Australian National Diabetes Information Audit & Benchmarking (ANDIAB) 2011 Final Report

Methodology & Data Verification Issues in 2011

Comments on the methodology used and issues occurring in this year's study

Page last updated: December 2011

This year [as in previous ANDIAB collections], Age, {which was previously calculated as an integer [year of survey minus year of birth]}, was calculated in days [full date of survey minus full date of birth] and thence converted to years by dividing by 365.25. In the Final Report - Pooled Data (December 2011) [Appendix 7], 1998 & 1999 Age data were recalculated in line with year 2011 survey methodology for the purposes of direct comparison.

It should be noted that duration of diabetes was calculated from a ‘Year of Diagnosis’ field. As noted in section 2.7 [and as in 1999 onwards], we have grouped those diagnosed in 2010 or 2011 in a ≤ 18 months duration category. The calculations differ from 1998, where “…if this year was 1998 (the year of the survey) then the duration was 1998-1998=0 years, and if 1997 was 1998-1997=1 year. As the project was conducted mid-year [May/June 2011], duration of diabetes was calculated as: [2011 minus stated ‘Year of Diagnosis’]. The resulting integer would be 0 if diagnosed in 2011, and 1 if diagnosed in 2010 [and in fact a maximum of 18 months – 1 Jan ’10 diagnosis to 30 Jun ’11 survey]. Duration 18 months-5 years is thus a minimum 18 months {Dec ’09 diagnosis to Jun ’11 survey} to 5 years [2006-2011].

This has relevance for comparing and interpreting data using diabetes duration calculations [Tables 19 & 20 (pp 25-26) 1998] and [Tables 18 & 21 (pp 26 & 28) 2011]. Direct comparisons can be made with 1999 through to 2011 data, which used the same methodology.

In the Renal Failure and Erectile Dysfunction Fields, where there was a Yes recorded for both fields ‘developed in the past 12 months’ and ‘developed prior to the last 12 months’ [which is clearly not possible], the assumption was made that this Complication/Event had developed prior to the last 12 months [and was thus still present]. In these instances, the ‘Yes’ values in the field ‘developed in the past 12 months’ were ignored when calculating prevalence [See Table 7[a] in section 2.3].

Instances of reported Blindness and Renal Failure were verified with sites wherever the Visual Acuity data or Serum Creatinine respectively did not appear to match these diagnoses.

Document download

This publication is available as a downloadable document.

Australian National Diabetes Information Audit & Benchmarking (ANDIAB) 2011 Final Report(PDF 559 KB)