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Effects of a physical activity and nutrition program for seniors on body mass index and waist-to-hip ratio: A randomised controlled trial Linda Burke a, b, , Andy H. Lee a, b , Maria Pasalich a , Jonine Jancey a, b , Deborah Kerr a , Peter Howat a, b a School of Public Health, Curtin University, GPO Box U 1987, Perth, Western Australia, 6845, Australia b Centre for Behavioural Research in Cancer Control, Curtin University, GPO Box U 1987, Perth, Western Australia, 6845, Australia abstract article info Available online 1 April 2012 Keywords: Goal setting Intervention Nutrition Physical activity Objective. To investigate whether a home-based program, physical activity and nutrition for seniors (PANS), made positive changes to central obesity, measured by body mass index (BMI) and waist-to-hip ratio (WHR). Methods. A 6-month randomised controlled trial was conducted targeting overweight and sedentary older adults aged 60 to 70 years residing in low to medium socio-economic suburbs within metropolitan Perth. Intervention participants (n = 248) received mailed materials and telephone/email support to improve nutrition and physical activity levels. Controls (n=230) received small incentives to complete baseline and post- intervention questionnaires. Both groups reported anthropometric measures following specic written instructions. Generalised estimating equation models were used to assess repeated outcomes of BMI and WHR over both time points. Results. 176 intervention and 199 controls (response rate 78.5%) with complete data were available for analysis. After controlling for demographic and other confounding factors, the intervention group demonstrated a small (0.02) but signicant reduction in WHR (p = 0.03) compared to controls, no apparent change in BMI was evident for both groups. The 0.02 reduction in mean WHR corresponded to a 2.11 cm decrease in waist circumference for a typical hip circumference. Conclusion. PANS appears to improve the WHR of participants. Changes in BMI might require a longer term intervention to take effect, and/or a follow-up study to conrm its sustainability. © 2012 Elsevier Inc. All rights reserved. Introduction Obesity has reached epidemic proportions globally, with more than one billion adults overweight and at least 300 million of them clinically obese (World Health Organization, 2011). In Australia, the ageing population is heavier than they were a generation ago, with more than 79% of older Australians (aged 6574 years) now considered as obese or overweight (Australian Bureau of Statistics, 2009). Obesity is a major contributor to the global burden of chronic disease and disability (World Health Organization, 2011). It is also a costly public health problem. The nationwide annual cost of obesity in Australia is estimated to be $21 billion (Physical Activity Taskforce, 2007). Due to the ageing population, sound interventions capable of making a positive change to the health status of older adults are needed to curb the obesity epidemic. However, to date there is evidence that community-based interventions have had limited success in gaining substantial or lasting benets (Walls et al., 2011). Although the main causes of obesity are increased consumption of energy-dense foods high in saturated fats and sugars, and reduced physical activity (World Health Organization, 2011), many interven- tion programs for seniors have focused either solely on physical activity (Cox et al., 2008; Greaney et al., 2008; Jancey et al., 2008; Wilcox et al., 2008) or diet alone (Greene et al., 2008; Johnson et al., 2004). Recently, a few programs have considered both aspects with some promising results (Morey et al., 2009; Villareal et al., 2011). Among them, the physical activity and nutrition for seniors (PANS) program attempted to control overweight and obesity by improving both physical activity and dietary behaviour (reduce fat, increase bre, fruit and vegetable intake). It was a low cost and accessible home-based intervention developed specically for insufciently active older adults aged 60 to 70 years (Burke et al., 2010) . At the conclusion of the program, participants were found to increase their walking time and strength activities while reducing their sitting time and fat intake. Anthropometric measurements are typically used to assess the effectiveness of weight management and obesity control trials (Goodpaster et al., 2010). Apart from body mass index (BMI), waist- Preventive Medicine 54 (2012) 397401 Corresponding author at: School of Public Health, Curtin University, GPO Box U 1987, Perth, Western Australia, 6845, Australia. Fax: + 61 8 92662958. E-mail addresses: [email protected] (L. Burke), [email protected] (A.H. Lee), [email protected] (M. Pasalich), [email protected] (J. Jancey), [email protected] (D. Kerr), [email protected] (P. Howat). 0091-7435/$ see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.ypmed.2012.03.015 Contents lists available at SciVerse ScienceDirect Preventive Medicine journal homepage: www.elsevier.com/locate/ypmed

