Clinical Outcome Assessments (COAs) are important for evaluating the impact of medical interventions on patients’ well-being and quality of life. To ensure their effectiveness and accuracy, we must consider the readability of these assessments in their development for new cultural or linguistic contexts.

A readability assessments can assess the ease of understanding of a COA for different target populations, ensuring that patients can meaningfully engage with the instruments.

Why assess for readability?

  • Enhance Patient Understanding

Identifying potential barriers to patient understanding is important – complex language or ambiguous phrasing can hinder patients’ comprehension, leading to misinterpretations or incomplete responses.

  • Improve Data through Patient Engagement

When COAs are written in a way that aligns with patients’ literacy levels, age, or degree of cognitive impairment, it promotes active participation and encourages patients to provide more detailed and accurate responses.

  • Increase Patient Satisfaction

By making COAs easier to read and understand, patients feel empowered and engaged in their own healthcare – enhancing satisfaction with the healthcare experience.

  • Enhance Equity and Inclusivity

Assessing readability ensures that COAs are accessible to patients from diverse backgrounds, including those with varying educational levels and health literacy. It promotes equity by reducing disparities in patient engagement and allowing a broader range of individuals to provide insights into their health experiences.


How can we achieve this?

  • Readability Formulas

Formulas such as Flesch-Kincaid Grade Level, Gunning Fog Index, and Simple Measure of Gobbledygook (SMOG) calculate the complexity of text based on factors like sentence length, word difficulty, and syllable count. They provide a quantitative measure of readability, indicating the grade or reading age required to understand the text.

However, these types of readability formulas aren’t optimized for the structure of COAs, so may provide estimates that aren’t fully interpretable in their context.

  • User Testing

User testing involves direct engagement with the target population to assess their understanding of the COAs. This qualitative approach provides insights into comprehension, highlighting any areas of difficulty.

By observing patients as they interact with the COAs, researchers can identify specific language or concept-related challenges and make necessary revisions to improve the overall readability.

  • Plain Language Guidelines

Following plain language guidelines is an effective way to enhance readability of COAs. These emphasize using concise and jargon-free language, avoiding complex sentence structures, and organizing information in a logical manner. Adhering to plain language principles ensures that COAs are accessible to individuals with diverse reading abilities, including those with limited health literacy.

  • A Convergent Methodology

Although readability testing is recommended by the European Commission and FDA in certain contexts (e.g., the development of PILs or medication labelling) these bodies offer only general guidance regarding specific readability testing methodologies, which can lead to varied implementations and interpretability of results.  Ideally, we should use a readability testing methodology that combines convergent qualitative and quantitative measures.


Readability assessments in the development phase are crucial for ensuring their accessibility and comprehension. Investing in these assessments ultimately leads to more successful translations, and effective communication across cultures.

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The International Society for Quality of Life Research (ISOQOL) is a global community of researchers, clinicians, health care professionals, industry professionals, consultants, and patient research partners advancing health related quality of life research (HRQL).

Together, we are creating a future in which patient perspective is integral to health research, care and policy.