Cost-utility analysis of orthoptic screening in kindergarten: a Markov model based on data from Germany

Cost-effectiveness of screening for amblyopia among kindergarten children in China

Objective

Current cost-effectiveness analyses of amblyopia screening are mainly from western countries. It remains unclear whether it is cost-effective to implement a preschool amblyopia screening programme in China. Our study aimed to evaluate the cost-effectiveness of a hypothetical kindergarten-based amblyopia screening versus non-screening among 3-year-old children.

Methods

We developed a decision tree combined with a Markov model to compare the cost and effectiveness of screening versus non-screening for 3-year-old children from a third-party payment perspective. The primary outcomes were quality-adjusted life years (QALYs) and the incremental cost-effectiveness ratio (ICER). Costs were obtained from expert opinions in different regions of China. Transition probabilities and health utilities were mainly based on published literature and open sources. Sensitivity analyses were performed to assess the impact of parameters' uncertainty on results.

Results

Base-case analysis demonstrated that the ICER of screening versus non-screening was $17,466/QALY, well below the WTP threshold ($38,223/QALY) for China. One-way sensitivity analysis showed that the prevalence of amblyopia, the transition probability per year from untreated amblyopia to healthy, and the discount rate were the top three factors. The likelihood of cost-effectiveness of screening compared with non-screening was 92.56%, according to probabilistic sensitivity analysis. Scenario analysis also indicated that ICER was lower than the WTP threshold even if the time horizon was shortened or the screening was delayed to the age of 4 or 5.

Conclusions

Amblyopia screening could be considered a cost-effective strategy compared to non-screening for 3-year-old children in China. Screening for children at the age of 4 or 5 may even yield better results.

The cost-effectiveness of different visual acuity screening strategies in three European countries: A microsimulation study

Childhood vision screening programmes in Europe differ by age, frequency and location at which the child is screened, and by the professional who performs the test. The aim of this study is to compare the cost-effectiveness for three countries with different health care structures.

We developed a microsimulation model of amblyopia. The natural history parameters were calibrated to a Dutch observational study. Sensitivity, specificity, attendance, lost to follow-up and costs in the three countries were based on the EUSCREEN Survey. Quality adjusted life-years (QALYs) were calculated using assumed utility loss for unilateral persistent amblyopia (1%) and bilateral visual impairment (8%). We calculated the cost-effectiveness of screening (with 3.5% annual discount) by visual acuity measurement at age 5 years or 4 and 5 years in the Netherlands by nurses in child healthcare centres, in England and Wales by orthoptists in schools and in Romania by urban kindergarten nurses. We compared screening at various ages and with various frequencies.

Assuming an amblyopia prevalence of 36 per 1,000 children, the model predicted that 7.2 cases of persistent amblyopia were prevented in the Netherlands, 6.6 in England and Wales and 4.5 in Romania. The cost-effectiveness was €24,159, €19,981 and €23,589, per QALY gained respectively, compared with no screening. Costs/QALY was influenced most by assumed utility loss of unilateral persistent amblyopia. For all three countries, screening at age 5, or age 4 and 5 years were optimal.

Despite differences in health care structure, vision screening by visual acuity measurement seemed cost-effective in all three countries.

Economic evaluations of vision screening to detect amblyopia and refractive errors in children: a systematic review

OBJECTIVE

To synthesize and appraise economic evaluations of vision screening to detect vision impairment in children.

METHODS

Literature searches were conducted on seven electronic databases, grey literature, and websites of agencies conducting health technology assessments. Studies were included if they (1) were full, comparative economic evaluations that used cost-utility, cost-benefit, cost-effectiveness, cost-consequence, or cost-analysis methods; (2) described screening services designed to detect amblyopia, strabismus, or uncorrected refractive errors in children under 6 years of age; and (3) published after 1994. High-quality studies were synthesized descriptively. Currencies were reported in 2019 Canadian dollars. Quality was assessed with the Pediatric Quality Appraisal Questionnaire (PQAQ).

