Seeing the unseen: hidden disabilities as a diversity factor in clinical trials

Diversity, equity, and inclusivity is critical in clinical trial conduct. Not just a way to improve reputation or a regulatory requirement, but a cornerstone of developing medicines for people who need them most.

We read clinical trial diversity action plans all the time. They’re generally comprehensive and well-considered. But there’s a gap. Often, they focus on the diversity factors we can see – race, age, and sex. But what about all the other factors that make us unique?

The WHO estimates that around 16% of people have a disability, and up to 80% of these are non-visible (including neurodiversity and chronic conditions). That’s over 1 billion people who need equal access to healthcare and, by extension, clinical trials.

But deliberate exclusions are very real

Clinical trials have eligibility criteria for good reason – to protect participant safety, adherence, and the validity of results.

However, 1 in 3 trials actively exclude people with disabilities (the majority due to behavioural or psychiatric conditions), often based on poorly defined or subjective criteria.

Equally, there are gaps in our understanding of the lived experiences of people with invisible conditions. 1 in 3 people living with chronic pain also have depression. However, such patients are excluded from almost 60% of chronic pain trials.

This all creates friction and frustration for otherwise eligible participants, uneven ground for site staff responsible for screening, and risks unbalancing medicines development long-term.

Many are being accidentally excluded too

Diversity conversations cannot focus solely on who is invited to enrol – they must also cover who can sustain participation.

Participant burden in clinical trials (routine procedures, lab work, questionnaires, visit length) has grown steadily over the past 15 years, often in the interest of serving secondary or exploratory endpoints. Burden of visits and procedures is a well-known, universal retention factor in clinical trials.

It’s fair to conclude that this burden is amplified in people living with long-term conditions and fluctuating health. For example:

• Rheumatoid arthritis flares are unpredictable, and make it difficult to balance daily responsibilities
• Fatigue is an overwhelmingly common impact of lupus, especially during flares
• For people with chronic fatigue syndrome, the exhaustion that comes after even minor physical exertion can last days or even weeks

The burden of study visits may not be immediately obvious, but in many cases, the delayed consequences could affect subsequent visits and retention long-term.

Clinical study sites are often busy, hectic places, and even the environment can have an impact. Up to 90% of people with autism have sensory sensitivities to things like noise, smells, or fluorescent lighting, and lack of autonomy over sensory environments can make daily tasks much more challenging.

Treating people with invisible conditions as equal partners in clinical research means understanding their needs as a whole. If a person with autism is taking part in an asthma trial, is there an appropriate environment to meet their sensory needs? If someone with chronic fatigue is in a dermatology trial, are the visits, tests, and procedures flexible enough to minimise their exertional burden?

It may feel like common sense to just ask people what they need. However, many people do not disclose invisible traits due to fear of stigma, and people living with fluctuating health often struggle to communicate physical, emotional and cognitive changes. Equally, there is evidence that site staff sometimes have only a superficial understanding of how invisible conditions impact daily life – and fewer than half of trial participants with disabilities report being asked about their preferences and support needs.

This creates a Catch-22. How do we address the needs of people with non-visible disabilities if they’re not disclosed? And why would clinical trial participants feel comfortable disclosing them unless there’s evidence we’re addressing them?

So what can be done?

Just as people with non-visible conditions may be underrepresented in clinical trials, their needs and preferences are still somewhat underrepresented in the discourse.

But there are many ways to turn the insights we do have into action:

• Carefully consider eligibility criteria in line with the lived experience of your target population. Ensure exclusions are scientifically sound, and support them with robust, objective guidance
• Invest in communications training for site teams to help them create environments of trust and support, so participants feel comfortable to disclose any invisible disabilities, and confident in discussing their needs and wants. Where feasible, explore discrete signposts like lanyards so staff can be aware of invisible disabilities without participants having to constantly re-disclose
• Consider whether all your procedures are essential, especially if they’re for secondary or exploratory endpoints. Where possible, build in flexibility for protocol deviations, or the possibility of “low intensity” participant cohorts
• Build in “adjustment check-ins” during screening processes and other scheduled touchpoints, such as pre-visit calls, to identify triggers for things like flare-ups early and take precautions to manage them  
• Explore decentralised trial design models, where appropriate, like home visits or remote check-ins. But remember that the relationship between participants and their site teams is critical, no matter the model. Decentralisation should always be explored as an option, not an obligation
• Don’t assume a standard base rate reimbursement for participants; take into consideration additional or more accessible transport and accommodation needs, which may fluctuate from one visit to the next  

In short, building your protocol and participant engagement strategy with invisible disabilities in mind is not just being “patient-friendly”. It’s an opportunity to improve recruitment and retention, and support equitable healthcare for over 1 billion people.

If you’d like to explore any of these ideas in more detail, let’s talk.

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