Department of Psychiatry and Behavioral Medicine, Center for AIDS Intervention Research, Medical College of Wisconsin, Milwaukee, WI 53202, USA.
Eval Rev. 2011 Oct;35(5):550-65. doi: 10.1177/0193841X11432196. Epub 2011 Dec 27.
A mathematical model of HIV/sexually transmitted infections (STI) transmission was used to examine how linearity or nonlinearity in the relationship between the number of unprotected sex acts (or the number of sex partners) and the risk of acquiring HIV or a highly infectious STI (such as gonorrhea or chlamydia) affects the utility of sexual behavior change measures as indicators of the effectiveness of HIV/STI risk-reduction interventions. Findings indicate that the risk of acquiring HIV through vaginal intercourse is essentially a linear function of the number of unprotected sex acts and is nearly independent of the number of sex partners. Consequently, the number of unprotected sex acts is an excellent marker for the risk of acquiring HIV through vaginal intercourse, whereas the number of sex partners is largely uninformative. In general, the number of unprotected sex acts is not an adequate marker for the risk of acquiring a highly infectious STI due to the highly nonlinear per act transmission dynamics of these STIs. The number of sex partners is a reasonable indicator of STI risk only under highly circumscribed conditions. A theoretical explanation for this pattern of results is provided. The contrasting extent to which HIV and highly infectious STIs deviate from the linearity assumption that underlies sexual behavior outcome measures has important implications for the use of these measures to assess the effectiveness of HIV/STI risk-reduction interventions.
我们构建了一个 HIV/性传播感染（STI）传播的数学模型，旨在研究性行为中未保护措施的数量（或性伴侣数量）与感染 HIV 或高传染性 STI（如淋病或衣原体）风险之间的关系是否线性或非线性，这对性行为改变措施作为 HIV/STI 减少干预效果的指标有何影响。研究结果表明，阴道性交感染 HIV 的风险基本是未保护性行为数量的线性函数，且与性伴侣数量几乎无关。因此，未保护性行为的数量是通过阴道性交感染 HIV 风险的一个极好的标志物，而性伴侣的数量则在很大程度上没有信息。一般来说，由于这些 STI 的性行为每一次性传播具有高度非线性动力学，未保护性行为的数量并不是感染高度传染性 STI 的风险的充分标志物。只有在高度受限的条件下，性伴侣的数量才是 STI 风险的合理指标。我们提供了对这种结果模式的理论解释。HIV 和高传染性 STI 与性行为结果测量所依据的线性假设偏离的程度不同，这对这些措施用于评估 HIV/STI 减少干预效果有重要影响。