RESULTS

Vision screening services were conducted by paid staff, volunteers, or health care professionals in schools or clinics. Thirteen studies were published from five countries: China (n = 1), United States (n = 4), United Kingdom (n = 1), Canada (n = 1), and Germany (n = 6). Analytical techniques included cost-utility/cost-effectiveness combination (n = 2), cost-effectiveness analysis (n = 7), cost-utility analysis (n = 1), cost-benefit analysis (n = 1), cost-consequence analysis (n = 1), and cost analysis (n = 1). Incremental cost-effectiveness ratios ranged from C$1,056 to C$151,274 per additional case detected/prevented and from C$9,429 to C$30,254,703 per additional QALY gained, depending on the type of screening service and comparator. Six studies were determined to be of high quality.

CONCLUSION

Vision screening to detect amblyopia for young children may be cost-effective compared with no screening if amblyopia reduced quality of life. Studies varied significantly in the type of screening services and comparators used. Methodological limitations were common. Future studies would be aided immensely by prospective studies on the impact of amblyopia on the health-related quality of life of young children and guidelines on the effective conduct of vision screening.

The health burden and costs of incident fractures attributable to osteoporosis from 2010 to 2050 in Germany--a demographic simulation model

To predict the burden of incident osteoporosis attributable fractures (OAF) in Germany, an economic simulation model was built. The burden of OAF will sharply increase until 2050. Future demand for hospital and long-term care can be expected to substantially rise and should be considered in future healthcare planning.

INTRODUCTION

The aim of this study was to develop an innovative simulation model to predict the burden of incident OAF occurring in the German population, aged >50, in the time period of 2010 to 2050.

METHODS

A Markov state transition model based on five fracture states was developed to estimate costs and loss of quality adjusted life years (QALYs). Demographic change was modelled using individual generation life tables. Direct (inpatient, outpatient, long-term care) and indirect fracture costs attributable to osteoporosis were estimated by comparing Markov cohorts with and without osteoporosis.

RESULTS

The number of OAF will rise from 115,248 in 2010 to 273,794 in 2050, cumulating to approximately 8.1 million fractures (78 % women, 22 % men) during the period between 2010 and 2050. Total undiscounted incident OAF costs will increase from around 1.0 billion Euros in 2010 to 6.1 billion Euros in 2050. Discounted (3 %) cumulated costs from 2010 to 2050 will amount to 88.5 billion Euros (168.5 undiscounted), with 76 % being direct and 24 % indirect costs. The discounted (undiscounted) cumulated loss of QALYs will amount to 2.5 (4.9) million.

CONCLUSIONS

We found that incident OAF costs will sharply increase until the year 2050. As a consequence, a growing demand for long-term care as well as hospital care can be expected and should be considered in future healthcare planning. To support decision makers in managing the future burden of OAF, our model allows to economically evaluate population- and risk group-based interventions for fracture prevention in Germany.

The potential cost-effectiveness of amblyopia screening programs

PURPOSE

To estimate the incremental cost-effective-ness of amblyopia screening at preschool and kindergarten, the costs and benefits of three amblyopia screening scenarios were compared to no screening and to each other: (1) acuity/stereopsis (A/S) screening at kindergarten, (2) A/S screening at preschool and kindergarten, and (3) photoscreening at preschool and A/S screening at kindergarten.

METHODS

A probabilistic microsimulation model of amblyopia natural history and response to treatment with screening costs and outcomes estimated from two state programs was programmed. The probability was calculated that no screening and each of the three interventions were most cost-effective per incremental quality-adjusted life year (QALY) gained and case avoided.

RESULTS

Assuming a minimal 0.01 utility loss from monocular vision loss, no screening was most cost-effective with a willingness to pay (WTP) of less than $16,000 per QALY gained. A/S screening at kindergarten alone was most cost-effective at a WTP between $17,000 and $21,000. A/S screening at preschool and kindergarten was most cost-effective at a WTP between $22,000 and $75,000, and photoscreening at preschool and A/S screening at kindergarten was most cost-effective at a WTP greater than $75,000. Cost-effectiveness substantially improved when assuming a greater utility loss. All scenarios were cost-effective when assuming a WTP of $10,500 per case of amblyopia cured.

CONCLUSION

All three screening interventions evaluated are likely to be considered cost-effective relative to many other potential public health programs. The choice of screening option depends on budgetary resources and the value placed on monocular vision loss prevention by funding agencies.

