ISPED, Inserm, Bordeaux Population Health Research Center, UMR 1219, University of Bordeaux, Bordeaux, France.
Department of Maternal, Newborn, Child and Adolescent Health, World Health Organization, Geneva, Switzerland.
J Int AIDS Soc. 2020 Oct;23(10):e25609. doi: 10.1002/jia2.25609.
Definitions of retention-in-care in Prevention of Mother-to-Child Transmission of HIV (PMTCT) vary substantially between studies and programmes. Some definitions are based on visits missed/made, others on a minimum total number of visits, or attendance at a final clinic visit at a specific time. An agreed definition could contribute to developing evidence-based interventions for improving retention-in-care. In this paper, we estimated retention-in-care rates according to different definitions, and we quantified and visualized the degree of agreement between definitions.
We calculated retention in care rates using nine definitions in the six INSPIRE PMTCT intervention studies, conducted in three sub-Saharan African countries between 2013 and 2017. With data from one of the studies (E4E), we estimated the agreement between definitions using Gwet's agreement coefficient (AC1) and concordance. We calculated positive predictive values (PPV) and negative predictive values (NPV) for all definitions considering successively each definition as the reference standard. Finally, we used a Multiple Correspondence Analysis (MCA) to examine clustering of the way different definitions handle retention-in-care.
Retention-in-care rates among 5107 women ranged from 30% to 76% in the complete dataset with Gwet's AC1 being 0.56 [0.53; 0.59] indicating a moderate agreement between all definitions together. Two pairs of definitions with high inner concordance and agreement had either very high PPV or very high NPV, and appeared distinct from the other five definitions on the MCA figures. These pairs of definitions were also the ones resulting in the lowest and highest estimates of retention-in-care. The simplest definition, that only required a final clinic visit to classify women as retained in care, and classified 55% of women as retained in care, had a PPV ranging from 0.7 to 1 and a NPV ranging from 0.69 to 0.98 when excluding the two pairs afore-mentioned; it resulted in a moderate to substantial agreement and a 70% to 90% concordance with all other definitions.
Our study highlights the variability of definitions in estimating retention-in-care. Some definitions are very stringent which may be required in some instances. A simple indicator such as attendance at a single time point may be sufficient for programme planning and evaluation.
预防母婴传播艾滋病毒（PMTCT）中“留医率”的定义在不同的研究和项目中差异较大。有些定义基于错过/进行的就诊次数，有些则基于就诊次数的最低总数，或在特定时间参加最后一次门诊就诊。一个被认可的定义有助于制定基于证据的干预措施，以提高留医率。在本文中，我们根据不同的定义来估计留医率，并量化和可视化定义之间的一致性程度。
我们使用在 2013 年至 2017 年间在三个撒哈拉以南非洲国家进行的六项 INSPIRE PMTCT 干预研究中的九个定义来计算留医率。根据 E4E 研究的数据，我们使用 Gwet 一致性系数（AC1）和一致性来估计定义之间的一致性。我们考虑到每个定义依次作为参考标准，计算了所有定义的阳性预测值（PPV）和阴性预测值（NPV）。最后，我们使用多对应分析（MCA）来检查不同定义处理留医率的方式聚类情况。
5107 名妇女的留医率在完整数据集中从 30%到 76%不等，Gwet 的 AC1 为 0.56 [0.53; 0.59]，表明所有定义之间存在中度一致性。两个定义组具有很高的内部一致性和一致性，它们要么具有非常高的 PPV，要么具有非常高的 NPV，并且在 MCA 图上与其他五个定义明显不同。这两个定义组也是导致留医率最低和最高估计的定义组。最简单的定义只需要最后一次门诊就诊就可以将妇女归类为留医，将 55%的妇女归类为留医，在排除上述两个定义组后，PPV 范围为 0.7 到 1，NPV 范围为 0.69 到 0.98；它与所有其他定义都有中度到高度的一致性和 70%到 90%的一致性。
我们的研究强调了在估计留医率时定义的可变性。在某些情况下，一些定义可能非常严格。像在单一时间点就诊这样的简单指标可能足以进行方案规划和评估。
