Department of Pediatrics and Child Health, University of Nairobi, Nairobi, Kenya.
BMC Infect Dis. 2011 Sep 30;11:259. doi: 10.1186/1471-2334-11-259.
In resource-limited settings, such as Kenya, access to CD4 testing is limited. Therefore, evaluation of less expensive laboratory diagnostics is urgently needed to diagnose immuno-suppression in children.
To evaluate utility of total lymphocyte count (TLC) as surrogate marker for CD4 count in HIV-infected children.
This was a hospital based retrospective study conducted in three HIV clinics in Kisumu and Nairobi in Kenya. TLC, CD4 count and CD4 percent data were abstracted from hospital records of 487 antiretroviral-naïve HIV-infected children aged 1 month--12 years.
TLC and CD4 count were positively correlated (r = 0.66, p < 0.001) with highest correlation seen in children with severe immuno-suppression (r = 0.72, p < 0.001) and children >59 months of age (r = 0.68, p < 0.001). Children were considered to have severe immuno-suppression if they met the following WHO set CD4 count thresholds: age below 12 months (CD4 counts < 1500 cells/mm(3)), age 12-35 months (CD4 count < 750 cells/mm(3)), age 36-59 months (CD4 count < 350 cells/mm(3), and age above 59 months (CD4 count < 200 cells/mm(3)). WHO recommended TLC threshold values for severe immuno-suppression of 4000, 3000, 2500 and 2000 cells/mm(3) for age categories <12, 12-35, 36-59 and >59 months had low sensitivity of 25%, 23%, 33% and 62% respectively in predicting severe immuno-suppression using CD4 count as gold standard. Raising TLC thresholds to 7000, 6000, 4500 and 3000 cells/mm3 for each of the stated age categories increased sensitivity to 71%, 64%, 56% and 86%, with positive predictive values of 85%, 61%, 37%, 68% respectively but reduced specificity to 73%, 62%, 54% and 68% with negative predictive values of 54%, 65%, 71% and 87% respectively.
TLC is positively correlated with absolute CD4 count in children but current WHO age-specific thresholds had low sensitivity to identify severely immunosuppressed Kenyan children. Sensitivity and therefore utility of TLC to identify immuno-suppressed children may be improved by raising the TLC cut off levels across the various age categories.
在资源有限的环境下，例如肯尼亚，CD4 检测的获取受到限制。因此，急需评估更廉价的实验室诊断方法，以诊断儿童免疫抑制情况。
评估总淋巴细胞计数（TLC）作为 HIV 感染儿童 CD4 计数替代标志物的效用。
这是一项在肯尼亚基苏木和内罗毕的三个 HIV 诊所进行的基于医院的回顾性研究。从 487 名未接受抗逆转录病毒治疗的 HIV 感染儿童的医院记录中提取 TLC、CD4 计数和 CD4 百分比数据。这些儿童的年龄为 1 个月至 12 岁。
TLC 与 CD4 计数呈正相关（r = 0.66，p < 0.001），在严重免疫抑制（r = 0.72，p < 0.001）和> 59 个月的儿童中相关性最高（r = 0.68，p < 0.001）。如果儿童符合以下世卫组织设定的 CD4 计数阈值，则被认为患有严重免疫抑制：12 个月以下（CD4 计数<1500 个细胞/mm3）、12-35 个月（CD4 计数<750 个细胞/mm3）、36-59 个月（CD4 计数<350 个细胞/mm3）和> 59 个月（CD4 计数<200 个细胞/mm3）。世卫组织建议 TLC 阈值用于严重免疫抑制的年龄类别为<12 个月为 4000 个细胞/mm3、12-35 个月为 3000 个细胞/mm3、36-59 个月为 2500 个细胞/mm3、> 59 个月为 2000 个细胞/mm3，使用 CD4 计数作为金标准时，预测严重免疫抑制的敏感度分别为 25%、23%、33%和 62%。将 TLC 阈值分别提高到每个所述年龄类别中的 7000、6000、4500 和 3000 个细胞/mm3，可将敏感度提高至 71%、64%、56%和 86%，阳性预测值分别为 85%、61%、37%和 68%，但特异性分别降至 73%、62%、54%和 68%，阴性预测值分别为 54%、65%、71%和 87%。
TLC 与儿童的绝对 CD4 计数呈正相关，但当前的世卫组织年龄特异性阈值对识别肯尼亚严重免疫抑制儿童的敏感性较低。通过提高各个年龄组的 TLC 截止值，TLC 对识别免疫抑制儿童的敏感性（即效用）可能会提高。
