regular exercise and reduction of high fat foods (Davin & Taylor, 2009). Treatment adherence is defined by WHO (2003) as the extent to which a person's ...
Development and preliminary validation of the Adherence to Weight Control Questionnaire
Abstract Background and Purpose: This study tests the psychometric properties of the Adherence to Weight Control Questionnaire, a new screening tool to measure treatment adherence (TAWC) and the risk of non-adherence to weight control (RNAWC) in adolescents. Methods: Participants are 92 adolescents (12-18 years) from a Paediatric Obesity Clinic. Construct validity were evaluated using a principal-axis factoring method with varimax rotation. Reliability and criterion-related validity of both scales were also checked. Results: Both scales presented good reliability values (0.770 and 0.908). Statistical analyses yielded a one-factor solution for the RNAWC and a four-factor solution for the TAWC. Criterionrelated validity of scales was also checked. Conclusions: Results showed that this theory-driven measure of adherence to weight control has adequate psychometric properties to support both research and the clinical practice.
Keywords: Adolescents; Weight control; Treatment adherence; validation; Instrument development
Introduction The problem of obesity assumes a leading role, being considered as the epidemic of the XXI century (White House Task Force on Childhood Obesity, 2010; Carmo, Santos, Camolas, & Vieira, 2009; Carmo et al., 2008; Sousa, 2008; Steele, Nelson, & Jelalian, 2008; WHO, 2006). The obesity epidemic has built up in recent decades as a result of the changing social, economic, cultural and physical environment and raises one of the most serious public health challenges in the WHO European Region (McAllister et al., 2009). Overweight and obesity mostly affect people in lower socioeconomic groups, what contributes to a widening of health and social inequalities (WHO, 2013). The prevalence of overweight among preschool children in the European Union ranges from 11.8% to 32.3% (Cattaneo et al., 2010). In EU, overweight affects almost 1 in 4 children, with Spain, 1
Portugal and Italy presenting levels of overweight higher than 30% in children between 7 to 11 years. In the USA, 1 in 3 children (31.7%) aged 2 to 19 years is already overweight (White House Task Force on Childhood Obesity, 2010). The obesity epidemic slowed down in several OECD countries during the past years (OECD, 2011). Rates grew less than previously projected, or did not grow at all. Child obesity rates also stabilised in England, France, Korea and United States. However, rates and social disparities remained unchangeable. Many governments have stepped up efforts to tackle the root causes of obesity, embracing increasingly comprehensive strategies and involving communities and key stakeholders (OECD, 2011). Effective weight loss treatment requires adherence to behavioural recommendations. These changes require the patient to make specific lifestyle changes including strict dietary portion control, regular exercise and reduction of high fat foods (Davin & Taylor, 2009). Treatment adherence is defined by WHO (2003) as the extent to which a person’s behaviour (e.g. taking medication, following a diet, and/or executing lifestyle changes) corresponds with agreed recommendations from a health care provider. Adherence in Paediatrics relates not only to the child but also to the parents, who will be primarily responsible actors for treatment. In most cases, treatment recommendations involve mostly educational and attitudinal issues, as well as drug prescriptions (Santos, 2005). Approaching adherence from a patient-centred approach supports the goal of nursing by allowing consideration of what is best in the context of each patient’s life (Bissonnette, 2008). A better understanding of the phenomenon of therapeutic adherence in children tailored to the family needs, may facilitate the health care delivery (Chisholm et al., 2007). Poor adherence to treatment of chronic diseases, as obesity, is a worldwide problem of striking magnitude. The impact of poor adherence increases as the burden of chronic disease grows worldwide (WHO, 2003). Low adherence may result in worsening of symptoms and disease progression, increased morbidity, an increase in the number of appointments and hospitalizations and unnecessary expenses, representing an inefficient use of the health system (Klein & Gonçalves, 2005; Santos, 2005).
