Background
Participating in research studies often involves interactions with healthcare professionals, potentially influencing the participant’s future help-seeking behaviour. We investigated whether participating in the Childhood Health Activity and Motor Performance School Study – Denmark (CHAMPS) (2008–2014), which involved telephone consultations and clinical assessments by healthcare professionals with participants experiencing musculoskeletal complaints, changed frequency of contacts with primary public healthcare services among participants over the subsequent five-years-period, compared to non-participating children.

Methods
Using Danish health register data from 1998 to 2020, we compared CHAMPS participant’s and two control group’s contacts with private physiotherapists, chiropractors (outside hospitals), and general practitioners: a random 10% sample of children from Denmark (National Controls), and a secondary local control group (Local Controls) during three periods: Before (1998–31.10.2008), during (01.11.2008–20.06.2014), and after (21.06.2014–31.12.2019) the CHAMPS-study. Separate multivariable Poisson regression models were used to assess the differences between groups for the outcome variables: contacts with physiotherapists, chiropractors, and general practitioners, and overall contacts.

Results
Compared to National Controls, the CHAMPS-Group had fewer physiotherapy contacts before the study with an estimated mean of 0.01 vs 0.02 per person-year, and after (0.13 vs 0.18 per person-year), corresponding to a crude incidence rate ratio (IRR) of 0.69 (95% confidence intervals (CI): 0.58–0.83) after the study period. However, they had more chiropractor contacts before (0.05 vs 0.03), and after (0.21 vs 0.09) the study, with a crude IRR of 2.29 (95% CI: 1.93–2.71) after the study period. General practice contacts were equal for the CHAMPS-group compared to national controls (5.84 vs 5.84) before the study but reduced during and after (3.21 vs 3.71), with a crude IRR of 0.86 (95% CI: 0.83–0.90) after the study. Comparable patterns of contacts changes from before to after the study were observed between the CHAMPS-group and the Local Controls except for physiotherapy which was equal between the two groups after the study.

Conclusion
Our findings suggest that research studies involving systematic engagement with participants experiencing musculoskeletal complaints can influence subsequent healthcare-seeking behaviour. Future research should address the influence of health literacy, health education, and healthcare provider recommendations on healthcare decisions during such research studies.