But they warn that this could create "severe workforce planning challenges" for the NHS, which has traditionally relied on international medical graduates, especially in the less popular specialties such as psychiatry.
These papers are published following the RCGP being cleared of ethnic discrimination in clinical skills assessment. A High Court judge has ruled that the assessment required to become a GP in the United Kingdom does not unlawfully discriminate against ethnic minority candidates.
The healthcare workforce is becoming increasingly international and globalised. In the UK, in 2012, 37% of the doctors registered with the GMC qualified in other countries, with 27% obtaining their medical degree from outside the European Economic Area (EEA). The studies were carried out by researchers from University College London, University of Cambridge and Durham University.
In order to practise in the UK, doctors who qualify outside the EEA must pass the IELTS (International English Language Test System) exam and both parts of the General Medical Council (GMC) Professional and Linguistic Assessment Board (PLAB) test.
The PLAB test is designed to ensure that overseas doctors demonstrate the same level of medical knowledge and clinical skills as UK graduates who have completed their first foundation training year (F1).
It is already known that international medical graduates perform less well than UK graduates in postgraduate Royal College exams. International medical graduates are also more likely to be referred to the GMC for concerns relating to fitness to practice. However, the reasons for this are not clear.
Two studies published on bmj.com today attempt to assess whether the PLAB test results in equivalent postgraduate performance between doctors who qualified overseas and those who qualified from UK medical schools.
The first, by researchers at University College London and the University of Cambridge, linked PLAB data with data from the three Royal Colleges of Physicians and the Royal College of General Practitioners (RCGP) to compare performance of international (PLAB) graduates with UK graduates at the MRCP(UK) and MRCGP exams.
They found that PLAB is a valid assessment of medical knowledge and clinical skills and a good predictor of performance at MRCP(UK) and MRCGP. However, PLAB graduates performed substantially less well at MRCP (UK) and MRCGP, so that career progression was not equivalent.
They suggest that equivalent performance in MRCP(UK) and MRCGP would occur if the PLAB pass marks were raised considerably, but acknowledge that this would also reduce the pass rate, which would have workforce implications.
Getting the standard of PLAB at a correct level "is fundamental to ensuring the quality of postgraduate medical education and training, the delivery of medical care of the highest quality, and thus ensuring patient safety in the NHS," they conclude.
In the second study, researchers at the Durham University linked Annual Review of Competence Progression (ARCP) data with PLAB test performance and demographic data held by the GMC to compare postgraduate performance between international and UK medical graduates.
The study found that international medical graduates with better English language test performance, higher scores on the PLAB and fewer resits tended to have more satisfactory ARCP outcomes. However, they also show that the PLAB test does not currently result in equivalent performance between international and UK medical graduates.
Some, but not all, of the differences in ARCP performance "may be explained by disproportionately high membership exam failure rates, especially in psychiatry and general practice," they say.
Dr Paul Tiffin, Clinical Senior Lecturer in the School of Medicine, Pharmacy and Health at Durham University, said: "Further research is needed to understand the potential reasons for these differences in performance, and in particular, the possible role that language and culture may play. A more detailed analysis based on country, not just region, of qualification would also be important to conduct in the future." He adds: "There may be better ways of supporting overseas doctors to adjust to UK culture, and that of the health service more quickly."
Professor John McLachlan, Co-Director of Centre for Medical Education Research at Durham University, said: "It is important to appreciate that from patients' points of view, cultural differences are not absolutes. For instance, a doctor from a particular cultural background may be able to provide particularly valuable care to patients from the same background, be it ethnicity, socio-economic class or first language."