Evaluating the Quality of National Mortality Statistics from Civil Registration in South Africa, 1997–2007

Background
Two World Health Organization comparative assessments rated the quality of South Africa’s 1996 mortality data as low. Since then, focussed initiatives were introduced to improve civil registration and vital statistics. Furthermore, South African cause-of-death data are widely used by research and international development agencies as the basis for making estimates of cause-specific mortality in many African countries. It is hence important to assess the quality of more recent South African data.
Methods
We employed nine criteria to evaluate the quality of civil registration mortality data. Four criteria were assessed by analysing 5.38 million deaths that occurred nationally from 1997–2007. For the remaining five criteria, we reviewed relevant legislation, data repositories, and reports to highlight developments which shaped the current status of these criteria.
Findings
National mortality statistics from civil registration were rated satisfactory for coverage and completeness of death registration, temporal consistency, age/sex classification, timeliness, and sub-national availability. Epidemiological consistency could not be assessed conclusively as the model lacks the discriminatory power to enable an assessment for South Africa. Selected studies and the extent of ill-defined/non-specific codes suggest substantial shortcomings with single-cause data. The latter criterion and content validity were rated unsatisfactory.
Conclusion
In a region marred by mortality data absences and deficiencies, this analysis signifies optimism by revealing considerable progress from a dysfunctional mortality data system to one that offers all-cause mortality data that can be adjusted for demographic and health analysis. Additionally, timely and disaggregated single-cause data are available, certified and coded according to international standards. However, without skillfully estimating adjustments for biases, a considerable confidence gap remains for single-cause data to inform local health planning, or to fill gaps in sparse-data countries on the continent. Improving the accuracy of single-cause data will be a critical contribution to the epidemiologic and population health evidence base in Africa.

背景
世界卫生组织（World Health Organization）的两项对比评估将南非1996年的死亡数据质量评为低水平。此后，南非启动了针对性举措以完善民事登记（civil registration）与生命统计（vital statistics）系统。此外，南非的死因数据被众多科研机构及国际发展组织广泛采用，作为估算非洲多国分病因死亡率（cause-specific mortality）的基础。因此，评估南非近期死亡数据的质量具有重要意义。

方法
本研究采用9项评估指标对民事登记死亡数据的质量进行评价。其中4项指标通过分析1997年至2007年全国范围内发生的538万例死亡病例完成评估。针对剩余5项指标，我们通过梳理相关法律法规、数据存储库及研究报告，梳理了影响当前指标现状的相关发展进程。

结果
基于民事登记系统的全国死亡统计数据在死亡登记覆盖范围与完整性、时间一致性、年龄/性别分类、及时性以及分区域可用性方面均被评为合格。由于现有模型不具备适配南非场景的判别能力（discriminatory power），流行病学一致性（epidemiological consistency）无法得到确定性评估。现有相关研究以及不明原因/非特异性编码（ill-defined/non-specific codes）的使用比例均表明，单病因数据（single-cause data）存在显著缺陷。上述单病因数据相关指标及内容效度（content validity）均被评为不合格。

结论
在一个饱受死亡数据缺失与质量缺陷困扰的区域中，本研究通过展示南非从功能失调的死亡数据系统，升级为可提供经调整以用于人口与卫生分析的全死因数据（all-cause mortality data）的显著进展，传递出积极信号。此外，南非现已拥有符合国际标准、经过认证并完成编码的及时且分类细化的单病因数据。然而，若无法精准估算偏倚调整值，单病因数据在指导本地卫生规划，或是填补非洲大陆数据匮乏国家（sparse-data countries）的信息缺口方面，仍存在较大的可信度缺口。提升单病因数据的准确性，将为非洲的流行病学与人群健康证据库（epidemiologic and population health evidence base）做出关键贡献。