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Table 1 AMSTAR Self-assessment of the process used in the present study

From: Prevalence of obesity among school-age children and adolescents in the Gulf cooperation council (GCC) states: a systematic review

Questions

Yes/NO

Answers in detail

1) Did we have a PICO/PECO

Yes

Population = children and adolescents of school-age as defined by WHO (5-19 yrs) from GCC countries; E = exposure = obesity defined using an acceptable method based on BMI-for-age; Comparator = any appropriate reference data; Outcome = prevalence of obesity rather than overweight and not overweight/obesity combined, from 2007 onwards.

2) Did we specify review methods in advance of doing the review?

Yes

Registered in PROSPERO ref. CRD42017073692

3) Did we explain/justify inclusion criteria (based on study design)?

Yes

We did not exclude any study design, but RCT not likely to be that relevant (though RCT could contain relevant data and so not excluded)

4) Did we have a comprehensive lit search strategy?

Yes

Electronic databases from 2007 to 2018: See Methods and Additional file 1.

We were resourced to search for English language publications only, though literature suggested by expert contacts in the GCC (including grey literature) in Arabic would have been considered eligible.

Searched reference lists of eligible studies? Yes, both forward and backwards citation searching was carried out.

Consulted experts? Yes-list of n = 22 expert contacts in all GCC countries was consulted in October–November 2017.The experts from the GCC were asked to check on the results of the literature search and if they were aware of any grey literature which was relevant (e.g. national surveys)

Search within 24 month of planning the search - Yes, within 2 months

5) Did review authors agree on inclusions/exclusions of full text potentially eligible studies?

Yes

Both authors agreed on inclusions/exclusions of the full text articles screened

6) Data extraction from eligible studies- did both review authors do this/check this?

Yes

Both authors agreed on data extraction from the eligible studies

7) Is a list of all excluded studies provided, including the reasons for exclusion?

Yes

Appendix of excluded studies and reasons for exclusion is provided (Additional file 3).

8) Does the data extraction and narrative (Evidence tables and text) provide enough detail about the eligible studies?

Yes

Text summarises the eligible studies, and details of eligible studies are provided in Evidence Tables (Results section)

9) Did the review authors consider risk of bias?

Yes

Results section (Evidence Tables) contains data on possible sources of bias including: sample size; representativeness of sample; bias arising from definition of obesity used.

10) Did the review authors report sources of funding of their review?

Yes

Kuwait Cultural Office and Scottish Funding Council

11. & 12 Did the review authors do a meta-analysis? (Was this appropriate?)

No

No meta-analysis possible dues to degree of differences in study design and methods: different nations; differences in factors which create differences in prevalence estimates- different definitions of obesity, different age groups, different sex distributions in studies

13) Did the review authors consider sources of bias in eligible studies?

Yes

As above- the evidence tables deal with representativeness, sample size/power calculations, and biases in the definitions of obesity used by the studies

14) Did review authors consider sources of heterogeneity in eligible studies?

Yes

Different times, different obesity definitions, different ages and sexes, different countries and places all considered

15) Did review authors consider other sources of bias (in particular publication bias)

N/A

No formal testing for publication bias was possible due to small number of eligible studies.

Main sources of bias in prevalence studies were considered: sample size and representativeness; use of BMI to estimate obesity prevalence is biased (underestimates obesity prevalence) as noted in the manuscript.

16) Did review authors consider any conflicts of interest which arose when doing their review?

Yes

No conflicts to declare