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Biomedical subjects

D Howel

Publications and source records attributed to D Howel.

At least 19 recordsLinked to original sources
PubMed1999

Primary biliary cirrhosis once rare, now common in the United Kingdom?

There is a widespread impression that the number of patients with the autoimmune liver disease primary biliary cirrhosis (PBC) is increasing, although its incidence and prevalence vary widely. Using thorough case-finding methods and rigorous definitions to assess changes in incidence and prevalence with time and to explore the symptomatology and mortality of the disease in a large group of unselected patients, we performed a descriptive epidemiological study of PBC in a well defined population over a fixed period of time using established diagnostic criteria and with clinical follow-up of all cases. In a population of 2.05 million in northern England 770 definite or probable PBC cases were identified. Prevalence rose from 201.9 per 10(6) in the adult population and 541. 4 per 10(6) women over 40 in 1987 to 334.6 per 10(6) adults and 939. 8 per 10(6) women over 40 in 1994. Incidence was 23 per 10(6) in 1987 and 32.2 per 10(6) in 1994. Three hundred patients died in median follow-up of 6.27 years (141 liver deaths); the standardized mortality ratio was 2.85. At presumed diagnosis, 60.9% had no symptoms of liver disease. By June 1994 62% of prevalent patients had liver symptoms. PBC is apparently increasing. It is still unclear whether this is because of a true increase, case finding, or increased disease awareness. The study draws attention to (1) high mortality from liver disease and non-liver-related causes even in patients initially with no liver symptoms and (2) apparently poor diagnostic awareness of the disease.

Adult↗
PubMed1999

Mineral fibre analysis and routes of exposure to asbestos in the development of mesothelioma in an English region.

OBJECTIVES: To compare the concentrations of inorganic fibres in the lungs in cases of mesothelioma and controls: to determine whether concentrations of retained asbestos fibres differ with the different exposures identified from interview; and to investigate the existence of a cut off point in concentrations of asbestos fibres that indicates occupational exposure. METHODS: Case-control study; 147 confirmed cases of mesothelioma and 122 controls identified from deaths occurring in four districts of Yorkshire between 1979 and 1991. Surviving relatives were interviewed to determine lifetime exposure history to asbestos. Mineral fibre analysis was carried out on lung tissue from postmortem examinations. RESULTS: Odds on high concentrations of retained asbestos fibres were greater in cases than controls. After excluding subjects with occupational and paraoccupational exposure, the odds on high concentrations were still greater in cases than controls, but only significantly so for amphiboles. There was only a weak relation between probability of occupational exposure to asbestos and concentrations of retained asbestos fibres, and no significant difference in fibre concentrations was found between subjects who had been exposed to asbestos through different routes: these comparisons were only based on small groups. There was considerable overlap in concentrations of retained asbestos fibres between cases and controls with and without histories of occupational exposure. CONCLUSIONS: The study has confirmed previous results of higher concentrations of asbestos fibres in cases than controls, and has shown that this is still found in subjects with little evidence of occupational and para-occupational exposure. The overlap in concentrations of retained asbestos for different groups of subjects did not suggest a clear cut of value.

Aged↗
PubMed1999

Impact of clinical practice guidelines on clinicians' behaviour: tonsillectomy in children.

OBJECTIVE: This study was conducted to assess the extent to which developing and implementing clinical practice guidelines for listing children for tonsillectomy (with or without adenoidectomy) influenced the behaviour of participating ENT surgeons. METHOD: A before and after study in which the intervention (the development and dissemination of local practice guidelines) was introduced sequentially into different hospitals and surgical practice. The study was conducted in four ear, nose, and throat surgical services in the North of England, with 16 consultant ENT surgeons and their junior staff on 1190 children aged 0 to 14 years who were judged, prior to consultation with an ENT surgeon, to have been referred for throat-related problems for which tonsillectomy was one possible treatment option were included in the study. Decision reached by surgeons and proportion of decisions that complied with new guidelines. RESULTS: Of the clinical decisions to list children for tonsillectomy taken before introduction of locally agreed guidelines, 73% (486/660) conformed to the criteria in the subsequent guidelines, 15% (97/660) did not, and in 12% (77/660), it was impossible to judge. After the intervention, the corresponding figures were 73% (386/530), 14% (73/53), and 13% (71/530), respectively. When decisions were taken to break the guidelines, this was more often to list for tonsillectomy when it was not indicated--83% (141/170)--than to withhold tonsillectomy when it was indicated--17% (29/170). The aspects of guidelines that were breached in decisions to carry out tonsillectomy were: the age of the child was younger than the guidelines recommended--54% (75/141); there had been fever attacks of tonsillitis than the guidelines recommended--22% (32/141); and there were "significant" symptoms not included in the guidelines--20% (29/141). CONCLUSIONS: In spite of strong evidence to the contrary, local guidelines were formulated at a level that the majority of surgeons already attained. Guideline development and implementation, therefore, had very little impact on clinical practice. The process of local formulation of guidelines was not sufficient to achieve change toward evidence-based practice; clinical preference proved to be quite intractable. There is a need to enhance the ability of clinicians in the assessment and interpretation of research evidence. Previous work has emphasized the need to explore factors that influence clinical behaviour toward evidence-based practice. Our study suggests the need for more research into why clinicians continue to follow clinical preference even when invited to base agreed local clinical policies on evidence.

