Effects of numerical information on intention to participate in cervical screening among women offered HPV vaccination: a randomised study.

OBJECTIVES: To investigate the effects of different types of information about benefits and harms of cervical screening on intention to participate in screening among women in the first cohorts offered human papilloma virus (HPV) vaccination.

DESIGN: Randomised survey study.

SETTING: Denmark.

SUBJECTS: A random sample of women from the birth cohorts 1993, 1994 and 1995 drawn from the general population.

INTERVENTIONS: A web-based questionnaire and information intervention. We randomised potential respondents to one of the following four different information modules about benefits and harms of cervical screening: no information; non-numerical information; and two numerical information modules. Moreover, we provided HPV-vaccinated women in one of the arms with numerical information about benefits and harms in two steps: firstly, information without consideration of HPV vaccination and subsequently information conditional on HPV vaccination.

MAIN OUTCOME MEASURE: Self-reported intention to participate in cervical screening.

RESULTS: A significantly lower proportion intended to participate in screening in the two groups of women receiving numerical information compared to controls with absolute differences of 10.5 (95% CI: 3.3-17.6) and 7.7 (95% CI: 0.4-14.9) percentage points, respectively. Among HPV-vaccinated women, we found a significantly lower intention to participate in screening after numerical information specific to vaccinated women (OR of 0.38).

CONCLUSIONS: Women are sensitive to numerical information about the benefits and harms of cervical screening. Specifically, our results suggest that HPV-vaccinated women are sensitive to information about the expected changes in benefits and harms of cervical screening after implementation of HPV vaccination. KEY POINTS Women were less likely to participate in cervical screening when they received numerical information about benefits and harms compared to non-numerical or no information. Specifically, numerical information about the potential impact of the reduced risk of cervical cancer among HPV-vaccinated women reduced the intention to participate among vaccinated women.