Systematic Review and Meta-analysis Comparing Educational and Reminder Digital Interventions for Promoting HPV Vaccination Uptake

"Incorporating digital interventions into healthcare systems can effectively promote HPV vaccination uptake. Reminder interventions should be prioritized for promoting HVU."



Global human papillomavirus (HPV) vaccination rates remain low despite available World Health Organization (WHO)-approved vaccines. Digital interventions for promoting HPV vaccination uptake (HVU) offer a scalable and accessible solution to this issue. This paper presents a systematic review and meta-analysis with the primary objectives to: (i) obtain a comprehensive estimate of effect sizes for: digital client education (via website, social media, or texting); client reminder (via SMS (text messaging), email, or both); the combination of client education and reminder; provider education (via webinar or email); and provider reminder (via electronic medical records or texting); (ii) determine which of 5 five digital interventions significantly increase HVU; and (iii) compare the magnitudes of increasing HVU produced by each digital intervention type. This study also identifies factors influencing the effectiveness of these interventions. These data could enhance a customised digital intervention strategy and inform future research.



The researchers searched PubMed, PsycInfo, Web of Science, and the Cochrane Library from each database's inception to January 2023. From 1,929 references, 34 unique studies (281,280 unique participants) had sufficient data. Supplementary Table 1 provides a comprehensive summary of all studies included. The average duration of interventions was 8 months (range 1-24). Twenty-eight studies employed a traditional 2-arm randomised controlled trial (RCT) design (i.e., intervention vs. control), 5 studies employed a 3-arm RCT design, and 1 study employed a 4-arm RCT design. The primary outcome of 30 of the included studies was vaccine initiation, whereas the primary outcome of 4 studies was vaccine series completion. The majority (n = 27) of primary study outcomes utilised provider-validated measures or electronic medical records that were evaluated at baseline and post-assessment.



The review found significant increase in HVU (odds ratio [OR] 1.25; 95% confidence interval [CI], 1.16-1.34; P < 0.001; I2 = 57%) across all 41 comparisons from 34 studies, including all 5 intervention types. Studies that intervened with client reminder demonstrated the largest overall improvements in HVU, with significant effects (OR 1.41; 95% CI, 1.23-1.63; P < 0.001; I2 = 42%). Client reminder (OR 1.41; 95% CI, 1.23-1.63; P < 0.001), provider reminder (OR 1.39; 95% CI, 1.11-1.75; P = 0.005), provider education (OR 1.18; 95% CI, 1.05-1.34; P = 0.007), and client education plus reminder interventions (OR 1.29; 95% CI, 1.04-1.59; P = 0.007) increase HVU.



However, client education interventions did not (OR 1.08; 95% CI, 0.92-1.28; P = 0.35) significantly increase HVU in the studies reviewed. The characteristics of the participants (conducted in high-income countries) and education interventions (almost all are self-directed) reported in the included studies may explain this finding. Interventions that raise the basic level of parental knowledge are therefore more effective in areas where understanding and awareness is low compared to countries where it is comparatively higher and where educational barriers to HPV vaccination may be more subtle and linked to vaccine belief. The utility of educational strategies within standard practice may be further questioned when examined alongside the results of trials that provided parents with both vaccination education and reminders. This finding has implications for policy, as it suggests that reminder systems may be sufficient facilitators of HPV vaccination uptake.



Although improvements in HVU were reported by both genders, studies designed for only male or mixed-gender participants reported the greater benefit. Per the researchers, it may be that digital education and reminder interventions are as relevant for the unique challenges faced by male adolescents and parents of male adolescents (lower knowledge and awareness). Interventions designed to reach patients, parents, or providers were equally effective for increasing HVU. However, the combination of parents plus provider intervention was most effective. Reminder platforms (SMS, preference reminders, or electronic health record alert) had a greater impact on increasing HVU compared to education platforms (website, webinar, or Facebook) alone.



The magnitude of the effects, particularly for reminder interventions (OR = 1.41 for client reminder and OR = 1.39 for provider reminder), is not substantially different from the effect sizes identified in meta-analyses of face-to-face clinic-based (OR = 1.14) or school-based (OR = 1.46) interventions for promoting HVU. This comparison suggests that digital and face-to-face interventions might be similar in their effectiveness. However, some studies have suggested that digital interventions, particularly those involving client reminders and provider reminders, can be more cost-effective than traditional, face-to-face interventions. Digital reminders can also be more easily scaled up for large populations.



In conclusion: "The results suggest that client reminder and provider reminder interventions may be the most effective types of digital interventions for promoting HVU....However, there is also the need to extend and test their use in LMICs [low- and middle-income countries]. This meta-analysis further indicates that client education intervention might be less effective than the other types of digital interventions for increasing HVU, raising important questions about the generalizability of vaccine education intervention in cancer prevention and the mechanisms underlying change."