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Biomedical subjects

P Roderick

Publications and source records attributed to P Roderick.

At least 37 records · Page 2Linked to original sources
PubMed1999

Investigation of under-ascertainment in epidemiological studies based in general practice.

BACKGROUND: One of the aims of the Study of Infectious Intestinal Disease (IID) in England is to estimate the incidence of IID presenting to general practice. This sub-study aims to estimate and correct the degree of under-ascertainment in the national study. METHODS: Cases of presumed IID which presented to general practice in the national study had been ascertained by their GP. In 26 general practices, cases with computerized diagnoses suggestive of IID were identified retrospectively. Cases which fulfilled the case definition of IID and should have been ascertained to the coordinating centre but were not, represented the under-ascertainment. Logistic regression modelling was used to identify independent factors which influenced under-ascertainment. RESULTS: The records of 2021 patients were examined, 1514 were eligible and should have been ascertained but only 974 (64%) were. There was variation in ascertainment between the practices (30% to 93%). Patient-related factors independently associated with ascertainment were: i) vomiting only as opposed to diarrhoea with and without vomiting (OR 0.37) and ii) consultation in the surgery as opposed to at home (OR 2.18). Practice-related factors independently associated with ascertainment were: i) participation in the enumeration study component (OR 1.78), ii) a larger number of partners (OR 0.3 for 7-8 partners); iii) rural location (OR 2.27) and iv) previous research experience (OR 1.92). Predicted ascertainment percentages were calculated according to practice characteristics. CONCLUSION: Under-ascertainment of IID was substantial (36%) and non-random and had to be corrected. Practice characteristics influencing variation in ascertainment were identified and a multivariate model developed to identify adjustment factors which could be applied to individual practices. Researchers need to be aware of factors which influence ascertainment in acute epidemiological studies based in general practice.

Adolescent↗
PubMed1999

Assessment of the feasibility of conducting population prevalence studies of chronic renal failure according to ethnic group: a survey of clinical biochemistry laboratories in Greater London and south east England.

The planning of renal replacement therapy is based on assessment of population need for the white population, but uses historical trends in treatment uptake for black and Asian ethnic minority groups, for whom the incidence of chronic renal failure (CRF) is not known. Epidemiological studies of CRF are based upon follow-up of plasma creatinine results obtained from clinical biochemistry laboratories. We conducted a postal questionnaire survey of UK National Health Service (NHS) and private clinical biochemistry laboratories in Greater London and the south east of England to arrange the design and test the feasibility of carrying out a study to determine ethnic-specific rates of CRF. Fifty-five NHS laboratories (90%) and 19 private laboratories (57%) responded. Few pathology computer systems recorded ethnic group, patient post code, or diagnosis; although 31 of the laboratory computers (42%) were linked with the hospital Patient Administration System which could supply these data. Approximately 5.5 million electrolyte profiles and 20 million individual renal function tests are carried out annually in south east England. Ninety per cent of those were performed within NHS laboratories, implying that a study can use NHS sources alone without risk of any undue bias. Sixty laboratories (81%) included creatinine in their routine electrolyte profile, which would be a requirement for any study. Thirty-one laboratories (42%) archived tests within 1 year of entry, which would rule out a retrospective study design. A prospective study is feasible and should be carried out as soon as is practicable.

Clinical Laboratory Information Systems↗
PubMed1999

What determines geographical variation in rates of acceptance onto renal replacement therapy in England?

OBJECTIVE: To determine the independent effects of need and supply factors on the known geographical variation in acceptance rates onto renal replacement therapy (RRT) in England. METHODS: Data were obtained from all renal units in England on the characteristics of all cases aged 16 years and over, resident in England, who were accepted onto RRT in 1991 and 1992. Of these, 5715 (94.5%) had a valid postcode that could be matched to a census ward. Multilevel modelling using Poisson regression was used. The number of acceptances in each census ward within age bands 16-34, 35-64 and 65+ was the dependent variable. Independent effects modelled were: (1) individual factors (age, sex); (2) census ward need factors--ethnicity (expressed as the percentage of the ward population that was Asian or African-Caribbean), socio-economic deprivation--and supply factors--'access' to the nearest renal unit using crowfly and road travel time and distance, and services available to each ward expressed as number of haemodialysis stations per 100,000 catchment population of the nearest renal unit; (3) district health authority level effects. RESULTS: Age was a major determinant of acceptance, with a 7-fold higher rate in males aged over 64 years compared with younger men. Acceptance rates were lower in females, with a negative age-sex interaction in females aged over 64 years. The percentage of both Asian and African-Caribbean populations per ward was a highly significant positive determinant. Deprivation was also a significant determinant, best represented by a customised index. There was an inverse relation of acceptance with distance, especially road travel time. Other supply side variables had a significant effect though there was no independent district effect. There was some variation in the strength of these relationships by type of area (Greater London, urban and non-urban). CONCLUSIONS: Need and supply factors influence service use as expressed as acceptance onto RRT. Pressure to expand RRT services needs to be aimed at areas with large minority ethnic populations and those living far from existing units.

