Critical review of an article

1. Introduction:
Critical appraisal is ‘The process of carefully and systematically examining research to judge its
trustworthiness, and its value and relevance in a particular context’. It aims to help people develop
the necessary skills to make sense of scientific evidence, and has produced appraisal checklists
covering validity, results and relevance. All of us would like to enjoy the best possible health we
can. To achieve this we need reliable information about what might harm or help us when we make
healthcare decisions. Research involves gathering data, then collating and analysing it to produce
meaningful information. However, not all research is good quality and many studies are biased
and their results untrue. This can lead us to draw false conclusions. So, how can we tell whether a
piece of research has been done properly and that the information it reports is reliable and
trustworthy? How can we decide what to believe when research on the same topic comes to
contradictory conclusions? This is where critical appraisal helps[1] . We know that, Childhood
obesity is one of the major public health problems globally[2] . Childhood obesity is a risk factor
for several chronic diseases such as hypertension, type 2 diabetes, respiratory disease, and hepatic
abnormalities and coronary heart diseases during adulthood[3,4] . Additionally, overweight and
obesity affect selfesteem of children and impair social development[5,6] . Obesity in children and
adolescents is rising alarmingly and approaching epidemic proportion in many economically
developed countries, particularly in USA, Canada, Australia and several European countries[7] .
Likewise in developing countries this issue is emerging as a public health crisis. According to a
recent report, out of an estimated 43 million obese children worldwide in 2010, approximately
81% were from developing countries, half of which (18 million) were reported to be living in Asia
despite of huge burden of under-nutrition. By 2020, it is estimated that the global prevalence of
childhood obesity will reach approximately 60 million[8] . Factors contributing to the rising levels
of childhood obesity in developing countries include socio-economic development, changes in
lifestyle characterized by physical inactivity and unhealthy diet, living patterns, as well as rapid
epidemiological and demographic transition[9,10] . In Bangladesh, the context of obesity and
overweight has been underexplored, more so amongst younger age groups. Understanding the
current situation and trends will provide useful insights into its risk factors and will assist health
professionals and policy-makers in decision making and developing future research agenda[11] .

2. Review of a clinical paper:
 Title: Risk factors associated with overweight and obesity among urban school children
and adolescents in Bangladesh.
Comments: One of the most important issue and seemed to be significant.
 Objectives: To identify the risk factors associated with overweight and obesity among
school children and adolescents in Dhaka, Bangladesh.
Comments: The objective of the study were answerable and clearly and concisely stated
and reflect the title.
 Study design: Case control study.
Comments: Cohort studies more clearly indicate the temporal sequence between exposure
and outcome but case-control study design is less time consuming and less expensive. The
selection of study design seems appropriate.
 Study site: This study was conducted in seven schools located in Dhanmondi,
Mohammadpur and Siddheswari area in Dhaka, Bangladesh.
Comments: Dhanmondi, Mohammadpur and Siddheswari are seemed to be appropriate
study sites because highest numbers of schools are situated here.
 Study population: The study participants were students of age 10-15 years corresponding
to class 5 to class 10 in the selected school.
Comments: The title and objectives of the study reflects that the main characteristics of
the sample. Samples would have to be childrens and adolescents. The age ranges of study
cover both children and adolescent groups.
 Study sample: Cases are overweight children and controls are healthy or normal weight
childrens of age 10-15 years corresponding to class 5 to class 10 in the selected school.
Comments: Study samples were selected by teacher’s visual assessment. It was limited to
the researcher’s capabilities and resources.

3.  Sampling technique: Samples were selected purposely.
Comments: Simple random sampling method offers an equal probability of being chosen
but sample populations were not with the same characteristics. So, purposive sampling
method seems appropriate.
 Sample size: 198 students ; 99 cases and 99 controls. The participants were selected from
class 5 to class 10.
Comments: Sample size is not too large or too short. It is easily attainable number to
conduct the study.
 Exclusion criteria:
1. Any participant falling into the underweight category according to growth chart
was excluded from the study.
2. Age less than 10 years and greater than 15 years.
 Data collection: Structured questionnaires and telephone interview method.
 Data Analysis:
1. Descriptive statistics was used to determine the distribution of demographic
information.
2. t-test or Wilcoxon-rank sum test was used to compare mean or median of
variables between cases and controls.
3. Z-test to compare proportions between cases and controls.
4. To determine association between outcome (overweight/obese) and
exposure variables, simple logistic model (unadjusted model) was used.
5. Any exposure variable in simple logistic model with a beta coefficient at
significant level 0.3 was selected for the multiple logistic regression model
(adjusted model).
6. p-value of <0.05 as significant level in multiple logistic regression model.

