Objective To determine whether the use of the UK clinical aptitude test (UKCAT) in the medical schools admissions process reduces the relative disadvantage encountered by certain sociodemographic groups.

Design Prospective cohort study.

Setting Applicants to 22 UK medical schools in 2009 that were members of the consortium of institutions utilising the UKCAT as a component of their admissions process.

Participants 8459 applicants (24 844 applications) to UKCAT consortium member medical schools where data were available on advanced qualifications and socioeconomic background.

Main outcome measures The probability of an application resulting in an offer of a place on a medicine course according to seven educational and sociodemographic variables depending on how the UKCAT was used by the medical school (in borderline cases, as a factor in admissions, or as a threshold).

Results On univariate analysis all educational and sociodemographic variables were significantly associated with the relative odds of an application being successful. The multilevel multiple logistic regression models, however, varied between medical schools according to the way that the UKCAT was used. For example, a candidate from a non-professional background was much less likely to receive a conditional offer of a place compared with an applicant from a higher social class when applying to an institution using the test only in borderline cases (odds ratio 0.51, 95% confidence interval 0.45 to 0.60). No such effect was observed for such candidates applying to medical schools using the threshold approach (1.27, 0.84 to 1.91). These differences were generally reflected in the interactions observed when the analysis was repeated, pooling the data. Notably, candidates from several under-represented groups applying to medical schools that used a threshold approach to the UKCAT were less disadvantaged than those applying to the other institutions in the consortium. These effects were partially reflected in significant differences in the absolute proportion of such candidates finally taking up places in the different types of medical schools; stronger use of the test score (as a factor or threshold) was associated with a significantly increased odds of entrants being male (1.74, 1.25 to 2.41) and from a low socioeconomic background (3.57, 1.03 to 12.39). There was a non-significant trend towards entrants being from a state (non-grammar) school (1.60, 0.97 to 2.62) where a stronger use of the test was employed. Use of the test only in borderline cases was associated with increased odds of entrants having relatively low academic attainment (5.19, 2.02 to 13.33) and English as a second language (2.15, 1.03 to 4.48).

Conclusions The use of the UKCAT may lead to more equitable provision of offers to those applying to medical school from under-represented sociodemographic groups. This may translate into higher numbers of some, but not all, relatively disadvantaged students entering the UK medical profession.