RATIONALE, AIMS AND OBJECTIVES: The use of general clinical guidelines versus customization of patient care presents a dilemma for clinicians managing chronic illness. The objective of this project is to investigate the claim that the performance of customized strategies for the management of chronic illness depends on accurate patient categorization, and inaccurate categorization can lead to worse performance than that achievable using a general clinical guideline. METHODS: This paper is based on an analysis of a basic utility model that differentiates between the use of general management strategies and customized strategies. RESULTS: The analysis identifies necessary conditions for preferring general strategies to customized strategies as a trade-off between strategy performance and the probability of correct patient categorization. The analysis shows that customized treatment strategies developed under optimal conditions are not necessarily preferred. CONCLUSIONS: Results of the analysis have four implications regarding the design and use of clinical guidelines and customization of care: (i) the balance between the applications of more general strategies versus customization depends on the specificity and accuracy of the strategies; (ii) adoption of clinical guidelines may be stifled as the complexity of guidelines increases to account for growing evidence; (iii) clinical inertia (i.e. the failure to intensify an indicated treatment) can be a rational response to strategy specificity and the probability of misapplication; and, (iv) current clinical guidelines and other decision-support tools may be improved if they accommodate the need for customization of strategies for some patients while providing support for proper categorization of patients.