Definition

The indicator Cardiovascular event risk is defined as the mean of the absolute 10-year risk (in %) for the development of CHD among people with known type 2 diabetes and without CHD, calculated using the risk engine score from the UKPDS.

Operationalisation

The UKPDS risk engine score includes diabetes-specific information [age at diabetes diagnosis, duration of diabetes, HbA1c (long-term blood glucose level)] and generally established risk factors for cardiovascular disease [age, sex, SBP), total cholesterol, HDL cholesterol, smoking status, ethnicity]. The score is calculated using the following steps:

Data on age, sex, smoking status and age at diabetes diagnosis were collected from information provided by the respondents during a medical examination. The figures for HbA1c, total and HDL cholesterol and SBP are based on the results from blood tests/a medical examination undertaken in accordance with a standardised study protocol. Diabetes duration is defined as the difference between a person’s age when the examination took place and their age at diagnosis.

In order to focus on known type 2 diabetes, those who may have type 1 diabetes were identified and excluded from among participants with known diabetes by using an algorithm (age at diabetes diagnosis <30 years AND insulin treatment immediately after diagnosis AND current insulin treatment).

Reference population

Resident population in Germany with known type 2 diabetes and without CHD, aged 45 to 79 years 

Data source

Nationwide RKI interview and examination surveys 1997-1999 (GNHIES98) and 2008-2011 (DEGS1) based on a population registry sample and self-completed questionnaire, medical interview, automated medicine registration and examination.

Number of cases

• GNHIES98: n = 7,124
• DEGS1: n = 7,115 (of which n = 2,923 had also participated in GNHIES98)

For the Risk of a cardiovascular event indicator, data from the 45-to-79 age group with known type 2 diabetes and without CHD are evaluated:

• GNHIES98: n = 204
• DEGS1: n = 346

Calculation

• Description: For the indicator, the figures for total, women and men are provided and are stratified by age group, residential area and education as far as the number of cases available for the figure is ≥ 5 and the statistical uncertainty in the estimate of the indicator is not considered too large (a coefficient variation ≤ 33.5%).
• Stratification: The geographical classification of the residence of the participating person was carried out by east and west (east = former East Germany, including all of Berlin; west = former West Germany, not including West Berlin). Educational status was determined using the CASMIN index, which takes information on both school and vocational training into account and allows a categorisation into a low, medium and high education group.
• Weighting: In order to correct for deviations from the underlying reference population due to different participation rates or sampling probabilities, weighting factors were used when calculating the indicator. These adjust the surveys to the population structure of the reference population with regard to sex, age, federal state, German citizenship (yes / no), community type and education as of 31 December 1997 (GNHIES98) and 31 December 2010 (DEGS1). In DEGS1, the different participation probability of re-participants from GNHIES98 was also taken into account in the weighting.
• Age standardization: Age standardization and trend weighting was carried out by calculating the weighting factor in GNHIES98 using the age, sex and federal state structure of the reference population as of 31 December 2010.

Data quality

RKI interview and examination surveys provide representative results for the 18- to 79-year-old resident population of Germany. The population aged 80 years and over will only be included in future survey waves. As is the case in all population-based studies, underrepresentation of the seriously ill and those living in institutions must be assumed. Possible memory distortion (recall bias) due to self-reporting on the age at diabetes diagnosis.