Background: Cooperative group (CG) provided consent forms (CGP-CFs) undergo re-review and revision by local institutional review boards (IRB) before institutional approval. We compared the relative readability and length of IRB-approved consent forms (IRB-CFs) used at seven academic institutions with their corresponding CGP-CFs. We also assessed the variability of these metrics across our institutions.
Methods: This study included 197 consent forms (CFs) from 56 CG trials that were open in at least two of the participating institutions. The Flesch Reading Ease Score (FRES), the Flesch-Kincaid Grade Level (FKGL), and document length were collected on all CFs. Unpaired t test was used to compare length and readability of CGP-CF with the IRB-CF. Analysis of variance and Bonferroni-Dunn tests were used to assess interinstitutional variability in readability for all IRB-CFs. All statistical tests were two-sided.
Results: IRB-CFs were statistically significantly longer than CGP-CFs (mean number of pages = 17 vs 13; P < .001). Mean FKGLs were higher (10.3 vs 9.4; P < .0001) and the mean FRESs were lower (53.1 vs 57.1; P < .0001) for IRB-CFs compared with CGP-CFs. Readability varied statistically significantly between institutions for all sections of the IRB-CF (P < .0001). Finalized IRB-CFs for identical clinical trials at different institutions demonstrated substantial heterogeneity of readability and length.
Conclusions: As CFs progress from National Cancer Institute (NCI)-sponsored CGs to local IRBs, they seem to become longer and less readable. Interinstitutional heterogeneity in CF readability is substantial and widespread. More consistent adherence to CGP-CFs based on the newly revised NCI CF template with minimal modification by local IRBs should help simplify and standardize CFs used in cancer clinical trials.