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Preventive Medicine 54 (2012) 397–401

Contents lists available at SciVerse ScienceDirect

Preventive Medicine

j ourna l homepage: www.e lsev ie r .com/ locate /ypmed

Effects of a physical activity and nutrition program for seniors on body mass indexand waist-to-hip ratio: A randomised controlled trial

Linda Burke a,b,⁎, Andy H. Lee a,b, Maria Pasalich a, Jonine Jancey a,b, Deborah Kerr a, Peter Howat a,b

a School of Public Health, Curtin University, GPO Box U 1987, Perth, Western Australia, 6845, Australiab Centre for Behavioural Research in Cancer Control, Curtin University, GPO Box U 1987, Perth, Western Australia, 6845, Australia

⁎ Corresponding author at: School of Public Health,1987, Perth, Western Australia, 6845, Australia. Fax: +6

E-mail addresses: [email protected] (L. Burke),(A.H. Lee), [email protected] (M. Pasalich), J(J. Jancey), [email protected] (D. Kerr), P.Howat@cu

0091-7435/$ – see front matter © 2012 Elsevier Inc. Alldoi:10.1016/j.ypmed.2012.03.015

a b s t r a c t

a r t i c l e i n f o

Available online 1 April 2012

Keywords:Goal settingInterventionNutritionPhysical activity

Objective. To investigate whether a home-based program, physical activity and nutrition for seniors(PANS), made positive changes to central obesity, measured by body mass index (BMI) and waist-to-hip ratio(WHR).

Methods. A 6-month randomised controlled trial was conducted targeting overweight and sedentary olderadults aged 60 to 70 years residing in low to medium socio-economic suburbs within metropolitan Perth.Intervention participants (n=248) receivedmailedmaterials and telephone/email support to improve nutrition

and physical activity levels. Controls (n=230) received small incentives to complete baseline and post-intervention questionnaires. Both groups reported anthropometric measures following specific writteninstructions. Generalised estimating equation models were used to assess repeated outcomes of BMI and WHRover both time points.

Results. 176 intervention and 199 controls (response rate 78.5%) with complete data were available foranalysis. After controlling for demographic and other confounding factors, the intervention group demonstrateda small (0.02) but significant reduction inWHR (p=0.03) compared to controls, no apparent change in BMIwasevident for both groups. The 0.02 reduction in mean WHR corresponded to a 2.11 cm decrease in waistcircumference for a typical hip circumference.

Conclusion. PANS appears to improve the WHR of participants. Changes in BMI might require a longer termintervention to take effect, and/or a follow-up study to confirm its sustainability.

© 2012 Elsevier Inc. All rights reserved.

Introduction

Obesity has reached epidemic proportions globally, with morethan one billion adults overweight and at least 300 million of themclinically obese (World Health Organization, 2011). In Australia, theageing population is heavier than they were a generation ago, withmore than 79% of older Australians (aged 65–74 years) nowconsidered as obese or overweight (Australian Bureau of Statistics,2009). Obesity is a major contributor to the global burden of chronicdisease and disability (World Health Organization, 2011). It is also acostly public health problem. The nationwide annual cost of obesity inAustralia is estimated to be $21 billion (Physical Activity Taskforce,2007). Due to the ageing population, sound interventions capable ofmaking a positive change to the health status of older adults areneeded to curb the obesity epidemic. However, to date there is

Curtin University, GPO Box U1 8 [email protected]@curtin.edu.aurtin.edu.au (P. Howat).

rights reserved.

evidence that community-based interventions have had limitedsuccess in gaining substantial or lasting benefits (Walls et al., 2011).

Although the main causes of obesity are increased consumption ofenergy-dense foods high in saturated fats and sugars, and reducedphysical activity (World Health Organization, 2011), many interven-tion programs for seniors have focused either solely on physicalactivity (Cox et al., 2008; Greaney et al., 2008; Jancey et al., 2008;Wilcox et al., 2008) or diet alone (Greene et al., 2008; Johnson et al.,2004). Recently, a few programs have considered both aspects withsome promising results (Morey et al., 2009; Villareal et al., 2011).Among them, the physical activity and nutrition for seniors (PANS)program attempted to control overweight and obesity by improvingboth physical activity and dietary behaviour (reduce fat, increasefibre, fruit and vegetable intake). It was a low cost and accessiblehome-based intervention developed specifically for insufficientlyactive older adults aged 60 to 70 years (Burke et al., 2010) . At theconclusion of the program, participants were found to increase theirwalking time and strength activities while reducing their sitting timeand fat intake.

