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Biomedical subjects

Tom Marshall

Publications and source records attributed to Tom Marshall.

At least 19 recordsLinked to original sources
PubMed2006

A prospective study of the diagnostic potential of the knee tunnel view radiograph in assessing anterior knee pain.

The aim of this comparative study was to examine the potential advantage of the tunnel view radiograph over a series of weight bearing antero-posterior (AP), lateral and skyline radiographs. The study population consisted of 240 subjects with knee pain aged 19 to 93 years. A total of 309 knees had a weight bearing AP in extension, lateral, skyline and tunnel view radiographs. Each radiograph was reported with respect to features related to osteoarthritis, modified from the Ahlback system. Each feature was assessed using the tunnel radiograph alone and then the AP, lateral and skyline views in combination without, and blind to, the information from the tunnel view. On the basis of Bowker's test, the tunnel view was more likely to pick up abnormal intercondylar notch and tibial spine osteophytes but not loose bodies. We conclude that the tunnel view is a valuable addition in the routine assessment of the knee joint in osteoarthritis but not for the diagnosis of loose bodies alone.

Adult↗
PubMed2006

The myth of agency and patient choice in health care? The case of drug treatments to prevent coronary disease.

Patient choice is at the heart of health-care reform programmes in the UK and in many other countries. The success of patient choice initiatives is dependent on a well-functioning agency relationship in health care. We interviewed 197 patients from 13 general practices in the West Midlands, UK, both before and after coronary screening. Our study suggests that, for patients presenting for coronary risk screening in primary care, the agency relationship is not working well--patients' expressed preferences relating to decisions to commence drug treatments were largely over-ridden in the clinical consultation. Therefore, if choice is to be a real driver of change in health care it needs to encompass patient empowerment and be based on a more collaborative approach to decision making between patients and professionals.

Adult↗
PubMed2006

Equity in use of home-based or facility-based skilled obstetric care in rural Bangladesh: an observational study.

BACKGROUND: Few studies have assessed whether the poorest people in developing countries benefit from giving birth at home rather than in a facility. We analysed whether socioeconomic status results in differences in the use of professional midwives at home and in a basic obstetric facility in a rural area of Bangladesh, where obstetric care was free of charge. METHODS: We routinely obtained data from Matlab, Bangladesh between 1987 and 2001. We compared the benefits of home-based and facility-based obstetric care using a multinomial logistic and binomial log link regression, controlling for multiple confounders. FINDINGS: Whether or not a midwife was used at home or in a facility differed significantly with wealth (adjusted odds ratio comparing the wealthiest and poorest quintiles 1.94 [95% CI 1.69-2.24] for home-based care, and 2.05 [1.72-2.43] for facility-based care). The gap between rich and poor widened after the introduction of facility-based care in 1996. The risk ratio (RR) between the wealthiest and poorest quintiles was 1.91 (adjusted RR 1.49 [95% CI 1.16-1.91] when most births with a midwife took place at home compared with 2.71 (1.66 [1.41-1.96]) at the peak of facility-based care. INTERPRETATION: In this area of Bangladesh, a shift from home-based to facility-based basic obstetric care is feasible but might lead to increased inequities in access to health care. However, there is also evidence of substantial inequities in home births. Before developing countries reinforce home-based births with a skilled attendant, research is needed to compare the feasibility, cost, effectiveness, acceptability, and implications for health-care equity in both approaches.

Adult↗
PubMed2006

A laterally positioned concave trochlear groove prevents patellar dislocation.

Patellofemoral instability is a disabling condition that occurs in adolescence. Recurrence after patellar dislocation has been reported in 2-50% of patients. We compared the distal femur in patients with patellofemoral instability with distal femura of a healthy cohort using mathematical quantification of two-dimensional shape variation at the same position in different knees. One hundred eight computed tomography scans from 54 patients with patellofemoral instability were compared with 197 computed tomography scans from 102 subjects with normal knees. We used principal components analysis to quantify variation in shape of the trochlear groove as it allows comparison of knees with patellofemoral instability to healthy knees. We found that subjects who had dislocated their patella had a flattened trochlear groove, whereas normal knees had a more concave groove. The position of the trochlear groove was more medial in patients with patellofemoral instability compared with normal knees. Groove position was more important than shape when predicting which patellae were likely to dislocate.

Adolescent↗
PubMed2006

The cost-effectiveness of drug treatments for primary prevention of cardiovascular disease: a modelling study.