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Rudd (2000, in Ma, Chen, You, Luo, and Xing, 2012) suggests adherence is the willingness and ability of the individual to follow the clinical prescription (pharmacological or non-pharmacological) and that it is assessed by asking participants whether they are currently following each recommendation as prescribed. Others indicate that adherence should be evaluated as an entity, and according to the different aspects of treatment (e.g. diet, exercise and medication) (Ma et al., 2012). Health outcomes cannot be accurately assessed if they are predominantly measured by utilization and efficacy indicators. The population health outcomes predicted by treatment efficacy data cannot be achieved unless adherence rates are used to inform planning and project evaluation (WHO, 2003). Within the methods of assessing adherence, the self-evaluation is the most economical and simplest approach to gather information and give feedback (Ma et al., 2012). Although selfreport methods have inherent limitations, this assessment method is advantageous for capturing behaviours that occur in “real time” outside the treatment facility (Steele, Steele, & Hunter, 2009). These authors concluded that self-reported adherence presented a significant association with objective rates of adherence, as attendance to appointments. There are some instruments that measure treatment adherence to specific conditions such as diabetes, HIV and substance abuse (Cruess, Minor, Antoni, & Millon, 2007; DiMatteo, 2004; Gilmore, Lash, Foster, & Blosser, 2001; WHO, 2003). However, to our knowledge, there are no specific instruments for measuring weight control adherence. An accurate assessment of adherence behaviour is necessary for effective treatment planning and for ensuring that changes in health outcomes can be attributed to the recommended regimen (Cruess et al., 2007; Gilmore et al., 2001; Ruey-Hsia, Shu-Wen, Shan-Mei, Shu-Li, & Shu-Yuan, 2011). In addition, decisions to change recommendations, medications, and/or communication style in order to promote patient participation depend on a valid and reliable measurement of the adherence construct. Improvement of validity of the adherence assessment will allow researchers to more accurately identify how adherence affects adolescent outcomes in family-based behavioural interventions.
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The concept of adherence to weight control may be viewed within the context of the Health Promotion Model of Nola Pender (1996), a model intended to assist health professionals in understanding the major determinants of health behaviours as a basis for behavioural counselling to promote healthy lifestyles. Using the model and working collaboratively with the patient/client, changes can be made to achieve a lifestyle characterized by health promoting behaviours (Pender, Murdaugh, & Parsons, 2010). The model shows that the greater the commitment to a specific plan of action, the more likely health-promoting behaviours are to be maintained over time. This commitment to a plan of action is less likely to result in the desired behaviour when competing demands over which persons have little control, require immediate attention and when other actions are more attractive and thus preferred over the target behaviour. However, Pender (1996) believes that cognitions can be modified, as well as the interpersonal and physical environment, in order to create incentives for healthy actions. The purpose of this study was to develop and test the psychometric properties (preliminary validation) of the Adherence to Weight Control Questionnaire (AWCQ), a new screening tool to measure treatment adherence to weight control and the risk of non-adherence to weight control in adolescents.