Anthropometric measurements are typically used to assess theeffectiveness of weight management and obesity control trials(Goodpaster et al., 2010). Apart from body mass index (BMI), waist-

398 L. Burke et al. / Preventive Medicine 54 (2012) 397–401

to-hip ratio (WHR) has been shown to be a good indicator ofcardiovascular disease (Esmaillzadeh et al., 2004; Welborn andDhaliwal, 2007), trunk fat mass (Taylor et al., 2000) and all-causemortality (Welborn and Dhaliwal, 2007). In the absence of accurateclinical measurements which are preferable, self-reported data areoften taken as the proxy, especially in large community-based trialsto reduce cost and attrition rates (Dhaliwal et al., 2010). Recentresearch has confirmed the effectiveness of such self-reportedanthropometric measures (Burton et al., 2010; Dhaliwal et al., 2010;Fillenbaum et al., 2010; Stommel and Schoenborn, 2009).

This study aims to determine whether the PANS intervention hasmade a positive impact on the outcome measures of self-reportedBMI and WHR. The findings have important implications on thecontrol and prevention of central obesity for older adults.

Methods

Study design and procedure

PANS was a six-month two-arm randomised controlled trial delivered bymailed materials and telephone calls. It was developed as a home-basedintervention with the intention to accommodate insufficiently active seniors

Assessed for eligibi

Completed post-questionnaire (n=176)

Discontinued intervention (n=72)

changed mind (n=18) medical reasons (n=15) no reason given (n=14)

busy (n=10) family reasons (n=7) work reasons (n=5)

language barrier (n=3)

Allocated to intervention (n=248)Received baseline questionnaire and allocated

intervention

Allocat

Post-inte

Basel

Randomized

Enrollment

Fig. 1. Consort flow chart of participants

who could semi-tailor the program to suit their own pace and needs (Burkeet al., 2010). The project protocol was approved by the Human ResearchEthics Committee of the researchers’ institution and written consent wasobtained from all participants.

In 2010 a total of 478 participants residing in low to medium socio-economic suburbs within metropolitan Perth were recruited from theAustralian Federal Electoral Roll and randomly assigned to the intervention(n=248) and control (n=230) groups using a table of random numbers.More participants were allocated to the intervention group due to itsexpected higher attrition rate. Older adults aged between 60 and 70 yearssatisfied the selection criteria if they (a) were not on any special diet and (b)were “insufficiently active”, i.e. participated in less than 30 min of moderateactivity on at least 5 days per week (Brown et al., 2008), but (c) wereconsidered “healthy” to the extent that participation in a low-stress physicalactivity program would not place them at risk. Fig. 1 shows the flow chart ofthe recruitment procedure and corresponding sample sizes; details of whichhad been reported previously (Burke et al., 2010).

Intervention

The PANS intervention consisted of a specially designed booklet containinginformation on dietary guidelines, recommended physical activity levels andencouraged goal setting. The booklet was supplemented by additional writtenmaterials including an exercise chart, calendar and bi-monthly newsletters. The

lity (n=2196)

Excluded (n=1283)Not meeting inclusion criteria (n=1090) Medical conditions (n=193)

Discontinued intervention (n=31)

no reason given (n=15) changed mind (n=8) family reasons (n=5)

language barrier (n=1) medical reasons (n=1)

deceased (n=1)

Allocated to control (n=230) Received baseline questionnaire

Completed post-questionnaire (n=199)

ion

rvention

ine

(n=478)

Eligible (n=913)Potential Intervention (n=575)Potential Control (n=338)

Negative response (n=435)

and controls (2010, Perth, Australia).

Table 1Baseline characteristics of intervention participants and controls (2010, Perth,Australia).

