Evaluation of length and complexity of written consent forms in English and Hebrew for participation in clinical trials authorized in one medical institution in Israel: a descriptive study.

Informed consent forms (ICFs) in clinical trials are the only objective testimony whether the information provided to participants is comprehensive and presented in an accessible language. We evaluated the length of Hebrew ICFs and their English translations and evaluated the readability of the latter. In fifteen clinical trials (5 with pharmacogentic sub-study), the median number (IQR) of pages and words were: English clinical ICFs - 16 pages (13,18) and 7360 words (6959,8289); Hebrew clinical ICFs - 12 pages (10,14), 5807 words (5258,6403); English pharmacogenetics ICFs - 7 pages (4,11), 2930 words (2234,5100); Hebrew pharmacogenetics ICFs - 5 pages (4,8.5), 2273 words (1663,3889); the two English ICFs combined - 23 pages (18;29.5), 10820 words (9515,15600); and the two Hebrew ICFs combined - 19 pages (16,23), 8258 words (7340,10515). Differences between the Hebrew clinical trial ICFs and their English translations were significant (p<0.001). Median (IQR) Flesch Reading Ease scores for the clinical and the pharmacogenetics ICFs were 48.4 (42.7, 49.9) and 42.2 (41.7,42.65), respectively. Thirteen studies were multinational. Twelve were conducted simultaneously in the United States, where an assessment of readability scores is customary. In conclusion, the consent forms evaluated in this study were long, and readability scores were low.