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Second-eye cataract surgery in elderly women: a cost-utility analysis conducted alongside a randomized controlled trial |
Sach TH, Foss AJ, Gregson RM, Zaman A, Osborn F, Masud T, Harwood RH |
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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. CRD summary This study examined the cost-effectiveness of immediate second-eye cataract surgery for women aged 70 years or older, who had minimal visual dysfunction and had previously had successful first-eye cataract surgery. The authors concluded that second-eye cataract surgery was unlikely to be cost-effective, but provided slightly greater value for money in the long term. The study was well carried out and transparently reported and the authors’ conclusions appear to be robust and valid. Type of economic evaluation Study objective This study examined the cost-effectiveness of immediate second-eye cataract surgery for women aged 70 years or older, who had minimal visual dysfunction and had previously had successful first-eye cataract surgery. Interventions Immediate second-eye cataract surgery (median time to surgery 30 days) was compared with no surgery (waiting list). Location/setting UK/secondary care (ophthalmology clinic). Methods Analytical approach:The analysis was based on a single trial, with a one-year time horizon. The authors stated that the perspective of the National Health Service (NHS) and personal social services was taken.
Effectiveness data:The clinical evidence was from a published, prospective, randomised controlled trial (RCT; Foss, et al. 2006, see 'Other Publications of Related Interest' below for bibliographic details). Eligible women received either immediate (within approximately four weeks) second-eye cataract surgery or control, which was routine surgery, with a 12-month wait. The baseline visual acuity in the second eye was good (6/12 or better). A sample of 229 participants, with 116 in the intervention group and 113 in the control group, was considered for this analysis. These patients were followed-up for one year. The key endpoint of the trial was the improvement in visual disability.
Monetary benefit and utility valuations:The utility values were elicited from the sample of patients enrolled in the trial, using the European Quality of life (EQ-5D) questionnaire, administered at baseline and at six months.
Measure of benefit:Quality-adjusted life-years (QALYs) were the benefit measure.
Cost data:The economic analysis included the costs of contacts with health and social services, care home admissions, informal care, equipment, and home modifications. All costs were based on NHS and personal social services tariffs, except the cost of informal care time, which was based on average net weekly earnings, using the human capital approach. Resource use was assessed from patient diaries, which were kept during the RCT. The data were collected at three and nine months, by telephone interviews, and at six and 12 months, by face-to-face interviews. All costs were in UK pounds sterling (£) and the price year was 2004.
Analysis of uncertainty:Non-parametric bootstrapping was performed to generate cost-effectiveness acceptability curves for different willingness-to-pay thresholds for a QALY gained. Conventional sensitivity analyses were carried out, to assess whether the base-case findings were robust to variations in selected clinical and economic inputs. In an alternative scenario, a lifetime horizon was considered and assumptions were made to extrapolate the short-term costs and benefits to this longer period. In this scenario, the costs and the benefits were discounted at an annual rate of 3.5%. Results Over one year, excluding the costs of carer time, the immediate group had additional mean costs of £646 (95% CI 16 to 1,276) and a mean QALY gain of 0.015 (95% CI -0.039 to 0.068) over the control group. The incremental cost per QALY associated with immediate surgery was £44,263 (49% probability of being cost-effective at a willingness-to-pay threshold of £30,000 per QALY). This figure rose to £58,667 when the costs of carer time were included.
The threshold analysis showed that the cost of the cataract operation had to be reduced to 68% of its actual cost for the incremental cost per QALY to be below the threshold of £30,000 per QALY. Variations in other selected inputs did not alter these findings. When a lifetime horizon was considered, the incremental cost per QALY for immediate surgery fell to £17,299 (£41,973 when the costs of carer time were included). Authors' conclusions The authors concluded that second-eye cataract surgery was unlikely to be cost-effective in the short term, but provided greater value for money in the long term, compared with no second surgery. CRD commentary Interventions:The authors justified their selection of the comparators. First-eye cataract surgery only was the usual pattern of care, while immediate second-eye surgery was the proposed addition.
Effectiveness/benefits:: A RCT as the source of the clinical evidence was appropriate, given the strengths of this design. The two groups were well balanced at baseline in their clinical and demographic features. Further details of the trial were not reported, which reduces the possibility of judging the validity of the clinical data. Conservative assumptions were made to extrapolate the short-term data to a lifetime. QALYs are a validated benefit measure and the EQ-5D was an appropriate instrument for this patient population. The authors stated that, for cataract surgery, using patients to elicit the utility values has some limitations, and this might explain some differences between these findings and those of other published studies.
Costs:The economic analysis was clearly performed and was consistent with the perspective. Most of the details, such as the unit costs, quantities of resources used, price year, and data sources, were reported. The economic part of the study appears to have been transparently performed. The costs were treated deterministically in the base-case analysis, but alternative estimates were considered in the sensitivity analysis. The authors assumed that, except the initial cost of surgery, those costs recorded in the first year of the trial remained the same in the following years.
Analysis and results:The use of an incremental approach to synthesise the costs and benefits was appropriate. The issue of uncertainty was investigated well, using various approaches. In general, the results were clearly presented and discussed. Conventional discounting was applied for the long-term simulation. The authors stated that differences compared with other published studies might depend on the patients selected, which were those with good visual acuity.
Concluding remarks:The study was well performed and transparently reported. The authors’ conclusions appear to be robust and valid. Funding Funding received from Trent Regional NHS Research and Development scheme, and the PPP Foundation (now the Health Foundation). Bibliographic details Sach TH, Foss AJ, Gregson RM, Zaman A, Osborn F, Masud T, Harwood RH. Second-eye cataract surgery in elderly women: a cost-utility analysis conducted alongside a randomized controlled trial. Eye 2010; 24(2): 276-283 Other publications of related interest Foss AJ, Harwood RH, Osborn F, Gregson RM, Zaman A, Masud T. Falls and health status in elderly women following second eye cataract surgery: a randomised controlled trial. Age and Ageing 2006; 35: 66-71. Indexing Status Subject indexing assigned by NLM MeSH Aged; Aged, 80 and over; Cataract /economics; Cataract Extraction /economics; Cost-Benefit Analysis; Female; Health Care Costs; Humans; Models, Economic; Outcome Assessment (Health Care); Quality-Adjusted Life Years AccessionNumber 22010000802 Date abstract record published 29/09/2010 |
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