BACKGROUND: Efficient prevention policies need to be informed by knowledge of the cost-effectiveness of preventive treatments. This paper calculates the cost-effectiveness of aspirin, antihypertensive treatments and statins for prevention of cardiovascular disease. DESIGN: The investigation is a modelling study. METHODS: Ten-year cardiovascular risks and treatment eligibility were determined for each individual in a population of 5603 obtained from the Health Survey of England. Using published costs and evidence of effectiveness the cost-effectiveness of treating each eligible individual was determined over a 10-year time horizon. The marginal cost-effectiveness of additional antihypertensive drugs and increasing doses of statins were determined and a sensitivity analysis was carried out. RESULTS: Of the 5603 individuals 27.5% (95% confidence interval, 26.3-28.7%) were eligible for at least one treatment: the majority of these were eligible for all three. Cost per cardiovascular disease event prevented is strongly determined by pretreatment cardiovascular disease risk. In three-quarters of patients eligible for all three treatments, the lowest cost per event prevented was with aspirin and in the remainder with two-drug antihypertensive treatment. The marginal costs per event prevented were highest with the addition of a fourth antihypertensive drug and statins. These findings depend on the use of low-cost antihypertensives but are otherwise robust to a wide range of assumptions. CONCLUSIONS: Modelling the cost-effectiveness of treatments to prevent cardiovascular disease is feasible and provides valuable information. Cost-effectiveness analysis argues for more widespread use of aspirin and two-drug antihypertensive treatment and against the use of four-drug antihypertensive treatment or statins.

Adult↗
PubMed2006

Risk factors for subclinical mastitis among HIV-infected and uninfected women in Lusaka, Zambia.

Subclinical mastitis, defined as raised milk sodium/potassium (Na/K) ratio, is associated with poor infant growth and, among HIV-infected women, with increased milk HIV viral load. We conducted a longitudinal cohort study in Lusaka, Zambia, in order to investigate the relative importance of several potential causes of subclinical mastitis: maternal infection, micronutrient deficiencies and poor lactation practice. Women (198 HIV-infected, 189 HIV-uninfected) were recruited at 34 weeks' gestation and followed up to 16 weeks postpartum for collection of information on their health, their infant's health, infant growth and infant feeding practices. Milk samples were collected from each breast at 11 postpartum visits and blood at recruitment and 6 weeks postpartum. The geometric mean milk Na/K ratio and the proportion of women with Na/K ratio > 1.0 in one or both breasts were significantly higher among HIV-infected than among uninfected women. Other factors associated with the higher mean Na/K ratio in univariable analyses were primiparity, high maternal alpha(1)-acid glycoprotein (AGP) at 6 weeks, maternal overall morbidity and specific breast symptoms, preterm delivery, low infant weight or length, infant thrush and non-exclusive breast feeding. In multivariable analyses, primiparity, preterm delivery, breast symptoms, HIV status and raised AGP were associated with the raised Na/K ratio. Thus the main factors associated with subclinical mastitis that are amenable to intervention are poor maternal overall health and breast health. The impact of improved postpartum health care, especially management of maternal infections and especially in primiparous women, on the prevalence of subclinical mastitis and its consequences requires investigation.

Adult↗
PubMed2006

Estimating the value of information in strategies for identifying patients at high risk of cardiovascular disease.

BACKGROUND: There are many different potential strategies for identification of patients eligible for primary prevention of cardiovascular disease. The ability to use a more efficient strategy has a value. This paper models the costs and benefits of a number of identification strategies and estimates the additional value of an information-based strategy. DESIGN: Modelling study. METHODS: Ten-year Framingham cardiovascular risk was calculated for each individual in a population of 4471 persons aged 35-74 drawn from the Health Survey for England (equivalent to a total practice population of 12,000). Estimated Framingham risk was calculated using limited risk factor information and default risk factors. Costs of risk factor assessment were calculated using standard NHS costs. The outcomes of risk factor assessment were the total number of patients identified as eligible for treatment and the total burden of cardiovascular disease in eligible patients. Several strategies for prioritising patients for assessment were defined: opportunistic, diabetics and treated hypertensives first, ranked by estimated cardiovascular risk. The costs and outcomes of assessing increasing numbers of patients under each strategy were presented in graphical form. RESULTS: To identify 70% of the burden of cardiovascular disease in this population opportunistically costs Pounds 82,102; under a 'diabetics and hypertensives first' strategy it costs Pounds 72,916; under a strategy prioritising by estimated cardiovascular risk, Pounds 27,795. The value of information in this scenario is therefore at least Pounds 45,121. CONCLUSIONS: Because strategies prioritising patients by estimated cardiovascular risk dominate alternative strategies, it is possible to estimate the value of information in terms of reduced resources to achieve the same results. These resource savings largely represent savings in staff time.

Adult↗
PubMed2006

The use of cardiovascular risk factor information in practice databases: making the best of patient data.

