Assessments of the clinical circumstances of individual patient adverse events (AEs) have been important components of health care product monitoring programs every since systematic AE surveillance was first proposed in the early 1960s (Finney, 1963). Reliance on such methods is based on the view, shared by many safety professionals, that careful analysis of the diagnostic data found in AE reports can help to find causal product-AE relationships. In the 1970s and 1980s, signalling procedures based on the medical interpretation of individual patient experiences came to be described by the word "imputation", meaning an evaluation that summarizes the causally-related features pertaining to a single patient's AE (Venulet, 1984). It has been suggested that imputology can be an effective surveillance strategy for individual patient reports arising from studies (Emanueli and Sac-chetti, 1980; Jones, 1987), medical literature case reports (Venning, 1983; Rossi and Knapp, 1984), and spontaneous sources (Jones, 1994; Stephens, 1999) (see Table 18.1), all three of which contribute to both premarketing and postmarketing pharmacovigilance. Individual patient reports from clinical studies are useful in postmarketing surveillance when large phase IV trials are conducted for a product, and, conversely, individual patient reports from spontaneous sources are useful in premarketing surveillance when marketing is initiated outside of a product development territory. This chapter considers the use of imputation methods to evaluate patient AE experiences that come from any of these sources, focusing on their use both as report database screening devices for "interesting" product-AE pairs during the signal detection (report-based) phase of AE surveillance, as well as their value in analyzing series of cases of the same product-AE during the signal evaluation (case-based) phase of AE surveillance (see Chapter 19, Overview—Spontaneous Signalling).
Table 18.1. Data sources for single patient imputation methods.
Human studies (published or unpublished)
• From clinical studies
• From epidemiologic studies
Literature case reports
• Single case reports
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