Cascini Fidelia, Aiello Carola, Di Tanna Gianluca
Istituto di Medicina Legale, Università Cattolica del S Cuore, largo F. Vito, 1 00168 Roma, Italy.
Curr Drug Abuse Rev. 2012 Mar;5(1):32-40. doi: 10.2174/1874473711205010032.
The objective of this meta-analysis is to assess the data regarding changes in herbal cannabis potency over time (from 1970 to 2009).
Systematic searches of 17 electronic scientific databases identified studies on this topic, within which 21 case series studies satisfied our inclusion criteria of reporting the mean tetrahydrocannabinol (THC) value per number of samples per year. No language, publication date, publication type or status restrictions were imposed. The study selection and data extraction processes were performed independently but uniformly by two authors, included screening, determination of eligibility and inclusion of the eligible studies in the systematic review, and a meta-analysis of the results on THC content in herbal cannabis samples. We considered papers and not monographic scientific publications, rejecting all studies that were not focused on the subject of this review.
Meta-analysis by year was performed on 21 studies containing 75 total mean THC observations from 1979 to 2009 using the random effects model. The results revealed much variability between studies. Further, there was a significant correlation between year and mean THC in herbal cannabis. The combined data indicated the correlation between year and mean THC in herbal cannabis, revealing a temporal trend of increasing potency (5% above the mean THC value in the Poisson regression analysis).
The results of the analysis suggest that there has been a recent and consistent increase in cannabis potency worldwide.
本荟萃分析的目的是评估有关草药大麻效力随时间（1970年至2009年）变化的数据。
对17个电子科学数据库进行系统检索，以确定关于该主题的研究，其中21个病例系列研究符合我们的纳入标准，即报告每年每个样本数量的平均四氢大麻酚（THC）值。未施加语言、出版日期、出版类型或状态限制。研究选择和数据提取过程由两位作者独立且统一进行，包括筛选、确定 eligibility 以及将符合条件的研究纳入系统评价，并对草药大麻样本中THC含量的结果进行荟萃分析。我们考虑的是论文而非专题科学出版物，拒绝所有未聚焦于本综述主题的研究。
使用随机效应模型对1979年至2009年的21项研究进行逐年荟萃分析，这些研究共包含75个平均THC观测值。结果显示研究之间存在很大差异。此外，年份与草药大麻中的平均THC之间存在显著相关性。合并数据表明年份与草药大麻中的平均THC之间的相关性，揭示了效力增加的时间趋势（在泊松回归分析中比平均THC值高5%）。
分析结果表明，全球范围内大麻效力近期持续增加。