BACKGROUND: Primary care teams record cardiovascular risk factor data on their patients to help them identify and treat patients eligible for prevention. However, it is not known to what extent this information is already available to clinicians, or the extent to which it is used. AIM: To assess the extent to which risk factor is recorded, and to determine the cost-effectiveness of using recorded risk factor information in order to identify and treat eligible patients. DESIGN OF STUDY: An Excel-based model of the incremental costs and benefits of assessment and treatment. SETTING: Two general practices in the West Midlands. METHOD: Untreated, non-diabetic patients, aged 35-74 years, were identified from each practice, and risk factor data was uploaded into an Excel spreadsheet. The completeness of risk factor data was assessed. The costs and benefits of assessing and treating patients, in descending order of estimated cardiovascular risk, were then modelled. RESULTS: In each practice, 72.9% and 77.7% of patients had a record of their blood pressure, 26.9% and 25.7% were eligible for at least one treatment: aspirin was the most common treatment followed by antihypertensives. With patients systematically assessed in descending order of cardiovascular risk, 78% of eligible patients and 87% of preventable cardiovascular events are found in the first two deciles of the target population. CONCLUSIONS: Lack of risk factor information is not the principal constraint on cardiovascular prevention. Practices have sufficient risk factor data to inform an efficient, targeted prevention strategy.

Adult↗
PubMed2005

Are these data real? Statistical methods for the detection of data fabrication in clinical trials.

OBJECTIVES: To test the application of statistical methods to detect data fabrication in a clinical trial. SETTING: Data from two clinical trials: a trial of a dietary intervention for cardiovascular disease and a trial of a drug intervention for the same problem. OUTCOME MEASURES: Baseline comparisons of means and variances of cardiovascular risk factors; digit preference overall and its pattern by group. RESULTS: In the dietary intervention trial, variances for 16 of the 22 variables available at baseline were significantly different, and 10 significant differences were seen in means for these variables. Some of these P values were extraordinarily small. Distributions of the final recorded digit were significantly different between the intervention and the control group at baseline for 14/22 variables in the dietary trial. In the drug trial, only five variables were available, and no significant differences between the groups for baseline values in means or variances or digit preference were seen. CONCLUSIONS: Several statistical features of the data from the dietary trial are so strongly suggestive of data fabrication that no other explanation is likely.

Adult↗
PubMed2005

The effect of scientific misconduct on the results of clinical trials: a Delphi survey.

OBJECTIVES: To discover what types of scientific misconduct are most likely to influence the results of a clinical trial. DESIGN: Delphi survey of expert opinion with three rounds of consultation. SETTING: Non-industry clinical trial "community". PARTICIPANTS: Experts identified from invitees to a previous MRC consultation on clinical trials. 32 out of the 40 experts approached agreed to participate. RESULTS: We identified thirteen forms of scientific misconduct for which there was majority agreement (>50%) that they would be likely or very likely to distort the results and majority agreement (>50%) that they would be likely or very likely to occur. Of these, the over-interpretation of 'significant' findings in small trials, selective reporting and inappropriate subgroup analyses were the main themes. CONCLUSIONS: According to this expert group, the most important forms of scientific misconduct in clinical trials are selective reporting and the opportunistic use of the play of chance. Data fabrication and falsification were not rated highly because it was considered that these were unlikely to occur. Registration and publication of detailed clinical trial protocols could make an important contribution to preventing scientific misconduct.

Bias↗
PubMed2005

Evaluating national guidelines for prevention of cardiovascular disease in primary care.

INTRODUCTION: National guidelines for prevention of cardiovascular disease make different recommendations in relation to screening and treating patients with aspirin, antihypertensive treatment and statins. The resource cost and health implications of these differences are quantified in this paper. DATA SOURCES: Guidelines were obtained from Australia, New Zealand, Canada, UK and USA. Effectiveness data were obtained from published sources, costs and a model population of 2000 patients from US sources. METHOD: The resource costs and health effects of screening and treating a standard population of 2000 persons were determined for each of the five national guidelines. Costs and effects were calculated over a 5-year time horizon and cost-effectiveness determined cost per cardiovascular event prevented. RESULTS: Cost per cardiovascular event prevented is lowest in older patients and very high under 35. The New Zealand guidelines are more cost-effective of the national guidelines, however, they would be more effective if they incorporated US recommendations on the use of aspirin. Further antihypertensive treatment is the least cost-effective of the interventions considered. DISCUSSION: Cardiovascular disease prevention guidelines should focus on older rather than younger patients. Treatment eligibility should be informed more by risk than by individual risk factor status. Guidelines should put greater emphasis on the use of aspirin and initial antihypertensive treatment than on achieving blood pressure targets. CONCLUSION: In order to justify their recommendations guidelines should quantify the resource implications in relation to the health benefits.

Adolescent↗
PubMed2005

Informed consent for mammography screening: modelling the risks and benefits for American women.

