Public understanding and acceptance of randomisation

Although most health professionals accept that randomisation in clinical trials is important there is evidence that patients may not understand randomisation (either the word or the concept) and may not accept its validity. A study in North Staffordshire UK has shown that, while most people understand randomisation, many do not accept it.

The participants were 130 students at five further education and leisure courses. They varied in age from 18 to 70 years (mean 32 years) and in occupation from unskilled to professional. Two thirds were women. Participants were given two scenarios, one medical (referral to a consultant nearby or far away) and one non-medical (a free trip locally or to Spain) and asked to say which of five methods of allocation were random. The methods were selection by computer with no information about individuals, toss of a coin, drawing paper slips out of a hat, individual choice, and alternate allocation in turn. They were then asked to imagine they had been asked to take part in a clinical trial comparing two drugs, each of them known to be of value, to try to find out which drug was the better. The five methods of allocation were stated again and participants were asked to decide whether each method was acceptable. (It was left open whether that meant acceptable to the participant as a patient or acceptable as a feature of the trial.) Half of the participants were given a written justification for randomisation in clinical trials and half were not.

Most participants (73–92%) considered computer allocation, coin tossing, and drawing from a hat to be random methods. Most (77–92%) considered patient choice to be non-random. Participants were divided about allocation in turn. The answers were similar for the medical and the non-medical scenario. On the whole most people did not find any method of randomisation acceptable in a clinical trial. Among those who judged the randomness of each of the five methods correctly a minority (around one third) considered randomisation acceptable. Three quarters of the group considered that asking the patients to choose their own allocation was acceptable. When written justification of randomisation was given, the proportion of participants considering computer allocation to be acceptable rose to 58% but a majority still considered tossing a coin or drawing from a hat unacceptable.

Members of the general public mostly understand randomisation but balk at its use in clinical trials. Methods such as tossing a coin or drawing from a hat are considered too frivolous for medical use but computer allocation, after explanation, is more acceptable.