What consent forms actually score on readability tests

An eighth-grade reading level is the standard most guidance points to for informed consent documents. A cross-sectional analysis of 14 real consent forms for ketamine trials in mental health conditions, pulled directly from ClinicalTrials.gov, found that 13 of them exceeded it.

The actual numbers behind "too complex"

The study measured readability across several established metrics, not just one. Flesch-Kincaid grade level ranged from 5.7 to 11.5 across the 14 forms, with a mean of 9.8, well above the eighth-grade target and, for several forms, closer to a university reading level. The Gunning Fog Index, another standard readability measure, ranged from 7.7 to 13.8, mean 11.7. The Flesch Reading Ease score, where higher numbers mean easier reading, averaged 52.8, generally considered "fairly difficult" on the scale's usual interpretation.

Length compounded the problem. Document length ranged from 1,681 to 8,637 words, averaging 5,031, translating into an average reading time of 21.4 minutes, with some forms taking as long as 36 minutes to read at a typical pace. That's a substantial amount of dense material to ask a prospective participant to process and genuinely understand before signing, particularly relevant given the population in this specific study, psychiatric patients, some of whom may have compromised cognitive capacity that the authors specifically flagged as a reason this matters more, not less, for this population.

The researchers' recommendation was direct: sponsors and ethics committees should require consent materials to meet an eighth-grade reading level, verified by a documented readability assessment before approval. Not aspired to. Verified, with an actual assessment on file.

Simplification isn't a compromise on what gets communicated

A natural worry about simplifying consent language is that something gets lost, nuance, precision, the legal completeness the document exists to provide. An earlier study addressing informed consent simplification directly tested this concern and found it doesn't hold up. Comprehension, measured both objectively and through participants' own sense of how well they understood the material, was significantly higher with simplified consent forms than with standard ones.

The more interesting finding sits in who benefited. The interaction between consent form type and health literacy level on understanding was not significant, meaning simplification didn't just help people with lower health literacy catch up to those with higher literacy. It improved understanding across the board, for participants regardless of where they started. That reframes what simplified language is actually for. It isn't an accommodation for a subset of participants who might otherwise struggle. It's a better default for everyone, and the specific techniques the study used to achieve it, plain language, short sentences, diagrams, pictures, and bullet points, are concrete, learnable techniques rather than a vague instruction to "write more simply."

Why this gap persists despite being well documented

Neither of these findings is new in the sense of being a surprising discovery. The eighth-grade guidance has existed for years, and the case for simplification's universal benefit has been demonstrated for even longer. What the ketamine trial analysis shows is that documented best practice and actual practice remain far apart in real, currently registered trials, not a hypothetical worst case.

Part of the explanation is likely structural rather than a simple failure of will. Legal and regulatory language tends to accumulate protective clauses over successive amendments and reviews, each individually reasonable, collectively producing a document that reads like it was written to survive scrutiny rather than to be understood by the person signing it. A consent form assembled this way, revised amendment by amendment over a study's lifetime, will drift toward complexity by default unless something actively pulls it back, since removing language feels riskier to whoever's approving the next revision than leaving it in.

What this means for how a consent form actually gets produced

A few concrete steps follow from putting these findings together:

• Run an actual readability assessment before approval, not just a legal review. The ketamine trial researchers' recommendation to verify an eighth-grade level with a documented assessment is a specific, checkable step, not a vague aspiration, and readability tools that calculate Flesch-Kincaid or similar scores are widely available and simple to apply.
• Treat simplification as a benefit for every participant, not an accommodation for some. The non-significant interaction with health literacy level means there's no meaningful trade-off to weigh here between "keeping it accessible for some" and "keeping it precise for others."
• Use the specific techniques shown to work: plain language, short sentences, diagrams, and bullet points, rather than treating simplification as purely a subjective editing judgement.
• Revisit consent language at each amendment, not just add to it. A document that only ever grows across successive revisions will keep drifting away from readability regardless of how well it started.

The underlying message is a genuinely encouraging one, even though the ketamine trial's findings are stark: this isn't a problem without a known fix. The techniques exist, the evidence that they work is solid, and the gap is one of consistent implementation rather than an unsolved question.