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Weekly versus daily changes of in-line suction catheters: impact on rates of ventilator-associated pneumonia and associated costs |
Stoller J K, Orens D K, Fatica C, Elliott M, Kester L, Woods J, Hoffman-Hogg L, Karafa M T, Arroliga AC |
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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 In-line suction catheters (ILSC) were used to reduce the risk of ventilator-associated pneumonia (VAP) during the mechanical ventilation of patients suffering from respiratory failure.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised all patients receiving suctioning, through endotracheal or tracheostomy tubes, in the MICU. The study did not explicitly state any exclusion criteria.
Setting The setting was secondary care. The study was conducted in The Cleveland Clinic, USA.
Dates to which data relate The effectiveness and resource use data were collected during two 3-month periods. These were a control period (May to July, 1998) and a treatment period (May to July, 1999). The price year was 1997-1998.
Source of effectiveness data The effectiveness data were derived from a single study.
Link between effectiveness and cost data The costing was undertaken prospectively on the same patient sample as that used in the effectiveness study.
Study sample The use of power calculations to determine the sample size was not reported. The sample was selected by observing all patients receiving suctioning through endotracheal or tracheostomy tubes. One hundred and forty-six patients were observed during the control period (May to July 1998). Their mean age was 63.5 years (standard deviation, SD=14.5) and 50% were female. During the treatment period (May to July 1999), 143 patients were observed. Their mean age was 59.6 years (SD=16.1) and 45% were women. The authors did not report excluding any patients from the initial sample.
Study design This was prospective cohort study that was conducted in a single centre. The duration of follow-up was 3 months and no loss to follow-up was explicitly reported.
Analysis of effectiveness Not all the patients included in the study were accounted for in the analysis of outcomes. The primary outcome end point of the study was the rate of VAP. The criteria for diagnosing VAP required the occurrence (beginning at least 48 hours after admission) of a new or progressive infiltrate for at least 48 hours, and the achievement of at least 10 points according to the stated criteria:
the presence of polymorphonuclear leukocytes on sputum Gram stain (grades 0 - 4),
the presence of a predominant organism on culture (grades 0 - 4),
white blood cell count exceeding 15,000/mm3 (1 point),
temperature exceeding 38.5 degrees C (1 point), and/or
evidence of copious secretions (grades 0 - 4).
The rates of VAP were calculated as the mean per 100 ventilator days for each 3-month observation period. The number of patients presenting with VAP in both groups was compared using Fisher's exact test. The secondary outcomes examined were the intensive care unit (ICU) readmission rate, the length of stay in the ICU, and the frequency of bacteraemia. The groups were shown to be comparable in terms of age, gender and prognostic features. The authors reported that there were no statistically significant differences between the groups.
Effectiveness results There were two episodes of VAP in the control group versus none in the treatment group.
The VAP rate was 0.19 in the control group and zero in the treatment group. However, this result was not statistically significant, (p=0.5).
The lower ICU length of stay and ICU readmission rates in the treatment group were not statistically significant.
The frequency of bacteraemia did not differ between the groups.
Clinical conclusions The authors reported that changing ILSC weekly, as opposed to daily, was associated with non significant trends toward a lower frequency of VAP, shorter ICU length of stay, and lower frequency of ICU readmission within 24 hours of discharge.
Measure of benefits used in the economic analysis No summary measure of benefit was used in the economic analysis. In effect, a cost-consequences analysis was performed.
Direct costs The study perspective was unclear, but it appears to have been that of the MICU. The direct costs reported were for the in-line endotracheal tube and tracheostomy suction kits used. The quantities and the costs were reported separately. The number of suction kits used was obtained from the cohort study. The unit costs were reported, but not their source. The same price was used for the two separate periods of analysis. Discounting was not relevant as the costing only covered a 3-month period. The price year used was 1998-1999.
Statistical analysis of costs The costs were treated deterministically. No statistical tests were reported.
Indirect Costs No indirect costs were included in the analysis.
Sensitivity analysis No sensitivity analysis was reported.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section
Cost results The total costs of changing the ILSC were $1,330.25 for weekly changes and $6,025.80 for daily changes.
Synthesis of costs and benefits Authors' conclusions A policy of weekly (versus daily) changes in in-line catheters was associated with substantial cost-savings and no increase in the frequency of ventilator-associated pneumonia (VAP).
CRD COMMENTARY - Selection of comparators A justification was given for the comparator used. It represented current practice in the authors' setting. The authors mentioned relevant alternatives to reduce the risk of VAP, but these were not included in the study. You should decide if this represents a widely used health technology in your own setting.
Validity of estimate of measure of effectiveness The analysis was based on a cohort study, which was not entirely appropriate for the study question since it is vulnerable to bias and confounding. A randomised clinical trial would have been more appropriate and would have helped to eliminate these factors. The authors did not report the use of power calculations. Thus, it is not possible to determine whether the results were due to chance, or whether there was a lack of power to detect significant differences in the strategies. The authors did not provide any information to help assess whether the study sample was representative of the study population. This fact may limit the generalisability of the results. The patient groups were shown to be comparable at analysis, although the authors did not attempt to adjust for potential biases and/or confounding factors. In addition, the number of patients in both groups varied across the different secondary outcomes. Given these limitations, the internal validity of the study is likely to be low.
Validity of estimate of measure of benefit No summary measure of health benefit was derived. In effect, a cost-consequences analysis was conducted.
Validity of estimate of costs The perspective of the study was not stated. The direct costs included only those health care costs related to the strategies under investigation. Some relevant costs (staff, equipment used, length of stay, overheads and drug treatments) were omitted from the analysis, but the authors provided no justification for their omission. Consequently, the cost of the intervention might have been overestimated. The costs and the quantities were reported separately, which will enhance the generalisability to other settings. It was not reported whether a cost-to-charge mechanism was used and it was not possible to infer from the study whether such a mechanism was applied, as no sources for the unit costs were explicitly reported. In addition, no statistical analyses of the quantities of resource use or prices were conducted. The price year was reported, which will aid any future reflation exercises.
Other issues The authors made appropriate comparisons of their findings with those from other studies, finding their results to be fairly consistent. The issue of generalisability to other settings was not addressed. The authors appear to have presented their results selectively, although this may be due to reporting restrictions. A number of further limitations to their study were reported. First, the possibility of the results being biased by natural variation in the event rates. Second, the data on key secondary outcomes and characteristics of the study population were incomplete. Finally, the diagnostic criteria for VAP were based on clinical features and not on quantitative cultures.
Implications of the study The authors stated that the findings support a policy of changing ILSC weekly, or even not at all, rather than daily. However, the concerns about the validity of the evidence used in the economic evaluation, as discussed already, should be borne in mind when considering this recommendation.
Bibliographic details Stoller J K, Orens D K, Fatica C, Elliott M, Kester L, Woods J, Hoffman-Hogg L, Karafa M T, Arroliga AC. Weekly versus daily changes of in-line suction catheters: impact on rates of ventilator-associated pneumonia and associated costs. Respiratory Care 2003; 48(5): 494-499 Indexing Status Subject indexing assigned by NLM MeSH Catheterization /adverse effects /economics /utilization; Cost-Benefit Analysis; Humans; Intensive Care Units /economics; Middle Aged; Pneumonia, Bacterial /epidemiology /etiology; Respiration, Artificial /adverse effects; Suction /adverse effects /economics; Time Factors; Ventilators, Mechanical /adverse effects AccessionNumber 22003006426 Date bibliographic record published 28/02/2005 Date abstract record published 28/02/2005 |
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