Reproducibility of determining vitamin A status by impression cytology

Impression cytology is a simple technique for detecting vitamin A deficiency. Methods of specimen collection, fixation, and staining are amenable to use in developing countries. Routine use of the technique requires good interobserver agreement. We compared the impression cytology results of 206 patient examinations analyzed by an experienced observer with those obtained by a newly trained observer. Percent agreement measured 96% (197/206) with a kappa of 0.90, indicating excellent agreement. Further improvement in interobserver agreement may be obtainable by simplification of the staining process to highlight the presence or absence of goblet cells, and by simplification of the staging criteria.