Oliver Rivero-Arias

Estimating the association between SF-12 responses and EQ-5D utility values by response mapping.

Background. Reliably mapping from generic or diseasespecific health status measures into health state utilities would assist health economists. Existing studies mainly use ordinary least squares (OLS) regression equations to predict utility values for particular health states. The authors examine an alternative approach tomap between 2 generic health status instruments, the SF-12 and the EQ-5D. Methods. Multinomial logit regression is used to estimate the probability that a respondent will select a particular level of response to questions in the EQ-5D, using individual question responses and summary scores from the SF-12 as predictors. Monte Carlo simulation methods are used to generate predicted EQ-5D responses, and utility scores (tariffs) are then attached. Results are comparedwithanalternativeapproach based on direct mapping to utility scores using OLS. Data. The authors estimate equations using 12,967 adult survey responses-from the 2000 US Medical Expenditure Panel Survey. They report mean squared error (MSE) andmean absolute error (MAE) of their predicted utilitieswithin this sample, and out-of-sample using 13,304 adults from the 1996 Health Survey for England. Results. The authors obtain an in-sample and out-of-sample MSE of 0.03, compared with 0.02 for the OLS approach. Their MAE of 0.11 is similar to OLS results. The authors’ method predicts groupmean utility scores and differentiates between groups with or without known existing illness. Conclusions. The authors’ approach has higher MSE than the direct OLS approach but givesmore descriptive data on domains of health effects. Further outofsample prediction work will help test the validity of these methods.

Surgical stabilisation of the spine compared with a programme of intensive rehabilitation for the management of patients with chronic low back pain: cost utility analysis based on a randomised controlled trial.

Abstract Objective To determine whether, from a health provider and patient perspective, surgical stabilisation of the spine is cost effective when compared with an intensive programme of rehabilitation in patients with chronic low back pain. Design Economic evaluation alongside a pragmatic randomised controlled trial. Setting Secondary care. Participants 349 patients randomised to surgery (n = 176) or to an intensive rehabilitation programme (n = 173) from 15 centres across the United Kingdom between June 1996 and February 2002. Main outcome measures Costs related to back pain and incurred by the NHS and patients up to 24 months after randomisation. Return to paid employment and total hours worked. Patient utility as estimated by using the EuroQol EQ-5D questionnaire at several time points and used to calculate quality adjusted life years (QALYs). Cost effectiveness was expressed as an incremental cost per QALY. Results At two years, 38 patients randomised to rehabilitation had received rehabilitation and surgery whereas just seven surgery patients had received both treatments. The mean total cost per patient was estimated to be £7830 (SD £5202) in the surgery group and £4526 (SD £4155) in the intensive rehabilitation arm, a significant difference of £3304 (95% confidence interval £2317 to £4291). Mean QALYs over the trial period were 1.004 (SD 0.405) in the surgery group and 0.936 (SD 0.431) in the intensive rehabilitation group, giving a non-significant difference of 0.068 (–0.020 to 0.156). The incremental cost effectiveness ratio was estimated to be £48 588 per QALY gained (–£279 883 to £372 406). Conclusion Two year follow-up data show that surgical stabilisation of the spine may not be a cost effective use of scarce healthcare resources. However, sensitivity analyses show that this could change—for example, if the proportion of rehabilitation patients requiring subsequent surgery continues to increase.

Mapping the modified Rankin scale (mRS) measurement into the generic EuroQol (EQ-5D) health outcome.