Variable Intervention group(n=176)

Control group(n=199)

p a

Age: mean (SD) years 65.80 (2.95) 65.75 (3.19) 0.88Gender: male (%) 93 (52.8) 101 (50.8) 0.69Relationship status: with partner (%) 128 (72.7) 159 (79.9) 0.10Work status: working (%) 77 (43.8) 80 (40.2) 0.49Co-morbidity b: yes (%) 129 (73.3) 139 (69.8) 0.46Education level: primary school (%) 8 (4.5) 16 (8.0) 0.48secondary school (%) 83 (47.2) 91 (45.7)trade certificate/diploma (%) 48 (27.3) 57 (28.6)University (%) 37 (21.0) 35 (17.6)Financial struggle: never (%) 24 (13.6) 25 (12.6) 0.95Sometimes (%) 115 (65.3) 131 (65.8)Always (%) 37 (21.0%) 43 (21.6)Alcohol drinking: yes (%) 116 (65.9) 137 (68.8) 0.54Smoking status: never (%) 97 (55.1) 94 (47.2) 0.28Former (%) 69 (39.2) 94 (47.2)Current (%) 10 (5.7) 11 (5.5)

SD: standard deviation.a Chi-square or t test between intervention and control groups.b Presence of at least one of nine common health conditions.

Table 2Comparison of anthropometric outcomes between intervention participants andcontrols (2010, Perth, Australia).

Outcome Intervention group(n=176)

Control group(n=199)

t test

Baseline Post Baseline Post

Body mass index:mean (SD) kg/m2

27.71(4.36)

27.61(4.34)

27.27(4.56)

27.13(4.40)

p2=0.34p3=0.28

p1=0.13 p1=0.15Waist-to-hip ratio:mean (SD)

0.94(0.09)

0.92(0.08)

0.93(0.09)

0.92(0.09)

p2=0.31p3=0.81

p1=0.001 p1=0.58

p1 : baseline versus post p value.p2 : baseline intervention versus baseline control p value.p3 : post intervention versus post control p value.SD: standard deviation.

399L. Burke et al. / Preventive Medicine 54 (2012) 397–401

participants were also given a pedometer to keep track of their daily steps and aresistance band to perform strength exercises suggested in the booklet.Strength exercises were intended to reduce fat mass and help increase musclemass (Banz et al., 2003; DeNysschen et al., 2009). Moreover, group guidesprovided telephone and email support, as well as the coordination of non-compulsory group meetings. The PANS participants could semi-tailor theprogram to suit their own pace and need, and participated asmuch or as little astheywantedwithout restriction over the six-month period. Further informationon the intervention can be found elsewhere (Burke et al., 2010). The programresources were subsequently evaluated using a feedback sheet. Controlsreceived baseline and post-intervention questionnaires at the same time asthe PANS participants and were given a small incentive upon completion andreturn of the postal questionnaires.

Anthropometric measures

In addition to demographic and lifestyle characteristics, physical activityand dietary behaviours, the self-completion questionnaires solicited infor-mation on height, weight, waist and hip girth measurements at baseline andat six months post intervention. All subjects were provided with a tapemeasure and clearly written instructions on how to accurately measurethemselves at both time points. They were reminded not to wear shoes whenmeasuring height and weight. The instructions explained how to measurewaist circumference “halfway between the lowest rib and top of hipbone,roughly in line with the belly button”, and hip circumference “at the pointwhere the buttocks protrude the most”. Subjects were requested to “breatheout normally”, then “measure directly against their skin and make sure thetape was snug and not twisted, without compressing the skin”, beforerecording to the nearest 0.5 inch or cm (Commonwealth of Australia, 2009).

Statistical analysis

Descriptive statistics were first applied to summarise the baselinedemographic profile and lifestyle characteristics of the sample. The continuousoutcomes of BMI and WHR were then compared between intervention andcontrol groups across the two time points using independent samples andpaired t-tests. To accommodate the inherent correlation of observations takenfrom the same individual, generalised estimating equation (GEE) models withexchangeable correlation structure were fitted to assess the two repeatedmeasures over time, while accounting for the effects of potential confoundingfactors. An intention-to-treat analysis was also performed to assess thesensitivity of the analysis. All statistical analyses were undertaken in the SPSSpackage version 18.

