Value, challenges and practical considerations when designing, conducting and analysing a longitudinal qualitative study in family medicine.

Qualitative longitudinal design has a long tradition in a variety of social science disciplines and is increasingly used in applied healthcare research, including family medicine. While there are many definitions of longitudinal qualitative research (LQR), its most common characteristics are multiple data collection points and its focus on temporality, which prioritise the study of change and continuity. Thus, LQR can provide insights into the nature, causes and consequences of change (or its absence). In this paper, we discuss the key steps and considerations related to designing and conducting LQR in family medicine and community health. These include (1) deciding on the length of data collection and timing and number of interviews, (2) planning recruitment: attrition versus oversampling, (3) approaching data collection: asking the same or different questions, (4) planning and conducting the analysis and writing up findings, and (5) conducting ethical LQR. We also highlight what LQR can offer family medicine and community health, including (1) allowing exploration of views and experiences of a variety of participants over time; (2) following participants through important transitions; (3) studying implementation of new practices, processes or interventions; (4) exploring the importance of historical change and/or macro context on individuals' lives; and (5) developing a deeper understanding of phenomena under study. While a lot of attention has been paid to using LQR when studying patients' and/or carers' experiences, we highlight its value when studying a variety of actors relevant to family medicine, including healthcare professionals and policy makers.