obesity reviews
doi: 10.1111/j.1467-789X.2011.00923.x
Outcome results for the Ma’alahi Youth Project, a Tongan community-based obesity prevention programme for adolescents _923
41..50
K. F. Fotu1, L. Millar2, H. Mavoa2*, P. Kremer3, M. Moodie4, W. Snowdon5, J. Utter6, P. Vivili1, J. T. Schultz7, M. Malakellis2, M. P. McCabe3*, G. Roberts5 and B. A. Swinburn2*
1
Summary
Collaborating Centre for Obesity Prevention,
Tonga has a very high prevalence of obesity with steep increases during youth, making adolescence a critical time for obesity prevention. The Ma’alahi Youth Project, the Tongan arm of the Pacific Obesity Prevention in Communities project, was a 3-year, quasi-experimental study of community-based interventions among adolescents in three districts on Tonga’s main island (Tongatapu) compared to the island of Vava’u. Interventions focused mainly on capacity building, social marketing, education and activities promoting physical activity and local fruit and vegetables. The evaluation used a longitudinal design (mean follow-up duration 2.4 years). Both intervention and comparison groups showed similar large increases in overweight and obesity prevalence (10.1% points, n = 815; 12.6% points, n = 897 respectively). Apart from a small relative decrease in percentage body fat in the intervention group (-1.5%, P < 0.0001), there were no differences in outcomes for any anthropometric variables between groups and behavioural changes did not follow a clear positive pattern. In conclusion, the Ma’alahi Youth Project had no impact on the large increase in prevalence of overweight and obesity among Tongan adolescents. Community-based interventions in such populations with high obesity prevalence may require more intensive or longer interventions, as well as specific strategies targeting the substantial socio-cultural barriers to achieving a healthy weight.
Ministry of Health, Nuku’alofa, Tonga; 2WHO
Deakin University, Geelong, Victoria, Australia; 3
School of Psychology, Deakin University,
Geelong, Victoria, Australia; 4Deakin Health Economics, Deakin University, Burwood, Victoria, Australia; 5Pacific Research Centre for the Prevention of Obesity and Non-communicable Diseases (C-POND), Fiji School of Medicine, Suva, Fiji; 6School of Population Health, University of Auckland, Auckland, New Zealand; 7National Food and Nutrition Centre, Suva, Fiji; *These authors are at the Burwood campus
Received 19 April 2011; revised 8 July 2011; accepted 8 July 2011
Address for correspondence: KF Fotu, Tonga Health System Support, Ministry of Health, Vaiola Hospital, Nuku’alofa, Tonga. E-mail:
[email protected] Re-use of this article is permitted in accordance with the Terms and Conditions
Keywords: Adolescence, intervention, obesity, Tonga. obesity reviews (2011) 12 (Suppl. 2), 41–50
set out at http://wileyonlinelibrary.com/ onlineopen#OnlineOpen_Terms
Introduction Overweight and obesity are major public health issues globally, and are especially important among Pacific nations, including the Kingdom of Tonga. Tonga, a nation of just over 101,000 people, has the fourth highest prevalence of overweight/obesity in the world (1) with recent studies showing prevalence rates of 84% among male adult and 93% among female adult (2). For adolescents, approximately one-third of male and approximately one half of female adolescents (3) are overweight/obese. This sharp
weight increase during young adulthood (4) makes it critical to prevent unhealthy weight gain among adolescents. Obesity and its chronic disease consequences of diabetes and cardiovascular diseases are a large health burden in Tonga with non-communicable diseases accounting for 10.4% of hospital admissions but, a disproportionate, 19.6% of the health budget (5). Tonga, like other Pacific Island countries, has limited resources and this amplifies the medical and social burden of obesity. The nature of food, transport and built environments impact on everyday eating and physical activity patterns
© 2011 The Authors obesity reviews © 2011 International Association for the Study of Obesity 12 (Suppl. 2), 41–50
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(6). The Tongan food environment has become increasingly ‘obesogenic’, as traditional foods (e.g. root crops, fish and green vegetables) have been replaced with less healthy imported foods (e.g. corned beef and carbonated drinks) that are high in fat, salt and/or sugar (7). This nutrition transition has been coupled with a rise in sedentary behaviours in the Pacific (8). Furthermore, strong socio-cultural factors support preferences for a larger body sizes relative to Western ideals (9), as well as the provision of ample quantities of food to express love, care and respect (10–12). In contrast to many Western societies, where healthy choices are more common in those with high incomes and educational attainment, health is not a primary consideration in food selection. Indeed, Tongans with high incomes purchase higher quantities of unhealthy foods relative to Tongans on lower incomes (13). Together, the food environment and underlying