With the increasing prevalence of chronic conditions, there is need for a standardized definition of chronicity for use in research, to evaluate the population prevalence and general practice management of chronic conditions. Our aims were to determine the characteristics required to define chronicity, apply them to a primary care classification and provide a defined codeset of chronic conditions. A literature review evaluated characteristics used to define chronic conditions. The final set of characteristics was applied to the International Classification of Primary Care-Version 2 (ICPC-2) through more specific terms available in ICPC-2 PLUS, an extended terminology classified to ICPC-2. A set of ICPC-2 rubrics was delineated as representing chronic conditions. Factors found to be relevant to a definition of chronic conditions for research were: duration; prognosis; pattern; and sequelae. Within ICPC-2, 129 rubrics were described as 'chronic', and another 20 rubrics had elements of chronicity. Duration was the criterion most frequently satisfied (98.4% of chronic rubrics), while 88.2% of rubrics met at least three of the four criteria. Monitoring the prevalence and management of chronic conditions is of increasing importance. This study provided evidence for multifaceted definitions of chronicity. While all characteristics examined could be used by those interested in chronicity, the list has been designed to identify chronic conditions managed in Australian general practice, and is therefore not a nomenclature of all chronic conditions. Subsequent analysis of chronic conditions using pre-existing data sets will provide a baseline measure of chronic condition prevalence and management in general practice.
