Gaur Aditya H, Flynn Patricia M, Bitar Wally, Liang Hua
Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
AIDS Res Hum Retroviruses. 2013 Mar;29(3):418-22. doi: 10.1089/AID.2012.0175. Epub 2012 Oct 31.
Current HIV guidelines recommend monitoring CD4 counts every 3-4 months. In the era of highly active antiretroviral therapy (HAART) and HIV PCR, this retrospective study reexamines the required frequency of the CD4 assay. Predictor variables, including age, previous CD4 count, HIV viral load (VL), time interval since last VL and CD4 count (TINT), and antiretroviral history, were abstracted. A recursive partitioning-based regression tree analysis was used to determine if the absolute current CD4 count was above or below the age appropriate Pneumocystis jiroveci pneumonia (PCP) prophylaxis cutoff. We analyzed concurrently obtained VLs and CD4 count including 601 results from 43 HIV-infected children aged 1-<6 years (Group I) and 1,364 results from 93 children/adolescents 6-<23 years (Group II). Using 75% of observations to build a predictive model (learning dataset), the ability to correctly predict the range of the outcome variable in the remaining 25% of observations (training dataset) was 93% in Group I and 97% in Group II. Predictor variables included age, recent VL and CD4 count, and TINT. A total of 1,000 repeats of this model building using randomly selected observations showed a correct predictive ability of 89.6% [standard error (SE) 2.3%] in Group I and 95.6% (SE 1%) in Group II. The ability of a classification tree to determine if the current CD4 count is above or below the age-specific cutoff for PCP prophylaxis is very good and allows less frequent CD4 assays. The principles underlying this modeling-based approach have broad applicability and cost saving implications.
当前的艾滋病病毒指南建议每3 - 4个月监测一次CD4细胞计数。在高效抗逆转录病毒治疗（HAART）和艾滋病病毒聚合酶链反应（HIV PCR）时代，这项回顾性研究重新审视了CD4检测所需的频率。提取了预测变量，包括年龄、既往CD4细胞计数、艾滋病病毒载量（VL）、自上次VL和CD4细胞计数以来的时间间隔（TINT）以及抗逆转录病毒治疗史。使用基于递归划分的回归树分析来确定当前绝对CD4细胞计数是高于还是低于适合年龄的耶氏肺孢子菌肺炎（PCP）预防临界值。我们分析了同时获得的VL和CD4细胞计数，包括来自43名1 - <6岁感染艾滋病病毒儿童（第一组）的601份结果以及来自93名6 - <23岁儿童/青少年（第二组）的1364份结果。使用75%的观察值构建预测模型（学习数据集），在其余25%的观察值（训练数据集）中正确预测结果变量范围的能力在第一组为93%，在第二组为97%。预测变量包括年龄、近期VL和CD4细胞计数以及TINT。使用随机选择的观察值对该模型构建进行总共1000次重复，结果显示在第一组中正确预测能力为89.6% [标准误差（SE）2.3%]，在第二组中为95.6%（SE 1%）。分类树确定当前CD4细胞计数高于还是低于PCP预防的年龄特异性临界值的能力非常好，并且可以减少CD4检测的频率。这种基于建模方法的基本原理具有广泛的适用性和节省成本的意义。
