Data from: Coverage of the 2011 Q fever vaccination campaign in the Netherlands, using retrospective population-based prevalence estimation of cardiovascular risk-conditions for chronic Q fever

Background: In 2011, a unique Q fever vaccination campaign targeted people at risk for chronic Q fever in the southeast of the Netherlands. General practitioners referred patients with defined cardiovascular risk-conditions (age >15 years). Prevalence rates of those risk-conditions were lacking, standing in the way of adequate planning and coverage estimation. We aimed to obtain prevalence rates retrospectively in order to estimate coverage of the Q fever vaccination campaign. Methods: With broad search terms for these predefined risk-conditions, we extracted patient-records from a large longitudinal general-practice research-database in the Netherlands (IPCI-database). After validation of these records, obtained prevalence rates (stratified for age and sex) extrapolated to the Q fever high-incidence area population, gave an approximation of the size of the targeted patient-group. Coverage calculation addressed people actually screened by a pre-vaccination Q fever skin test and serology (coverage) and patients referred by their general practitioners (adjusted-coverage) in the 2011 campaign. Results: Our prevalence estimate of any risk-condition was 3.1% (lower-upper limits 2.9-3.3%). For heart valve defects, aorta aneurysm/prosthesis, congenital anomalies and endocarditis, prevalence was 2.4%, 0.6%, 0.4% and 0.1%, respectively. Estimated number of eligible people in the Q fever high-incidence area was 11,724 (10,965-12,532). With 1330 people screened for vaccination, coverage of the vaccination campaign was 11%. For referred people, the adjusted coverage was 18%. Coverage was lowest among the very-old and highest for people aged 50–70 years. Conclusion: The estimated coverage of the vaccination campaign was limited. This should be interpreted in the light of the complexity of this target-group with much co-morbidity, and of the vaccine that required invasive pre-vaccination screening. Calculation of prevalence rates of risk-conditions based on the IPCI-database was feasible. This procedure proved an efficient tool for future use, when prevalence estimates for policy, implementation or surveillance of subgroup-vaccination or other health-care interventions are needed.

背景：2011年，荷兰东南部针对慢性Q热（Q fever）高危人群开展了一项特殊的疫苗接种项目。全科医师将年龄＞15岁、确诊存在明确心血管危险因素的患者纳入转诊范围。当时此类危险因素的患病率数据缺失，这阻碍了接种项目的合理规划与覆盖率评估。本研究旨在通过回顾性分析获取相关患病率数据，以评估此次Q热疫苗接种项目的覆盖率。
研究方法：针对预设的危险因素，通过宽泛的检索词从荷兰大型纵向全科医学研究数据库（IPCI-database）中提取患者病历。对提取的病历进行验证后，将按年龄和性别分层得到的患病率数据外推至Q热高发区域的总人口，以此估算目标患者群体的规模。本次覆盖率计算涵盖两类人群：一是2011年接种项目中实际接受Q热疫苗接种前皮肤试验与血清学筛查的人群（基础覆盖率），二是经全科医师转诊的人群（调整后覆盖率）。
研究结果：本研究估算的任意一种心血管危险因素的患病率为3.1%（上下限为2.9%~3.3%）。其中，心脏瓣膜缺损、主动脉瘤/主动脉假体、先天性心血管异常以及心内膜炎的患病率分别为2.4%、0.6%、0.4%与0.1%。Q热高发区域内符合接种条件的人群估算规模为11724人（区间为10965~12532人）。本次接种项目中共有1330人接受了筛查，基础覆盖率为11%；针对转诊人群的调整后覆盖率则为18%。覆盖率在高龄老年人群中最低，而在50~70岁年龄段人群中最高。
研究结论：本次Q热疫苗接种项目的估算覆盖率偏低。该结果需结合以下两点综合解读：一是目标人群合并症繁多、构成复杂，二是该疫苗需进行有创的接种前筛查。基于IPCI数据库的危险因素患病率计算方法具备可行性，且在未来需要为政策制定、项目实施或亚组疫苗接种及其他医疗干预措施的监测开展患病率估算时，可作为高效实用的工具加以应用。