Adolescent↗
PubMed1998

Computer simulation to estimate the effectiveness of carotid endarterectomy.

OBJECTIVES: To investigate the benefit of carotid endarterectomy relative to medical treatment, by comparing the outcome for different groups of patients following transient ischaemic attacks. METHODS: A Markov model was used to describe the survival and quality of life of patients treated for a transient ischaemic attack. The benefit is measured in terms of quality adjusted life months (QALMs). The outcome was estimated using a computer simulation with parameters based on published studies on the probability of events following treatment. The benefit of carotid endarterectomy was explored using a baseline set of parameters and a sensitivity analysis. RESULTS: The baseline scenario of a 65-year-old male patient with the model factors set at an intermediate level showed a benefit for surgery of 3 QALMs compared with medical treatment alone. The sensitivity analysis showed that the most favourable combination of factors had a benefit of 13.4 QALMs and the least favourable a loss of 2 QALMs. Of all 128 factor combinations, 79.9% showed a benefit for surgery, 5.5% showed equal benefit, and 15.6% showed a benefit for medical treatment. CONCLUSIONS: Computer simulations have the potential for deriving estimates of benefit for different patient groups from the results of clinical trials. Combined with reliable information on costs, the technique could also demonstrate variations in cost-effectiveness for these groups. For patients following a transient ischaemic attack, the results from this simulation and limited cost information suggest that carotid endarterectomy is unlikely to be a cost-effective intervention in the UK for many patient groups despite a reduction in the risk of stroke.

Aged↗
PubMed1997

Incidence and prevalence of primary biliary cirrhosis in the city of Newcastle upon Tyne, England.

OBJECTIVE: To describe the incidence and prevalence of primary biliary cirrhosis in an urban population between 1987 and 1994, using stringent inclusion criteria and a well-defined study area and population. DESIGN: Descriptive study based on a case register compiled by a retrospective and prospective case-finding exercise and examination of case notes. SETTING: The city of Newcastle upon Tyne. MAIN INCLUSION CRITERIA: (1) Definite cases: fulfilling all three of the following diagnostic criteria: positive antimitochondrial antibody (AMA) > or = 1:40; cholestatic liver function tests (LFT); diagnostic or compatible liver histology. (2) Probable cases: fulfilling two of these criteria. SUBJECTS: All cases of primary biliary cirrhosis identified by multiple case-finding methods, alive from 1 January 1987 to 31 December 1994, in the defined area. MAIN OUTCOME MEASUREMENTS: Incidence and point prevalence rates by age and sex. RESULTS: In all, 202 potential cases were identified, of whom 160 met at least two inclusion criteria. In definite cases annual incidence varied from 14 to 32 (mean 22) per million whole population (with no clear trend) and point prevalence rose from 180 per million in 1987 to 240 in 1994. Mean age at diagnosis in cases incident during the study period was 63.2 years (S.D. 11.1 years, range 39.8-85.7 years). CONCLUSIONS: Primary biliary cirrhosis is much more common in Newcastle than has previously been reported anywhere in the world, and prevalence appears to be rising.

Adult↗
PubMed1997

Routes of asbestos exposure and the development of mesothelioma in an English region.

OBJECTIVES: To investigate the contribution of exposure to asbestos through different routes in the development of mesothelioma. METHODS: Case-control study. 185 confirmed cases of mesothelioma and 160 controls were identified, when death had occurred between 1979 and 1991 in four health districts in Yorkshire. The surviving relatives were interviewed to ascertain lifetime exposure to asbestos. Adjusted odds ratios (ORs) of exposure to asbestos (through occupational, paraoccupational, and residential routes) were calculated for cases and were compared with controls. RESULTS: Likely or possible occupational exposure to asbestos was more common in cases than in controls (OR 5.6, 95% confidence interval (95% CI) 3.1 to 10.1). After excluding those with likely or possible occupational exposure, likely or possible paraoccupational exposure was more common in cases than controls (OR 5.8, 95% CI 1.8 to 19.2). Only six cases of mesothelioma were identified as being solely exposed to asbestos through their residence, compared with nine controls. The OR for residential exposure to asbestos varied between 1.5 and 6.6, depending on which potential industrial sources were included, but the 95% CIs were so wide that slightly reduced or greatly increased odds comparing cases with controls could not be excluded. CONCLUSION: Study results support previous evidence that occupational and paraoccupational exposure to asbestos is associated with developing mesothelioma. Despite a rigorous search, purely residential exposure seemed to account for only 3% of identified cases. No firm conclusion can be drawn about the risks from residential exposure alone, as many of the study subjects could also have been occupationally or paraoccupationally exposed to asbestos.

