Takeda Pharmaceuticals, 40 Landsdowne St, Cambridge, MA, 02139, USA.
Ther Innov Regul Sci. 2021 Jul;55(4):743-754. doi: 10.1007/s43441-021-00279-8. Epub 2021 Mar 30.
It is challenging to elucidate the effects of changes in external influences (such as economic or policy) on the rate of US drug approvals. Here, a novel approach-termed the Chronological Hurst Exponent (CHE)-is proposed, which hypothesizes that changes in the long-range memory latent within the dynamics of time series data may be temporally associated with changes in such influences. Using the monthly number FDA's Center for Drug Evaluation and Research (CDER) approvals from 1939 to 2019 as the data source, it is demonstrated that the CHE has a distinct S-shaped structure demarcated by an 8-year (1939-1947) Stagnation Period, a 27-year (1947-1974) Emergent Period, and a 45-year (1974-2019) Saturation Period. Further, dominant periodicities (resolved via wavelet analyses) are identified during the most recent 45-year CHE Saturation Period at 17, 8 and 4 years; thus, US drug approvals have been following a Juglar/Kuznet mid-term cycle with Kitchin-like bursts. As discussed, this work suggests that (1) changes in extrinsic factors (e.g., of economic and/or policy origin) during the Emergent Period may have led to persistent growth in US drug approvals enjoyed since 1974, (2) the CHE may be a valued method to explore influences on time series data, and (3) innovation-related economic cycles exist (as viewed via the proxy metric of US drug approvals).
阐明外部影响（如经济或政策）变化对美国药物批准率的影响具有挑战性。在这里，提出了一种新方法——称为时间序列数据动态的时序赫斯特指数（CHE），该方法假设在时间序列数据的动力学中存在的长期记忆变化可能与这些影响的变化在时间上相关。使用美国食品和药物管理局（FDA）药物评估和研究中心（CDER）从 1939 年到 2019 年每月批准的数量作为数据源，证明 CHE 具有独特的 S 形结构，由 8 年（1939-1947 年）停滞期、27 年（1947-1974 年）新兴期和 45 年（1974-2019 年）饱和期界定。此外，在最近的 45 年 CHE 饱和期内，通过小波分析确定了主要的周期性（17、8 和 4 年）；因此，美国药物批准一直遵循朱格拉/库兹涅茨中期周期和类似基钦的爆发。如前所述，这项工作表明：（1）在新兴期内外部因素（例如经济和/或政策起源）的变化可能导致自 1974 年以来美国药物批准率持续增长，（2）CHE 可能是探索时间序列数据影响的有价值方法，以及（3）存在与创新相关的经济周期（如通过美国药物批准的代理指标来看）。
