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Clin Chem Lab Med. 2012 Jan 26;50(6):1041-8. doi: 10.1515/cclm-2011-0756.

Volume, rates, source and types of add-on pathology test requests across five hospitals.

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  • 1Centre for Health Systems and Safety Research, University of New South Wales, Sydney, NSW, Australia.



Add-on test requests, where a clinician requests further test assays on an existing specimen, contribute disproportionately to pathology service workload. However, little research has quantified the volume, rates, source or types of add-on tests. This study provides a descriptive analysis of add-on testing within a pathology service serving five hospitals.


We analyzed 6 months of test data extracted from a pathology service in metropolitan Sydney, Australia. Add-on requests were analyzed in terms of total volume and as a proportion of all test requests and test assays; ten most frequently requested add-on test types for clinical chemistry and hematology; by patient registration category; and proportions of add-on requests received within 1-, 4-, 8-, and 24-h of specimen collection.


Add-on test requests constituted 3.7% (n=19,541) of the total 529,361 test requests. Clinical chemistry and hematology add-on requests accounted for 76.9% of all add-on requests. The add-on request rate was higher in the clinical chemistry (5.4%) than in hematology (1.3%). Patients who entered hospital via the emergency department had the highest rates of add-on requests. A total of 79.5% of add-on requests across the pathology service were made within 24-h of specimen collection.


The volume of add-on requests is substantial and varies considerably by test type and patient registration category thus impacting differentially upon pathology service departments. While some add-on requests are unavoidable in clinical practice, others are precipitated by inadequate information at the point of care. Improving appropriate utilization of add-on testing will reduce their burden on pathology services.

[PubMed - indexed for MEDLINE]
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