Hbs108 Health Information And Data Assessment Answers

The following questions are based on the study by Ladabaum et al. (2014).

 

1. (a) Is this study based on a cross-sectional survey design, a cohort study design, or a randomised controlled trial design?

(b) Participants were grouped into three levels of leisure-time physical activity: ideal, intermediate, and none. What type of measurement scale is this?

(c) Anthropometric measures included height, weight and waist circumference. What type of measurement scales were used to measure (i) height (in cm) and (ii) weight (in kg)?
(iii) The researchers measured waist circumference (in cm) and then stated that “Abdominal obesity was defined based on a waist circumference of >88 cm for women and >102 cm for men”. What type of measurement scale was “abdominal obesity”?

 

(d) The authors state that “While height, weight and waist circumference are measured, caloric intake and physical activity are self-reported, and we analyzed caloric intake on 24-hour recall. Caloric intake may be under-reported and physical activity overestimated.” Why might caloric intake be under-reported and physical activity over-reported? Is this a form of measurement error or measurement bias? (Briefly explain the reason for your answer).

(e) In Table 1, the proportion of the population of women aged 18 years and older who were obese (based on BMI) in 1988-1994 was reported as: 24.9 (23.1-26.8). Briefly explain what these three figures mean. Your answer should include completing the following sentence: “The 95% confidence limit (23.1-26.8) means that……”

(f) In Table 1, the proportion of the population of women aged 18 years and older who were obese (based on BMI) in 2009-2010 was reported as: 35.4 (33.6-37.3). By comparing data for 1988-1994 [in Q1(e)] with the data for 2009-2010, has there been a statistically significant change in the proportion of the population of women aged 18  years and older who were obese between these two time periods? Briefly explain your answer, using percentages who are obese and 95% confidence intervals.

(g) In the Results section the authors state that “Compared to the previous year, the odds ratio for being categorized as obese in any given year was 1.026 (95% CI, 1.019-1.033) for women [aged 18 years and older].” Based on this finding, was there a statistically
significant change in the likelihood of being obese from one year to the following year? Briefly explain how you used this data to come to your conclusion. Include in your answer, what an odds ratio of 1.026 means.

(h) Implications for practice:

(i) The authors state that “Our findings do not support the popular notion that the rise in obesity in the U.S. can be attributed primarily to sustained increases over time in the average daily caloric intake of Americans.” What evidence (from Table 2) supports this statement? Include in your answer whether or not there has been a statistically significant change in “Mean energy intake in kcal/day (95% CI)” between 1988-1994 and 2009-2010 for women in the age range 18 years and older, and how you decided this –
use either the kcal/day (95% CI) data or the APC (Annual Percentage Change) data.

(ii) Drawing on the wider body of research evidence (in the Discussion section), do the authors conclude that energy intake has had little impact on changes in levels of obesity? What evidence (from the wider body of research) do the authors cite to back up their statement? 

(iii) Based on the study findings and the additional research findings referred to in the Discussion, would you recommend that programs aimed at reducing overweight and obesity should promote increased physical activity, reduced caloric intake or both?

Task B

These questions are based on the study by Metzgar et al. (2015).

2. (a) What was the study aim? (Please write this in your own words).

(b) What reasons did the authors give for exploring both weight loss and weight loss maintenance?

(c) What data collection method was used? Why is this data collection method appropriate for addressing the study aim?

(d) In the data analysis, the researchers identified nine major themes (Table 3):

1. Weight loss journey
2. Accountability and support 
3. Planning ahead, mindfulness and awareness
4. Nutrition education
5. Portion control
6. Exercise
7. Motivation
8. Total lifestyle change
9. Eating patterns and snacking

If you were responsible for the coding analysis, identify the key theme into which you would code each of the following participants’ comments1.

To save on words, just write the key theme and the letter that identifies the comment - you do not have to write out the comments. Reading the results section of the journal article will assist in making your coding decisions; and if in doubt about a coding decision, opt for the theme that you consider to be closest to the participant’s comment.

A. “I make myself do a menu plan each week, and make sure I only buy what’s on my list.”
B. “No-one else in the family seems to care about their weight, so they think I’m a bit strange.”
C. “I went out and bought a whole new dinner set with smaller plates.”
D. “I feel as if I’ve been on a yo-yo diet for most of my life.”
E. “I kept on reminding myself that I wasn’t on a diet, I was just living my life differently.”
F. “I kept reminding myself that the occasional slip-up was okay - I didn’t beat up on myself when I didn’t do all the things I wanted to.”

 

(e) Based on the study findings, briefly describe, in your own words, four things that future weight loss and weight loss maintenance programs could do to achieve sustained weight loss for women.

Task C

The following questions are based on the study by Foster-Schubert et al. (2012).

