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White rice consumption and risk of type 2 diabetes: meta-analysis and systematic review

BMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e1454 (Published 15 March 2012) Cite this as: BMJ 2012;344:e1454

Re: White rice consumption and risk of type 2 diabetes: meta-analysis and systematic review

Rapid Response[i] :

The author’s main objective was to assess the association between white rice consumption and risk of type 2 diabetes. The primary outcome analysed in the review was “risk of type 2 diabetes”. However, the authors did not clearly report the methods used to measure the primary outcome which was stated as self reported. In table 2 there is some indication of type 2 diabetes confirmation by medical practitioners. On closer inspection this confirmation by medical testing was only carried out on those subjects who reported positive for diabetes by self report and not all subjects.  

 

A comprehensive search strategy was not reported in the review, hence, it was not possible to assess if all relevant studies were included. The decision to include only published prospective cohort studies in English may have introduced bias into this systematic review via the exclusion of unpublished studies and those in other languages. The Data Quality Assessment appeared to have been devised by the authors of the review and was not a standard tool for critical appraisal.[ii] [iii]

 

The authors found that three studies showed a statistically significant association between high intake of white rice and risk of type 2 diabetes.  The authors reported the results of included studies to be significantly heterogeneous (Overall: I2  72.2%, P= 0.001). However, they did not discuss the possible reasons of heterogeneity in their analysis and proceeded to pool the findings for analysis.

 

In part the heterogeneity of the results might be explained by the range of prevalence reported in Table 1.  Five of the seven studies reported prevalence up to 2.5%. Studies from Japan and Australia reported prevalence of 1.4% and 1.15% respectively. Given that global prevalence for diabetes worldwide was estimated by the WHO as 2.8% in the year 2000 and is predicted to rise to 4.4% by 2030,[iv]  the reported low prevalence in these studies could be due to the fact that diabetes was self reported in these studies and thus did not reflect the actual prevalence of the disease. What is clear from this review is that future studies with robust methodologies will be essential to investigate any association between white rice consumption and risk for type 2 diabetes.

 

 

Table 1 (Taken from table 1 in the systematic review)

Study

Country

Cases

Total

Prevalence

Hodge et al 2004 (41.1% male)

Australia

365

31641

1.153567

Villegas et al, 2007 (Female only)

China

1608

64191

2.505024

Sun et al, 2010 (Male only)

United States

2648

39765

6.659122

Sun et al, 2010 (Female only)

United States

5500

69120

7.957176

Sun et al, 2010 (Female only)

United States

2359

88343

2.670274

Nanri et al, 2010 (Male only)

Japan

625

25666

2.435128

Nanri et al, 2010 (Female only)

Japan

478

33622

1.421688

 

 

 

It was a group work done in the workshop “How to Practice Evidence-Based Health Care”, Oxford on 28th March 2012. By: Syed Ali Raza Naqvi*, Sarah Westwater-Wood*, Ghada  Alarfaj**, Helen Atherton**, Charles Cachoeira**, Joseph Marcel El Khoury**, Mary Ann McLane**, Laurence Pollissard-Badroy**, Liubov Yashina**, Carl Heneghan***.

 

 

* Co-facilitators

** Participants

*** Facilitator

 

 

References




[i] In the critical appraisal workshop (How to Practice Evidence-Based Health Care), at Oxford, we critically appraised the systematic review by Hu and colleagues as part of a group exercise.  (Centre for Evidence Based Medicine, How to Practice EBHC (Evidence-Based Health Care) [online] http://www.cebm.net/index.aspx?o=6562)

 

[ii] Public Health Resources U. Critical Appraisal Skills Programme (CASP), 2007.

 

[iii] Higgins JPT, Green S. Cochrane Handbook for Systematic Reviews of Interventions, 2011

 

[iv] Wild et al ., 2004, Global prevalence of diabetes. DIABETES CARE,(27) 5 , 1047-1053 [online] http://www.who.int/diabetes/facts/en/diabcare0504.pdf

Competing interests: No competing interests

04 April 2012
Syed Ali Raza Naqvi
Research Officer
Sarah Westwater-Wood, Ghada Alarfaj, Helen Atherton, Charles Cachoeira, Joseph Marcel El Khoury, Mary Ann McLane, Laurence Pollissard-Badroy, Liubov Yashina, Carl Heneghan
Evidence Adoption Centre
Douglas House, 18 Trumpington Road, Cambridge, CB2 8AH.