Application of classic utilities to published pediatric cost-utility studies

OBJECTIVE

Economic analyses, such as cost-utility analyses (CUAs), are dependent on the quality of the data used. Our objective was to test how health utility values (measurements of patient preference) assessed by recommended methods (classic utilities) would impact the conclusions in published pediatric CUAs.

METHODS

Classic utilities for pediatric health states were obtained by recommended utility assessment methods, time trade-off, and standard gamble in 4016 parent interviews. To test the impact of these utilities on published studies, we obtained a sample of published pediatric CUAs by searching Medline, EMBASE, EconLit, Health Technology Assessment Database, Cochrane Database on Systematic Reviews, Database of Abstracts of Reviews of Effects, and the Cost Effective Analysis (CEA) Registry at Tufts Medical Center, using search terms for cost-utility analysis. Articles were included when results were presented as cost per quality adjusted life-years (QALYs), the interventions were for children <18 years of age and included at least one of the following health states: attention deficit hyperactivity disorder, asthma, gastroenteritis, hearing loss, mental retardation, otitis media, seizure disorder, or vision loss. Studies that did not include these or equivalent health states were excluded. For each CUA, we determined utilities (values for patient preference), the utility assessment method used, and presence of one-way sensitivity analyses (SAs) on utilities. When one-way SAs were conducted, we determined if using our classic utilities would change the result of the CUA. When an SA was not presented, we determined if using our classic utilities would tend to support or not support the published conclusions.

RESULTS

We evaluated 39 articles. Eighteen articles presented results of one-way SAs on utilities. Seven articles presented SAs over a range that included our classic utilities. In 4 of the 7, using classic utilities would change the conclusion of the study. For the 32 articles where no one-way SA were presented (n = 21), or where the classic utilities fell outside the range tested (n =11), a change to classic utility would tend against the study conclusion in 12 articles (31%).

CONCLUSIONS

More than a third of published CUA studies could change if pediatric utilities obtained by recommended, classic methods were used. One-way SAs on utilities are often not presented, making comparison between studies challenging.

Developing an algorithm to convert routine measures of vision into utility values for glaucoma

PURPOSE

Measures of quality of life called utility values (UVs) are needed to deliver the most cost-effective health care for glaucoma patients. UVs are rarely measured in clinical research and practice whereas clinical outcomes such as visual field are routinely collected. The aim of this study was to develop an algorithm that calculates UVs directly from combinations of routine measures of binocular visual field, visual acuity, and contrast sensitivity.

METHODS

A total of 132 outpatients with primary open angle glaucoma were recruited. The Time Trade-off (TTO) question was administered during face-to-face interviews. Binocular ETDRS logMAR visual acuity (VA(B)), binocular Pelli-Robson contrast sensitivity (CS(B)), and Humphrey 24-2 monocular visual field tests were performed on the same day. Integrated (binocular) visual field (IVF) scores were derived. Tobit regression analyses were used to model utility values based on combinations of IVF, VA(B), CS(B) and other controlling factors.

RESULTS

UVs recorded for 123 cases correlated significantly with both clinical measures of binocular visual function (r = -0.47, IVF; r = -0.48, VA(B); r = 0.50, CS(B); P <0.0001) and measures of vision-specific quality of life (r = 0.54-0.6, P <0.0001). Two final models incorporate terms for IVF and VA(B), with or without living arrangements, and explain 22% and 31% of variation in utilities. CS(B) was not included in either model due to co-linearity between CS(B) and VA(B) confounding the models.

CONCLUSION

The models provide preliminary algorithms for predicting the expected UVs for glaucoma populations directly from clinical outcomes collected routinely in clinical practice.

Vision screening in preschool children: do the data support universal screening?

BACKGROUND

Comprehensive, systematic reviews on the benefit of vision screening in preschool children were published in 2008 by major national organizations in both Germany and the United Kingdom. These reviews raised public interest in the topic.

METHODS

This article contains a discussion of the sensitivity, specificity, efficacy, and cost-effectiveness of preschool vision screening, on the basis of the two national reports mentioned above as well as relevant literature retrieved by a selective PubMed search.

