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

2.5 Missing Data

Shows amounts of missing data and how this has been compensated for in the analysis

Page last updated: December 2011

With regard to Missing Data, Table 23[b], detail Missing Data [Adult Forms], listing in increasing frequency, the missing data items.

Whilst some data items were almost 100% collected, overall Missing Data ranged from [n=24] 0.5% [Sex of Individual] to [n=2674] 57.8% [Retinal Camera], thence [n=2382] 51.5 % [Visual Acuity-Left] and [n=2381] 51.4% [Visual Acuity-Right]. There were 13.9% of the data items less than 20% missing {[0-5] 5.2% / [5-10] 3.5% / [10-15] 2.6% / [15-20] 2.6%]}, 27.8% were missing from 20-40% of records and 58.3% were missing from >40% of records [Table 24].

Overall, the ‘least’ collected/recorded data items were again [as in previous years] Visual Assessment fields.

Table 24 - Final Missing Data Overall

Missing data
0 and <=5%
>5 and <=10%
>10 and <=15%
>15 and <=20%
>20 and <=40%
>40%
5.2%
3.5%
2.6%
2.6%
27.8%
58.3%
Sites were given an opportunity to supply any missing data and to validate questionable data. Table 24[a] shows the Missing ‘Vital’ Data items obtained by requesting their provision from sites – with reasonable improvements [except Weight (only 13.4% obtained), and Height (only 15.4% obtained)]. As can be seen from the Table below, this process reduced the missing data in six of the nine elements sought, by a half - to over 85% {56.5-86.5%}.

Table 24[a] - Missing Data Obtained from Sites

Data Item
Initially Missing
Still Missing
Obtained
[%]
n =
[%]
n =
[%]
Date of Birth
139
3.0%
49
1.1%
64.7%
Sex
177
3.8%
24
0.5%
86.4%
Height
738
15.8%
624
13.5%
15.4%
Weight
201
4.3%
174
3.8%
13.4%
Initial Visit
146
3.1%
29
0.6%
80.1%
Diagnosis Year
221
4.7%
148
3.2%
33.0%
Diabetes Type
230
4.9%
60
1.3%
73.9%
Diabetes Therapy
69
1.5%
30
0.6%
56.5%
Insulin Since
1827
39.1%
246
5.3%
86.5%
Note that we have contributed to this in some ways, by application of the Validation Rules [Section 1.6] …
  • increasing missing data in some fields, by removing incorrect / impossible results; and
  • decreasing missing data in some fields by other data manipulations [eg the eGFR and eGFRresult fields - where in cases when an eGFR result was provided, but the eGFR Yes/No field was empty – we have changed this to Yes or No appropriately].

Document download

This publication is available as a downloadable document.

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