Methods Study design and participants This is a cross-sectional study with a convenience sample (N = 92) that includes adolescents from a Paediatric Obesity Clinic (Portugal), aged between 12 and 18, fulfilling the WHO’s criteria (BMI percentile ≥ 95th) for overweight (inclusion criteria). Exclusion criteria are the presence of severe psychopathology reported in the adolescent clinical file, inability to communicate in writing and having been proposed for bariatric surgery. Sample recruitment had the support of Paediatric Obesity Clinic clinical staff. All eligible adolescents with appointments between January 1st and December 31st 2012, were included in the study - consecutive sampling. Data collection for this research occurred in 2012. 4
Measures Demographic and clinical data. Data on gender, age, BMI z-score and waist circumference percentile were extracted from the adolescents’ clinical file. Anthropometric data were measured by trained health professionals from the clinic. The WHO BMI charts (de Onis, Garza, Onyango, & Borghi, 2007) were used. Adolescent Lifestyle Profile (ALP). This instrument is designed to measure the frequency of health promoting behaviours in adolescents (early, middle and late). The Portuguese version of ALP was validated by Sousa et al. (2013), from the original version of ALP (Hendricks, Murdaugh, & Pender, 2006). The Portuguese version has 36 items organized into 7 factors (Health Responsibility, Physical Activity, Nutrition, Positive Life Perspective, Interpersonal Relationship, Stress Management and Spiritual Health). This model showed adequate adjustment indices: CMIN / DF = 1.667, CFI = 0.807, GFI = 0.822, RMR = 0.051, RMSEA = 0.053, PNFI = 0.575, PCFI = 0.731. The scale has a high reliability score (α = 0.866), subscale reliability values between 0.492 and 0.747. Adherence to Weight Control Questionnaire (AWCQ). This screening tool was developed by the researchers. It measures “Treatment Adherence to Weight Control” (TAWC) and the “Risk of Non-Adherence to Weight Control” (RNAWC) in adolescents. The TAWC scale was designed to evaluate the adherence behaviours/strategies as well as the intention/expectation of adherence, including the perception of benefits, interpersonal influences and self-efficacy. The RNAWC scale was designed to evaluate the perception of barriers to adherence. The initial versions of the TAWC and RNAWC consisted of 43 items and 7 items respectively, with a five-point Likert-type format.
Procedures and Statistical Analysis Phase I - item generation. The initial item pool of the AWCQ was derived from (a) the literature review, namely the Nola Pender’s Health Promotion Model, (b) the content of the current existing questionnaires that examine health behaviours related to weight control. The authors searched adherence-related instruments for weight control treatment, and compiled a list of items 5
across all the Health Promotion Model domains. Items with similar or redundant meanings were deleted, resulting in 48 items across two domains: treatment adherence and risk of non-adherence. Phase II - content validity. To establish content validity, a panel of experts was conducted in two rounds. A panel of five investigators with extensive in working with adolescents and extensive background research on health intervention programs, behavioural modification and health promotion, with post-graduated formation in Medicine, Nursing and Exercise Physiology were invited to participate. Each expert evaluated each AWCQ item from Phase I for its appropriateness, explicitness and representativeness. In the first round, two items were identified as containing different meanings, leading to having been spitted into four items. After this review, the AWCQ was returned to the same panel of experts for the 2nd round. The results demonstrated agreement for two domains (treatment adherence and risk of non-adherence) and 50 items. Each dimension originated a distinct scale: the Treatment Adherence to Weight Control scale (TAWC) and the Risk of Non-Adherence to Weight Control scale (RNAWC). The initial versions of the TAWC and RNAWC consisted of 43 items and 7 items respectively. Phase III - construct validity. An exploratory factor analysis (EFA) was performed to examine the factor structure of the TAWC and the RNAWC scales. Principal-axis factoring method with varimax rotation was used and the number of factors was decided on the basis of a scree plot analysis. The Kaiser-Meyer-Olkin (KMO) index and the Bartlett's sphericity tests were run, in order to assess the adequacy of the sample to produce a satisfactory factor analysis. The criteria for item/factor retention in the EFA were: (a) saturation above 0.30 (Kline, 1994), (b) not inclusion of items that saturate into two or more components, with less than 0.10 between them and (c) each obtained component should have at least three items. Pearson correlations between TAWC and RNAWC scales were calculated. Phase IV - reliability testing. After an initial descriptive study of the results, the instruments’ reliability was checked. Cronbach’s Alpha was calculated for TAWC and RNAWC, as well as for each subscale, and the homogeneity indices (corrected element-total correlation) of the items were analysed in order to determine whether it would be wise to suppress some of them - items 6
with a score of less than 0.20 should be suppressed (Hair, Anderson, Tatham, & Black, 2010). A good reliability should correspond to an α of 0.80 or greater (Nunnally, 1978; Streiner & Norman, 2008). Phase V - criterion-related validity. Criterion-related validity was assessed by the Adolescent Lifestyle Profile (ALP), an instrument designed to measure the frequency of health promoting behaviours in adolescents. The hypothesized relationships between TAWC and ALP were positive; and between RNAWC and ALP were negative. The obesity treatment depends on patient adherence to behavioural changes and a healthy lifestyle (Elfhag & Rossner, 2005).