Adult↗
PubMed1996

Late-onset idiopathic scoliosis in children six to fourteen years old. A cross-sectional prevalence study.

We performed a point-prevalence survey of 15,799 children, six to fourteen years old, who formed part of a prospective longitudinal study. Our purpose was to detect the prevalence of scoliosis and to investigate associated factors. On the basis of the initial screening, 934 children (5.9 per cent) were referred for additional clinical and radiographic examinations; 896 children returned for this second evaluation. A lateral spinal curve with a Cobb angle of more than 5 degrees was seen in 431 children (2.7 per cent of the 15,799 children). Only seventy-six children (0.5 per cent) had a curve that met our definition of idiopathic scoliosis (a curve of more than 10 degrees with concordant apical rotation). The point-prevalence rate was higher in girls, and it increased with age. The rate was 0.1 per cent (four of 5246) in the age-group of six to eight years, 0.3 per cent (sixteen of 5831) in the age-group of nine to eleven years, and 1.2 per cent (fifty-six of 4722) in the age-group of twelve to fourteen years old. With allowance for the fact that different definitions of idiopathic scoliosis have been used in earlier studies, our results suggest that the natural history of idiopathic scoliosis may be becoming more benign spontaneously.

Adolescent↗
PubMed1995

Psychological morbidity and the availability of assisted conception: a group comparison study.

BACKGROUND: Given its limited availability, it is worth while to explore the relationship between the non-availability of assisted conception and psychological morbidity among subfertile women, to see if those denied the procedure experience poorer health. METHODS: A non-randomized group comparison study was carried out in Bradford Health Authority, England. Sixty-six women who had reached the point at which assisted conception was deemed appropriate, but for whom such treatments were not available, were compared with 49 parous women, and 73 newly diagnosed subfertile women. The General Wellbeing Index (GWI) was used to measure their psychological wellbeing. RESULTS: Cases and subfertile controls have similar levels of wellbeing, whereas parous controls have significantly higher average levels than cases. This pattern is seen in the simple unadjusted comparison and also when adjustments are made for the distributions of age, life event score and social class. CONCLUSIONS: Subfertile women experience poorer psychological health than similar parous women. Subfertile women, for whom assisted conception is an appropriate but unavailable treatment option, appear to have similar psychological health to those who are being investigated and treated by other means.

Adaptation, Psychological↗
PubMed1994

Statistical analysis of compositional data in anatomy.

BACKGROUND: Variables which describe the composition, or relative size of components, of an organism need to be analysed in an appropriate manner. METHODS: A few of the appropriate descriptive and inferential techniques have been described and applied to a number of anatomical data sets. RESULTS: When applied to data on the composition of the vastus medialis in adults, a small but significant difference in average muscle fibre type distribution was demonstrated between males and females. There was little evidence for a relationship between fibre type distribution and age over the range considered. CONCLUSIONS: Graphical displays via ternary diagrams are a simple way of illustrating compositional data simultaneously between and within groups. Numerical analysis is likely to involve transformation of original variables before standard univariate or multivariate statistical techniques can be used.

Adult↗
PubMed1993

The health care experience and health behaviour of the Chinese: a survey based in Hull.

Lack of knowledge about the health care experience and health behaviour of an important ethnic minority group prompted a study to inform the provision of health care and promote local action in Hull. Thirty Chinese 'takeaway' shops were randomly selected from the Yellow Pages of the Hull telephone directory, and all Chinese people working in them asked to complete a questionnaire. It contained questions on their knowledge, use and experience of primary health care and health promotion, together with aspects of their health behaviour. The same questionnaire in English was delivered to all workers in 30 fish and chip shops, to provide a White comparison group. Eighty (71 per cent) of the Chinese returned their questionnaire, and 73 (67 per cent) were returned from the chip-shop workers. The results indicate that the Chinese in Hull are not making optimal use of health services; they use some services inappropriately, whereas others, such as preventive health programmes, are under-used. One of the main reasons is identified as the language/communication difficulties faced by many Chinese. Other reasons are also highlighted and their implications discussed. The findings of this survey are in keeping with the mainly unpublished work undertaken elsewhere on this comparatively little researched ethnic minority group.

Adult↗