“Princess and the pea” – an assessment tool for palpation skills in postgraduate education

BACKGROUND: In osteopathic medicine, palpation is considered to be the key skill to be acquired during training. Whether palpation skills are adequately acquired during undergraduate or postgraduate training is difficult to assess. The aim of our study was to test a palpation assessment tool developed for undergraduate medical education in a postgraduate medical education (PME) setting. METHODS: We modified and standardized an assessment tool, where a coin has to be palpated under different layers of copy paper. For every layer depth we randomized the hiding positions with a random generator. The task was to palpate the coin or to determine that no coin was hidden in the stack. We recruited three groups of participants: 22 physicians with no training in osteopathic medicine, 25 participants in a PME course of osteopathic techniques before and after a palpation training program, 31 physicians from an osteopathic expert group with at least 700 h of osteopathic skills training. These experts ran the test twice to check for test-retest-reliability. Inferential statistical analyzes were performed using generalized linear mixed models with the dichotomous variable “coin detected / not detected” as the dependent variable. RESULTS: We measured a test-retest reliability of the assessment tool as a whole with 56 stations in the expert group of 0.67 (p < 0.001). For different paper layers, we found good retest reliabilities up to 300 sheets. The control group detected a coin significantly better in a depth of 150 sheets (p = 0.01) than the pre-training group. The osteopathic training group showed significantly more correct coin localizations after the training in layer depths of 200 (p = 0.03) and 300 sheets (p = 0.05). This group also had significantly better palpation results than the expert group in the depth of 300 sheets (p = 0.001). When there was no coin hidden, the expert group showed significantly better results than the post-training group (p = 0.01). CONCLUSIONS: Our tool can be used with reliable results to test palpation course achievements with 200 and 300 sheets of paper. Further refinements of this tool will be needed to use it in complex assessment designs for the evaluation of more sophisticated palpatory skills in postgraduate medical settings.