Ethical considerations This study was approved by the Ethical Committee for Health (Lisbon, Portugal) in January 2012 and funded by the Foundation for Science and Technology (FCT), Portugal, in December 2012. All eligible adolescents and respective parents signed the informed consent where the study objectives were explained, in accordance with the Declaration of Helsinki (World Medical Association, 2008) and the ethical principles of the American Psychological Association (2010). This study is part of the trial registered in the FCT (the central Portuguese governmental institution responsible for financing and evaluating the scientific and technological system): PTDC/DTPPIC/0769/2012.
Results Demographic characteristics of sample A total of 140 adolescents were invited to participate, 46 refused, and two adolescents were rejected because more than 50% of the questions were incomplete. Finally, there were 92 adolescents in the study, 45 boys (48.9%) and 47 girls (51.1%), with a mean age of 14.210 (SD = 1.501). The mean BMI z-score was 2.641 (SD = 0.740), with a mean waist circumference percentile of 91.783 (SD = 3.378).
Preliminary analysis 7
Based on the inadequate values of “Cronbach's Alpha if item deleted”, eleven items of TAWC were deleted on successive rounds (items 7, 8, 11, 15, 16, 17, 25, 26, 33, 45 and 49). Furthermore, three items of TAWC were removed due to cross loadings in a preliminary EFA (items 18, 31 and 44).
Descriptive analysis of the items The descriptive study of TAWC showed some irregular behaviour of items variability and central tendency (Table 1). The mean score of the items ranged from 4.696 + 0.691 (item 10) to 2.099 + 1.248 (item 43). Some items had a non-adequate skewness and kurtosis values. The items with the highest skewness values were item 10 (-2.371) and item 1 (-2.135). The highest Kurtosis values occurred in item 10 (5.032), item 1 (4.433), item 21 (3.367), item 38 (3.083) and item 39 (2.129). The mean score of the items of the RNAWC scale ranged from 2.245 + 1.335 (item 9) to 2.842 + 1.383 (item 6). All items presented adequate skweness values (-1 < sk < 1), however, item 3 (-1.007) and item 6 (-1.154) had Kurtosis values > 1 (Table 2).
Construct validity (Phase III) Construct validity were evaluated using a principal-axis factoring method with varimax rotation. The EFA of the TAWC showed that the data were appropriate to be used for factor analysis (Bartlett’s test of sphericity = 1431.173, p = 0.000; KMO measure of sampling adequacy = 0.829) (Table 3). A four-factor solution was chosen on the basis of a scree plot analysis, which accounted for 49.882% of the total variance. The factors were labelled as SEA (Self-Efficacy and Adherence behaviours), PPI (Parents and Providers Influence), FSI (Friends and School Influence) and PB (Perceived benefits). The SEA factor consisted of twelve items, the PPI factor consisted of eight items, FSI had six items and PB had three items. The items’ communalities ranged from 0.287 (item 36) to 0.725 (item 30) and the factor loadings from the rotated matrix ranged from 0.429 (item 35) to 0.799 (item 38). Although the results of the EFA of the RNAWC showed that the data were appropriate to be used for factor analysis (Bartlett’s test of sphericity = 161.133, p = 0.00; KMO = 0.756), a one-factor 8
solution was chosen on the basis of a scree plot analysis, which accounted for 34.845% of the total variance. RNAWC consisted of seven items, with communalities ranging from 0.185 (item 6) to 0.601 (item 24) and factor loadings ranging from 0.431 (item 6) to 0.775 (item 24).
