 -0.22
House of bricks 0.84 0.01 0.26
House of wood 0.04 0.01 -0.12
Bathroom 0.57 0.02 0.24
Toilet inside the house 0.67 0.02 0.27
Flush toilet 0.84 0.01 0.25
Pit toilet, bucket or communal toilet 0.16 0.01 -0.25
Tabs inside house 0.74 0.02 0.25
Tab in the yard 0.16 0.01 -0.13
Water tank or communal tab 0.10 0.01 -0.22
Cooking with electricity 0.93 0.01 0.18
Cooking with gas, paraffin stove or fire 0.07 0.01 -0.18
a Standard deviation (SD)
b Factor score
c In South Africa: Reconstruction and Development Programme house
e…