Adolescent↗
PubMed1999

Unpacking the black box of therapy -- a pilot study to describe occupational therapy and physiotherapy interventions for people with stroke.

OBJECTIVE: To describe the components used in the practice of occupational therapy and physiotherapy for people with stroke and to examine variability between services. DESIGN: A time-sampling strategy in which therapists recorded their face-to-face interventions with stroke patients during 12 weeks over a total of 17 months. SETTINGS AND SUBJECTS: Six occupational therapists and seven physiotherapists from four services (three day hospitals and one domiciliary stroke rehabilitation service) recorded interventions with 89 stroke patients recruited to a larger randomized controlled trial. MAIN OUTCOME MEASURES: Frequencies of use of interventions, together with other details about delivery of therapy, were recorded using a data collection booklet and coding system designed by the participating therapists. RESULTS: The median treatment time for a session was 45 minutes. The most frequently recorded components of physiotherapy intervention were 'walking', 'standing balance' and 'upper limb movement pattern', and of occupational therapy 'physical function', 'social and leisure activities' and 'other'. There was variability between the services in terms of median treatment time, use of intervention codes, frequency of treatment sessions, amount of time spent working with assistance and amount of group work. CONCLUSIONS: The findings support the view that occupational therapy and physiotherapy with people with stroke are not homogeneous activities, and vary between therapists and services. Recommendations include further development of the tool, and use of other methodologies to explore the process and nature of stroke rehabilitation.

Aged↗
PubMed1998

An epidemiological needs assessment of carotid endarterectomy in an English health region. Is the need being met?

OBJECTIVE: To compare the level of provision of carotid endarterectomy (an intervention of proved efficacy for prevention of stroke in patients with symptomatic high grade carotid artery stenosis) with estimates of need. DESIGN: Comparison of regional, district, and age-sex specific operation rates derived from hospital episode statistics with estimates of need based on demographic and epidemiological data; interviews with regional vascular surgeons and a joint provider-purchaser workshop to discuss implications. SETTING: Former Wessex Regional Health Authority, 1991-2 to 1995-6. SUBJECTS: All residents covered by Wessex region treated for carotid artery reconstruction. MAIN OUTCOME MEASURES: Regional, district, and age-sex operation rates as three year average 1993-6 (use) compared with respective estimates of need for carotid endarterectomy among those who presented with symptomatic carotid disease-transient ischaemic attack or minor stroke. RESULTS: The operation rate more than doubled between 1991-2 and 1995-6, from 35 to 89 per million population, compared with an estimated level of need in the region's general population of 153 per million population (transient ischaemic attack 77, minor stroke 76). The ratio of use to need was 0.47 (95% confidence interval 0.4 to 0.54); district ratios were 0.28 (0.19-0.38) to 0.81 (0.62 to 1.06). The annual use:need ratio rose over the three years 1993-6 from 0.38 to 0.59. Use:need ratios were lower in elderly and female patients. Providers were keen to develop guidelines for referral and to increase access to diagnostic facilities; purchasers were more reluctant, given the limited impact of this intervention on the incidence of stroke and the relatively high cost of the operation. CONCLUSION: Although treatment rates increased in Wessex there is still unmet need. Further research is needed to determine the referral pathways of patients with symptomatic carotid disease for diagnosis and operation and to evaluate strategies to improve access to diagnostic facilities.

Adolescent↗
PubMed1998

Population screening in the NHS: a systematic pathway from evidence to policy formulation.