Background. Mapping disease-specific instruments into generic health outcomes or utility values is an expanding field of interest in health economics. This article constructs an algorithm to translate the modified Rankin scale (mRS) into EQ-5D utility values. Methods. mRS and EQ-5D information was derived from stroke or transient ischemic attack (TIA) patients identified as part of the Oxford Vascular study (OXVASC). Ordinary least squares (OLS) regression was used to predict UK EQ-5D tariffs from mRS scores. An alternative method, using multinomial logistic regression with a Monte Carlo simulation approach (MLogit) to predict responses to each EQ-5D question, was also explored. The performance of the models was compared according to the magnitude of their predicted-to-actual mean EQ-5D tariff difference, their mean absolute and mean squared errors (MAE and MSE), and associated 95% confidence intervals (CIs). Out-of-sample validation was carried out in a subset of coronary disease and peripheral vascular disease (PVD) patients also identified as part of OXVASC but not used in the original estimation. Results. The OLS and MLogit yielded similar MAE and MSE in the internal and external validation data sets. Both approaches also underestimated the uncertainty around the actual mean EQ-5D tariff producing tighter 95% CIs in both data sets. Conclusions. The choice of algorithm will be dependent on the study aim. Individuals outside the United Kingdom may find it more useful to use the multinomial results, which can be used with different country-specific tariff valuations. However, these algorithms should not replace prospective collection of utility data.

Epidemiology of fragile X syndrome: a systematic review and meta-analysis.

Prevalence estimates for fragile X syndrome vary considerably. This systematic review and meta‐analysis was conducted to provide an accurate prevalence estimate for this disorder using primary publications in PubMed, Embase, and the Cochrane library. Data were pooled using Bayesian fixed‐effects and random‐effects models. Primary analyses assessed the frequency of the full mutation and premutation in males and females in the total population (no bias against individuals with intellectual disability) and in female carriers of the premutation in normal populations (biased against individuals with intellectual disability), based on diagnosis by polymerase chain reaction or Southern blotting. A sensitivity analysis included studies using any diagnostic testing method and conference abstracts. Sixty‐eight recorded observations provided data for the primary (56 observations) and sensitivity (12 observations) analysis. Using the random‐effects model, frequency of the full mutation was 1.4 (95% CI: 0.1–3.1) per 10,000 males and 0.9 (95% CI: 0.0–2.9) per 10,000 females (1:7,143 and 1:11,111, respectively) in the total population. The premutation frequency was 11.7 (95% CI: 6.0–18.7) per 10,000 males and 34.4 (95% CI: 6.3–83.3) per 10,000 for females (1:855 and 1:291, respectively) in the total population. The prevalence of female carriers of the premutation in the normal population was 34.4 (95% CI: 8.9–60.3) per 10,000, or 1:291. Sensitivity analyses resulted in similar prevalence estimates but with wider heterogeneity. Prevalence estimates for the full mutation from this meta‐analysis are lower than those in previous reviews of fragile X syndrome epidemiological data.

Treatment Pathways, Resource Use, and Costs of Endovascular Coiling Versus Surgical Clipping After aSAH

Background and Purpose— The International Subarachnoid Aneurysm Trial (ISAT) reported that endovascular coiling yields better clinical outcomes than surgical clipping at 1 year. The high cost of the consumables associated with the endovascular coiling procedure (particularly the coils) led health care purchasers to conclude that coiling was a more costly procedure overall. To examine this assumption and provide evidence for future policy, accurate and comprehensive data are required on the overall resource usage and cost of each strategy. Methods— We provide detailed results of patient treatment pathways, resource utilization, and costs up to 24 months postrandomization for endovascular and neurosurgical treatment of aSAH. We report data on costs related to initial and subsequent procedures (ward days, ITU, equipment, staff, consumables, etc), adverse events, complications, and follow up. The data are based on a subsample of all patients randomized in ISAT, containing all patients across 22 UK centers (n=1644). Results— There was a nonsignificant difference −£1740 (−£3582 to £32) in the total 12-month cost of treatment in favor of endovascular treatment. Endovascular patients had higher costs than neurosurgical patients for the initial procedure, for the number and length of stay of subsequent procedures, and for follow-up angiograms. These were more than offset by lower costs related to length of stay for the initial procedure. In the following 12- to 24-month period, costs for subsequent procedures, angiograms, complications, and adverse events were greater for the endovascular patients, reducing the difference in total per patient cost to −£1228 (−£3199 to £786) over the first 24 months of follow-up. Conclusions— No significant difference in costs between the endovascular and neurosurgery groups existed at 12- or 24-month follow up.

