Baseline recruitment and analyses of nonresponse of the Heinz Nixdorf Recall Study: identifiability of phone numbers as the major determinant of response

Eur J Epidemiol. 2005;20(6):489-96. doi: 10.1007/s10654-005-5529-z.


The Heinz Nixdorf Recall Study is an ongoing population-based prospective cardiovascular cohort study of the Ruhr area in Germany. This paper focuses on the recruitment strategy and its response results including a comparison of participants of the baseline examination with nonparticipants. Random samples of the general population were drawn from residents' registration offices including men and women aged 45-74 years. We used a multimode contact approach including an invitational letter, a maximum of two reminder letters and phone calls for the recruitment of study subjects. Nonparticipants were asked to fill in a short questionnaire. We calculated proportions of response, contact, cooperation and recruitment efficacy to characterize the participation. Overall, 4487 eligible subjects participated in our study. Although the elderly (65-75 years) had the highest contact proportion, the cooperation proportion was the lowest among both men and women. The recruitment efficacy proportion was highest among subjects aged 55-64 years. The identifiability of the phone number of study subjects was an important determinant of response. The recruitment efficacy proportion among subjects without an identified phone number was 11.4% as compared to 65.3% among subjects with an identified phone number. The majority of subjects agreed to participate after one invitational letter only (52.6%). A second reminding letter contributed only very few participants to the study. Nonparticipants were more often current smokers than participants and less often belonged to the highest social class. Living in a regular relationship with a partner was more often reported among participants than nonparticipants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Aged
  • Correspondence as Topic
  • Death, Sudden / epidemiology
  • Epidemiologic Methods*
  • Female
  • Germany / epidemiology
  • Humans
  • Male
  • Middle Aged
  • Myocardial Infarction / epidemiology
  • Patient Selection*
  • Prospective Studies
  • Refusal to Participate / psychology
  • Refusal to Participate / statistics & numerical data*
  • Reminder Systems
  • Research Subjects / classification*
  • Research Subjects / psychology
  • Risk Assessment
  • Selection Bias
  • Sex Factors
  • Socioeconomic Factors
  • Surveys and Questionnaires
  • Telephone / classification*