Selection in general practice research: analysis of representativeness in a cohort of pregnant Danish women

Ruth K. Ertmann* (Corresponding Author), Dagny R Nicolaisdottir, Jakob Kragstrup, Volkert Siersma , Gritt Overbeck, Philip Wilson, Melissa C Lutterodt

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Objective: The aim of the present study was to examine selection in a general practice-based pregnancy cohort.
Design: Survey linked to administrative register data.
Setting and Subjects: In spring 2015, GPs were recruited in two regions of Denmark and asked to invite all pregnant women in their practice who had their first prenatal care visit before 15 August 2016 to participate in the survey.
Outcome measures: Characteristics of GPs and the pregnant women were compared at each step in the recruitment process – invitation of the GP, GP agreement to participate, actual GP participation, participation of the woman – with an uncertainty coefficient to quantify the step where the largest selection occurs.
Results: Significant differences were found between participating and non-participating practices with regards to practice characteristics such as number of patients registered with the practice, age and sex of doctors, and type of practice. Despite these differences, the characteristics of the eligible patients differed little between participating and nonparticipating practices. In participating practices, significant differences were however, observed between recruited and non-recruited patients.
Conclusion: The skewed selection of patients was mainly caused by a high number of nonparticipants within practices that actively took part in the study. We recommend a focus on the sampling within participating practices as the most important factor in representative
sampling of patient populations in general practice.
Original languageEnglish
JournalScandinavian Journal of Primary Health Care
Publication statusAccepted/In press - 12 Sep 2020

Keywords

  • general practices
  • selection
  • representativeness
  • participating patients
  • pregnancy

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    Ertmann, R. K., Nicolaisdottir, D. R., Kragstrup, J., Siersma , V., Overbeck, G., Wilson, P., & Lutterodt, M. C. (Accepted/In press). Selection in general practice research: analysis of representativeness in a cohort of pregnant Danish women. Scandinavian Journal of Primary Health Care.