Results

Of the total 478 recruited seniors who completed the baselinequestionnaire, 176 intervention participants and 199 controls withcomplete data were available for analysis, giving a final response rateof 78.5%. Table 1 presents the characteristics of the completers atbaseline. The intervention and control groups were similar in terms ofdemographic and lifestyle variables. Overall, the mean age was66 years, about half were male, the great majority of them had apartner and experienced common health conditions prevalent amongolder adults. Just less than half the seniors received tertiary educationwhile over 40% continued working. No differences in alcohol drinkingand smoking status were found between the intervention partici-pants and controls.

Table 2 compares the BMI and WHR outcomes between theintervention and control groups across the two time points. The meanBMI measures at six months were similar to those at baseline for bothgroups. However, a significant improvement inmeanWHR from baselineto post-programwas evident among the intervention participants but notthe controls, even though the reduction of 0.02 appeared small inmagnitude. This 0.02 reduction in meanWHR corresponded to a 2.11 cmdecrease in waist circumference for a typical hip circumference amongthe intervention participants.

Results of the GEE analyses are given in Table 3. After controllingfor demographic and other confounding factors, the intervention

group demonstrated a significant reduction in WHR (p=0.03) relativeto the controls, but no change in BMI was apparent for both groupsthrough the group×time interaction term. In addition, WHR waspositively associatedwith themale gender, whereas the presence of co-morbidity had more significant impact on the seniors’ BMI than theirWHR. The estimated correlations between the repeated observationswere substantial which justified the fitting of GEE models.

An intention-to-treat analysis was next performed. For bothintervention and control groups, no significant differences in baselinevariables were found between completers and non-completers, sothat the post-program BMI and WHR outcomes of the latter could beconsidered as missing at random (results omitted for brevity). Withthe inclusion of the non-completers' baseline data, the correspondingGEE fits are shown in Table 4. The results were generally comparablewith those in Table 3, though the effect of the group×time interactionterm became marginal (p=0.06) for WHR.

Process evaluation of the program resources provided the followingfeedback. The great majority (80%) of PANS participants reportedinformation given in the booklet was useful, easy to understand andsuitable for their age group, which encouraged them to think aboutphysical activity and nutrition behaviours. They believed the exercisechart was appropriate (74%) and used the resistance band provided topractise the suggested stretch and strength exercises (63%). Over 90% ofparticipants said they used the pedometer. Moreover, many partici-pants (64%) perceived that the provision of additional support through

Table 3Generalised estimating equations analysis of body mass index and waist-to-hip ratio before and after intervention (2010, Perth, Australia).

Body mass index Waist-to-hip ratio

Parameter coefficient (SE) p coefficient (SE) p

Intercept 29.74 (5.31) b0.001 91.70 (6.68) b0.001Age −0.08 (0.08) 0.28 −0.12 (0.10) 0.24Gender: male 0.55 (0.47) 0.25 12.04 (0.71) b0.001Relationship: with partner 1.05 (0.55) 0.06 0.48 (0.84) 0.57Work status: working −0.22 (0.52) 0.67 −0.68 (0.68) 0.32Co-morbidity: yes 1.61 (0.50) 0.001 1.27 (0.64) 0.04Alcohol drinking: yes −0.01 (0.18) 0.94 0.89 (0.66) 0.18Smoking status: current 0.25 0.81Never 0.84 (0.60) −0.75 (1.18)Former 0.77 (0.48) −0.68 (1.14)Financial struggle: always 0.62 0.99Never −0.55 (0.87) −0.02 (1.17)Sometimes −0.54 (0.56) −0.04 (0.76)Education level: university 0.34 0.06primary school 2.15 (1.35) 0.49 (1.46)secondary school 0.33 (0.61) 1.80 (0.79)trade certificate/diploma 0.74 (0.66) 2.11 (0.88)Group: intervention 0.55 (0.44) 0.22 0.77 (0.65) 0.24Time: post −0.15 (0.10) 0.13 −0.20 (0.36) 0.57Group×Time 0.05 (0.12) 0.69 −1.16 (0.55) 0.03Exchangeable correlation 0.99 0.66

SE: standard error.

400 L. Burke et al. / Preventive Medicine 54 (2012) 397–401

group guides could facilitate individuals to set and achieve personalphysical activity and nutrition goals.

