基于医疗机构的疟疾监测：年龄、居住地和诊断方法对检测阳性率的影响。
Health facility-based malaria surveillance: the effects of age, area of residence and diagnostics on test positivity rates.
机构信息
Department of Medicine, University of California, San Francisco General Hospital, 1001 Potrero Ave, Bldg, 30, Rm, 408, San Francisco, CA 94110, USA.
出版信息
Malar J. 2012 Jul 7;11:229. doi: 10.1186/1475-2875-11-229.
BACKGROUND
The malaria test positivity rate (TPR) is increasingly used as an indicator of malaria morbidity because TPR is based on laboratory-confirmed cases and is simple to incorporate into existing surveillance systems. However, temporal trends in TPR may reflect changes in factors associated with malaria rather than true changes in malaria morbidity. This study examines the effects of age, area of residence and diagnostic test on TPR at two health facilities in regions of Uganda with differing malaria endemicity.
METHODS
The analysis included data from diagnostic blood smears performed at health facilities in Walukuba and Aduku between January 2009 and December 2010. The associations between age and time and between age and TPR were evaluated independently to determine the potential for age to confound temporal trends in TPR. Subsequently, differences between observed TPR and TPR adjusted for age were compared to determine if confounding was present. A similar analysis was performed for area of residence. Temporal trends in observed TPR were compared to trends in TPR expected using rapid diagnostic tests, which were modelled based upon sensitivity and specificity in prior studies.
RESULTS
Age was independently associated with both TPR and time at both sites. At Aduku, age-adjusted TPR increased relative to observed TPR due to the association between younger age and TPR and the gradual increase in age distribution. At Walukuba, there were no clear differences between observed and age-adjusted TPR. Area of residence was independently associated with both TPR and time at both sites, though there were no clear differences in temporal trends in area of residence-adjusted TPR and observed TPR at either site. Expected TPR with pLDH- and HRP-2-based rapid diagnostic tests (RDTs) was higher than observed TPR at all time points at both sites.
CONCLUSIONS
Adjusting for potential confounders such as age and area of residence can ensure that temporal trends in TPR due to confounding are not mistakenly ascribed to true changes in malaria morbidity. The potentially large effect of diagnostic test on TPR can be accounted for by calculating and adjusting for the sensitivity and specificity of the test used.
背景
疟疾病例检出率（TPR）作为疟疾发病率的指标，应用日益广泛，因为它基于实验室确诊病例，并且易于纳入现有的监测系统。然而，TPR 的时间趋势可能反映出与疟疾相关的因素变化，而不是疟疾发病率的真实变化。本研究在乌干达疟疾流行程度不同的两个地区的两个卫生机构，检验了年龄、居住地区和诊断检测对 TPR 的影响。
方法
该分析纳入了 2009 年 1 月至 2010 年 12 月在 Walukuba 和 Aduku 卫生机构进行的诊断性血涂片数据。独立评估年龄与时间以及年龄与 TPR 之间的关系，以确定年龄是否会混淆 TPR 的时间趋势。随后，比较观察到的 TPR 与年龄调整后的 TPR，以确定是否存在混杂因素。对居住地区也进行了类似的分析。比较观察到的 TPR 时间趋势与使用灵敏度和特异性来自先前研究的快速诊断检测的 TPR 预期趋势。
结果
年龄与两个地点的 TPR 和时间均独立相关。在 Aduku，由于年龄与 TPR 之间的关联以及年龄分布的逐渐增加，年龄调整后的 TPR 相对观察到的 TPR 增加。在 Walukuba，观察到的 TPR 和年龄调整后的 TPR 之间没有明显差异。居住地区与两个地点的 TPR 和时间均独立相关，但两个地点的 TPR 调整后和观察到的 TPR 时间趋势没有明显差异。基于 pLDH 和 HRP-2 的快速诊断检测（RDT）的预期 TPR 在所有时间点均高于两个地点的观察 TPR。
结论
调整年龄和居住地区等潜在混杂因素，可以确保因混杂因素导致的 TPR 时间趋势不会被错误地归因于疟疾发病率的真实变化。可以通过计算和调整所用检测的灵敏度和特异性，来解释和调整诊断检测对 TPR 的潜在重大影响。
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