socio-cultural and socioeconomic factors create an obesogenic environment that promotes unhealthy weight gain and predisposes the population to non-communicable diseases at increasingly younger ages. Evidence-based strategies are essential for reducing unhealthy weight gain and, in Tonga, the rapid weight gain during adolescence makes this a crucial life stage to focus on. Interventions aiming to change attitudes, behaviours and obesogenic environments need to be holistic and reflect environmental, socio-cultural and socioeconomic factors that contribute to energy-dense diets and sedentary lifestyles (14). For community-based interventions, priority needs to be given to multi-strategy, multi-setting solutions, particularly when interventions target children and adolescents (15). Controlled obesity prevention trials in childhood and adolescence are few in number, mostly short-term (3 SD from mean) values on the anthropometric variables at baseline or follow-up were removed from analyses (30). Demographic data were analysed using descriptive statistics, independent groups’ t-tests or, where appropriate, chi-squared tests. Differences between follow-up (participants who were measured twice) and non-follow-up (those who were measured once) were tested with t-tests or chi-squared tests as appropriate, and where significant effects were discerned these variables were then entered into a logistic regression model for further testing. The difference from baseline to follow-up in prevalence of overweight/obesity within condition and gender was tested for significance using Newcombe’s paired differences (31). Differences in follow-up anthropometry and quality of life were determined by separate linear regression models with group (intervention or comparison) entered into the model with the following covariates: baseline variable, age at follow-up, height at follow-up (weight), gender and duration between measurements. Differences in follow-up weight status and behaviours (categorical measures) were also determined by separate logistic regression models with group (interven-
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tion or comparison) entered into the model with the following covariates: baseline variable, age at follow-up, gender and duration between measurements. Analyses were conducted using Stata release 11.0 (StataCorp, College Station, TX, USA; 2009), and in all cases, P < 0.05 was considered statistically significant.
Results Figure 1 shows the flow diagram for participants of the two groups. There were 2,610 adolescents living in the intervention communities, of whom 41% were measured at baseline and, of those, 75% (n = 815) were re-measured at follow-up. In the comparison group, 2,182 adolescents were eligible to participate, and 64% were measured at baseline and, of those, 66% (n = 897) were followed up. The majority of participants lost to follow-up had moved from the area to attend senior secondary schools or tertiary institutions or to live elsewhere. The demographic characteristics of participants and differences between characteristics of follow-up and those lost to follow-up are indicated in Table 1. The intervention and comparison groups were well matched at baseline. At baseline, intervention participants were younger (and consequently, lighter and shorter) than the comparison group. The followed-up group were more likely to be younger (OR 1.36; P < 0.001), female (OR 0.71; P < 0.001) and with a lower BMI-z (OR 1.36; P = 0.04) compared to the lost to follow-up group. The main reason for loss to follow-up was that those participants had moved away, as shown in Fig. 1. Older male adolescents in Tonga often move out of the district so the composition of the followed-up group was not surprising. Additionally, there was a rapid increase in the prevalence of overweight and obesity during adolescence so the higher mean BMI-z of the group who was not followed up was also unsurprising. The association found between BMI-z and follow-up is therefore unlikely to be related to refusal by heavier participants. There were no differences between intervention and comparison groups within those not followed up.
Anthropometric outcomes Differences (unadjusted and adjusted) in anthropometric outcomes between the intervention group and the comparison group from baseline to follow-up are presented in Table 2. At follow-up, the intervention group recorded less body fat percentage than the comparison group and this finding was statistically significant when controlling for baseline variable, age, height, gender and duration between measures. There were no statistically significant differences in outcomes in weight, BMI and BMI-z, or prevalence of overweight/obesity between the intervention and comparison groups.
© 2011 The Authors obesity reviews © 2011 International Association for the Study of Obesity 12 (Suppl. 2), 41–50
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Outcomes of the Ma’alahi Youth Project
Follow-up
Allocation
Enrolment
Intervention
Analysis
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K. F. Fotu et al.
