Cost-effectiveness of pertussis booster vaccination for preschool children in Japan

Psychometric Properties of Child Health Utility 9D (CHU9D) Proxy Version Administered to Parents and Caregivers of Children Aged 2-4 Years Compared with Pediatric Quality of Life Inventory™ (PedsQL)

OBJECTIVE

This study examines the psychometric properties of the Child Health Utility 9D (CHU9D) proxy version administered to parents/caregivers of 2-4-year-old Australian children compared with Pediatric Quality of Life Inventory™ version 4.0 (PedsQL).

METHODS

Data collected in 2021/2022 from parents/caregivers of 2-4-year-olds from the Australian pediatric multi-instrument comparison study were used. Feasibility, ceiling/floor effects, test-retest reliability, convergent validity, known-group validity, and responsiveness were assessed.

RESULTS

A total of 842 caregivers completed the survey at baseline, with 513 completing the follow-up survey. The CHU9D did not demonstrate ceiling effects in the sample with special health care needs, with only 6% of respondents reporting best levels for all nine dimensions. CHU9D correlated with PedsQL moderately-to-strongly between comparable items (correlation coefficients 0.34-0.70). CHU9D was able to differentiate between groups with known health differences with moderate-to-large effect sizes (Cohen's d 0.58-2.03). Moderate test-retest reliability was found for CHU9D in those reporting no health change at a 2-day follow-up (ICC 0.52). A standard response mean (SRM) of 0.25-0.44 was found for children with changes in general health and a SRM of 0.72-0.82 for children who reported worsened health when developing new illnesses, indicating small-to-large responsiveness according to different definitions of health changes. Compared with PedsQL, CHU9D had similar known-group validity and responsiveness and slightly poorer test-retest reliability.

CONCLUSION

The CHU9D was found to be valid and reliable to measure health-related quality-of-life in children aged 2-4 years, although with relatively low test-retest reliability in some dimensions. Further development and validation work is warranted.

Cost-effectiveness analysis of pertussis booster vaccination for adolescents in Japan

INTRODUCTION

In Japan, the introduction of a fifth diphtheria-tetanus-acellular pertussis (DTaP) vaccination has been considered, and adolescents aged 11-12 years old who are currently receiving the diphtheria-tetanus (DT) vaccine are one candidate group. We analyze the cost-effectiveness of replacing the DT vaccine with the DTaP vaccine for 11-year-old adolescents and investigate the indirect effect of vaccinated adolescents on unvaccinated infant siblings. We undertake two analyses using high- and low-morbidity pertussis cases, and based on the results, present suggestions for pertussis prevention in the post-COVID-19 pandemic era.

METHOD

We used the number of pertussis cases in 2019 as the high-morbidity case and the average number of cases in 2020-2021 as the low-morbidity case, and evaluated the incremental cost-effectiveness ratio (ICER) of the DTaP strategy to the DT strategy based on quality-adjusted life years (QALYs). The economic model contained adolescent and infant sub-models. The indirect effect for infants was considered as the probability of unvaccinated infants avoiding pertussis infection from their vaccinated siblings.

RESULTS

The ICER from the payers' perspective was Japanese yen (JPY) 4,254,515 per QALY gained in the high-morbidity case and JPY 62,546,776 per QALY gained in the low-morbidity case. The sensitivity analysis showed that the utility of pertussis had the greatest impact on the ICER, with a 60.58% and 0% probability that the ICER was less than JPY 5 million per QALY gained in the high-morbidity case and low-morbidity case, respectively.

CONCLUSION

The cost-effectiveness of replacing the DT vaccine with the DTaP vaccine is affected by the level of pertussis morbidity, with the ICER becoming more favorable in the high-morbidity case. The indirect effect has little impact on the ICER. Thus, policy-makers should continue to monitor the pertussis epidemic in the post-COVID-19 era, and determine the need to introduce a booster based on perceived trends.