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Jennifer Roberts

Publications and source records attributed to Jennifer Roberts.

At least 19 recordsLinked to original sources
PubMed2006

Modelling SF-6D health state preference data using a nonparametric Bayesian method.

This paper reports on the findings from applying a new approach to modelling health state valuation data. The approach applies a nonparametric model to estimate SF-6D health state utility values using Bayesian methods. The data set is the UK SF-6D valuation study where a sample of 249 states defined by the SF-6D (a derivative of the SF-36) was valued by a representative sample of the UK general population using standard gamble. The paper presents the results from applying the nonparametric model and comparing it to the original model estimated using a conventional parametric random effects model. The two models are compared theoretically and in terms of empirical performance. The paper discusses the implications of these results for future applications of the SF-6D and further work in this field.

Bayes Theorem↗
PubMed2006

Efficient and persistent splice switching by systemically delivered LNA oligonucleotides in mice.

Locked nucleic acid (LNA) oligomers were found to be very effective in their ability to modulate alternative splicing in vivo in transgenic mice that ubiquitously express a modified EGFP pre-mRNA containing an aberrantly spliced beta-globin intron (IVS2-654). Following intraperitoneal injections, the splice-switching oligonucleotide LNA SSO-654 targeted to the aberrant 5' splice site in EGFP-654 pre-mRNA corrected aberrant splicing and increased production of repaired EGFP mRNA mainly in the liver, colon, and small intestine. Little or no effect was detected in heart, lung, or kidney, the organ where most of the oligonucleotide was distributed after four consecutive daily injections. In the liver, LNA SSO-654 had an EC(50) of 3 mg/kg, approximately 17-fold more potent than its 2'-O-methyl congener. Moreover, in the liver, colon, and small intestine oral doses of 50 mg/kg resulted in detectable levels of splice switching. The effects of four daily injections at 25 mg/kg persisted for up to 29 days but did not result in liver toxicity. The results indicate that the LNA backbone confers sequence- and organ-specific functional biodistribution of the oligonucleotides and that these potent compounds have the potential to be safe and long-acting modulators of diseases treatable by splicing manipulation.

Administration, Oral↗
PubMed2006

Using rank data to estimate health state utility models.

In this paper we report the estimation of conditional logistic regression models for the Health Utilities Index Mark 2 and the SF-6D, using ordinal preference data. The results are compared to the conventional regression models estimated from standard gamble data, and to the observed mean standard gamble health state valuations. For both the HUI2 and the SF-6D, the models estimated using ordinal data are broadly comparable to the models estimated on standard gamble data and the predictive performance of these models is close to that of the standard gamble models. Our research indicates that ordinal data have the potential to provide useful insights into community health state preferences. However, important questions remain.

Health Status Indicators↗
PubMed2005

Comparison of valuation methods used to generate the EQ-5D and the SF-6D value sets.

An interview study with 101 members of public compared the protocols used in valuation studies for EQ-5D (using ranking, visual analogue scale, and time trade-off), and SF-6D (using ranking and standard gamble). Respondents were given one of the two protocols and asked to value four states each from EQ-5D and SF-6D. VAS scores suggest the narrower range of SF-6D values is partly attributable to the descriptive system; TTO values for milder states were higher than SG values; and the mean value for EQ-5D pits using TTO and SF-6D pits using SG were closer than across the two original valuation studies.

Health Status Indicators↗
PubMed2005

Estimating a preference-based index for a menopause specific health quality of life questionnaire.

