Have information sheets changed over time?

Our data demonstrate that information sheets have grown longer over time. This may be a result of the increasing focus on patient safety – what some might term risk aversion – over the period of study. ^{Reference Glasziou and Chalmers19,Reference Hearnshaw20} This is noteworthy because previous research found that more detailed information sheets are less well understood than briefer versions. ^{Reference Mann1–Reference Rogers, Tyson, Kennedy, Broyles and Hickman3} Longer information sheets are also less likely to be read. ^{Reference Dresden and Levitt2,Reference Sharp4} Taken with these findings, our results imply that participants' understanding may have actually decreased over time. This is a hypothesis that needs testing, as it has implications for ethics committee advice. On the positive side, information sheets do not appear to have become more complex over time.

Is readability affected by study characteristics?

Information sheets for studies investigating dementias and intellectual disabilities were easier to read than studies in some other areas. This is unsurprising, since many studies belonging to this CSG used simplified language supported with lots of pictures. However, even with this adjustment, information sheets in this CSG only crept into the ‘standard’ range of reading difficulty (Flesch index score 61–70), ^{Reference Flesch15} requiring an estimated reading grade of 9 or 13–14 years old. Information sheets for all other CSGs were firmly in the ‘fairly difficult’ category (Flesch index score 51–60). In addition, the mean score for the most complex section in every CSG fell into the ‘difficult’ category (Flesch index score 31–50).

Our data also show that the information sheets for observational studies were significantly shorter than some other types. This is unsurprising since observational studies need not describe interventions, the process of group allocation or masking procedures. Perhaps more interesting is the average length of information sheets for studies including a pharmacological or device intervention – a staggering 3000 words. Pharmacological and device intervention studies also performed poorly with regard to the most complex section, with the average score falling into the ‘very difficult’ category (0–30). Texts scoring in this range are comparable to scientific writings. ^{Reference Flesch15} This is of particular importance since more complex information sheets tend to accompany studies which carry the most risk. ^{Reference Mader and Playe21}

Higher levels of patient involvement seem to facilitate briefer information sheets. This could be a product of patients reviewing information sheets and commenting on sections which could be shortened. It is interesting to note, however, that patient involvement did not seem to mitigate against complex information sheets overall nor against very dense sections of text.

Collapsing the groups used in this study, the average whole-sheet Flesch index score was 59, corresponding to US grade 10, or a reading age of 15–16 years old. This is higher than the UK national reading age of US grade 8, or 13–14 years old. ^{Reference Williamson and Martin22} It is also markedly higher than the recommended reading age for patient information texts (US grade 6, or 10–11 years). About 89% of the information sheets in our sample were at or above the national reading age, and 96% were at or above the recommended age for patient information texts.

The most complex sections of information sheets were very demanding. On average they scored 42 on the Flesch index, which corresponds to a reading age of 18–19. One information sheet we analysed scored 73 (fairly easy) for the whole sheet but a dismal 12 (very difficult) for the most complex section, showing how important it is to consider the complex section in any analysis.

Despite the poor performance of the information sheets we analysed, the results were better than those reported by others. A study of mental health research recorded a mean Flesch index score of 48, or grade 12. ^{Reference Christopher, Foti, Roy-Bujnowski and Appelbaum8} Similarly, oncology studies scored 45, ^{Reference Sharp4} anaesthesia research a reading grade 12, ^{Reference Taylor and Bramley10} and one cross-discipline French study actually reported a median Flesch index score of 24 (very difficult). ^{Reference Sharp4} We have examined the methods of these studies and they are comparable to our own. The different results might therefore be attributed to variation in the composition of study samples. It seems likely, for example, that a sample of anaesthesia studies would contain more clinical trials than our own sample.

