Quality of requests for serum digoxin concentrations: experience from an Australian Regional Health Service

Abstract

What is already known about this subject • Therapeutic drug monitoring of serum digoxin concentrations (SDC) is considered useful in enhancing the therapeutic benefits of digoxin and minimizing the incidence of adverse drug reactions. • The quality of requests for SDC has been reported to be generally unsatisfactory. However, studies have focused on few information parameters. • A better knowledge of these issues might be useful to target appropriate areas of weakness within heathcare systems. What this study adds • The poor quality of the information in SDC requests involves a wide range of codes from the contact details of the requester to the time interval between the last dose of digoxin and blood sampling. • Misuse of the therapeutic drug monitoring service is common across different specialties and healthcare settings. Aims To assess the quality of the information provided with serum digoxin concentration (SDC) requests received by a therapeutic drug monitoring service in a regional health service. Methods We conducted a retrospective audit of a consecutive series of 685 SDC requests during a 7‐month period. Information regarding (i) contact details, (ii) reasons for request, (iii) dose, (iv) route of administration, (v) concurrent therapy, (vi) treatment duration and (vii) time interval between the last dose and sampling was reviewed and coded as appropriate or inappropriate/missing. Data were analysed according to the origin of request, i.e. from different specialties/wards (emergency department and critical care, cardiology and coronary care unit, medicine and aged care, surgery, and general/private practice) and healthcare settings (teaching hospital, geriatric hospital and general/private practice). Results The quality of SDC requests was generally poor across different specialties and healthcare settings. The information provided for the coded parameters was appropriate only in 19.1% (i), 6.4% (ii), 54.7% (iii), 45.8% (iv), 12.8% (v), 32.9% (vi) and 47.1% (vii) of cases. No SDC request was complete in all the information codes. SDC requests from general/private practice lacked more often details regarding the dose (information provided in 46.7% of requests, P = 0.007 vs. other specialties; P = 0.02 vs. other settings) and the route of administration (20.0%, P < 0.001 vs. other specialties and vs. other settings). SDC requests from the emergency department and critical care unit lacked more often details regarding the treatment duration (22.6%, P < 0.001 vs. other specialties) and the time interval between the last dose and blood sampling (40.1%, P = 0.01 vs. other specialties). Conclusions The quality of the information in SDC requests is poor across different specialties and healthcare settings. Educational strategies to ensure the appropriate use of this service are urgently needed.

Appropriateness of digoxin level monitoring in a childrens hospital

“…Some caregivers are unaware that digoxin samples should be taken at least 6 hours after dosing and are confused by choices of multiple blood collection times (Matzuk et al, 1991;Bernard et al, 1996), the Fudan Children's Hospital has two main blood collection times, 13:30 and 15:00, and a common error is to reverse the timing. What's more, our study findings showed that the quality of requests was generally poor (Table 6), in fact, not a single digoxin therapeutic monitoring request had all the information codes required, this make hard for the pharmacists to correct the errors, another study reported similar findings (Ellington et al, 2007).…”

Abstracts of the Dutch Society of Clinical Pharmacology and Biopharmacy Meeting of October 4, 2010

“…However, in clinical practice, TDM requests are often inadequate: many requests are inappropriately timed or omitted because the indication is unknown or not recognized. (Ellington et al, 2007) Clinical rules are part of 'the next generation' medication safety systems. Incorporated in a clinical decision support system (CDSS), clinical rules are able to continuously monitor all individual electronic patient data available in the electronic medical record (EMR).…”

An agenda for UK clinical pharmacology: Monitoring drug therapy

“…This often tends to produce both over‐sampling and under‐interpretation of the results, and prescribers mostly implement therapeutic adjustments by trial and error. Data for formal dosage adjustments are often not recorded along with blood sampling [19]. Monitoring is insufficient in some therapeutic areas and exaggerated in others, and large numbers of tests requested by practitioners are of questionable usefulness.…”

“…1 Most monitoring procedures have been devised and set up mainly, if not exclusively, on empirical grounds, without critical assessment of the underlying evidence and rationale [18].This often tends to produce both oversampling and under-interpretation of the results, and prescribers mostly implement therapeutic adjustments by trial and error. Data for formal dosage adjustments are often not recorded along with blood sampling [19].…”