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Once-daily aminoglycoside dosing: impact on requests and costs for therapeutic drug monitoring |
Nicolau D P, Wu A H, Finocchiaro S, Udeh E, Chow M S, Quintiliani R, Nightingale C H |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Implementation of a programme of once daily aminoglyocosides (ODA) to treat gram-negative bacteria in hospitalised patients.
Economic study type Cost-effectiveness analysis.
Study population All adult patients at a community hospital receiving aminoglycosides except those with ascites, more than 20% total body burns, pregnancy, enterococcal endocarditis or end stage renal disease.
Setting Hospital. The economic analysis was conducted in Hartford, Connecticut, USA.
Dates to which data relate Effectiveness and resource use data were collected between 1991 and 1994. Data for the control group using conventional administration were collected between April and June 1991. Data from Phase I and Phase II of the study were collected between April and June 1993 and April and November 1994, respectively. Price dates were not stated.
Source of effectiveness data Effectiveness data were derived from a single study.
Link between effectiveness and cost data Cost data were collected retrospectively using the same patient sample as that used in the effectiveness study.
Study sample Whilst the number of patients included in the control group (conventional administration) was not clearly stated, the study sample included a total of 1,102 individuals (500 and 602 for phase I and II, respectively). The sample included all eligible patients at the hospital in the three study periods. No power calculations were reported.
Study design Single centre case-control study. Patients were followed up until the end of the period for which either conventional aminoglycoside or ODA treatment was required and until nephrotoxicity had been evaluated. For the conventional and phase I groups the length of follow up was not stated. For the phase II, group follow up was to November 1994.
Analysis of effectiveness The principle used in the analysis (intention to treat or treatment completers) was not stated. The primary health outcomes were mean peak and through concentrations and the rates of incidence of nephrotoxicity. This was defined as a 0.5 mg/dL increase in baseline serum creatinine concentrations. These were, in turn, measured on an Ektachem 700 chemistry analyzer. No information was provided on age, sex or prognostic features of the different patient groups.
Effectiveness results Mean (SD) peak and through concentrations during the pre-ODA period were 4.9 (1.5) and 1.5 (1.2) ml/L for gentamicin and 5.6 (5.2) and 1.7 (1.3) mg/L for tobramycin. For the phase 1 of the ODA, mean (SD) random blood concentrations were 3.7 (4.7) and 4.1 (5.3) mg/L for gentamicin and tobramycin. The values of the phase II ODA were not reported; the authors stated that average serum concentrations for peak, through, and random samples were "similar to those obtained during the previous two periods". The rates of incidence of nephrotoxicity were estimated in phase I and phase II to be 1.2 and 1.3%, respectively, compared with the 5% rate in the conventional group.
Clinical conclusions The introduction of a programme of ODA administration did not lead to an increase in toxicity compared with conventional administration.
Measure of benefits used in the economic analysis The measure of benefits in the economic analysis was cases of toxicity avoided.
Direct costs The cost differences following the onset of the ODA programme associated with operating (drugs, labour, supplies), overheads and capital hospital costs were estimated. The reduction in the number of requests for TDM were analysed separately from total costs. The estimates of cost were based on actual data from the clinical study. Results were presented normalized to a total patient group of 600 individuals. Price years were not stated. Data on requests for therapeutic drug monitoring (TDM) (serum aminoglycoside concentrations of gentamicin and tobramycin) were averaged for data collected between April and June for each one of the years 1991, 1993 and 1994.
Sensitivity analysis No sensitivity analysis was conducted.
Estimated benefits used in the economic analysis The rates of incidence of nephrotoxicity were estimated in phase I and phase II to be 1.2% and 1.3%, respectively, compared with the 5% rate in the conventional group.
Cost results The authors estimated that, since the implementation of the programme, costs for the 2,200 patients, had fallen by more than $40,000 compared with conventional therapy in terms of drugs, supplies and labour. Requests for TDM related to gentamicin had reduced by approximately 300 per month (40% reduction) and requests for TDM related to tobramycin had decreased by 50 per month compared with the conventional group. This reduction in TDM requests was estimated by the authors to reduce institutional costs by more than $100,000over a year (inclusive of reagents, equipment, labour and overheads).
Synthesis of costs and benefits Since the intervention was the dominant strategy, costs and benefits were not combined.
Authors' conclusions The authors concluded that reductions in the level of TDM would become increasingly important as clinical laboratories switched from fee-for-service to capitation and managed care environments. One way in which this might be done is by using an ODA programme, which is as effective as conventional administration without increasing the level of toxicity whilst reducing the level of costs to the hospital by reducing the number of TDMs and changes to the preparation of therapy.
CRD COMMENTARY - Selection of comparators Given that only the method of administration differed, rather than the therapy itself, the reason for comparing ODA with conventional administration of aminoglycoside is clear.
Validity of estimate of measure of benefit No information was provided by the authors on the composition of the three groups in the different phases of the study. The historical nature of the control group is a potential source of bias.
Validity of estimate of costs Insufficient details were provided of the source and nature of the costs included. Only direct costs were estimated and only the perspective of the hospital was adopted. No details of the price years were given.
Other issues Cost data and levels of request for TDM may not be generalisable to other settings or countries
Implications of the study Well designed studies examining the impact of ODA should be conducted in this and other settings and countries.
Bibliographic details Nicolau D P, Wu A H, Finocchiaro S, Udeh E, Chow M S, Quintiliani R, Nightingale C H. Once-daily aminoglycoside dosing: impact on requests and costs for therapeutic drug monitoring. Therapeutic Drug Monitoring 1996; 18(3): 263-266 Other publications of related interest The clinical effectiveness of the ODA method was reported by the authors in a previous paper. Nicolau DP, Freeman CD, Belliveau PP, Nightingale CH, Ross J, Qintiliani R. Experience with once daily aminoglycoside program administered to 2,184 adult patients. Antimicrobial Agents and Chemotherapy 1995;56:561-3.
Indexing Status Subject indexing assigned by NLM MeSH Adult; Anti-Bacterial Agents /administration & Drug Monitoring /economics; Gentamicins /administration & Humans; Retrospective Studies; Tobramycin /administration & dosage /economics /pharmacokinetics; dosage /economics /pharmacokinetics; dosage /economics /pharmacokinetics AccessionNumber 21996000665 Date bibliographic record published 31/01/1999 Date abstract record published 31/01/1999 |
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