Cost-utility analysis of physiotherapy treatment compared with physiotherapy advice in low back pain.

Study Design. Economic evaluation alongside a pragmatic multicenter randomized controlled trial from the National Health Service (NHS) and societal perspective. Objective. To perform a cost-utility analysis of routine physiotherapy treatment compared with an assessment session and advice from a physiotherapist for patients with subacute and chronic low back pain. Summary of Background Data. Lack of evidence for some types of physiotherapy intervention and a paucity of cost-effectiveness data for treatment of low back pain has led to controversy and uncertainty within the medical and allied professions. Patients and Methods. A total of 286 patients with low back pain of more than a 6-week duration were randomized to physiotherapy treatment or advice on remaining active from a physiotherapist. Data were collected on back pain-related NHS and patients’ costs over a 12-month post randomization period. The primary outcome measure was the Oswestry Disability Index at 12 months, with additional Oswestry Disability Index measures at 2 and 6 months. The EuroQol EQ-5D was used to calculate quality adjusted life years. Cost-effectiveness was expressed as the incremental cost per quality adjusted life year gained. Uncertainty was handled using confidence ellipses for the ratio and cost-effectiveness acceptability curves. Results. The total NHS costs were not significantly different at £179 (£221) for physiotherapy and £159 (£260) for the advice group. However, patients in the physiotherapy group had significantly higher out-of-pocket health care expenditure (£40, 95% confidence interval £9 to £71). Utility levels improved in both groups from baseline to 12 months, with no significant differences between groups. Conclusions. The results indicate no significant differences in either NHS costs or effects. However, the significantly higher out-of-pocket expenses incurred by patients receiving routine physiotherapy suggests that advice given by a physiotherapist should be considered as the first-line treatment for patients with this level of back pain disability.

Healthcare and social services resource use and costs of self-harm patients

BackgroundPatients who have self-harmed have increased morbidity across a wide range of health outcomes, but there is no evidence on their pattern of health and social service use, and its relationship with repetition of self-harm. Previous studies have shown that resource use and costs in the short-term hospital management of self-harm is associated with certain patient and service characteristics but their impact in the longer term has not been demonstrated. The aim of this study is to test the association between changing levels of costs of health and social care with further episodes of self-harm and to identify the clinical and social factors associated with this.MethodThis was a cost-analysis incidence study of a sample of patients from a cohort of self-harm patients who remained within one region over the course of their follow-up. Resource use was retrospectively observed from their first episode of self-harm (dating back on some occasions to the 1970’s), and costs applied. Panel data analyses were used to identify factors associated with observed costs over time.ResultsPatients with five or more episodes of self-harm had the highest levels of resource costs. Health and social care costs reduced with time from last episode of self-harm. In the year following the first episode of self-harm, psychiatric care accounted for 69% and psychotropic drug prescriptions 1% of the mean resource costs.ConclusionsThe management of self-harm occurs within a complex system of health and social care. Major self-harm repeaters place the greatest cost burden on the system. Better understanding of the impact of risk assessment models and consequent service provision on clinical outcome may help in the design of effective services for this patient group.

