Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK.
Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK.
Lancet Public Health. 2018 Jan;3(1):e44-e51. doi: 10.1016/S2468-2667(17)30238-4. Epub 2017 Dec 19.
Health equality is increasingly being considered alongside overall health gain when assessing public health interventions. However, the trade-off between the direct effects of vaccination and herd immunity could lead to unintuitive consequences for the distribution of disease burden within a population. We used a transmission dynamic model of human papillomavirus (HPV) to investigate the effect of ethnic disparities in vaccine and cervical screening uptake on inequality in disease incidence in England.
We developed an individual-based model of HPV transmission and disease, parameterising it with the latest data for sexual behaviour (from National Survey of Sexual Attitudes and Lifestyles [Natsal-3]) and vaccine and screening uptake by ethnicity (from Public Health England [PHE]) and fitting it to data for HPV prevalence (from ARTISTIC, PHE, Natsal-3) and HPV-related disease incidence (from National Cancer Registry [ONS]). The outcome of interest was the age-adjusted incidence of HPV-related cancer (both cervical and non-cervical) in all women in England in view of differences and changes in vaccination and screening uptake by ethnicity in England, over time. We also studied three potential public health interventions aimed at reducing inequality in HPV-related disease incidence: increasing uptake in black and Asian females to match that in whites for vaccination; cervical screening in women who turn 25 in 2018 or later; and cervical screening in all ages.
In the pre-vaccination era, before 2008, women from ethnic minorities in England reported a disproportionate share of cervical disease. Our model suggests that Asian women were 1·7 times (95% credibility interval [CI] 1·1-2·7) more likely to be diagnosed with cervical cancer than white women (22·8 vs 13·4 cases per 100 000 women). Because HPV vaccination uptake is lower in ethnic minorities, we predict an initial widening of this gap, with cervical cancer incidence in Asian women up to 2·5 times higher (95% CI 1·3-4·8) than in white women 20 years after vaccine introduction (corresponding to an additional 10·8 [95% CI 10·1-11·5] cases every year). In time, we predict that herd immunity benefits will diffuse from the larger white sub-population and the disparity will narrow. Increased cervical screening uptake in vaccinated women from ethnic minorities would lead to rapid improvement in equality with parity in incidence after 20 years of HPV vaccination.
Our study suggests that the introduction of HPV vaccination in England will initially widen a pre-existing disparity in the incidence of HPV-related cancer by ethnicity, partly due to herd immunity disproportionately benefiting subgroups with high vaccination rates. Although in time this induced disparity will narrow, increasing cervical screening uptake in girls from ethnic minorities should be encouraged to eliminate the inequality in cervical cancer incidence in the medium term. We recommend that dynamic effects should be considered when estimating the effect of public health programmes on equality.
Cancer Research UK.
在评估公共卫生干预措施对整体健康的影响时，健康公平性越来越被视为与整体健康增益同等重要。然而，疫苗接种的直接效果和群体免疫之间的权衡取舍，可能会导致人群中疾病负担分配出现意想不到的后果。我们使用人乳头瘤病毒（HPV）传播动力学模型，研究了疫苗接种和宫颈筛查参与度方面的种族差异对英格兰疾病发病率不平等的影响。
我们开发了一个 HPV 传播和疾病的个体基础模型，使用最新的性行为数据（来自全国性态度和生活方式调查[NatSAL-3]）和按种族划分的疫苗和筛查接种率数据（来自英格兰公共卫生部[PHE]）对其进行参数化处理，并使用 HPV 流行率数据（来自 ARTISTIC、PHE 和 NatSAL-3）和 HPV 相关疾病发病率数据（来自国家癌症登记处[ONS]）对其进行拟合。我们感兴趣的结果是，考虑到英格兰各族裔之间疫苗接种和筛查参与度的差异和变化，英格兰所有女性 HPV 相关癌症（包括宫颈和非宫颈癌症）的年龄调整发病率。我们还研究了三种潜在的公共卫生干预措施，旨在减少 HPV 相关疾病发病率的不平等：提高黑人和亚裔女性的疫苗接种率，使其与白人女性的接种率相匹配；对 2018 年及以后年满 25 岁的女性进行宫颈筛查；对所有年龄段的女性进行宫颈筛查。
在疫苗接种前的时期，即 2008 年之前，英格兰少数民族女性报告的宫颈疾病比例过高。我们的模型表明，亚裔女性被诊断为宫颈癌的可能性比白人女性高 1.7 倍（95%置信区间[CI]1.1-2.7；22.8 与 13.4 例/每 10 万名女性）。由于少数族裔的 HPV 疫苗接种率较低，我们预测最初会出现差距扩大，疫苗接种引入 20 年后，亚裔女性的宫颈癌发病率可能高达白人女性的 2.5 倍（95%CI1.3-4.8；每年额外增加 10.8[95%CI10.1-11.5]例）。随着时间的推移，我们预计群体免疫效益将从更大的白人亚群中扩散，差距将缩小。少数族裔女性中接受疫苗接种的女性增加宫颈筛查，将在 HPV 疫苗接种 20 年后迅速改善发病率的平等性。
我们的研究表明，HPV 疫苗在英格兰的引入最初将扩大按种族划分的 HPV 相关癌症发病率方面已有的差异，部分原因是群体免疫不成比例地使高疫苗接种率亚群受益。尽管随着时间的推移，这种诱导的差异将会缩小，但应该鼓励增加少数族裔女孩的宫颈筛查，以在中期消除宫颈癌发病率的不平等。我们建议在估计公共卫生项目对平等的影响时，应考虑动态效应。
英国癌症研究中心。