Discussion

This study investigated the effectiveness of the PANS interventionin terms of anthropometric end points. The moderate sample sizesprovided sufficient statistical power for evaluation of the repeatedmeasures (Burke et al., 2010). As expected, the attrition was higheramong the intervention participants (29%) than the control group(13.5%), but the rates were comparable with similar physical activitytrials in the literature (Cox et al., 2008; Jancey et al., 2008). Futurestudies should take account of barriers when designing programs forolder adults, and may consider using computer-assisted telephoneinterviewing (Wilson et al., 2001) instead of self-completion postal

Table 4Intention-to-treat Generalised estimating equations analysis of body mass index and waist

Body mass index

Parameter coefficient (SE)

Intercept 31.39 (5.27)Age −0.11 (0.08)Gender: male 1.07 (0.45)Relationship: with partner 0.49 (0.51)Work status: working −0.17 (0.49)Co-morbidity: yes 1.53 (0.46)Alcohol drinking: yes 0.02 (0.22)Smoking status: currentNever 1.34 (0.77)Former 1.19 (0.07)Financial struggle: alwaysNever −0.85 (0.81)Sometimes −0.72 (0.52)Education level: universityprimary school 2.47 (1.21)secondary school 0.69 (0.57)trade certificate/diploma 0.50 (0.59)Group: intervention 0.49 (0.43)Time: post −0.18 (0.10)Group×Time 0.05 (0.12)Exchangeable correlation 0.93

SE: standard error.

questionnaire to improve the response rate. Moreover, processevaluation of PANS revealed that the program strategies andresources were relevant to the target group, assisting participants toincrease their level of physical activity and improve dietary intake.

According to Dhaliwal and Welborn (2009), the differencebetween two successive measurements in a subject will be consid-ered significant in clinical practice if the value is greater than themeasurement error, which is 0.02 for WHR for both males andfemales. Therefore, the mean WHR reduction of 0.02 observed in theintervention group would be regarded as clinically relevant. Despitebeing home-based, the PANS intervention was successful in motivatingparticipants to engage inwalking and strength exerciseswhile reducingtheir sitting time and fat intake (Lee et al., 2011). It is likely that thesepositive behavioural changes contributed to their significant decreaseinWHR over the six-month period. As changes in central obesity can be

-to-hip ratio before and after intervention (2010, Perth, Australia).

Waist-to-hip ratio

p coefficient (SE) p

b 0.001 82.10 (7.27) b0.0010.17 0.04 (0.10) 0.700.02 7.47 (0.71) b 0.0010.33 3.41 (0.81) b0.0010.73 1.14 (0.71) 0.110.001 1.06 (0.68) 0.120.92 1.39 (0.66) 0.040.19 0.10

−2.69 (1.38)−1.76 (1.34)

0.36 0.840.66 (1.27)0.46 (0.86)

0.21 0.190.09 (1.48)1.04 (0.85)1.96 (0.96)

0.26 0.66 (0.69) 0.340.07 −0.25 (0.37) 0.490.65 −1.01 (0.55) 0.06

0.62

401L. Burke et al. / Preventive Medicine 54 (2012) 397–401

effectively measured via WHR (Welborn and Dhaliwal, 2007), theobserved improvement in WHR among the PANS participants haveimportant consequences for implementing obesity control and man-agement for older adults in the clinical setting.

Although the recommended strength exercises using the resis-tance band might increase the build-up of muscle mass (Banz et al.,2003; DeNysschen et al., 2009), the reduction in BMI among theintervention participants was not statistically significant. A longertime frame for the intervention program is probably required todemonstrate substantial changes in BMI. A follow-up study to collectanthropometric measurements is also recommended to confirm thesustainability of the PANS intervention beyond six months.

Two pertinent factors were found to be associated with BMI andWHR. In this sample, males had significantly higher WHR than theirfemale counterparts, whereas the presence of some common healthconditions (heart disease, stroke, diabetes, cancer, osteoporosis, arthri-tis, high blood pressure, high cholesterol and constipation) impactedpositively on the anthropometric outcomes, especially BMI. Theseeffects were expected and consistent with the literature; WHR tendsto be higher in men than women (Ferrara et al., 2008; Lee et al., 2005;Wu et al., 2007), and the existence of chronic health conditions havebeen associated with elevated BMI (Must et al., 1999).