Reliability (Phase IV) Once interpreting the global alpha corresponding to the TAWC measuring instrument, a value of 0.908 was obtained. The reliability values of the four subscales ranged from 0.772 (PB) to 0.897 (SEA) (Table 3). Analysing the mean scores in the different subscales, we found that the highest values were in PPI (4.473 + 0.580) and the lowest in SEA (3.233 + 0.822). The corrected item-total correlation ranged from 0.313 (item 2) to 0.741 (item 47) (Table 1). The Cronbach’s alpha of the RNAWC scale was 0.770. The corrected item-total correlation ranged from 0.379 (item 3) to 0.672 (item 24) (Table 2). Table 4 presents the Pearson correlations between TAWC and RNAWC scales. All correlations between TAWC factors are positive and statistically significant (p < 0.05). The RNAWC scale presented a negative and statistically significant correlation with the TAWC total score (-0.322; p < 0.001) and with factors SEA (-0.357; p < 0.001) and FSI (-0.279; p < 0.001).
Criterion-related validity of TAWC and RNAWC (Phase V) The criterion-related validity was assessed by ALP and by the analyses of the correlations between the factor and the overall scores (Table 5). The correlation between the overall adherence score of TAWC and the ALP total score (r = 0.481, p < 0.01), and the correlation between the overall score of RNAWC and ALP (r = -0.229, p < 0.05) were significant and in the expected direction. These results supported the external validity of the instrument. Therefore, the final instrument includes 36 items organized in two scales. The TAWC (29 items) includes four subscales: SEA (12 items), PPI (8 items), FSI (6 items) and PB (3 items). The RNAWC (7 items) presented a one-factor solution. 9
Discussion The purpose of this research was to validate a self-reported general questionnaire to measure adherence to weight control and the risk of non-adherence. Separate analyses were conducted with the TAWC and the RNAWC scales. After EFA, four factors were extracted from TAWC (SEA, PPI, FSI and PB). The cumulative contribution rate was 49.882% for TAWC, which may be recognized as adequate to capture the main features of a phenomenon (Ma et al., 2012). The correlation coefficients between the total TAWC scale score and the factor scores ranged from 0.507 to 0.877, which were higher than the correlation coefficients for each factor (0.226 - 0.502), indicating that the scale presented good construct validity (Ma et al., 2012). SEA is the first subscale of TAWC and measures the Self-Efficacy and Adherence behaviours. It represents the judgment of personal capability to organize and execute a particular health behaviour. If one is self-confident in performing successfully the weight control program and shows intention to carry out the treatment, identifying specific strategies to do so successfully, its adherence score in SEA will be high. PPI is the second subscale of TAWC and FSI is the third. They evaluate the interpersonal and contextual influence of parents, providers, friends and school. Interpersonal influences evolves perceptions concerning behaviours, beliefs, attitudes of relevant others in regard to engaging in a specific health behaviour. Situational influences are perceptions of the compatibility of life or environmental contexts once engaging in specific health behaviours (Pender et al., 2010). Perceived benefits (PB) of weight control are perceptions of the positive or reinforcing consequences of undertaking the treatment program. The EFA of the RNAWC conducted to a one-factor solution, which allows inferring that the risk of non-adherence to weight control is a one-dimensional construct. The TAWC presented an alpha coefficient of 0.908 and the RNAWC reliability score was 0.770. A reliability of 0.80 or higher is preferable if an instrument is to be suitable for use in research (Nunnally & Bernstein, 1994). The Cronbach’s alpha values are sensitive to the scale number of items 10