4.  Key variables:
Overweightandobesity
Having at least one
overweightparent
Total physical
activities per day
Physical activities at
home per day
Physical activities at
school per day
Sedentary activities
Sex
Maternal education
Sleeping time
Monthly household
expenditure

5.  Findings:
 Multiple logistic regression analysis revealed that having at least one overweight parent
(OR = 2.8, p = 0.001) and engaging in sedentary activities for >4 hours a day (OR =
2.0, p = 0.02) were independent risk factors for childhood overweight and/or obesity
while exercising ≥ 30 minutes a day at home was a protective factor (OR = 0.4, p =
0.02).
 There were no significant associations between childhood overweight and sex,
maternal education or physical activity at school.
Comments: The findings were well organized, sectioned, and reported objectively. The
tables were well organized.
 Conclusions: Author’s concluded that, “Having overweight parents along with limited
exercise and high levels of sedentary activities lead to obesity among school children in
urban cities in Bangladesh. Public health programs are needed to increase awareness on
risk factors for overweight and obesity among children and adolescents in order to reduce
the future burden of obesity-associated chronic diseases.”
Comments: The conclusions were based on the findings and logically stated.
 Overall limitations:
1. Short duration, 2 months.
2. Risk factors that the author’s identified may not be representative of every urban city
in Bangladesh.
3. Cases were selected by purposely and by teacher’s visual assessment.
4. More chance of biased, not reliable and inaccuarate.
5. They could not inform if the activities done at home by the healthy children (controls)
were likely to be of a higher intensity compare to overweight or obese children (cases).
6. They did not collect data on individual games they played at home or in school rather
they asked them to report their engagement in the activities that was included in the
list (e.g. football, cricket, and other outdoor games, running and cycling).

6. References:
1. Burls A. What is critical appraisal? 2nd ed. Oxford, UK: University of Oxford; 2009. (What is…?
series).Available
from:http://www.medicine.ox.ac.uk/bandolier/painres/download/whatis/what_is_critical_appraisa
l.pdf.
2. Urbano MRD,Vitalle MSS, Juliano Y, Amancio OMS. Iron, copper and zinc in adolescent during
pubertal growth spurt. J Pediatr 2002; 78: 327-34.
3. Aronne L. Classification of Obesity and Assessment of Obesity-Related Health Risks. Obesity
Research. 2002; 10(S12):105S-115S.
4. Dietz WH: Overweight in childhood and adolescence. N Engl J Med 2004, 350:855–857.
5. Friedlander SL, Larkin EK,Rosen CL,Palermo TM,Redline S: Decreasedquality of life associated
with obesity in school-aged children. Arch Pediatr Adolesc Med 2003, 157:1206–1211.
6. Hesketh K, Wake M, Waters E: Body mass index and parent-reported self-esteem in elementary
school children: evidence for a causalrelationship. Int J Obes Relat Metab Disord 2004, 28:1233–
1237.
7. Wang Y, Lobstein T: Worldwide trends in childhood overweight and obesity. Pediatr Obes 2006,
1(1):11–25. doi:10.1080/17477160600586747.
8. de Onis M, Blossner M, Borghi E: Global prevalence and trends of overweight and obesity among
preschool children. Am J Clin Nutr 2010, 92(5):1257–1264. doi:10.3945/ajcn.2010.29786.
9. Popkin BM: An overview on the nutrition transition and its health implications: The Bellagio
meeting. Public Health Nutr 2002, 5(1A):93–103. doi:10.1079/PHN2001280.
10. Davison KK,Birch LL: Childhood overweight: a contextual model and recommendations for future
research. Obes Rev 2001, 2(3):159–171. doi:10.1046/j.1467-789x.2001.00036.x.
11. Arksey H, O’Malley L: Scoping studies: towards a methodological framework. Int J Soc Res
Methodol 2005, 8(1):19–32. doi:10.1080/1364557032000119616.