BACKGROUND: The aim of the study was to develop a menopause-specific, preference-based health-related quality-of-life (HRQoL) index reflecting both menopausal symptoms and potential side-effects of Hormone Replacement Therapy (HRT). METHODS: The study had three phases: the development of a health state classification, a prospective valuation survey and the estimation of a model to interpolate HRQoL indices for all remaining health states as defined by the classification. A menopausal health state classification was developed with seven dimensions: hot flushes, aching joints/muscles, anxious/frightened feelings, breast tenderness, bleeding, vaginal dryness and undesirable androgenic signs. Each dimension contains between three and five levels and defines a total of 6,075 health states. A sample of 96 health states was selected for the valuation survey. These states were valued by a sample of 229 women aged 45 to 60, randomly selected from 6 general practice lists in Sheffield, UK. Respondents were asked to complete a time trade-off (TTO) task for nine health states, resulting in an average of 16.5 values for each health state. RESULTS: Mean health states valued range from 0.48 to 0.98 (where 1.0 is full health and zero is for states regarded as equivalent to death). Symptoms, as described by the classification system, can be rank-ordered in terms of their impact (from high to low) on menopausal HRQoL as follows: aching joints and muscles, bleeding, breast tenderness, anxious or frightened feelings, vaginal dryness, androgenic signs. Hot flushes did not significantly contribute to model fit. The preferred model produced a mean absolute error of 0.053, but suffered from bias at both ends of the scale. CONCLUSION: This article presents an attempt to directly value a condition specific health state classification. The overall fit was disappointing, but the results demonstrate that menopausal symptoms are perceived by patients to have a significant impact on utility. The overall effect is modest compared to the more generic health state descriptions such as the EQ-5D. The resultant algorithm generates a preference-based index that can be used economic evaluation and that reflects the impact of this condition.

Female↗
PubMed2005

Health state values for the HUI 2 descriptive system: results from a UK survey.

This paper reports the results of a study to estimate a statistical health state valuation model for a revised version of the Health Utilities Index Mark 2, using Standard Gamble health state preference data. A sample of 51 health states were valued by a sample of the 198 members of the UK general population. Models are estimated for predicting health state valuations for all 8000 states defined by the revised HUI2. The recommended model produces logical and significant coefficients for all levels of all dimensions in the HUI2. These coefficients appear to be robust across model specifications. This model performs well in predicting the observed health state values within the valuation sample and for a separate validation sample of health states. However, there are concerns over large prediction errors for two health states in the valuation sample. These problems must be balanced against concerns over the validity of using the VAS based health state valuation data of the original HUI2 valuation model.

Data Collection↗
PubMed2004

A comparison of the EQ-5D and SF-6D across seven patient groups.

As the number of preference-based instruments grows, it becomes increasingly important to compare different preference-based measures of health in order to inform an important debate on the choice of instrument. This paper presents a comparison of two of them, the EQ-5D and the SF-6D (recently developed from the SF-36) across seven patient/population groups (chronic obstructive airways disease, osteoarthritis, irritable bowel syndrome, lower back pain, leg ulcers, post menopausal women and elderly). The mean SF-6D index value was found to exceed the EQ-5D by 0.045 and the intraclass correlation coefficient between them was 0.51. Whilst this convergence lends some support for the validity of these measures, the modest difference at the aggregate level masks more significant differences in agreement across the patient groups and over severity of illness, with the SF-6D having a smaller range and lower variance in values. There is evidence for floor effects in the SF-6D and ceiling effects in the EQ-5D. These discrepancies arise from differences in their health state classifications and the methods used to value them. Further research is required to fully understand the respective roles of the descriptive systems and the valuation methods and to examine the implications for estimates of the impact of health care interventions.

Activities of Daily Living↗
PubMed2004

To what extent do people prefer health states with higher values? A note on evidence from the EQ-5D valuation set.

The EQ-5D general population valuation set (or 'tariff') is increasingly being used in the evaluation of health care interventions and has been recommended by the National Institute for Clinical Excellence (NICE) for use in cost-utility analyses of health technologies. To be of use to decision-makers, the health gain implied by changes in health state values must reflect individual preferences. At the simplest level, if State A has a higher mean value than State B, then the majority of people should consider a move from B to A to be a good thing. In this paper, we examine the extent to which this is true by re-analysing data from the general population study used to derive the EQ-5D tariff. We show that, on average, the difference in value between two states has to be as large as 0.20 (on a scale where one represents full and zero represents death) for 70% of respondents to agree with the sign of that difference (never mind its size). Results such as these have important implications for the use of the EQ-5D tariff that has been generated from these data.

Consumer Behavior↗
PubMed2004

The estimation of a preference-based measure of health from the SF-12.

