Objective:
To assess the positive and negative predictive values of osteoarthritis (oa) diagnoses contained in an administrative database.
Methods:
We identified all members (> or =18 years of age) of a massachusetts health maintenance organization with documentation of at least one health care encounter associated with an oa diagnosis during the period 1994-1996. from this population, we randomly selected 350 subjects. in addition, we randomly selected 250 enrollees (proportionally by the age and sex of the 350 subjects) who did not have a health care encounter associated with an oa diagnosis. trained nurse reviewers abstracted oa-related clinical, laboratory, and radiologic data from the medical records of both study groups (all but 1 chart was available for review). pairs of physician reviewers evaluated the abstracted information for both groups of subjects and rated the evidence for the presence of oa according to 3 levels: definite, possible, and unlikely.
Results:
Among the group of patients with an administrative diagnosis of oa, 215 (62%) were rated as having definite oa, 36 (10%) possible oa, and 98 (28%) unlikely oa, according to information contained in the medical record. the positive predictive value of an oa diagnosis was 62%. in those without an administrative oa diagnosis, 44 (18%) were assigned a rating of definite oa. the negative predictive value of the absence of an administrative oa diagnosis was 78%.
Conclusion:
Use of administrative data in epidemiologic and health services research on oa may lead to both case misclassification and under ascertainment.