In 1994 the Chief Medical Officer of England set out a framework for the evaluation and implementation of national screening programmes in the National Health Services (NHS). The framework highlighted the importance of the link between research evidence and the formulation of national policy. It also stressed the necessity for monitoring, evaluation and quality control as integral components for all new screening programmes. There is now an established link between the Health Technology Assessment programme of the NHS Research and Development Directorate and the NHS's new policy advisory group, the National Screening Committee. The objective of this systematic approach is to ensure that screening programmes are not introduced into the NHS unless there is robust evidence that benefit outweighs harm. The Population Screening Panel, an advisory panel of the NHS Health Technology Assessment programme, has the responsibility for determining priorities in research on proposed or existing population screening programmes. The National Screening Committee has a remit to consider this research evidence and to advise government ministers and the NHS on the appropriateness of the implementation, development and modification of national screening programmes. The example of prostatic cancer screening is presented as an illustration of how the NHS is developing a systematic approach to the implementation of screening policy based upon the strategic commissioning of research evidence.

Cost-Benefit Analysis↗
PubMed1998

Hip fracture incidence and mortality in an English Region: a study using routine National Health Service data.

BACKGROUND: We investigated the validity of routine hospital and mortality hip fracture data in one English Region and estimated trends in hip fracture between 1978-1981 and 1993-1995. METHODS: We identified from Hospital Episode System (HES) data for 1993-1995 all hip fracture episodes relating to individual patients aged over 65 years resident in Wessex. We determined from the discharge method code whether an individual had died during that admission. The number of individual regional and district admissions and deaths were compared with those presented in the Public Health Common Data Set. We compared regional admission rates with data for 1978-1981 from a previous study. RESULTS: National comparative indicators for hip fracture overestimated individual admissions in Wessex by 17 per cent (in health authorities by 1-56 per cent). National comparative indicators for hip fracture mortality underestimated individual deaths in Wessex by 48 per cent. Between 1978-1981 and 1993-1995 the age-sex-standardized hip fracture rates rose from 1.90 to 2.63 per 1000 per year for men and from 5.70 to 7.70 per 1000 per year for women. Rates increased in all age groups except those aged 65-69 years. There was also a small fall in absolute mean annual numbers in this age group. The rates also fell in females aged 70-74. CONCLUSIONS: It is possible to adjust routine national HES data to take account of multiple episodes within a single admission. These methods should be applied to national comparative indicators for hip fracture admission and deaths. Hip fracture rates continue to rise in those aged over 70 years. There may be a cohort effect with those born after 1925 showing stable rates which needs further investigation.

Age Distribution↗
PubMed1998

Improving health outcomes--a review of case studies from English health authorities.

We review a series of case studies from English health authorities that have tackled the assessment and improvement of health outcomes. We reflect their concerns and difficulties and the lessons they learnt. We identified case studies from a telephone survey of 91 representatives of the 100 English health authorities (61 were directors of public health). We edited 26 structured case studies which described how they had used population health outcome assessments or indicators. The health outcome assessments included service reviews, needs assessment projects, case-control studies, small area variations analyses, action research, and the use of focus groups. Many case studies highlighted inequalities in health service delivery. Health authorities chose some topics because they were outliers on national indicators, others had found unacceptable inequalities within their district, and others had been concerned that clinicians were not using the most effective interventions. Public health departments played a major role in these population-based health outcome assessments. The case studies highlighted the strengths and weakness of national population-based health outcome indicators, the difficulties of using information on effectiveness, the role of evidence-based process proxies for outcome, the need to extend information sources, the involvement of patients and carers, and the difficulty of changing clinical behaviour. We make recommendations as to how the Department of Health and NHS Executive could help health authorities improve the health outcomes of the populations they serve.

England↗
PubMed1998

What do health authorities think of population based health outcome indicators?

OBJECTIVES: To determine the role of population based indicators of health outcome in local health outcome assessments; the constraints of using such indicators; how they could be made more useful; and whether health authorities had developed their own indicators of health outcome. DESIGN: A structured telephone interview with representatives of 91 of the 100 English health authorities. RESULTS: Interviewees, asked to give details on two clinical areas in which population health outcome assessments had been of most value, nominated 147 examples in over 30 clinical areas. They chose 50 (34%) of the examples because of an outlying national indicator, and 20 (14%) because of local variations in a national indicator. The main perceived constraints in the use of population based indicators of health outcome were: data validity and timeliness; the attributability of these health outcomes to the quality of health care; the difficulties of changing clinical behavior; and organisational change within health authorities. To make these indicators more useful interviewees wanted an increased use of process indicators as proxies for health outcome, indicator trend data, and indicator comparisons of districts with similar population structures. Some recent publications have started to consider some of these issues. 27 (30%) health authorities had developed their own indicators, mostly provider based process indicators. 10 of these used their own indicators to manage the performance of local provider units. CONCLUSIONS: Population based indicators of health outcome had an important role in prompting districts to undertake population health outcome assessments. Health authorities also used these indicators to examine local variations in health outcome. They helped to highlight areas for further investigation, initiated data validation, and enabled the monitoring of changes to services. Comparative population based indicators of health outcome may have an increasing part to play in assessing the performance of health authorities.

