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Estimated cost-effectiveness of active middle-ear implantation in hearing-impaired patients with severe external otitis |
Snik A F, Van Duijnhoven N T, Mylanus E A, Cremers C W |
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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 The health technology assessed was surgical implantation of middle-ear implants in hearing-impaired patients. The comparator was no middle-ear implant. All patients had used a conventional hearing aid before the implantation, but several patients had stopped using them because of irritation.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised patients with symmetrical sensorineural hearing loss and chronic therapy-resistant external otitis.
Setting The setting was inpatient, secondary care. The economic study was carried out in the Netherlands.
Dates to which data relate The cost data related to 2005. The effectiveness data were collected prior to implantation, and at 6 and 12 months after recruitment during the time period of approximately years 2000 - 2005.
Link between effectiveness and cost data The costing study was undertaken on the same patient sample as that used in the effectiveness study. It appears to have been conducted retrospectively after the effectiveness results were known.
Study sample The study sample was selected by convenience sampling from the centre where this study was conducted. Sample size calculations were not reported. Of the original 25 participants identified, the study sample comprised 21 final participants. There were 9 men and 12 women and their mean age was 52.4 years (range: 18 to 79) at the time of implantation. Of these 21 patients, 13 received the Vibrant Soundbridge implant and 8 received the Otologics MET device, both with relevant audio processors. Four participants were subsequently excluded from the study: one died from a degenerative disease while three developed health contraindications. Eighty-four per cent (21 out of 25) of the overall sample completed the study and all of these were included in the analyses.
Study design The study design was a case series with study participants being assessed at baseline and post-implantation. The underlying assumption was that middle-ear implants would improve hearing and health status compared with that prior to implantation. The study was carried out in a single centre. The duration of follow-up was 12 months post-implantation. There were no losses to follow-up.
Analysis of effectiveness The clinical outcomes used in the analysis were three health-related quality of life measures. Specifically, the Medical Outcomes Short-Form 36 (SF-36) questionnaire, the Nijmegen Cochlear Implant Questionnaire and the Glasgow Benefit Inventory. Positive change scores represented health improvement across all three questionnaires. The Glasgow Benefit Inventory involved asking questions that were framed retrospectively and this was administered once after implantation. The investigators did not state the magnitude of change scores required to reach clinical meaningfulness, but provided information on statistical significance. All patients completed the SF-36 and Nijmegen Cochlear Implant Questionnaire measures, but only 17 patients (81%) completed the Glasgow Benefit Inventory.
Effectiveness results Higher scores on all three questionnaires represent better health status.
The mean individual increases were -0.033 (95% confidence interval, CI: -0.03 to -0.002; p=0.05) in the SF-36 physical score and 0.046 (95% CI: 0.012 to -0-079; p=0.01) for the SF-36 mental health score.
The mean individual increases in the Nijmegen Cochlear Implant Questionnaire score were 9.7 (95% CI: 3.8 to 13.5; p=0.002,) for communication status, 10.5 (95% CI: 2.8 to 18.2; p=0.01) for psychological status and 13.6 (95% CI: 6.4 to 20.7; p=0.001) for social status.
The mean increase in the Glasgow Benefit Inventory mean score was 33.9 (95% CI: 27.3 to 41.4; p<0.001).
Clinical conclusions The authors reported that the effect of middle-ear implantation on health status was smaller in comparison with that for cochlear implantation in deaf patients (also treated at the same medical centre), although the target populations were not exactly equal. The authors could not explain the negative effect on health status found in the SF-36 physical score. The result for the Glasgow Benefit Inventory was comparable to results obtained in other studies on different patient samples.
Measure of benefits used in the economic analysis The health outcome used for the economic analysis was a measure calculated as profitable years (the number of years of effective use of middle-ear implants) multiplied by mean change score in the SF-36 mental summary score. The authors referred to this summary measure as a quality-adjusted life-year (QALY).
Direct costs The direct costs included costs incurred by the health service and incorporated costs incurred during the phases of patient selection, implantation, rehabilitation and aftercare of middle-ear implants. These costs included medical and administration personnel, hospital stay, implant and surgical materials. The costs that might have been incurred had there not been middle-ear implants were not evaluated. In addition, the direct costs relating to re-implantation were omitted. The source of the costs was not reported, but they appear to have been retrospective estimates at October 2005. Although not stated, the costs appear to have been reported as the average costs per person. The costs were not discounted, which was appropriate as they appear to have been incurred around the time of surgery and, therefore, discounting was not relevant. With the exception of hospital stay (2 days), the resource quantities were not reported.
Statistical analysis of costs The resource costs were reported as point estimates. No statistical analyses were undertaken for either the resource quantities or costs.
Indirect Costs No productivity costs were included.
Currency Euros (EUR). The exchange rate to US dollars ($) was $1 = EUR 0.825292 on October 10, 2005.
Sensitivity analysis The authors did not investigate variability in the data estimates.
Estimated benefits used in the economic analysis The estimated mean profitable years of middle-ear use was 19.4 years (standard deviation 9.0).