INTRODUCTION: In order to facilitate informed decision making, women require information on the probabilities of different outcomes with mammography screening. This paper derives these probabilities for a US population and illustrates them visually in a readily understandable format. METHODS: Probabilities of the breast cancer mortality, all cause mortality and further investigation are derived from published data on mortality from breast cancer and published estimates of effectiveness using a life-table method. Probabilities are calculated of surviving to age 75 from age 40 with and without two-yearly mammography screening from age 40 and age 50. Probabilities are also calculated that a woman will be referred for further assessment or biopsy or die from breast cancer despite screening. To avoid being misled, these outcomes are presented in the form of a single decision aid illustrating the outcomes for 1000 women choosing each alternative: mammography screening or no mammography screening. RESULTS: Of 1000 women undergoing two-yearly mammography screening from age 40 an additional four (3.7 per 1000) will reach the age of 75; of the survivors 514 will be referred for further investigation and 138 will undergo biopsy. Of 1000 women screened from age 50 an additional three (3.3 per 1000) will reach age 75; of the survivors 408 will be referred for further investigation and 94 will undergo biopsy. Mammography from age 40 to 49 reduces mortality by 0.4 in 1000. This information is readily presented visually. CONCLUSIONS: It is possible to provide realistic estimates of the effects of mammography screening on mortality in a readily understandable format. Women require this information if they are to make informed choices about mammography screening.

Adult↗
PubMed2005

Social inequalities in maternal opinion of child development in southern Brazil.

AIMS AND METHODS: Concurrent validity of maternal opinion of child development was estimated in a cross-sectional, population-based survey of 6-59-mo children (n=3025), using a standard measure devised from the Denver Developmental Screening Test. RESULTS: Sensitivity, specificity and negative predictive value increased with maternal education and family income. Positive predictive value was higher in low-income families and children with impairments, low birthweight and long hospital stays. CONCLUSION: Children at social and clinical risk should be assessed more carefully, even if maternal report is normal or advanced.

Brazil↗
PubMed2005

A practical method for monitoring general practice mortality in the UK: findings from a pilot study in a health board of Northern Ireland.

BACKGROUND: The Baker report into Dr Harold Shipman's murders recommended monitoring mortality in general practice, but there is currently no practical method available to implement this. AIM: To monitor mortality rates in response to the Baker report and to use the data to improve quality of care. DESIGN OF STUDY: Prospective mortality monitoring study. SETTING: Eastern Health and Social Services Board, Northern Ireland. METHOD: Linked quarterly mortality data from 1994-2001 were compiled for 114 general practices in Eastern Health and Social Services Board in Northern Ireland. Cross-sectional control charts compared crude and adjusted mortality rates across all the practices. Longitudinal control charts analysed quarterly mortality rates over 28 quarters within each practice. Practices were sent their own control charts and invited to feedback workshops. Special cause variation in mortality was investigated as follows: checks on data, case-mix, practice structures, processes of care and finally individual carers. RESULTS: Age, sex and deprivation adjusted cross-sectional control charts identified 18 practices as showing special cause variation in their mortality (11 high and 7 low). Assignable causes were found for all high special cause practices: large numbers of nursing home patients (six practices), very high levels of deprivation and high morbidity not captured by our case-mix adjustment (five practices). For three of seven low special cause practices, case-mix adjustment underestimated affluence and overestimated morbidity levels. Feedback indicated widespread support for the principle of monitoring, but concerns about the public disclosure of mortality data. CONCLUSIONS: We have successfully developed and piloted a general practice mortality monitoring system with the support and participation of local stakeholders. This used control charts for analysis and followed a scientific strategy for investigating special cause variation.

Epidemiologic Methods↗
PubMed2004

[Social inequalities and other determinants of height in children: a multi-level analysis].

A cross-sectional household survey of height among children under five years of age (n = 2,632) was conducted in the city of Porto Alegre, Rio Grande do Sul State, Brazil. Multi-level linear regression was applied to investigate the effect of socioeconomic and demographic factors, physical and social environment, and health conditions on children s height, measured by the height-for-age z-scores of the National Center for Health Statistics standards. Area of residence (census tract) was classified as good versus poor in terms of housing and sanitation standards. On average, children s height was -0.18 z-score. Average height increased with maternal and paternal schooling, parents work skills, per capita family income, improved housing, maternal age, birth intervals, and birth weight. Height decreased with hospitalization in the first two years of life, number of under-five children in the household, and preterm birth. In the poor residential areas, the effect of maternal schooling was twice as great as in the better-off areas. The effect of parental work skills was only evident in the more deprived areas. Area of residence modified the effects of socioeconomic conditions on children s growth. Housing and sanitation programs are potentially beneficial to offset the negative effect of social disadvantage on children's growth.

Body Height↗