Community Health Planning↗
PubMed1997

Predicting the future demand for renal replacement therapy in England using simulation modelling.

BACKGROUND: The purpose of the study was to estimate the future demand for renal replacement therapy in England. Simulation modelling was used to estimate the future demand, under varying assumptions, about the growth in the acceptance rate for renal replacement therapy, patient and treatment survival, and the availability of kidney transplants. METHODS: Data were obtained from the National Renal Review, the European Dialysis and Transplant Registry, and the United Kingdom Transplant Support Services Authority. They were analysed to provide transfer and survival data on patients treated for end-stage renal failure in England and in four exemplary district health authorities. The simulation runs provided estimates of numbers of patients being treated by dialysis and transplantation over the next 15 years. RESULTS: The results indicated that the number under treatment was predicted to rise by between 50 and 100% over the next 15 years, with a disproportionate increase in dialysis of up to 150%. There will be more 'high-risk elderly' people under treatment, particularly amongst the dialysis patients. The growth in numbers will vary between districts depending on their level of need and current service position. CONCLUSION: There will be increasing numbers of patients, particularly elderly patients with associated comorbidity, receiving treatment. Given the shortage of kidneys for transplantation, the demand will fall on haemodialysis and continuous ambulatory peritoneal dialysis facilities. Purchasers are thus faced with steeply rising costs for this patient group, especially in areas of high need, whilst needing to find improvements in their quality of care.

Adolescent↗
PubMed1997

The identification of bias in studies of the diagnostic performance of imaging modalities.

The demand for evidence-based healthcare is increasing nationally and internationally and it is equally necessary in both diagnostic and therapeutic practice. Evidence may be collected and combined by means of a systematic literature review of published and unpublished data on a well-defined topic. The output of such reviews is then available to guide health policy, influence good practice or direct research. Published guidelines are available on the performance of systematic reviews, especially those of randomized controlled trials. Although there is an extensive literature base of research data in diagnostic imaging there are few such trials, but it is still possible to perform systematic reviews. With the alternative study designs encountered it is important to be aware of the main threats to study validity. In this paper the biases likely to be encountered in studies of diagnostic performance are reviewed, with particular reference to diagnostic imaging tests. The biases are sub-divided into three categories. The first category is patient selection and covers the validity of generalizing results beyond the study population. The other two, concerning study design and execution and the interpretation of results, affect the likely validity of the results of a study. An understanding of these factors is an essential prerequisite for those undertaking or using a systematic literature review in the field of diagnostic imaging. The definitions form the foundations of a defensible review protocol.

Bias↗
PubMed1997

A randomized trial to evaluate the effectiveness of dietary advice by practice nurses in lowering diet-related coronary heart disease risk.

BACKGROUND: Dietary factors are an important contribution to the high rates of coronary heart disease in the UK. One approach to achieving change is health-promoting advice in primary care. AIM: To compare the effectiveness of structured dietary advice by practice nurses with standard health education in changing serum cholesterol, weight and diet. METHOD: Randomized, controlled trial within eight general practices in England and Wales allocated within matched geographical pairs to 'dietary advice' or 'usual care'. Men and women aged 35-59 years, recruited opportunistically by their GPs, underwent health checks. In 'dietary advice' practices, subjects received dietary advice from specially trained nurses based on negotiated change principles, reinforced at follow up. In 'usual care' practices, subjects were only given standard health education materials. RESULTS: A total of 956 patients were recruited: 473 in 'dietary advice' practices and 483 in 'usual care' practices. Compliance with annual follow up was 80%. Compared with 'usual care' practices, there was a mean 0.20 mmol/l lower serum cholesterol (95% CI -0.38 to -0.03 at 1 year) in 'dietary advice' practices. There was a small fall in weight of 0.56 kg (95% CI -1.04 to -0.07) and reductions in total and saturated fat. Factor VII coagulant activity fell by a mean of 6.7% of the standard (95% CI -15.4 to +2.0). CONCLUSION: Provision of standard health education material alone as part of a health check had no effect on coronary heart disease risk factors. There were modest changes in diet and associated risk factors when a more intensive and individual approach to dietary advice was given by practice nurses. This is, however, probably an ineffective use of resources, except in those at high risk of coronary heart disease. Whole-population strategies to achieve dietary change are required.

Adult↗