The mean change or improvement in the SF-36 mental score was 0.046.
Multiplying the profitable years by the SF-36 mental score resulted in a mean incremental QALY value of 0.89 for the sample.
Cost results For middle-ear implants compared with no implants, the costs were EUR 687 for the selection phase, EUR 1,599 for surgery, EUR 1,031 for follow-up care and EUR 9,902 for materials.
The total overall costs were EUR 14,354 per patient.
The cost of the implant device was by far the highest cost item (EUR 9,500) and represented two thirds of the total costs.
Synthesis of costs and benefits The average cost per QALY gained was EUR 16,085.
No other analyses of the costs or benefits were undertaken.
Authors' conclusions The authors suggested that their results confirmed the cost-effectiveness of middle-ear implantation for hearing-impaired individuals with severe otitis. Further, they stated that their results, in conjunction with the results of a companion study using cochlear implants, should encourage approval and justification for middle-ear implantation in the future.
CRD COMMENTARY - Selection of comparators The authors did not explicitly justify the choice of the comparator, but using a case series reflects current practice.
Validity of estimate of measure of effectiveness The effectiveness analysis was based on a small prospective case series which, given the study question, may be associated with some limitations. For example, there was no control group to ascertain efficacy and the characteristics of the group may have changed over time, leading to selection bias. There may also have been measurement bias, which the authors sought to minimise. The authors did not indicate that they made any adjustments for confounding variables. No justification for the choice of the study design was provided. The authors appear to have used appropriate health-related quality of life instruments to assess health status in their specific sample, and described these measures well. No power calculations were reported, thus it was not possible to determine with any certainty whether the results obtained were due to the implantation or to chance. In addition, it was difficult to interpret the results for wider populations as the characteristics of the participants were inadequately reported.
Validity of estimate of measure of benefit The authors were explicit in how they derived the measure of benefit. However, they did not use either utility scores or patient life-years. Utility is not the same as health status but rather an indication of an individual's preferences (or values) for health states. A summary score of the SF-36 cannot be used to represent a utility score. SF-36 scores need to be converted to SF-36 utility scores via a formula, but the authors did not carry out this process. The authors also used the expected useful life of the implant devices as a proxy for patient life-years and this is not standard practice. To this end, they should not have used the term 'quality-adjusted life-years' and this study is not strictly a cost-utility analysis.
Validity of estimate of costs From the perspective of the health service, it appears that all the relevant costs have been included. The costs that might have been incurred had there been no middle-ear implants were not evaluated. This, if anything, the study was biased slightly against middle-ear implants. Only brief details of the collection, estimation and valuation of the resources were reported and it is unclear what source(s) were used (i.e. patient chart reviews, authors' estimation). The resource quantities were not provided separately from the costs, which will make it difficult for readers to plan for, or implement, a similar service in their own setting. The authors did not include the costs of re-implantations because this represented teething problems associated with the implant devices. However, they did not provide details on how often this occurred, and the likely implications to their cost (or effectiveness) analysis. This should have been explicitly reported or handled within a sensitivity analysis.
Other issues The authors discussed the findings in the context of other studies with different patients and different ear devices because there were no studies on patients with sensorineural-impaired hearing with severe external otitis. It is unclear whether these comparisons are relevant since there were insufficient details of the characteristics of the small sample in this study. The authors did not discuss limitations in relation to the study design. They also do not appear to have presented their results selectively, although the negative results for the SF-36 physical summary score were not included in the measure of benefit used in the cost-effectiveness study. The authors did not provide a rationale for why they did not use the overall SF-36 score (including the physical summary score) which evidently would have decreased their effectiveness measurement and subsequently increased the cost-effectiveness ratio. The results from the other two instruments should also not be confused as contributing to the authors' conclusion of favourable cost-effectiveness of middle-ear implantation.
Implications of the study The authors claimed that the cost-effectiveness of middle-ear implantation was sufficient to approve its future use. However, it should be noted that the intervention was more costly than the conventional intervention and cost-effectiveness depends on the decision-maker's willingness to pay. Further, the cost and health outcome data are partial and the effectiveness evidence possibly biased. Further research, in the form of a randomised controlled trial of sufficient power to firmly establish the efficacy of middle-ear implantation, is required.
Bibliographic details Snik A F, Van Duijnhoven N T, Mylanus E A, Cremers C W. Estimated cost-effectiveness of active middle-ear implantation in hearing-impaired patients with severe external otitis. Archives of Otolaryngology Head and Neck Surgery 2006; 132(11): 1210-1215 Indexing Status Subject indexing assigned by NLM MeSH Adolescent; Adult; Aged; Chronic Disease; Cost-Benefit Analysis; Female; Hearing Loss, Sensorineural /therapy; Humans; Male; Middle Aged; Netherlands; Ossicular Prosthesis /economics; Otitis Externa /complications; Prospective Studies; Quality of Life AccessionNumber 22006002419 Date bibliographic record published 31/07/2007 Date abstract record published 31/07/2007 |
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