Definition

The indicator group Cardiovascular diseases refers to selected cardiovascular comorbidities in persons with type 2 diabetes: namely coronary heart disease (CHD), heart failure and stroke.

Operationalisation

In order to measure cardiovascular disease, information provided by the respondents was gathered via a computer-assisted medical interview that posed the following questions:

1. ‘Have you ever been diagnosed by a doctor with an impaired blood supply tothe heart, narrowing of the coronary arteries, or angina pectoris?’
2. ‘Have you ever been diagnosed by a doctor as having had a myocardial infarction?’
3. ‘Have you ever been diagnosed by a doctor as having had heart failure or cardiac insufficiency?’
4. ‘Have you ever been diagnosed by a doctor as having had a stroke?’

• Answer options in each case:

  • Yes
  • No
  • I do not know

• CHD was identified if one of the first two questions was answered affirmatively; if both questions were answered in the negative, the participant was assumed not to have CHD.
• Cardiovascular disease was identified if at least one of the four questions was answered affirmatively; if all four questions were answered in the negative, the participant was assumed not to have cardiovascular disease.

Indicators depicted separately for people with known type 2 diabetes and without known diabetes.

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 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 known diabetes, 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

  • n = 333 people with known type 2 diabetes
  • n = 3,270 people without known diabetes

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

  • n = 501 people with known type 2 diabetes
  • n = 3,954 people without known diabetes

Data for the Cardiovascular diseases indicator were collected completely among people aged 45-79 years.

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.
• Absolute values: Number of persons with cardiovascular diseases in the population aged 45-79 years with type 2 diabetes (reference population), determined by extrapolating the number in the sample to the number in the reference population.
• 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.