Inter-observer variation in assessment of the prostate by digital rectal examination

In a prospective study, inter-observer variation in the assessment of the prostate by digital rectal examination (DRE) by a urologist and a general practitioner was analysed. The 2 physicians performed independent assessment of the prostate in 933 men aged 50 to 69 years with regard to 9 variables as part of a screening programme for carcinoma of the prostate. Complete agreement for all observations was reached in 46.5% of the men. Using kappa (K) statistics, the values were adjusted for the expected chance agreement. K values between 0.485 and 0.682 were obtained for 6 variables representing good agreement; these were size, tenderness, midline furrow, symmetry, induration and nodularity. Agreement regarding fixation, lateral sulci and seminal vesicles was poor owing to the small number of cases deviating from normal. Contrary to the general belief that DRE is highly subjective, our results show a good correspondence between the observations of the examiners when assessing the prostate in a systematic way.