Suggested terminology for talking about participation changes

What is it?

PeRSEVERE principle O1 says that everyone involved in clinical trials (in any capacity) should understand the potential complexities around participation changes, and that we should aim to use language that communicates these complexities.

In our project, we have developed some suggested terminology that could achieve this, and aims to be explicit in meaning the same thing to everyone.

Who is it for?

Everyone involved in clinical trials, in any capacity.

More details

In our experience, there can be confusion and ambiguity around terms commonly used to describe stopping study participation, such as ‘withdrawn’, ‘lost to follow-up’, ‘drop-out’ or ‘off-trial’.

In general, we aim in our guidance to describe participation ending or changing as plainly as we can, using language with explicit meaning which, as a result, can mean the same thing to everyone.

Some suggestions for clearer terminology are outlined in ‘Read more‘, below. We suggest these, or similarly clear terminology, could be used in many situations when designing, running, analysing and reporting studies, including in study protocols, study reports, and in communications between researchers and study participants.

This level of detail may not be necessary in all situations. For example, by the time of a study’s final analysis, it may be useful to simply summarise which participants we have study outcome data for and which we do not. However, use of the suggested terminology below does not prevent this sort of summarisation taking place when it is needed.

Read More

Change in participation status or just participation change can be used as general terms used to mean all instances where a participant makes a decision – communicated to researchers or not – to end or reduce study participation (or in some cases where a decision is made on their behalf).

For aspects of study participation requiring ongoing commitment (for example receipt of intervention, attendance at clinic visits, completion of questionnaires):

  • When a participant decides to completely stop an aspect of participation before it was supposed to finish, we suggest using the phrase “stopped … early”. For example “stopped study-specific visits early”.
  • In some cases it might be useful to distinguish between participation changes following a participant’s decision and changes (particularly to medical treatment or procedures) guided by clinical decisions of a participant’s doctors. For example, if a participant’s doctor decided it was in their best interests to stop receiving a study treatment, they could be described as having “stopped treatment early based on a clinical decision”.
  • When a participant decides to reduce their level of commitment, without totally having stopped, we suggest using the term “reduced…”. For example, “reduced frequency of study visits”. This can also be used to describe changes in receipt of study treatment or intervention, but study protocols often make specific provisions around dose delays or modifications (if this is the case, the protocol’s terminology should be used).
    • When some alternative, specific arrangement has been made with a participant regarding their participation, we suggest this should be explicitly stated, for example “stopped study visits early; telephone follow-up only”.
    • Alternatively, the general term “changed…” can be used, for example “follow-up changed from study visits to telephone follow-up only”.
  • When a participant has stopped an aspect of participation at the time that the study protocol specified it was supposed to stop, we suggest using “completed…”. For example, “completed study visits”.
    • In some studies, there may not be a set period of time when participants get treatment/intervention. For example, participants may continue receiving treatment until it does not seem to be working any more. In these cases, the idea of stopping treatment ‘early’ might not be quite right, but nor might it be right to say they have ‘completed’ treatment. In these cases, we suggest the phase “(permanently) stopped treatment because [of]…”. For example, “stopped treatment because it was no longer beneficial”, or “stopped treatment because of side-effects”.

For aspects of study participation that do not require ongoing, active commitment (for example clinical trials units getting additional data for the study from routine healthcare data providers like NHS digital, or biological samples being stored for future research projects) we suggest “no longer agrees to…”. For example, “the participant no longer agrees to have their biological sample stored for future research”.

Where a piece of research only involves this sort of activity, it may not be within the scope of the PeRSEVERE principles; see ‘Scope and limitations’. The suggestion here is more relevant where a research study involves these activities as well as other activities involving more ongoing, active commitment.

Loss of contact:

  • We expect study protocols to specify how to manage loss of contact with participants (this means without them having expressed any explicit wish about stopping study participation). This should include a set process to follow, and criteria for judging when to stop trying to contact someone (or stop for the time being). At this point, we suggest describing the person as having lost contact for now. This implies that it should be possible to try again at a later date to contact them, for example prior to the final study analysis. The study protocol should specify when this later contact should be.
  • At the end of the study, there may be a group of participants who lost contact with the study without explicitly asking to stop participating and for whom no further data was ever obtained. We suggest these participants could be described as having lost contact and never regained, with no further follow-up. 
  • If data about these participants is obtained through other sources (for example from routine healthcare data providers like NHS Digital, and always in line with participant consent), they might instead be categorised as having had lost contact and never regained, but with some indirect follow-up.