全球消除C型肝炎感染的可行性如何？
資料來源：刺胳針期刊；www.thelancet.com Published online January 28,2019；財團法人台灣紅絲帶基金會編譯
2013年引進的直接作用之抗病毒藥物徹底改變了C型肝炎病毒（HCV）感染的治療方法。治療時間短至8週，副作用少，實際上超過90％的患者可以治癒，並且在引入學名藥治療後，更加實惠的藥品價格已成為許多HCV感染者的實際可行的選擇。 2016年，約有150萬人接受了HCV治療。這些與治療相關的發展，以及由於對病毒性肝炎所引起的全球發生率和死亡率顯著增加有更好的理解，導致了對病毒性肝炎倡導了更多的行動來解決肝炎問題。最值得注意的是，2016年，世界衛生組織的194個成員國首次採用了這種以消除為背景來制定目標之全球肝炎戰略行動，定義為合併B乙型肝炎和C型肝炎其發生率降低90％ — 即B肝發生率降低95％，C肝發生率降低80％—到2030年死亡率降低65％。該戰略目前正在納入國家消除肝炎計畫，一些國家正在按計畫劃實現目標。然而，這些目標是否可在全球範圍內實現，以及實現這些目標需要採取那些的措施仍然存在問題。
Alastair Heffernan及其同事們在「剌胳針」雜誌中幫助解決了這些問題，作者們以數學模型預測了在四種外加之介入措施情境下對HCV相關發生率和死亡率的影響：（1）實施全面的血液安全和感染控制措施; （2）擴展靜脈注射藥癮者(PWID)的減害服務（阿片類藥物替代療法和針具交換計畫）; （3）為目前被診斷為HCV感染的所有人提供治療，無論處於疾病何種階段; （4）擴大HCV檢測，在2030年達到讓所有HCV感染者中有90％被診斷出來，並提供治療。為了做到這一點，作者群開發了一個模型，該模型使用複雜的統計方法，並依賴截至2015年各國特定的HCV盛行率、HCV測試率和治療率等估計值；該模型還考慮了HCV再感染風險和HCV治療的預防效果。
作者們得出結論認為，儘管到了2032年可以達到WHO戰略定義中HCV的消除，並且在2030年可以防止1,510萬（95％信賴區間13.8-16.1百萬）HCV之感染和150萬之死亡（95％信賴區間1.4-1.6百萬）然而，只有透過結合方案4措施才能實現消除目標，如此將可以防止在非靜脈藥癮者中80％的感染，達到為40%之靜脈藥癮者提供減害服務，並將HCV診斷和治療擴大到90％的感染人群中。計畫之進展在地理上會有所不同，靜脈藥癮者中HCV發生率高的地區，直到2050年之後才會達到發生率消除之目標。最後，只有四個國家（中國，埃及，印度和巴基斯坦）因HCV感染人數眾多，而對實現這些目標產生了巨大影響。如果這些國家未能實施所有上述四項介入措施，那麼直到2050年才能在全球範圍內實現世衛組織的發生率消除之目標。
Heffernan及其同事們的分析主要之局限性在於模型數據的不確定性。這些數據不是測量值，而是基於模型，或者在某些情況下基於專家意見。此外，對於沒有可用數據的國家，估算是從鄰國借來的。這些估計數的不確定性，將影響目標的實現日期，但其對不同介入措施的估計影響較小，因為這些介入措施的效果主要取決於介入措施的效果，而不是各該國家特定的資訊。
隨著世界衛生組織戰略的採用，並在可持續發展目標中提及「對抗肝炎」，以及在一些國家中擴大之肝炎服務，消除肝炎的概念正在增強。因此，Heffernan及其同事們的分析令人鼓舞，也表明了這個概念是可以實現的。然而，他們的分析也表明消除的道路將是困難的。要擴大肝炎服務需要政治上之意願以及源自國家預算和全球資金等來源的大量新投資。作者們沒有提出消除所需花費的成本，但世界衛生組織估計，在2016 – 21年期間實施其戰略將花費119億美元。在全球衛生投資減少和關注全民健康之覆蓋而非特定疾病計畫之重點轉移的情況下，要確認這些資源將是特別困難。。
How feasible is the global elimination of HCV infection?
The introduction of direct-acting antiviral agents in 2013 revolutionised the treatment of hepatitis C virus
(HCV) infection.1 With duration of therapy as short as 8 weeks, few side-effects, the fact that more than
90% of patients can be cured, and more affordable drug prices following the introduction of generics, treatment
has become a realistic option for many people living with HCV infection. In 2016, approximately 1·5 million
people received HCV treatment.2 These treatment-related developments along with an improved understanding
of the substantial global morbidity and mortality attributable to viral hepatitis led to increased advocacy for
more action to address hepatitis.3 Most notably, in 2016, the 194 member states of WHO adopted the first-ever
global hepatitis strategy, which framed its targets in the context of elimination, defined as a combined 90% reduction in hepatitis B and HCV incidence—comprising a 95% reduction in hepatitis B incidence and an 80% reduction in HCV incidence—and 65% reduction in mortality by 2030.4 The strategy is now being adapted into national hepatitis elimination plans and some countries are on track to reach the targets.5 However, questions remain on whether these goals are attainable on a global scale and what it will take to achieve them.
Alastair Heffernan and colleagues in The Lancet help to address these questions.6 The authors developed a
mathematical model that projects the impact on HCV related incidence and mortality of four additive intervention
scenarios: (1) implementation of comprehensive blood safety and infection control measures; (2) expansion of
harm reduction services (opioid substitution therapy and needle and syringe programmes) for people who inject
drugs (PWID); (3) provision of treatment for all people currently diagnosed with HCV infection, regardless of
disease stage; and (4) expansion of HCV testing such that 90% of all people with HCV infection are diagnosed
and offered treatment by 2030. To do this, the authors developed a model that uses sophisticated statistical methods and relies on country-specific estimates of HCV prevalence and rates of HCV testing and treatment as of 2015. The model also accounts for HCV reinfection risk and the prevention effect of HCV treatment.
The authors conclude that elimination of HCV as defined in the WHO strategy is possible, albeit by 2032, and would prevent 15·1 million (95% credible interval 13·8–16·1) HCV infections and 1·5 million (1·4–1·6) deaths by 2030. However, elimination is only achievable by the combined interventions (scenario 4), which would prevent 80% of infections in the non-PWID population, provide harm reduction services to 40% of all PWID, and expand HCV diagnosis and treatment to 90% of the infected population. Progress would vary geographically, and regions with a high proportion of HCV incidence among PWID would not reach the incidence elimination target until after 2050. Finally,
just four countries (China, Egypt, India, and Pakistan) have an outsized influence on reaching these targets because of their large populations of people with HCV infection. If these countries fail to implement all four interventions, the WHO incidence elimination target will not be reached globally until nearly 2050.
The principal limitation of the analysis by Heffernan and colleagues relates to the uncertainty of the data inputs to their model. These are not measured values but rather are based, themselves, on models or, in some cases, on expert opinion.