統計的力,サンプルサイズ,およびランダム化制御試験におけるその報告
D Moher1, C S Dulberg, G A Wells
1Clinical Epidemiology Unit, Loeb Medical Research Institute, Ottawa Civic Hospital, Ontario, Canada.
JAMA
|July 13, 1994
まとめ
陰性結果のランダム化対照試験 (RCT) のほとんどは,十分な統計力および適切なサンプルサイズ計算が欠けている. サンプルサイズ計算の報告は改善されていますが,有意義な差異を検出する能力は,時間の経過とともに低いままです.
科学分野:
- 医学研究方法論 医学研究方法論
- 臨床試験のデザイン
- 医学における統計分析
背景:
- ランダム化対照試験 (RCT) は,エビデンスベースの医学にとって極めて重要です.
- RCTの負の結果は,統計的パワーとサンプルサイズに関して慎重に解釈する必要があります.
- 統計力の報告とサンプルサイズの計算の動向を評価することは,研究の質を改善するために不可欠です.
研究 の 目的:
- 統計力の動向とサンプルサイズ計算の動向を分析するために,公表されたRCTでネガティブな結果を報告する.
- ネガティブなRCTにおけるサンプルサイズが時間とともに適切であるかを評価する.
- ネガティブなRCTにおける臨床的意義の報告を評価する.
主な方法:
- 1975年,1980年,1985年,1990年に主要な医学雑誌 (JAMA,Lancet,NEJM) に掲載されたRCTの記述的調査.
- 単純な2グループ並列設計による負の結果試験の統計力の計算.
- 試験結果を分類し,主要なアウトカムを特定するための基準の開発.
主要な成果:
- 審査されたRCTの27%が否定的な結果をもたらし,その割合は安定したままでした.
- ネガティブな結果の試験の16%と36%だけが,相対的な差異をそれぞれ25%と50%検出するのに十分なパワー (80%) を持っていました.
- サンプルサイズ計算の報告は1975年の0%から1990年の43%に改善したが,臨床的意義については否定的な試験の20%しか議論されなかった.
結論:
- ほとんどのネガティブなRCTは,臨床的に重要な差異を検出する能力が不足しており,この状況は時間とともに変わっていません.
- サンプルサイズの計算に関する報告の改善が認められているが,統計力は依然として不十分である.
- ネガティブなRCTにおける統計的力,サンプルサイズ計算,臨床的有意性に関する報告を強化する必要がある.
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