Adaptive health technology assessment: a scoping review of methods.
BACKGROUND
Health technology assessment (HTA) is an established mechanism for explicit priority setting to support universal health coverage. However, full HTA requires significant time, data, and capacity for each intervention which limits the number of decisions it can inform. Another approach systematically adapts full HTA methods by leveraging HTA evidence from other settings. We call this 'adaptive' HTA (aHTA), although in settings where time is the main constraint, it is also called 'rapid HTA'.


METHODS
The objectives of this scoping review were to identify and map existing aHTA methods, and to assess their triggers, strengths, and weaknesses. This was done by searching HTA agencies' and networks' websites, and the published literature. Findings have been narratively synthesized.


RESULTS
This review identified 20 countries and one HTA network with aHTA methods in the Americas, Europe, Africa, and South-East Asia. These methods have been characterized into five types: rapid reviews, rapid cost-effectiveness analyses, rapid manufacturer submissions, transfers, and de facto HTA. Three characteristics 'trigger' the use of aHTA instead of full HTA: urgency, certainty, and low budget impact. Sometimes, an iterative approach to selecting methods guides whether to do aHTA or full HTA. aHTA was found to be faster and more efficient, useful for decision makers, and to reduce duplication. However, there is limited standardization, transparency, and measurement of uncertainty.


CONCLUSION
aHTA is used in many settings. It has potential to improve the efficiency of any priority-setting system, but needs to be better formalized to improve uptake, particularly for nascent HTA systems.