There are a number of techniques to reduce the reading age of information sheets which are obvious – using shorter words, sentences and paragraphs and replacing complex medical and research terms with simple words. ^{Reference Hartley and Burnhill23} Unfortunately, the UK Health Research Authority (HRA) in the UK issue only vague guidance on the drafting of information sheets. ²⁴ For example, they unhelpfully suggest that ‘A participant information sheet should be as long as it needs to be’. Nor do the HRA recommend a particular Flesch index range, although they do advocate use of the measure to ‘help improve readability of your information sheet’. The University of Michigan already provides a guide for simplifying medical terms. ²⁵ A similar glossary could be produced to include research terms such as ‘randomisation’ and ‘double-blind’. In the Appendix, we demonstrate that it is possible to dramatically improve the readability of complex passages without extending – and in some cases reducing – overall length. In one case, we were able to increase the Flesch index score from 18.9 (very difficult) to 73.6 (fairly easy).

Does readability have implications for recruitment?

Our analysis showed that the complexity of information sheets had little bearing on successful recruitment. The odds ratio of one indicates that even very large changes in Flesch index score are unlikely to affect the chances of recruitment success. Our results therefore suggest that information sheet complexity, at least as measured by the Flesch index, remains an ethical problem rather than an ingredient for study success.

We found that studies including a pharmacological or device intervention were less likely to have reached their target than observational studies even in this non-commercial funded dataset. Overall, however, this finding will not come as a surprise to many readers: difficulty in recruiting to drug trials is an enduring issue. ^{Reference Hunninghake, Darby and Probstfield26–Reference Treweek, Mitchell, Pitkethly, Cook, Kjeldstrøm and Taskila29} Qualitative studies have shown that some people dislike the idea of ‘being a guinea pig’, ^{Reference Roberson30} the rigidity of treatment regimes and the prospect of side-effects. ^{Reference Mills, Seely, Rachlis, Griffith, Wu and Wilson31}

Studies which included the highest level of patient involvement were more likely to have reached their recruitment target. This finding replicates our earlier work with a much larger sample, ^{Reference Ennis and Wykes14} which provides further evidence of the importance of this factor in recruitment success.

Limitations

There are two limitations to this study. The first is that the study did not investigate comprehension by real people but instead used an analogue – the Flesch index. Although the Flesch index is an accepted proxy for reading difficulty, actual comprehension in terms of a research study is impossible to capture with a formula. Information sheets are typically augmented by conversations with research or clinical staff at the point of consent. However, the information sheet is what the potential participant can take away from this encounter and if they do not understand it then there are clearly ethical implications. The second limitation concerns our findings relating to recruitment success. We have not conducted a randomised controlled trial, and therefore we cannot rule out confounding. We have tried to capture many different variables that are thought to be important in the largest observational study to date. Further information from qualitative or randomised studies would be helpful.

Policy and ethics implications

Information sheets are approved by ethics committees, and yet they tend to consist of text written at a level far higher than can be assumed of the average reader. Information sheets are also becoming longer, and this may further impede participants' understanding.

Some have suggested that their length and complexity are increasing because ethics committees and principal investigators now emphasise the legal, rather than communicative, aspects. ^{Reference Sharp4} In our study, the most complex section was often standardised content such as insurance arrangements or confidentiality policies. Other investigators have found that attempts to simplify these template passages are rejected because of concerns of how text alterations might affect the legality of the statements. ^{Reference Beyer, Lauer and Davis32} Clearly this creates an impasse whereby important legal text will never be understood. If this is the case, fear of litigation has distorted the real purpose of study information sheets, leaving review boards protected but participants uninformed.

Principal investigators and ethics committees must balance legal and ethical issues and we consider that this is now out of kilter. We therefore suggest that they critically review their standardised content. It is ethically unsound to allow such text to be included when it is clear that to understand it participants would need their own lawyers to provide an explanation.

Clearly, there is some way to go before information sheets are written to a standard which is likely to be understood by most potential participants. We did find that the information sheets we analysed were considerably easier to read than in some other recent studies, but this provides little solace as they were generally still much more complex than the recommended grade 6 level. Principal investigators and ethics committees must consider the length, complexity, and – most importantly – the purpose of information sheets if this standard is to be achieved.