In a paper in the British Medical Journal, ethics researchers say doctors can be paid thousands of pounds per patient by pharmaceutical companies.

They say well-organised general practices can earn up to £15,000 a year for work that takes just three hours a week.

The researchers, from the West Midlands Multicentre Research Ethics Committee, say they have heard anecdotal evidence that some hospitals depend on the regular income they receive from clinical trials.

The researchers say being paid could influence a doctor's decision to join a trial, and the payments involved in commercial studies could mean that research which does not offer payments could fail to attract medics.

Time payment

Royal College of Physicians guidelines say per capita payments, which reward doctors for the number of patients they recruit, are unethical.

The rules add payment for time spent working on trials is acceptable, but should be declared to a research ethics committee.

The researchers say commercial companies effectively do pay per capita, saying they are paying for the work involved in conducting the trial rather than for recruiting patients, then overestimating the amount of time required for each patient.

Many patients also believe such payments are wrong.

An American study found 80% of patients felt they had a right to know if their doctor would be paid for enrolling them in a study.

Just over half said payments to clinicians were unacceptable.

The most common scenario where doctors are offered payments is for so-called postmarketing (Phase IV) research, which takes place once a drug has been licensed.

The aim is to familiarise doctors with the new drugs.

Pharmaceutical companies say this work has to be carried out as research and not as part of the system of monitoring new drugs, because that may not pick up every adverse reaction or problem with a drug.

The researchers add there would be no opposition to changes to regulations to make disclosure mandatory.

Frank disclosure

In the BMJ, the researchers write: "A system that allows commercially driven and clinically dubious research to crowd out good and much needed clinical trials, and denies patients the opportunity to put their altruism to the best possible test, is unethical and unacceptable."

They add: "If we are ever to reach the ideal of involving patients in the design and conduct of clinical trials then we could do worse than to treat patients as equal partners by making full and frank disclosure if payments that trial sponsors make to doctors for recruiting their patients."

Dr Jammi Rao, chairman of the West Midlands Multicentre Research Ethics Committee who led the study, told BBC News Online: "At the moment the guidelines and requirements of the Central Office for Research and Ethics Committees do not make it explicit that the amount of money a doctor is paid has to be put in the patient information form."

He added that, in contrast, patients sometimes found it hard to be reimbursed for taking part in studies.

"I find it absolutely appalling that patients get paid only 'reasonable' expenses, and have to give receipts for those things."

Dr Michael Wilks, chairman of the British Medical Association's medical ethics committee said: "I think this is a grey area but it would be helpful to reform it in the direction of openness to patients.

"There can't be any harm in putting the facts before the patients.

"I wouldn't think it's going to affect very many patients' decision about being recruited into trials."