and short subscales as RNAWC may present lower Cronbach’s alpha values (Ma et al., 2012). Therefore, it is suggested to report the item-total correlations, being the standard cr0iteria more than 0.30 (Nunnally & Bernstein, 1994). The item-total correlation for the RNAWC ranged from 0.384 to 0.673, providing evidence of the reliability of the questionnaire. All correlations between TAWC factors are positive (0.226 to 0.502), as well as the correlations between the factors and the total score (0.507 to 0.877), as expected. Additionally, the RNAWC scale presented a negative correlation with the TAWC overall score, which corroborates the coherence of the internal structure of both scales of the AWCQ within the adherence/non-adherence concept. Furthermore, the positive correlation between the overall adherence (TAWC total score) and the health promoting behaviours (ALP total score), as well as the negative correlation between the risk of non-adherence and the health promoting behaviours supported the external validity of the TAWC and the RNAWC. Adherence to treatment is an important catalyst of the effectiveness of health systems, so focus on adherence can be the best investment in the control of chronic diseases (Davin & Taylor, 2009; WHO, 2003). Davin and Taylor (2009) underline the role of treatment adherence as a predictor of successful weight loss. The weight control adherence is indeed a critical component in the treatment success. The problem of non-adherence to treatment remains a challenge for health professionals and researchers. As a result of the widespread problem of adherence, substantial numbers of patients do not get the maximum benefit of medical treatment, resulting in poor health outcomes, lower quality of life and increased health care costs (Dulmen et al., 2007). This study has some limitations. A small convenience sample of overweight adolescents was used, and research settings did not cover different regions, which may have impaired the strength of the conclusions. These adolescents present severe obesity and are under ambulatory treatment at a highly differentiated clinic. A second limitation is the exclusive use of a self-report questionnaire to assess a psychological and behavioural indicator such as adherence. This can lead to social desirability, although minimized 11
by the guarantee of anonymity. Although this adherence assessment method has some limitations, it may be a more cost-effective option for capturing the several behaviours that are determinant for effective weight loss in the “real world” setting (Steele et al., 2009). For all these reasons, the authors assume the need to be cautious in the generalisation of results.
Conclusions Results showed that this theory-driven measure of adherence to weight control has adequate psychometric properties. Theoretical statements derived from the Health Promotion Model provide a basis for future research on health behaviours and adherence to weight control, and sustain this measure of adherence to weight control, an innovative and practical instrument to support both research and clinical practice. The development and preliminary validation of the TAWC and RNAWC make important theoretical and practical contributions to the field of psychology and health sciences. Researchers using these instruments can measure the commitment to the program, based on the intention/expectations of adherence and on the objective adherence to the recommendations, as well as the risk of non-adherence to weight control, based on the barriers perceived. Furthermore, adolescents themselves can use this instrument to objectively assess their level of adherence to the treatment recommendations. Another advantage of the instrument is its ability to measure differences in the different domains of adherence: self-efficacy, perception of benefits and interpersonal influences. This questionnaire has several potential applications for research and clinical practice. The information given by this instrument offer healthcare providers specific circumstances that promote a more directed discussion about adherence intervention. Considering it as a research tool, it can provide a helpful outcome variable, when adherence is assessed over time in response to a multidisciplinary intervention. This questionnaire can thus be used to evaluate within-patient or between-patient changes in adherence behaviour over time. As a research tool, it can also be used to
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assess the effectiveness of interventions designed to improve patients’ adherence (Sousa, Fonseca, Gaspar, & Gaspar, 2013).
Acknowledgements: This work was funded by Fundação para a Ciência e a Tecnologia (PTDC/DTPPIC/0769/2012) and supported by the Polytechnic Institute of Leiria, Portugal and the Department of Pediatrics at Hospital de Santa Maria, Lisbon, Portugal. We gratefully acknowledge the clinical staff of the Pediatric Obesity Clinic for their dedication. We also thank all the adolescents and parents for their participation and collaboration.
