Definition

The indicator depressive symptoms is assessed by the German version of the Patient Health Questionnaire-8 (PHQ-8). It is defined as the proportion of people with known diabetes compared to those without diabetes who have had current depressive symptoms in the previous two weeks (PHQ-8 sum score ≥ 10).

Operationalisation

The PHQ-8 questionnaire assesses the symptoms of major depression (not including suicidal thoughts) in accordance with DSM-IV with regard to the frequency of their occurrence over the past two weeks. Participants with a total PHQ-8 sum score of ≥ 10 are considered to show depressive symptoms.

• Symptoms: The initial question ‘Over the last 2 weeks, how often have you been bothered by…?’ was used to measure little interest or pleasure, depressed mood, sleep disturbances, tiredness or little energy, poor appetite or overeating, feelings of worthlessness or guilt, trouble concentrating, psychomotor retardation or agitation.
  The following responses were provided:

  • 0 = Not at all
  • 1 = Several days
  • 2 = More than half of the days
  • 3 = Nearly every day

• PHQ-8 total score: sum of the scores gained from the responses to questions about the eight symptoms.

• Known diabetes in the last 12 months: The introductory question ‘Have you had any of the following diseases or complaints in the last 12 months?’ was used to collect data on individual diseases/complaints, including ‘diabetes (not including gestational diabetes)’. The following responses were provided:

  • Yes
  • No
• Indicators depicted separately for people with or without known diabetes in the past 12 months.

Reference population

German-speaking resident population in Germany with and without known diabetes, aged 18 years and over

Data source

Nationwide RKI interview surveys GEDA 2014/2015-EHIS based on a sample from registration offices and self-completion questionnaire (online/written) as well as GEDA 2019/2020-EHIS based on telephone sample (landline and mobile phone) and a telephone-based questionnaire.

Number of cases

• GEDA 2014/15-EHIS: n = 24,016

  • n = 1,712 people with known diabetes in the past 12 months
  • n = 21,633 people without known diabetes in the past 12 months

• GEDA 2019/2020-EHIS: n = 22,708 (aged 18 years and over), among them 

  • 2,059 people with known diabetes in the past 12 months
  • 20,615 people without known diabetes in the past 12 months

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 region (north-east, north-west, middle-east, middle-west and south). 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, a weighting factor was used when calculating the indicator. This adjusts the survey to the structure of the resident population in Germany of the reference population in terms of sex, age, federal state and district type as of 31 December 2014 (GEDA 2014/15-EHIS) and of 31 December 2019 (GEDA 2019/20-EHIS) as well as of the distribution of education levels in the microcensus 2013 (GEDA 2014/15-EHIS) and 2017 (GEDA 2019/20-EHIS).
• Age standardisation: Direct age standardization to the adult resident population in Germany as of 31 December 2019.

Data quality

RKI interview surveys provide representative results for the resident population of Germany aged 18 years and over. As is the case in all population-based studies, underrepresentation of the seriously ill and those living in institutions must be assumed. Furthermore, all information is self-reported and not based on personal interviews conducted by study physicians or standardized measurements or examinations.