As you know a part of my work consists to participate in studies based on the extraction from retrospective databases and the analysis of the informations thus retrieved. The eligibility of the beneficiaries to the provision that represents the study’s outcome is always a major concern. There is two explanations for a beneficiary not having access to a care according to the data retrieved from the reimbursement base: either a real lack of access or a non eligibility of the care for a record in the reimbursement data base (for example if the insured is covered by another insurance or has lost his coverage and has exited from the health plan)*. I have always to keep in mind that I work on secondary data which are only a reflection of the primary data the reality of which I try to apprehend.
The dilemma is pretty well addressed in this article:
*as always there is a third possibility: the data concerning the care has been erased from or not yet recorded in the base. The timeline of the refreshment of the base (ie the loading and the purifying of the data) must be precisely described in the methodology of the study.
1)- Motheral, B., Brooks, J., Clark, M. A., Crown, W. H., Davey, P., Hutchins, D., Martin, B. C. and Stang, P. (2003),
A Checklist for Retrospective Database Studies—Report of the ISPOR Task Force on Retrospective Databases.
Value in Health, 6: 90–97. doi: 10.1046/j.1524-4733.2003.00242.x
Two other articles address the pitfalls of inferring from secondary data extracted from a retrospective data base:
2)- Berger M, Mamdani M, Atkins D, Johnson M.
Good Research Practices for Comparative Effectiveness Research: Defining, Reporting and Interpreting Nonrandomized Studies of Treatment Effects Using Secondary Data Sources: The ISPOR Good Research Practices for Retrospective Database Analysis Task Force Report—Part I.
Value in Health 2009 ; 12(8) :1044-52
The use of claims databases for outcomes research : Rationale, challenges, and strategies. Annual international meeting of the Association for Pharmacoeconomics and Outcome Research.
Philadelphia, Pennsylvania (USA), 1996/05/12. CLINICAL THERAPEUTICS, vol. 19, n° 2, 1997, pages 346-366, 74 réf., ISSN 0149-2918, USA. MOTHERAL (B.R.) *, FAIRMAN (K.A.). Outcomes Research. Express Scripts. Inc. Maryland Heights. USA
Full text of the article here: