Public Health England, London, UK.
Medical Affairs and Innovation, Hema-Quebec, Quebec, QC, Canada.
Vox Sang. 2019 Oct;114(7):666-674. doi: 10.1111/vox.12826. Epub 2019 Aug 1.
Eight published studies modelled the impact of changing from a lifetime to time-limited deferral for men who have sex with men (MSM); each predicted greater risk impact than has been observed. This study uses these previous efforts to develop an 'optimized' model to inform future changes to MSM deferrals.
HIV residual risk was calculated using observed HIV incidence/prevalence prior to the change in MSM deferral, then with the additional MSM expected under a 12-month deferral for five compliance scenarios, and finally using data observed after implementation of the deferral. Monte Carlo simulation calculated 95% confidence intervals (CI).
The architecture of reviewed models was sound, and two were selected for combination into the optimized model. HIV risk estimated by this in the UK under MSM lifetime deferral was 0·102 (95% CI: 0·050-0·172) per million. The model predicted from a 27·8% decrease to a 47·6% increase depending upon compliance pre-implementation of the 12-month deferral. A decrease of 0·9% was observed post-implementation. For Canada, HIV risk under a 5-year deferral was 0·050 (95% CI: 0·00003-0·122) per million. Pre-implementation of the 12-month deferral, the model predicted from 30·2% decrease to 10-fold increase. A decrease of 47·0% was observed after implementation.
The optimized model predicted HIV risk under 12-month MSM deferral in UK and Canada would remain low, and this was confirmed post-implementation. While the model is adaptable to other deferral scenarios, improved data quality would improve precision, particularly estimates of incidence in individuals likely to donate.
有八项已发表的研究对男男性行为者（MSM）的终生转为限时延期的影响进行了建模；每一项研究预测的风险影响都比实际观察到的要大。本研究利用之前的这些研究成果，开发了一种“优化”模型，为未来 MSM 延期政策的改变提供信息。
使用改变 MSM 延期前观察到的 HIV 发病率/流行率来计算 HIV 残余风险，然后在五种合规情况下，加上 12 个月延期预计新增的 MSM 数量，最后使用延期实施后的实际数据。蒙特卡罗模拟计算了 95%置信区间（CI）。
所审查模型的结构合理，选择了其中两个进行组合，形成了优化模型。该模型预测，在英国，对 MSM 终生延期的情况下，HIV 风险为每百万 0.102（95%CI：0.050-0.172）。该模型预测，在实施 12 个月延期前，HIV 风险将从 27.8%下降到 47.6%。实施后，观察到风险下降了 0.9%。在加拿大，对 5 年延期的情况下，HIV 风险为每百万 0.050（95%CI：0.00003-0.122）。在实施 12 个月延期前，该模型预测 HIV 风险将从 30.2%下降到 10 倍。实施后，观察到风险下降了 47.0%。
在英国和加拿大，实施 12 个月 MSM 延期的情况下，优化模型预测 HIV 风险仍将保持较低水平，这一点在实施后得到了证实。虽然该模型可以适应其他延期情况，但数据质量的提高将提高预测的准确性，特别是对可能捐赠者的个体发病率的估计。