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Table 1 – Descriptive statistics, corrected item-total r and Cronbach's alpha if item deleted of the TAWC scale
4.533 0.857 -2.135 4.433 4.011 1.227 -1.298 0.826 3.659 1.147 -0.605 -0.169
Cronbach's Alpha if Item Deleted 0.423 0.906 0.313 0.908 0.619 0.903
3.769 1.096 -0.612 -0.334 4.696 0.691 -2.371 5.032 3.615 1.227 -0.402 -0.725
0.605 0.472 0.640
0.903 0.906 0.902
4.576 0.683 -1.550
1.839
0.517
0.906
-1.477 1.325 -0.646 -0.474 -1.787 3.367 -0.711 0.053 -1.325 1.782
0.501 0.594 0.366 0.520 0.446
0.906 0.903 0.907 0.905 0.906
1.466
0.471
0.906
M 1 2 4 5 10 12 13 14 19 21 22 23 27 28 30 32 34 35 36 38 39 40 41 42 43 46 47 48 50
Item description … lose weight to feel better with my body … lose weight to be happier … accomplish the treatment even if I feel is not working … accomplish the treatment even if I'm tired … lose weight to be healthier … accomplish the treatment even if I'm not in the mood .. believe in the information given by health Professionals … family encourages me … … accomplish the treatment even if I'm alone … family believes that I will lose weight … friends believes I will lose weight ... understand the information given by health Professionals … lose weight to have better performance in Sports … friends usually offer to exercise with me … friends encourage me to maintain treatment … friends help me to plan treatment activities … friends make positive comments about my Appearance … have adequate conditions in my school … … have adequate conditions in home ... … trust in health professionals … … strategies proposed by health professionals are important … … plan specific times for exercise or sport during the week… … fulfil the recommendations of health professionals on nutrition … progressively define more ambitious goals … make records on my nutrition … make records on m exercise … fulfil the recommendations of health professionals on exercise … have strategies to remember the treatment … diversify my exercises to avoid monotony
4.554 3.652 4.380 4.033 4.391
SD
0.717 1.253 0.947 0.988 0.825
Sk
4.163 1.062 -1.348
Ku
Corrected item-total r
3.185 3.769 2.956 3.500
1.266 1.096 1.228 1.124
-0.224 -0.561 -0.135 -0.427
-0.776 -0.190 -0.670 -0.310
0.476 0.615 0.456 0.324
0.906 0.903 0.906 0.908
3.457 4.109 4.478 4.609
1.190 1.032 0.851 0.695
-0.435 -0.466 -1.081 0.801 -1.775 3.083 -1.707 2.129
0.330 0.411 0.453 0.383
0.908 0.907 0.906 0.907
2.815 1.406
0.191 -1.187
0.374
0.908
3.707 0.978 -0.456 -0.426
0.675
0.902
3.396 2.099 2.435 3.707
0.451 0.489 0.428 0.741
0.906 0.905 0.907 0.901
0.533 0.577 TOTAL
0.905 0.904 0.908
1.094 -0.377 -0.290 1.248 1.002 0.039 1.369 0.533 -0.954 1.144 -0.524 -0.669
2.967 1.313 2.901 1.239
0.061 -0.963 0.084 -0.901
TAWC – Treatment Adherence to Weight Control
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Table 2 – Descriptive statistics, corrected item-total r and Cronbach's alpha if item deleted of the RNAWC scale
Item description (“…might not meet the treatment if”) 3 6 9 20 24 29 37
I don't have enough time it interferes with school or work I don't like the recommendations I have don't have support … I'm very tired the recommendations are difficult… I don't understand it …
