Terminology changes may affect reusability of data, hence the need for methods for managing changes. Along these lines, we have developed a formal representation of the concept-term relationship, around which we have also developed a methodology for management of terminology changes. We have implemented our methodology in a terminology maintenance tool. To evaluate our methodology, we compared two methods for retrieving ICD-9-CM data, based on their recall when retrieving data for ICD-9-CM terms whose codes had changed but which had retained their original meaning. Our results show that recall is either the same or better with a retrieval method that takes into account the effects of terminology. Statistically significant differences were detected (p<0.05) with the McNemar test for two terms whose codes had changed. Furthermore, when all the cases are combined in an overall category, our method 2 also performs statistically significantly better than default method 1 (p < 0.05).