3. (a) Identify the study design used by Foster-Schubert et al. (2012). Based on this study design, are the study findings likely to have good internal validity? Briefly explain the reasons for your answer. Based on the sample used in the study, is this study likely to have good external validity? Briefly explain the reasons for your answers.

1 These participant comments have been made up for the purposes of this assignment. 

 

(b) In the Results section, the authors stated that “With the exception of percent fat intake in the diet estimated by FFQ, there were no statistically significant differences in any demographic or lifestyle variables between the study groups at baseline.”

What element of the study design is likely to have contributed to this finding, and why is this considered a strength of the study design used?

(c) What was the independent study variable? What was the primary dependent study variable?

(d) Based on the outcome measure of ‘waist circumference’ (cm) in Table 2, which intervention group had the greatest percentage change (% Δ) in waist circumference between baseline and 12-month follow-up? Name the group and the percentage change. For this group, what was the p-value for the change from baseline to 12- month follow-up for this intervention group compared to the control group? Does this p-value indicate a statistically significant difference between this intervention group compared to the control group? (Briefly explain the reason for your answer, in terms of how p-values are interpreted).

(e) Based on the overall pattern of changes in various measures of body weight and adiposity, which intervention group resulted in the greatest changes? (There is no need to include data in your answer to this question).

Task D

4. Suppose you are a Policy Officer in the Population Health Division of the Commonwealth Department of Health. You are required to write a policy brief for the Health Minister that summarises the key findings from the three studies in this assignment related to the three questions above, and concludes with a recommendation for future action. You must include in-text citations for the study findings you refer to, but there is no need to include the actual data – just provide a very brief summary of what the key findings were. 

Your recommendation might be for a more comprehensive review of the evidence, further research, or the introduction of programs or policies to improve healthy eating and/or physical activity. If, so, include a specific example (eg based on the evidence youhave reviewed, what should be included in a more comprehensive review, what further research is required, or what programs or policies should be implemented)?

Task A

Q1(a) Cross-sectional survey design

(b) Ordinal scale

(c) i) Ratio scale

iii) Interval scale

(d) Caloric intake may be under-reported since most individuals tend to underestimate the sizes of their food portions, they overlook the consumption of foods which are perceived as unhealthy. According to Basiotis, et al., (2000), people also have the tendency of exaggerating foods they perceive to be good for their health. Most individuals especially obese individuals tend to overestimate the energy they expend in physical activities. Persons who present with the inability to shed weight regardless of a history of caloric restriction are among a group of individuals who are prone to misreport their caloric intake and level of physical activity (Lichtman, et al., 1992).

This is a measurement bias because they are resulting from the poor measurement of the outcome being measured.

(e) The figure 24.9 means that obese women made up 24.9% of the total population. This is within the range of 23.1% to 26.8%. The 95% confidence limit (23.1-26.8) means that there is a 95% chance that the interval 23.1-26.8 contains the true population mean.

(f) In the period between 1988 and 1994, 24.9% of women were obese compared to 35.4% in the period between 2009 and 2010. With a 95% confidence interval, in 1988-1995, there is a 95% chance that between 23.1% and 26.8% of the total population were obese females, whereas with the same interval, between 33.6% and 37.3% of the total population were obese females in 2009-2010.

(g) Yes, there was a statistically significant change in the likelihood of having obesity over the years. An odds ratio of 1.026 means that an individual had an increased chance (by 1.026) of being obese in the following year. The 95% confidence interval for 1.026 ranged from 1.019 to 1.033.

(h)

• This observation can be supported by a statistically insignificant change in the amount of calories taken between the two periods. In 1988-1994, women aged eighteen years and older only consumed a mean of 1761 Kcal whereas, in 2009-2010, they consumed a mean of 1781 Kcal. The difference between the mean is insignificant. The kcal/day (95% CI) data was used instead of the APC because the latter does not take into account the changing rates.
• The authors cite the lack of evidence in the increase in the average daily caloric intake over the previous two decades. The support their observation using a 2011 study by Austin and colleagues who made a conclusion of a decrease in caloric intake in the recent years (Austin, et al., 2011).
• Yes, I would recommend programs to focus on just increasing physical activity. This is supported by both the conclusion of the authors who stated that their results laid more emphasis on physical activity as proposed in the IOM report on obesity. The authors associate BMI and waist circumference trends with physical activity and not daily caloric intake (Ladabaum, et al., 2014).

Task B

2. (a) The aim of the study was to find out what facilitated or hindered weight loss and weight loss maintenance among women who participated in a comparative trial that ran for 18 weeks whose aim was to promote weight loss using and energy-restricted diet.

(b) i. After successive weight loss, maintenance of the new weight status often remains a challenge.

(c) The authors used questionnaires as the data collection tool. Questionnaires were ideal for the study aim as they facilitated probing and collection of data on bath facilitators, barriers and limitations to weight loss maintenance, and also facilitated investigation of weight regulation, eating patterns and perceptions of snacking among the participants. Questionnaires were the most ideal as they facilitated the above and also addresses constructs of theories including health belief model, social cognitive theory and theory of planned behaviour (Metzgar, et al., 2015).