Comparison
Three districts of Tongatapu were intervention sites: Houma, Kolonga & Nukunuku
The island of Vava’u was the comparison area
All adolescents in the intervention districts received the intervention. In total, 1,083 of 2,610 adolescents consented to data collection (response rate: 41%)
Adolescents from the comparison area received no intervention. In total, 1,396 of 2,182 adolescents consented to data collection (response rate: 64%)
Lost to follow-up: Refused (n = 10; 1%) Not available (n = 42; 4%) Moved elsewhere (n = 216; 20%)
Lost to follow-up: Refused (n = 12; 1%) Not available (n = 22; 2% ) Moved elsewhere (n = 465; 20%)
Intervention analysed: n = 815 adolescents Follow-up rate: 75%
Comparison analysed: n = 897 adolescents Follow-up rate: 64%
Excluded from analyses: •Anthropometric measures because of equipment problems, measurement or data entry error (number varies) •Knowledge, attitudes, behaviours and quality of life measures because of equipment problems or lack of relevance (number varies)
Excluded from analyses: •Anthropometric measures because of equipment problems, measurement or data entry error (number varies) •Knowledge, attitudes, behaviours and quality of life measures because of equipment problems or lack of relevance (number varies)
Figure 1 Flow diagram of participants.
Table 1 Unadjusted baseline and follow-up characteristics of the participants Intervention Baseline Total male n (%) Age (SD) (years) Height (SD) (cm) Weight (SD) (kg) BMI (SD) (kg m-2) BMI-z score (SD) Normal weight‡ (%) Overweight (%) Obese (%) Overweight/obese (%) Male Female Fat percentage (SD) Male Female Time between measures (SD) (years)
815 14.4 162.1 61.1 22.9 0.9 53.6 30.8 15.6 46.4 36.4 55.0 28.9 23.8 33.3
(45.9) (2.0)† (9.2)† (14.6)† (4.1) (0.90)
(9.7) (8.8) (8.0)
Comparison Follow-up
16.8 168.0 71.6 25.2 1.1 43.5 36.6 19.9 56.5 42.8 68.2 28.7 18.6 37.4 2.4
(2.2) (7.9) (13.8) (4.2) (0.90)
(11.8) (8.0) (6.6) (0.70)
Baseline 897 15.2 164.5 64.5 23.6 0.9 53.8 32.2 14.0 46.2 31.5 56.5 27.2 18.7 33.2
(41.4) (1.8) (8.6) (15.1) (4.4) (1.0)
(10.8) (8.1) (8.0)
Total Follow-up
17.54 168.8 73.7 25.8 1.1 41.3 39.9 18.8 58.7 42.9 69.9 29.8 17.0 38.7 2.4
(1.7) (7.8) (13.3) (4.2) (0.90)
(12.4) (6.9) (6.0) (0.40)
Non-follow-up
Baseline
Follow-up
1712 14.8 163.4 62.9 23.3 0.9 53.7 31.5 14.8 46.3 34.0 55.8 28.0 21.3 33.3
17.2 168.4 72.7 25.5 1.1 42.4 38.3 19.3 57.6 42.8 69.1 29.3 17.8 38.1
(43.5) (1.9) (9.0) (14.9) (4.3) (1.0)
(10.3) (8.8) (8.0)
(2.0) (7.9) (13.6 (4.2) (0.90)
(12.2) (7.5) (6.3)
1002(50.1)* 15.8 (2.2)* 166.4 (9.4)* 68.4 (15.6)* 24.5 (4.4)* 1.1 (0.90)* 46.0* 37.0* 17.0* 54.0* 47.4* 62.7* 28.0 (10.9)
*Follow-up and non-follow-up groups differ at baseline (P < 0.5). † Intervention and comparison groups differ at baseline (P < 0.5). ‡ Includes three participants in the thin category. BMI, body mass index; BMI-z, standardized body mass index; SD, standard deviation.
© 2011 The Authors obesity reviews © 2011 International Association for the Study of Obesity 12 (Suppl. 2), 41–50
obesity reviews
Table 2 Unadjusted and adjusted* differences in outcome measures between intervention and comparison (reference) groups and by subgroups
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Measure
All Weight (kg) BMI BMI-z Body fat percentage Proportion overweight/obese Male Weight (kg) BMI BMI-z Body fat percentage Proportion overweight/obese Female Weight (kg) BMI BMI-z Body fat percentage Proportion overweight/obese
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Difference (unadjusted)
Difference (adjusted)
SE
P
1.1 -0.1 -0.06 -2.4 -2.5†
0.05 -0.02 -0.03 -1.46 -0.05‡
0.35 0.02 0.03 0.21 0.24
0.89 0.36 0.26