Burden of disease and costs of aneurysmal subarachnoid haemorrhage (aSAH) in the United Kingdom

BackgroundTo estimate life years and quality-adjusted life years (QALYs) lost and the economic burden of aneurysmal subarachnoid haemorrhage (aSAH) in the United Kingdom including healthcare and non-healthcare costs from a societal perspective.MethodsAll UK residents in 2005 with aSAH (International Classification of Diseases 10th revision (ICD-10) code I60). Sex and age-specific abridged life tables were generated for a general population and aSAH cohorts. QALYs in each cohort were calculated adjusting the life tables with health-related quality of life (HRQL) data. Healthcare costs included hospital expenditure, cerebrovascular rehabilitation, primary care and community health and social services. Non-healthcare costs included informal care and productivity losses arising from morbidity and premature death.ResultsA total of 80,356 life years and 74,807 quality-adjusted life years were estimated to be lost due to aSAH in the UK in 2005. aSAH costs the National Health Service (NHS) £168.2 million annually with hospital inpatient admissions accounting for 59%, community health and social services for 18%, aSAH-related operations for 15% and cerebrovascular rehabilitation for 6% of the total NHS estimated costs. The average per patient cost for the NHS was estimated to be £23,294. The total economic burden (including informal care and using the human capital method to estimate production losses) of a SAH in the United Kingdom was estimated to be £510 million annually.ConclusionThe economic and disease burden of aSAH in the United Kingdom is reported in this study. Decision-makers can use these results to complement other information when informing prevention policies in this field and to relate health care expenditures to disease categories.

Valuation and Modeling of EQ-5D-5L Health States Using a Hybrid Approach.

Background: The EQ-5D instrument is the most widely used preference-based health-related quality of life questionnaire in cost-effectiveness analysis of health care technologies. Recently, a version called EQ-5D-5L with 5 levels on each dimension was developed. This manuscript explores the performance of a hybrid approach for the modeling of EQ-5D-5L valuation data. Methods: Two elicitation techniques, the composite time trade-off, and discrete choice experiments, were applied to a sample of the Spanish population (n=1000) using a computer-based questionnaire. The sampling process consisted of 2 stages: stratified sampling of geographic area, followed by systematic sampling in each area. A hybrid regression model combining composite time trade-off and discrete choice data was used to estimate the potential value sets using main effects as starting point. The comparison between the models was performed using the criteria of logical consistency, goodness of fit, and parsimony. Results: Twenty-seven participants from the 1000 were removed following the exclusion criteria. The best-fitted model included 2 significant interaction terms but resulted in marginal improvements in model fit compared to the main effects model. We therefore selected the model results with main effects as a potential value set for this methodological study, based on the parsimony criteria. The results showed that the main effects hybrid model was consistent, with a range of utility values between 1 and −0.224. Conclusion: This paper shows the feasibility of using a hybrid approach to estimate a value set for EQ-5D-5L valuation data.

Responsiveness of objective, disease-specific, and generic outcome measures in patients with chronic low back pain: an assessment for improving, stable, and deteriorating patients.

Study Design. Analysis of outcome data collected prospectively from 250 patients recruited to the UK Spine Stabilization Trial. Objectives. To compare the responsiveness of the Shuttle Walking Test (SWT), which is an objective outcome measure, with that of a disease-specific (the Oswestry Disability Index) and 2 generic (the EQ-5D and SF-36) instruments in patients with chronic low back pain (LBP). Summary of Background Data. Studies assessing the performance of subjective disease-specific and generic measures have increased in recent years, although there is a paucity of research reporting the responsiveness of objective measures in patients with LBP. The focus of investigation has been on responsiveness to improvements in LBP symptoms. For patients with deteriorating health, it remains largely unclear how outcome instruments perform. Methods. Baseline and 12-month outcome data collected on 250 patients with chronic LBP recruited to the Spine Stabilization Trial were analyzed using traditional measures of responsiveness. Analyses were performed for 3 groups of patients: those who rated their health status as improved, deteriorated, and stable at 12 months. Results. The SWT was shown by all measures to be responsive to health improvement, although less so than other instruments. All instruments were able to detect small-to-moderate reductions in health. Instrument floor effects may be responsible for small SF-36 change scores recorded for deteriorating patients. Conclusions. Although shown to be responsive, including the SWT alongside disease-specific and generic instruments is unlikely to add additional information. All instruments appear responsive to patient deterioration, however, further research for the SF-36 is required.