A potential limitation of the study concerned the self-reporting ofanthropometric measures, though the inherent inaccuracies wereexpected to be similar between the intervention and control groups.All subjects were provided with a tape measure and clearly writteninstructions on how to take measurements at both time points. Self-reported data have been considered as valid proxies to reduce cost andattrition rates in large scale community trials, and should be sufficientlyreliable formonitoring changes over time (Burton et al., 2010; Dhaliwalet al., 2010; Fillenbaum et al., 2010; Stommel and Schoenborn, 2009),which formed the basis of our evaluation. Self-selection bias wasminimised through randomisation, but participationwas voluntary dueto the home-based nature of the intervention. Therefore, reporting biasmight still pose a threat to the validity of the findings. Moreover,residual confounding could not be eliminated even though demo-graphic and other factors were adjusted for in the GEE regressionanalyses. As alluded above, the duration of the PANS interventionmightnot be of sufficient length to reflect significant changes in BMI. A longer,sustainable program should be considered in the future, but it mightincrease the likelihood of further attrition among older adults.

Conflict of interest statementNothing declared for all authors.

AcknowledgmentsThe authors are grateful to the seniors who participated in this project. The study

was funded by a research project grant from the Australian National Health andMedical Research Council (project number 533501) and the Centre for BehaviouralResearch in Cancer Control. The funding sources had no involvement in the studydesign, data collection, analysis or writing of papers including decisions in regard tosubmission of papers. The project protocol was approved by the Human ResearchEthics Committee of Curtin University (approval number HR 186/2008).

References

Australian Bureau of Statistics, 2009. National Health Survey: Summary of Results,2007–2008. A. C. T, Canberra.

Banz, W.J., Maher, M.A., Thompson, W.G., et al., 2003. Effects of resistance versus aerobictraining on coronary artery disease risk factors. Exp. Biol. Med. 228, 434–440.

Brown, W.J., Moorhead, G.E., Marshall, A.L., 2008. Choose Health: Be Active: A PhysicalActivity Guide for Older Australians, 3rd ed. Commonwealth of Australia andrepatriation Commission, Canberra.

Burke, L., Jancey, J., Howat, P., et al., 2010. Physical activity and nutrition program forseniors (PANS): protocol of a randomized controlled trial. BMC Public Health 10,751.

Burton, N., Brown, W., Dobson, A., 2010. Accuracy of body mass index estimated fromself-reported height and weight in mid-aged Australian women. Aust. N. Z. J. PublicHealth 34, 4.

Commonwealth of Australia, 2009. onlineavailable: http://www.measureup.gov.au/internet/abhi/publishing.nsf/Content/factsheet-waist-measurement [accessed October 2009].

Cox, K.L., Burke, V., Beilin, L.J., et al., 2008. Short and long-term adherence to swimmingand walking programs in older women-the Sedentary Women Exercise AdherenceTrial (SWEAT 2). Prev. Med. 46, 511–517.

DeNysschen, C., Burton, H., Horvath, P., Leddy, J., Browne, R., 2009. Resistance trainingwith soy vs whey protein supplements in hyperlipidemic males. J. Int. Soc. SportsNutr. 6, 8.

Dhaliwal, S., Howat, P., Bejoy, T., Welborn, T., 2010. Self-reported weight and height forevaluating community obesity studies. Am. J. Health Behav. 34, 489–499.

Dhaliwal, S.S., Welborn, T.A., 2009. Measurement error and ethnic comparisons ofmeasures of abdominal obesity. Prev. Med. 49, 148–152.

Esmaillzadeh, A., Mirmiran, P., Azizi, F., 2004. Waist-to-hip ratio is a better screeningmeasure for cardiovascular risk factors than other anthropometric indicators inTehranian adult men. Int. J. Obes. Relat. Metab. Disord. 28, 1325–1332.

Ferrara, C., Goldberg, A., Nicklas, B., Sorkin, J., Ryan, A., 2008. Sex differences in insulinaction and body fat distribution in overweight and obese middle-aged and oldermen and women. Appl. Physiol. Nutr. Metab. 33, 7.

Fillenbaum, G.G., Kuchibhatla, M.N., Whitson, H.E., et al., 2010. Accuracy of Self-reportedHeight and Weight in a Community-Based Sample of Older African Americans andWhites. J. Gerontol. A Biol. Sci. Med. Sci. 65A, 1123–1129.

