Swiss Tropical and Public Health Institute, Basel, Switzerland.
PLoS One. 2011 Apr 7;6(4):e18391. doi: 10.1371/journal.pone.0018391.
Trials of intermittent preventive treatment in infants (IPTi) and children (IPTc) have shown promising results in reducing malaria episodes but with varying efficacy and cost-effectiveness. The effects of different intervention and setting characteristics are not well known. We simulate the effects of the different target age groups and delivery channels, seasonal or year-round delivery, transmission intensity, seasonality, proportions of malaria fevers treated and drug characteristics.
We use a dynamic, individual-based simulation model of Plasmodium falciparum malaria epidemiology, antimalarial drug action and case management to simulate DALYs averted and the cost per DALY averted by IPTi and IPTc. IPT cost components were estimated from economic studies alongside trials.
IPTi and IPTc were predicted to be cost-effective in most of the scenarios modelled. The cost-effectiveness is driven by the impact on DALYs, particularly for IPTc, and the low costs, particularly for IPTi which uses the existing delivery strategy, EPI. Cost-effectiveness was predicted to decrease with low transmission, badly timed seasonal delivery in a seasonal setting, short-acting and more expensive drugs, high frequencies of drug resistance and high levels of treatment of malaria fevers. Seasonal delivery was more cost-effective in seasonal settings, and year-round in constant transmission settings. The difference was more pronounced for IPTc than IPTi due to the different proportions of fixed costs and also different assumed drug spacing during the transmission season. The number of DALYs averted was predicted to decrease as a target five-year age-band for IPTc was shifted from children under 5 years into older ages, except at low transmission intensities.
Modelling can extend the information available by predicting impact and cost-effectiveness for scenarios, for outcomes and for multiple strategies where, for practical reasons, trials cannot be carried out. Both IPTi and IPTc are generally cost-effective but could be rendered cost-ineffective by characteristics of the setting, drug or implementation.
间歇性预防治疗在婴儿（IPTi）和儿童（IPTc）中的试验已显示出在减少疟疾发作方面有良好的效果，但疗效和成本效益存在差异。不同干预措施和实施环境的特点所产生的影响尚不清楚。我们模拟了不同目标年龄组和实施渠道、季节性或全年实施、传播强度、季节性、疟疾发热治疗比例和药物特征的效果。
我们使用一种基于个体的恶性疟原虫疟疾流行病学、抗疟药物作用和病例管理的动态模拟模型，来模拟 IPTi 和 IPTc 预防的残疾调整生命年（DALYs）和每预防一个 DALY 的成本。IPT 成本组成部分是根据经济研究和试验估计的。
在模拟的大多数情况下，IPTi 和 IPTc 被预测是具有成本效益的。成本效益是由 DALYs 的影响驱动的，特别是对 IPTc 而言，以及成本低，特别是对于使用现有疫苗接种策略（EPI）的 IPTi。在低传播率、季节性设置中季节性实施时间不当、作用时间短和成本更高的药物、药物耐药性频率高以及发热疟疾治疗水平高的情况下，成本效益预计会降低。在季节性环境中，季节性实施比全年实施更具成本效益，而在持续传播环境中则是全年实施更具成本效益。由于固定成本的比例不同，以及在传播季节中假设的药物间隔不同，IPTc 比 IPTi 的差异更为明显。随着 IPTc 的目标五岁年龄组从五岁以下儿童转移到年龄较大的儿童，预计预防的残疾调整生命年（DALYs）数量将会减少，除非传播强度较低。
建模可以通过预测情景、结果和多种策略的影响和成本效益来扩展可获得的信息，而这些在实践上是无法进行试验的。IPTi 和 IPTc 通常都是具有成本效益的，但由于实施环境、药物或实施的特点，可能会变得不具有成本效益。
