post hoc解析とは
post hoc（事後）解析とは、臨床研究で当初予定してなかった解析を、データが取得された後で行うことです。post hoc解析には2種類あり、一つは当初予測できていなかった興味深い関係がありそうだと思ったときに、計画していなかった変数に関して解析を行うことです。つまり新しい仮説を検証することになります。もう一つは、全てのデータを解析するのでなく、被検者を何らかの方法でこまかくグループに分けて、特定のグループ（すなわち、サブグループ）に関してのみ仮説を検証するための統計学的な解析を行うことです。
AI による概要
Post-hoc analyses can involve both the re-examination of subgroups and the testing of unplanned new variables (or hypotheses) that were not specified in the original study plan. The term “post hoc” (Latin for “after this”) means the analysis is conducted after the data has been collected and examined.
The main characteristics are:
Unplanned Nature: The crucial aspect is that these analyses were not part of the original, pre-specified research protocol or statistical analysis plan. The ideas for the analyses often arise from observing interesting or unexpected patterns in the data after the main trial analyses are performed.
Subgroup Analysis: A common form of post-hoc analysis is to examine findings within specific subgroups of the study population (e.g., whether a drug works better in older adults vs. younger adults, or men vs. women) to see if the treatment effect differs among them.
Testing New Variables/Hypotheses: Researchers might also explore relationships between variables or outcomes that were not the primary or secondary endpoints of the original study.
Due to their unplanned nature and the potential for multiple comparisons, post-hoc analyses have a higher risk of producing false positive results (findings that appear significant by chance alone). Therefore, their findings are generally considered hypothesis-generating for future research, rather than definitive proof, and should be interpreted with caution.
ad hoc サブグループ解析
investigators frequently use analyses of subgroups of study participants to extract as much information as possible. Such analyses, which assess the heterogeneity of treatment effects in subgroups of patients, may provide useful information for the care of patients and for future research. However, subgroup analyses also introduce analytic challenges and can lead to overstated and misleading results. This report outlines the challenges associated with conducting and reporting subgroup analyses, and it sets forth guidelines for their use in the Journal.
Statistics in Medicine — Reporting of Subgroup Analyses in Clinical Trials Authors: Rui Wang, M.S., Stephen W. Lagakos, Ph.D., James H. Ware, Ph.D., David J. Hunter, M.B., B.S., and Jeffrey M. Drazen, M.D.Author Info & Affiliations Published November 22, 2007 N Engl J Med 2007;357:2189-2194 DOI: 10.1056/NEJMsr077003 VOL. 357 NO. 21 https://www.nejm.org/doi/full/10.1056/NEJMsr077003
In clinical trials, it is not uncommon that the primary analysis fails to achieve the study objective for demonstrating the safety and efficacy of a test treatment under investigation, while a specific sub-population analysis shows a significant positive result.
（A Proposal for Post Hoc Subgroup Analysis in Support of Regulatory Submission. Therapeutic Innovation & Regulatory Science, 13 Sep 2022, 57(2):196-208 https://doi.org/10.1007/s43441-022-00459-0 PMID: 36100794 ）
- Post Hoc Subgroup Analysis and Identification—Learning More from Existing Data Proceedings 2023, 91(1), 422; https://doi.org/10.3390/proceedings2023091422 Login to Jenni Published: 9 April 2024 https://www.mdpi.com/2504-3900/91/1/422
- JNCI Cancer Spectr. 2023 Nov 25;7(6):pkad100. doi: 10.1093/jncics/pkad100 Characteristics of post hoc subgroup analyses of oncology clinical trials: a systematic review https://pubmed.ncbi.nlm.nih.gov/38006333/ Subgroup analyses in clinical trials assess intervention effects on specific patient subgroups, ensuring generalizability. However, they are usually only able to generate hypotheses rather than definitive conclusions.
- A Proposal for Post Hoc Subgroup Analysis in Support of Regulatory Submission September 2022Therapeutic Innovation and Regulatory Science 57(2) DOI:10.1007/s43441-022-00459-0 https://www.researchgate.net/publication/363531808_A_Proposal_for_Post_Hoc_Subgroup_Analysis_in_Support_of_Regulatory_Submission
- Exploratory subgroup analysis: Post-hoc subgroup identification in clinical trials Alex Dmitrienko (Quintiles) Ilya Lipkovich (Quintiles) EMA Expert Workshop 2014 https://www.ema.europa.eu/en/documents/presentation/presentation-exploratory-subgroup-analysis-post-hoc-subgroup-identification-clinical-trials-alex-dmitrienko-ilya-lipkovich_en.pdf
参考
- 第12回（最終回特別編）EBMに潜む八つのワナ～論文を正しく読むコツ～2014/08/18 日経メディカル https://medical.nikkeibp.co.jp/leaf/mem/pub/series/noto/201408/537922.html 研究で実証できるエンドポイントは一次エンドポイントだけ 二次エンドポイントは仮説を実証するものではなく示唆するオマケにすぎない 後付け（post hoc）解析は情報バイアスが極めて大きいため、仮説検証ではなく仮説提唱・探求に過ぎない
- 7 サブグループ解析 オンライン版の R によるメタ分析：ハンズオン https://bookdown.org/content/25561078-f6d8-4a13-b4bd-45ebbc1b05c8/subgroup.html 固定効果（複数）モデルは、ランダム効果（サブグループ内）と固定効果（サブグループは固定されていると仮定されているため）の両方を含むので、文献上では混合効果モデル (mixed-effects model) としても知られている。
- ホーム カテゴリーなし サブグループ解析とはサブグループ解析とは何か＋失敗を防ぐには https://www.questionpro.com/blog/ja/ https://www.questionpro.com/blog/subgroup-analysis/ サブグループ解析とはサブグループ解析とは何か/ サブグループ解析は、2つのタイプに分類することができます： １．事前指定あり ２．ポストホックです。
post-hoc sub-analysisの例
- Blood pressure reduction with empagliflozin in Japanese patients with type 2 diabetes and cardiovascular diseases: a post-hoc sub-analysis of the placebo-controlled randomized EMBLEM trial Brief Communication Special Issue: Current evidence and perspectives for hypertension management in Asia Published: 24 May 2024 https://www.nature.com/articles/s41440-024-01725-4
サブ解析とサブグループ解析は同じ？
AIによる概要
「サブ解析」と「サブグループ解析」は、一般的に同じ意味で使われます。どちらも、データ全体の中から特定の属性を持つ集団（サブグループ）を抽出して分析する手法を指します。
サブグループ解析：試験参加者全体から、年齢、性別、疾患の重症度などの特定の属性を持つ集団を分ける分析方法です。
目的：特定のサブグループに対して、介入の効果がどのように異なるか（介入群間差の一様性）を確認すること。人種、年齢、性別など、様々な属性を持つ集団で結果がどのように異なるかを確認すること。