Goodpaster, B.H., DeLany, J.P., Otto, A.D., et al., 2010. Effects of Diet and PhysicalActivity Interventions onWeight Loss and Cardiometabolic Risk Factors in SeverelyObese Adults. JAMA 304, 1795–1802.

Greaney, M.L., Riebe, D., Ewing Garber, C., et al., 2008. Long-term effects of a stage-based intervention for changing exercise intentions and behavior in older adults.Gerontologist 48, 358.

Greene, G.W., Fey-Yensan, N., Padula, C., Rossi, S.R., Rossi, J.S., Clark, P.G., 2008. Changein fruit and vegetable intake over 24 months in older adults: results of the SENIORproject intervention. Gerontologist 48, 378.

Jancey, J., Clarke, A., Howat, P., Lee, A., Shilton, T., Fisher, J., 2008. A physical activityprogram to mobilize older people: A practical and sustainable approach.Gerontologist 48, 251–257.

Johnson, D., Beaudoin, S., Smith, L., Beresford, S., LoGerfo, J., 2004. Increasing fruit andvegetable intake in homebound elders: the Seattle Senior Farmers' MarketNutrition Pilot Program. Preventing Chronic Disease [serial online] date cited 28-11-11. Available from URL: http://www.cdc.gov/pcd/issues/2004/jan/03_00010a.htm.

Lee, A., Jancey, J., Howat, P., Burke, L., Kerr, D., Shilton, T., 2011. Effectiveness of a home-based physical activity and nutrition pilot program for seniors. J. Obes. 2011, 8.

Lee, C.C., Glickman, S.G., Dengel, D.R., Brown, M.D., Supiano, M.A., 2005. AbdominalAdiposity Assessed by Dual Energy X-Ray Absorptiometry Provides a Sex-Independent Predictor of Insulin Sensitivity in Older Adults. J. Gerontol. A Biol.Sci. Med. Sci. 60, 872–877.

Morey, M., Snyder, D., Sloane, R., et al., 2009. Effects of home-based diet and exercise onfunctional outcomes among older, overweight long-term cancer survivors. JAMA301, 1883–1891.

Must, A., Spadano, J., Coakley, E.H., Field, A.E., Colditz, G., Dietz, W.H., 1999. The DiseaseBurden Associated With Overweight and Obesity. JAMA 282, 1523–1529.

Physical Activity Taskforce, 2007. Premier's Physical Activity Taskforce: strategic plan2007–2011. Government of Western Australia.

Stommel, M., Schoenborn, C., 2009. Accuracy and usefulness of BMI measures based onself-reported weight and height: findings from the NHANES & NHIS 2001–2006.BMC Public Health 9, 421.

Taylor, R., Jones, I., Williams, S., Goulding, A., 2000. Evaluation of waist circumference,waist-to-hip ratio, and the conicity index as screening tools for high trunk fat mass,as measured by dual-energy X-ray absorptiometry, in children aged 3–19 y. Am. J.Clin. Nutr. 72, 6.

Villareal, D.T., Chode, S., Parimi, N., et al., 2011. Weight Loss, Exercise, or Both andPhysical Function in Obese Older Adults. N. Engl. J. Med. 364, 1218–1229.

Walls, H., Peeters, A., Proietto, J., McNeil, J., 2011. Public health campaigns and obesity -a critique. BMC Public Health 11, 136.

Welborn, T.A., Dhaliwal, S.S., 2007. Preferred clinical measures of central obesity forpredicting mortality. Eur. J. Clin. Nutr. 61, 1373–1379.

Wilcox, S., Dowda, M., Leviton, L.C., et al., 2008. Active for Life: Final Results from theTranslation of Two Physical Activity Programs. Am. J. Prev. Med. 35, 340–351.

Wilson, D., Taylor, A., Chittleborough, C., 2001. The Second Computer AssistedTelephone Interview (CATI) Forum: The state of play of CATI survey methods inAustralia. Aust. N. Z. J. Public Health 25, 272–274.

World Health Organization, 2011. Global Strategy on Diet, Physical Activity and Health.Obesity and Overweight. March 2011 ed. World Health Organization.

Wu, C.H., Heshka, S., Wang, J., et al., 2007. Truncal fat in relation to total body fat:influences of age, sex, ethnicity and fatness. Int. J. Obes. 31, 1384–1391.