RESULTS

All studies that have been published to date on the efficacy of preschool visual screening suffer from methodological flaws. The available data suggest a benefit from screening, though this has not been proven. Model calculations reveal that the positive predictive value of screening tests performed in isolation is inadequate. The authors of the two national reports applied different methods and arrived at similar, but not identical conclusions. Preschool vision screening may also be cost-effective; whether this is the case or not depends on the probability of a long-term benefit--specifically, on the probability of preventing bilateral loss of vision in adulthood. To prevent one such case, it is estimated that 13 cases of childhood amblyopia must be identified and successfully treated (number needed to treat [NNT] = 13).

CONCLUSION

The available data do not allow any firm conclusion about the efficacy and cost-effectiveness of preschool vision screening. Further clinical studies are needed to answer these questions.

Amblyopia

Results from recent randomised clinical trials in amblyopia should change our approach to screening for and treatment of amblyopia. Based on the current evidence, if one screening session is used, screening at school entry could be the most reasonable time. Clinicians should preferably use age-appropriate LogMAR acuity tests, and treatment should only be considered for children who are clearly not in the typical range for their age. Any substantial refractive error should be corrected before further treatment is considered and the child should be followed in spectacles until no further improvement is recorded, which can take up to 6 months. Parents and carers should then be offered an informed choice between patching and atropine drops. Successful patching regimens can last as little as 1 h or 2 h a day, and successful atropine regimens as little as one drop twice a week. Intense and extended regimens might not be needed in initial therapy.

Amblyopia: diagnostic and therapeutic options

PURPOSE

To provide an overview of the current state of knowledge of amblyopia and highlight recent advances in diagnosis and treatment.

DESIGN

Review of literature and perspective.

METHODS

MEDLINE search for amblyopia, with a review of all recent literature adding authors' personal perspectives on the findings.

RESULTS

Increased awareness of amblyopia and better screening techniques are required to identify children who are at risk for amblyopia at a younger age. Randomized, controlled trials have established atropine penalization as a viable alternative to occlusion therapy, have suggested that less treatment may be better tolerated and as effective as more traditionally used dosages, and have found no compelling evidence that treatment is beneficial clinically for older (over age 10) children with amblyopia.

CONCLUSION

Early detection and treatment of amblyopia can improve the chances for a successful visual outcome. Considering that the conditions that place a patient at risk for amblyopia can be identified, that amblyopia responds to treatment, and that well-tolerated treatments for the condition are now recognized, it is not unreasonable to imagine that, in the near future, severe amblyopia could be eliminated as a public health problem.

Quality-adjusted life-years lack quality in pediatric care: a critical review of published cost-utility studies in child health

OBJECTIVES

Cost-utility analysis in which health benefits are quantified in terms of quality-adjusted life-years (QALYs) has now become the standard type of cost-effectiveness analysis. These studies are potentially influential in determining the extent of funding for particular pediatric interventions, and so their methodologic quality is extremely important. The objective of this study was twofold: first, to critically appraise published cost-utility analyses of interventions in child and adolescent health care in terms of the methods used to derive QALYs and, second, to discuss unresolved methodologic issues that are pertinent to the measurement of QALYs in pediatric populations.

METHODS

A comprehensive search using computerized databases (including Medline, Embase, Econlit, and databases specific to economic evaluation), Web searches, and citation tracking was undertaken to identify cost-utility studies of interventions that were aimed at those who were younger than 16 years and published before April 2004. The methods of individual studies were compared with the recognized published guidelines of the US Panel on Cost-Effectiveness in Health and Medicine and the National Institute for Clinical Excellence in England and Wales, which recommend the use of a generic health state classification system (eg, Health Utility Index, EuroQol-5D), a choice-based valuation method (eg, standard gamble or time trade-off) and preferences of the general public in estimating QALYs. Studies therefore were categorized and evaluated according to the methods used to describe the health state, the valuation technique, and source of preferences.

