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Extending ventilator circuit change interval beyond 2 days reduces the likelihood of ventilator-associated pneumonia |
Fink J B, Krause S A, Barrett L, Schaaff D, Alex C G |
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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 Using 7- or 30-day versus 2-day circuit change intervals in patients receiving mechanical ventilation.
Economic study type Cost-effectiveness analysis.
Study population Patients in RICU or MICU, who were receiving mechanical ventilation.
Setting Hospital. The economic study was carried out in Chicago, USA.
Dates to which data relate The data relating to 2- , 7-, and 30-day intervals were collected from January 1991 to January 1993, from January 1993 to January 1994, and from January 1994 to December 1994, respectively. The dates for the resources used were not specified. 1994 prices were used.
Source of effectiveness data The evidence for the final outcomes was derived from a single study.
Link between effectiveness and cost data The costing was not performed on the same patient sample as that used for the effectiveness study.
Study sample Power calculations were not used to determine the sample size. The study sample consisted of 637 patients: 343 in the 2- day change group, 137 in the 7-day group and 157 patients in the 30 day change interval group.
Study design The study was a nonrandomised trial with historical controls, performed in a single centre.
Analysis of effectiveness It was not stated whether the analysis of the clinical study was based on intention to treat or treatment completers only. The health outcome measures consisted of the rate of ventilator-associated pneumonia (VAP) identified using 1988 CDC-defined criteria, average (SD) days to VAP, mortality rate, and risk of occurrence of VAP. A Cox proportional hazards model was performed using ventilator circuit change interval and hospital unit as the potential predictors. In the estimation of relative risk (RR), the adjustment was made for the type of hospital unit (MICU or RICU). The effect of a confounding variable (using heated wire circuit in 30-day change interval group) was investigated. The comparability of the characteristics of the study groups was not assessed.
Effectiveness results The 2-day change interval group had a rate of 11.88 VAP per 1,000 ventilator days versus 3.34 and 6.28 for the 7- and 30-day circuit change interval groups, respectively (P= 0.266 for the difference between the 7- and 30-day circuit change interval groups). In terms of days to VAP, the 2-day change interval group had, on average, 12.03 (SD=9.07) days to VAP versus 17.25 (7.09) and 14.5 (7.31) for the 7- and 30-day circuit change interval group, respectively. The RICU and MICU patients had total mortality rates of 33% (range: 25 - 43%) and 40% (range: 32 - 47%), respectively. The risk of occurrence of VAPwas significantly higher for the patients in the 2-day change interval group when compared to the 7-day group (RR=0.210, P= 0.003) and the 30-day group (RR= 0.407, P=0.013). The risk was higher for the patients in the 2-day group when compared with those in a group consisting of a combination of 7- and 30-day intervals (RR= 3.1; P= 0,0004; 95% CI: 1.662 - 5.812).
Clinical conclusions The study revealed that extending ventilator circuit change intervals beyond 2 days was a moreeffective health policy in terms of both the rate and the risk of VAP in comparison with the 2-day change interval policy.
Measure of benefits used in the economic analysis No summary benefit measure was identified in the economic analysis and only separate effectiveness outcomes were reported.
Direct costs The quantities and cost items were not reported separately. The average cost per patient per year and per patient per circuit change consisted of the supply and labour costs. The point of view of the cost analysis was not stated. The actual cost for supplies was used. The time standards of labour were estimated using the American Association for Respiratory Care uniform reporting method. 1996 and 1994 price data were used.
Sensitivity analysis No sensitivity analysis was carried out.
Estimated benefits used in the economic analysis Cost results The average cost per patient per year for the 2-, 7- , and 30-day intervals was $23,460, $4,522, and $612, respectively. The average cost per patient per circuit change (in terms of 1994 prices) for the 2-, 7- , and 30-day intervals was $114, $27.60, and $3.38, respectively.
Synthesis of costs and benefits No synthesis was performed by the authors since extending ventilator circuit change intervals beyond 2 days was the dominant strategy.
Authors' conclusions The authors concluded that circuit change intervals of 7 and 30 days had lower risks for VAP than the 2-day intervals, yielding substantial reductions in morbidity as well as labour and supply costs.
CRD COMMENTARY - Selection of comparators The justification for the choice of the comparator was implicit in that it accorded with the minimum circuit change interval recommended in the Centres for Disease Control (CDC) guidelines. You should consider whether this is applicable within your own setting.
Validity of estimate of measure of benefit In the absence of randomisation, potential for bias exists and the internal validity of the estimate of effectiveness may have been affected.
Validity of estimate of costs Resource quantities were not reported separately from the prices. Adequate details of the methods of cost estimation were not given.
Other issues Given the lack of randomisation, sensitivity analysis, and statistical analysis of the costs, the results need to be treated with some caution. The issue of generalisability to other settings or countries was not addressed.
Source of funding Supported by the Research Service of the Department of Veterans Affairs.
Bibliographic details Fink J B, Krause S A, Barrett L, Schaaff D, Alex C G. Extending ventilator circuit change interval beyond 2 days reduces the likelihood of ventilator-associated pneumonia. Chest 1998; 113(2): 405-411 Other publications of related interest Comment in: Chest 1998;113(2):267-9.
Indexing Status Subject indexing assigned by NLM MeSH Adult; Confidence Intervals; Cost Control; Costs and Cost Analysis; Critical Care /economics; Critical Illness; Cross Infection /prevention & Disposable Equipment /economics; Equipment Design; Hospitals, Veterans; Hot Temperature; Humans; Humidity; Pneumonia /prevention & Proportional Hazards Models; Prospective Studies; Respiration, Artificial /adverse effects /economics; Risk Factors; Survival Analysis; Time Factors; Ventilators, Mechanical /adverse effects /economics; control; control AccessionNumber 21998000362 Date bibliographic record published 31/01/1999 Date abstract record published 31/01/1999 |
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