BACKGROUND: The SF-12 is a multidimensional generic measure of health-related quality of life. It has become widely used in clinical trials and routine outcome assessment because of its brevity and psychometric performance, but it cannot be used in economic evaluation in its current form. OBJECTIVES: We sought to derive a preference-based measure of health from the SF-12 for use in economic evaluation and to compare it with the original SF-36 preference-based index. RESEARCH DESIGN: The SF-12 was revised into a 6-dimensional health state classification (SF-6D [SF-12]) based on an item selection process designed to ensure the minimum loss of descriptive information. SUBJECTS: A sample of 241 states defined by the SF-6D (of 7500) have been valued by a representative sample of 611 members of the UK general population using the standard gamble (SG) technique. ANALYSIS: Models are estimated of the relationship between the SF-6D (SF-12) and SG values and evaluated in terms of their coefficients, overall fit, and the ability to predict SG values for all health states. RESULTS: The models have produced significant coefficients for levels of the SF-6D (SF-12), which are robust across model specification. The coefficients are similar to those of the SF-36 version and achieve similar levels of fit. There are concerns with some inconsistent estimates and these have been merged to produce the final recommended model. As for the SF-36 model, there is evidence of over prediction of the value of the poorest health states. CONCLUSIONS: The SF-12 index provides a useful tool for researchers and policy makers wishing to assess the cost-effectiveness of interventions.

Aged↗
PubMed2004

Anuric renal failure associated with zinc toxicosis in a dog.

The development of anuric renal failure associated with zinc intoxication was detected in a dog following ingestion of an ornamental brass knob from a toilet paper holder. The 3-y-old, male neutered, 15.4 kg Welsh Corgi presented to a local veterinary clinic with a 2-w history of intermittent vomiting, inappetance and lethargy. The dog was transferred to a veterinary teaching hospital where surgery was performed to remove the foreign body. The dogwas euthanized 24 h post-surgery due to the development of anuric renal failure. Whole blood drawn at the time of surgery had a serum zinc concentration of 89.8 ppm (normal 0.7-2.0 ppm). The serum zinc concentration in this dog is the highest reported concentration in the literature. Ingestion of any zinc-containing metal object can potentially result in a severe intravascular hemolysis with subsequent renal impairment. Zinc intoxication should be suspected when hemolysis is accompanied by the finding of a metallic object in the gut.

Animals↗
PubMed2002

Design and performance of a multi-centre randomised controlled trial and economic evaluation of joint tele-consultations [ISRCTN54264250].

BACKGROUND: Appropriate information flow is crucial to the care of patients, particularly at the interface between primary and secondary care. Communication problems can result from inadequate organisation and training, There is a major expectation that information and communication technologies may offer solutions, but little reliable evidence. This paper reports the design and performance of a multi-centre randomised controlled trial (RCT), unparalleled in telemedicine research in either scale or range of outcomes. The study investigated the effectiveness and cost implications in rural and inner-city settings of using videoconferencing to perform joint tele-consultations as an alternative to general practitioner referral to the hospital specialist in the outpatient clinic. METHODS: Joint tele-consultation services were established in both the Royal Free Hampstead NHS Trust in inner London, and the Royal Shrewsbury Hospitals Trust, in Shropshire. All the patients who gave consent to participate were randomised either to joint tele-consultation or to a routine outpatients appointment. The principal outcome measures included the frequency of decision by the specialist to offer a follow-up outpatient appointment, patient satisfaction (Ware Specific Questionnaire), wellbeing (SF12) and enablement (PEI), numbers of tests, investigations, procedures and treatments. RESULTS: A total of 134 general practitioners operating from 29 practices participated in the trial, referring a total of 3170 patients to 20 specialists in ENT medicine, general medicine (including endocrinology, and rheumatology), gastroenterology, orthopaedics, neurology and urology. Of these, 2094 patients consented to participate in the study and were correctly randomised. There was a 91% response rate to the initial assessment questionnaires, and analysis showed equivalence for all key characteristics between the treatment and control groups. CONCLUSION: We have designed and performed a major multi-centre trial of teleconsultations in two contrasting centres. Many problems were overcome to enable the trial to be carried out, with a considerable development and learning phase. A lengthier development phase might have enabled us to improve the patient selection criteria, but there is a window of opportunity for these developments, and we believe that our approach was appropriate, allowing the evaluation of the technology before its widespread implementation.

Adult↗