M
SD
Sk
Ku
2.533 2.842 2.245 2.543 2.477 2.478 2.413
1.262 1.383 1.335 1.386 1.272 1.288 1.352
0.257 0.071 0.674 0.517 0.340 0.512 0.534
-1.007 -1.154 -0.798 -0.803 -0.832 -0.619 -0.866
Corrected item-total r 0.384 0.384 0.484 0.489 0.673 0.608 0.438 TOTAL
Cronbach's Alpha if Item Deleted 0.762 0.764 0.743 0.742 0.705 0.718 0.753 0.770
RNAWC – Risk of Non-Adherence to Weight Control
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Table 3 – Exploratory Factor Analysis and reliability of the TAWC scale
Alpha M SD Factor loading item 4 item 5 item 12 item 19 item 40 item 41 item 42 item 43 item 46 item 47 item 48 item 50 item 10 item 13 item 14 item 21 item 23 item 36 item 38 item 39 item 22 item 28 item 30 item 32 item 34 item 35 item 1 item 2 item 27
SEA 0.897 3.233 0.822
PPI 0.870 4.473 0.580
FSI 0.792 3.485 0.779
PB 0.772 4.236 0.831
0.555 0.601 0.530 0.513 0.655 0.652 0.628 0.722 0.593 0.666 0.647 0.640 0.579 0.787 0.564 0.494 0.799 0.460 0.799 0.758 0.589 0.566 0.753 0.653 0.535 0.429
Eigenvalues 8.745 3.851 2.175 % of variance ( = 49.882% ) 17.235 16.039 10.013 Number of itens 12 8 6 KMO = 0.829 Bartlett test of sphericity = 1431.173; p = 0.000
0.583 0.684 0.711
TOTAL 0.908 3.732 0.560 h2 0.457 0.451 0.481 0.481 0.470 0.579 0.434 0.589 0.384 0.664 0.454 0.480 0.531 0.678 0.440 0.339 0.656 0.287 0.677 0.593 0.472 0.432 0.725 0.501 0.313 0.254 0.555 0.502 0.589
1.617 6.596 3
TAWC – Treatment Adherence to Weight Control; SEA - Self-Efficacy and Adherence behaviours; PPI Parents and Providers Influence; FSI - Friends and School Influence; PB - Perceived benefits
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Table 4 – Pearson correlations between TAWC and RNAWC scales Variable
RNAWC
SEA
PPI
FSI
TOTAL TAWC
PB
RNAWC
1
SEA PPI FSI PB
-0.357** -0.127 -0.279** 0.052
1 0.319** 0.502** 0.270**
1 0.377** 0.432**
1 0.226*
1
TOTAL TAWC
-0.322**
0.877**
0.651**
0.732**
0.507**
1
**p < 0.001; *p < 0.05 RNAWC – Risk of Non-Adherence to Weight Control; TAWC – Treatment Adherence to Weight Control; SEA - Self-Efficacy and Adherence behaviours; PPI - Parents and Providers Influence; FSI Friends and School Influence; PB - Perceived benefits
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Table 5 – Correlations of the TAWC and the RNAWC and ALP Variables SEA PPI FSI PB Total TAWC RNAWC
HR 0.501** 0.134 0.188 0.027 0.396** -0.185
PA 0.554** 0.026 0.149 0.022 0.385** -0.134
N 0.325** 0.208* 0.021 0.173 0.287** -0.155
PLP 0.415** 0.380** 0.192 0.105 0.428** -0.235*
IR 0.123 0.189 0.086 0.107 0.169 -0.179
SM 0.322** 0.351** 0.238* 0.071 0.372** -0.102
SH 0.228* -0.006 0.087 0.070 0.171 -0.085
Total ALP 0.553** 0.257* 0.203 0.119 0.481** -0.229*
*p < 0,05; **p < 0,01 RNAWC – Risk of Non-Adherence to Weight Control; TAWC – Treatment Adherence to Weight Control; SEA - Self-Efficacy and Adherence behaviours; PPI - Parents and Providers Influence; FSI Friends and School Influence; PB - Perceived benefits. ALP – Adolescent Lifestyle Profile, HR - Health Responsibility, PA - Physical Activity, N - Nutrition, PLP - Positive Life Perspective, IR - Interpersonal Relations, SM - Stress Management, SH - Spiritual Health
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