General Practitioner Attendance in Proximity to HPV Vaccination: A Nationwide, Register-Based, Matched Case-Control Study

Tina Hovgaard Lützen; Charlotte Ulrikka Rask; Oleguer Plana-Ripoll; Bodil Hammer Bech; Lene Wulff Krogsgaard; Nanna Rolving; Dorte Rytter

doi:10.2147/CLEP.S253429

General Practitioner Attendance in Proximity to HPV Vaccination: A Nationwide, Register-Based, Matched Case-Control Study

Clin Epidemiol. 2020 Sep 8:12:929-939. doi: 10.2147/CLEP.S253429. eCollection 2020.

Authors

Tina Hovgaard Lützen¹, Charlotte Ulrikka Rask^{2

3}, Oleguer Plana-Ripoll⁴, Bodil Hammer Bech¹, Lene Wulff Krogsgaard¹, Nanna Rolving^{5

6}, Dorte Rytter¹

Affiliations

¹ Research Unit for Epidemiology, Department of Public Health, Aarhus University, Aarhus C 8000, Denmark.
² Research Unit, Department of Child and Adolescent Psychiatry, Aarhus University Hospital, Aarhus N 8200, Denmark.
³ Department of Clinical Medicine, Aarhus University, Aarhus N 8200, Denmark.
⁴ National Centre for Register-Based Research, Department of Economics and Business Economics, Aarhus University, Aarhus V 8210, Denmark.
⁵ University Clinic of Innovative Patient Pathways, Diagnostic Centre, Silkeborg Regional Hospital, Silkeborg 8600, Denmark.
⁶ DEFACTUM, Corporate Quality, Central Denmark Region, Aarhus N 8200, Denmark.

Abstract

Aim: This study aimed to describe and compare general practitioner (GP) attendance patterns in the years surrounding HPV-vaccination among cases suspected to experience adverse events and their matched controls in order to determine if a potential larger change in GP attendance among cases was observed in temporal relation to vaccination.

Methods: Register-based, matched case-control study. Cases were defined as women referred to specialized hospital settings (HPV-centers) for suspected adverse event between June 1st 2015 and December 31st 2015 (n=1458). Information on referral was obtained from the HPV-centers directly. Each case was matched with five controls on age at vaccination, region, time of first vaccine registration and total number of doses, resulting in a total study population of 8670 girls and women. Negative binomial regression analyses were used (i) to estimate mean yearly GP contacts among cases and controls, and (ii) to further investigate the relative difference in change in GP attendance following vaccination between cases and controls.

Results: Overall, cases displayed higher GP attendance than controls from five years before vaccination up until five years after. Compared to controls, cases increased their GP attendance more in the years following HPV vaccination, corresponding to a 40% increase in the incidence rate ratios (IRR) from before to after vaccination (ratio-IRR = 1.40 [1.36; 1.44]). The change occurred in close proximity to vaccination, and the pattern was the same independently of the year of vaccination. However, for the later vaccination years cases displayed an additional increase in their GP attendance around time of extensive media attention.

Conclusion: Girls and women being referred for suspected adverse events after HPV-vaccination changed their GP attendance pattern in close proximity to their first HPV-vaccination and not solely in temporal linkage to the onset of public debate.

Keywords: HPV vaccination; adverse effects; case–control; general practice attendance.

Grants and funding

This work was supported by grants from the Lundbeck Foundation (grants number: R218-2016-1424 and R221-2016-1476). The funding sources had no role in the design and conduct of the study; the collection, analysis and interpretation of data; or the preparation, review or approval of the manuscript.