RESULTS

Fifty-four studies were reviewed, 34 (63%) of which were published in the past 5 years. A generic health status classification instrument was used in 22 (35%) cases; the remainder developed study-specific health state descriptions or elicited preferences directly from patients or proxies. In 3 (5%) cases, sources were unclear. Preference weights were elicited using choice-based techniques in 28 (42%) cases, either as tariffs for health status classification instruments (17 cases) or by directly valuing health state descriptions or patient health (11 cases). Preferences of the general public were used in only 23 (37%) cases. Four studies aggregated QALYs for mother/child or parents/child pairs without giving any theoretical justification. Although there was an increasing tendency for studies to use generic health status classification instruments, choice-based methods, and preferences of the general public, the majority of studies still did not adhere to these standard recommendations even in the period between January 2000 and March 2004. Despite increasing standardization in the methods advocated for economic evaluation over the past 10 years, there remains extensive variation in the actual methods used by researchers to calculate QALYs for children and adolescents. It is unclear whether these results suggest poor practice or a set of positive (or reactive) choices made by analysts in a methodologically uncertain area in which specific guidance is lacking regarding how to address the complexities of pediatric outcomes within the QALY framework. Many aspects of QALY measurement in children are not yet fully developed. In particular, there is (1) a lack of appropriate health state classification instruments that take account of the dynamics of child development, (2) a lack of health state classification instruments for use in children and infants who are younger than 5 years, and (3) the need to understand fully the role of proxies for measuring and valuing child health. Additional research efforts are also required to develop methods that account for the health benefits of parents or caregivers of the child and to consider the implications of combining different forms of utility measurement in childhood and adulthood.

CONCLUSIONS

Although variations from standard recommendations may be attributable to poor practice among researchers who are either unaware of these recommendations or choose not to follow them, they could equally be the result of attempts to make research more rigorous and more defensible than it might be if the standard recommendations were followed. There are 4 potential approaches to conducting cost-utility analysis in pediatric populations: (1) the explicit development of a generic instrument designed to be applicable across both child and adult populations (likely to be difficult in practice), (2) insistence on use of a generic instrument developed for adults, (3) the use of generic instruments specifically developed for children without being concerned about comparability with interventions aimed at adults, and (4) abandoning attempts to use single outcome measures that combine mortality with quality weights. In the absence of a clear way forward, it is suggested that an expert panel be convened to debate and further consider these potential solutions and recommendations for best practice and future research. In the interim, comparisons of the relative cost-effectiveness reported as cost per QALY gained across interventions for different diseases and populations should be treated with extreme caution.

Amblyopia characterization, treatment, and prophylaxis

Amblyopia has a 1.6-3.6% prevalence, higher in the medically underserved. It is more complex than simply visual acuity loss and the better eye has sub-clinical deficits. Functional limitations appear more extensive and loss of vision in the better eye of amblyopes more prevalent than previously thought. Amblyopia screening and treatment are efficacious, but cost-effectiveness concerns remain. Refractive correction alone may successfully treat anisometropic amblyopia and it, minimal occlusion, and/or catecholamine treatment can provide initial vision improvement that may improve compliance with subsequent long-duration treatment. Atropine penalization appears as effective as occlusion for moderate amblyopia, with limited-day penalization as effective as full-time. Cytidin-5'-diphosphocholine may hold promise as a medical treatment. Interpretation of much of the amblyopia literature is made difficult by: inaccurate visual acuity measurement at initial visit, lack of adequate refractive correction prior to and during treatment, and lack of long-term follow-up results. Successful treatment can be achieved in at most 63-83% of patients. Treatment outcome is a function of initial visual acuity and type of amblyopia, and a reciprocal product of treatment efficacy, duration, and compliance. Age at treatment onset is not predictive of outcome in many studies but detection under versus over 2-3 years of age may be. Multiple screenings prior to that age, and prompt treatment, reduce prevalence. Would a single early cycloplegic photoscreening be as, or more, successful at detection or prediction than the multiple screenings, and more cost-effective? Penalization and occlusion have minimal incidence of reverse amblyopia and/or side-effects, no significant influence on emmetropization, and no consistent effect on sign or size of post-treatment changes in strabismic deviation. There may be a physiologic basis for better age-indifferent outcome than tapped by current treatment methodologies. Infant refractive correction substantially reduces accommodative esotropia and amblyopia incidence without interference with emmetropization. Compensatory prism, alone or post-operatively, and/or minus lens treatment, and/or wide-field fusional amplitude training, may reduce risk of early onset esotropia. Multivariate screening using continuous-scale measurements may be more effective than traditional single-test dichotomous pass/fail measures. Pigmentation may be one parameter because Caucasians are at higher risk for esotropia than non-whites.