(d) A - Planning ahead, mindfulness and awareness

B – Accountability and support

C - Portion control

D – Nutrition education

E – Motivation

F - Weight loss journeyQ2(e)

1. Tailor programmes to an individual’s needs, biology, physiology, and stage in life.
2. Programmes to reinforce the women’s planning skills
3. Portion control strategies and education are fundamental components of weight loss.
4. The inclusion of the elements of social support networks into weight loss and weight loss maintenance strategies.

Task C

3. (a) Is a randomized trial design. The findings have good internal validity because the study design avoids confounds. The authors have also demonstrated the internal validity using the statement ‘support the internal validity of our data’  (Foster-Schubert, et al., 2011).

In addition, the design and its conduct have striven to eliminate all possibilities of bias.

The study randomised a total of 439 women out of the 126, 802 eligible women. This represented only 0.3% of the total population. This may affect the external validity of the study owing to the fact that such a small sample is bound to have extreme scores which are mot balanced by more moderate scores. Therefore, such a small sample magnifies the probability of sampling error, and as a result, the conclusions arrived at ought to be tentatively generalised to the entire target population (Wright & Lake, 2016). Drawing conclusions from a small sample may not reflect the total target population.

(b) The element of randomisation could have contributed to the finding. Randomisation is a strength because it helps avoid selection bias.

(c) Independent variable is weight and body composition

Dependent variables are diet and exercise.

(d) The group that was on both diet and exercise with a -7.5% change.

The p-value for the change in this group when compared to the control group is <.0001. It is thus statistically significant. The p-value indicates strong evidence that diet and exercise can help in the regulation of body weight and composition. A p-value of =0.05 will have indicated no statistical significance in the interventions applied or not applied in either group whereas a p-value of >5 indicates no positive intervention in the diet and exercise group.

3(e) The diet and exercise group evidenced the greatest changes.

Task D - Conclusion

4. On healthy eating and physical activity’s contribution to weight control, Ladabaum et al. (2014) claim that there is no evidence supporting increased caloric intake and obesity among adults. As such, they recommend that obesity can be reduced through increased physical activity only. A randomised trial by Foster-Schubert et al. (2012) offers a better insight into the same by demonstrating a strong contributor of diet and exercise combined to weight management.

Pertaining to the barriers and facilitators of attaining healthy weight and maintenance, Metzgar et al. (2015) identifies the following factors.  Lifestyle change whereby one is expected to incorporate strategies for sustainable dietary and modification of physical activity, second is nutrition and education in which there is the need for dietitians to disseminate accurate nutrition information, and lastly is exercise, which ought to be incorporated into weight loss and weight loss maintenance interventions.

Recommendation: There is the need for more comprehensive review of the contradicting claims by the two groups of authors (Ladabaum et al. (2014) vs Foster-Schubert et al (2012)) in order to establish the ideal solution.

References

Austin, G., Ogden, L. & Hill, J., 2011. Trends in carbohydrate, fat, and protein intakes and association with energy intake in normal-weight, overweight, and obese individuals: 1971-2006.. Am J Clin Nutr, 93(4), pp. 836-43.

Basiotis, P., Lino, M. & Dinkins, J., 2000. Consumption of Food Group Servings: People’s Perceptions vs. Reality. Washington, D.C: USDA Center for Nutrition Policy and Promotion.

Foster-Schubert, K. et al., 2011. Effect of diet and exercise, alone or combined, on weight and body composition in overweight-to-obese post-menopausal. Obesity (Silver Spring), 20(8), pp. 1628-1638.

Ladabaum, U., Mannalithara, A., Myer, P. & Singh, G., 2014. Obesity, abdominal obesity, physical activity, and caloric intake in US adults: 1988 to 2010. American Journal of Medicine, 127(8), pp. 717-727.

Lichtman, S. W. et al., 1992. Discrepancy between Self-Reported and Actual Caloric Intake and Exercise in Obese Subjects. The New England Journal of Medicine, Volume 327, pp. 1893-1898.

Metzgar, C. J., Preston, A. G., Miller, D. L. & Nickols-Richardson, S. M., 2015. Facilitators and barriers to weight loss and weight loss maintenance: a qualitative exploration. Journnal of Human Nutrition and Dietetics, 28(6), pp. 593-603.

Motulsky, H., 2010. Intuitive Biostatistics: A Nonmathematical Guide to Statistical Thinking. 1st ed. Oxford: Oxford University Press.

Wright, L. L. & Lake, D. A., 2016. Basics of Research for the Health Professions. [Online] Available at: https://www.pt.armstrong.edu/wright/hlpr/toc.htm [Accessed 8 September 2017].