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Biomedical subjects

B C Reeves

Publications and source records attributed to B C Reeves.

At least 37 records · Page 2Linked to original sources
PubMed2001

The effects of different kinds of user fees on prescribing quality in rural Nepal.

This study evaluated the effects of three different kinds of user fee on the quality of prescribing in rural Nepal. Using data from 33 public health facilities, we performed a controlled before-and-after study, comparing a fee per prescription (covering all drugs in whatever amounts) against one- and two-band fees per drug item (covering a full course of treatment for each item). With the one-band item fee, each item incurred the same fee; with the two-band item fee, more expensive items incurred a higher fee and cheaper ones a lower fee. Thirteen indicators of prescribing quality were evaluated based on an average of 400 prescribing episodes per facility per year. The percentage of prescriptions conforming to standard treatment guidelines was 12% (95% confidence interval [CI] 3% to 21%) and 15% (95% CI 6% to 24%) greater with the one- and two-band item fees, respectively, than with the fee per prescription. Prescribing quality improved through a reduction in the number of unnecessary, but not necessary, drug items prescribed per patient. Item-based fees are associated with significantly better prescribing quality than a fee per prescription; therefore, item-based fees are preferred over a fee per prescription when considering methods of cost recovery.

Drug Utilization↗
PubMed2001

The effects of different kinds of user fee on prescribing costs in rural Nepal.

OBJECTIVES: (1) To estimate the cost of irrational prescribing, and (2) to compare the effect of three different kinds of user fee on prescribing costs, in rural Nepal. METHODS: A controlled before-after study was conducted in 33 government primary health care facilities in rural eastern Nepal during 1992-95. A fee per prescription (covering all drugs in whatever amounts) was regarded as the control against which two types of fee per drug item (covering a full course of treatment for each item) were compared. The average total cost to the patient for two drug items was the same in all fee systems. Total cost, expected cost (according to standard treatment guidelines) and wastage costs (total minus expected cost) per prescription were calculated from an average of 400 prescribing episodes per facility per year. The proportion of prescriptions conforming to standard treatment guidelines was calculated from 30 prescriptions per facility per year. RESULTS: 20-52% of total drug costs were due to inappropriate drug prescription. A fee per drug item, as compared with a fee per prescription, was associated with (1) significantly fewer drug items prescribed per patient, (2) significantly lower drug costs per prescription, (3) significantly lower wastage due to inappropriate drug prescription, and (4) a significantly greater proportion of prescriptions conforming to standard treatment guidelines. Average drug cost per prescription (which was 24-33 Nepali rupees [NRs] across districts and time) was 5.7 NRs (95% confidence interval 1.0 to 10.4) and 9.3 NRs (95% confidence interval 4.8 to 13.8) less with the two different item fees, respectively, than with the fee per prescription. CONCLUSION: The economic consequences of irrational prescribing are severe, particularly in association with charging a fee per prescription. Item fees in the public sector reduce irrational prescribing and associated costs.

Drug Costs↗
PubMed2001

Radiological features predictive of aseptic loosening in cemented Charnley femoral stems.

The radiological features of the cement mantle around total hip replacements (THRs) have been used to assess aseptic loosening. In this case-control study we investigated the risk of failure of THR as predictable by a range of such features using data from patients recruited to the Trent Regional Arthroplasty Study (TRAS). An independent radiological assessment was undertaken on Charnley THRs with aseptic loosening within five years of surgery and on a control group from the TRAS database. Chi-squared tests were used to test the probability of obtaining the observed data by chance, and odds ratios were calculated to estimate the strength of association for different features. Several features were associated with a clinically important increase (>twofold) in the risk of loosening, which was statistically significant for four features (p < 0.01). Inadequate cementation (Barrack C and D grades) was the most significant feature, with an estimated odds ratio of 9.5 (95% confidence interval 3.2 to 28.4, p < 0.0001) for failure.

Case-Control Studies↗
PubMed2001

Primary total hip replacement: variations in patient management in Oxford & Anglia, Trent, Yorkshire & Northern 'regions'.

OBJECTIVES: To examine national practice, and variations in practice, concerning total hip replacement; in particular the choice of prosthesis and the involvement of consultants in NHS operations. DESIGN: Pre-operative survey of patients undergoing total hip replacement. SETTING: Five English regions serving combined population of 16.8 million people. SUBJECTS: 13,343 total hip replacement operations in one year commencing September 1996, either in NHS or private sector. MAIN OUTCOME MEASURES: Prosthesis used for surgery, status of surgeons involved in operation, use of laminar flow operating theatre. RESULTS: Prostheses without well documented 5-year survival were used in 5504 (58%) of 9417 operations for which information was available. The consultant was the operator in 4810 (64%) of 7499 NHS operations. In 1352 trainee-led operations, the consultant was present for only 637 (47%); this figure was 54% for trainees in years 1-4 of their training. Substantial variation between NHS consultant firms occurred both for use of prostheses with well documented survival data, and supervision of trainees by the consultant. CONCLUSIONS: This large study is the first attempt to describe national practice for primary total hip replacement. Substantial variation among consultant firms was observed for all indices of practice reported.

Adult↗
PubMed2000

A systematic review of comparisons of effect sizes derived from randomised and non-randomised studies.

BACKGROUND: There is controversy about the value of evidence about the effectiveness of healthcare interventions from non-randomised study designs. Advocates for quasi-experimental and observational (QEO) studies argue that evidence from randomised controlled trials (RCTs) is often difficult or impossible to obtain, or is inadequate to answer the question of interest. Advocates for RCTs point out that QEO studies are more susceptible to bias and refer to published comparisons that suggest QEO estimates tend to find a greater benefit than RCT estimates. However, comparisons from the literature are often cited selectively, may be unsystematic and may have failed to distinguish between different explanations for any discrepancies observed. OBJECTIVES: The aim was to investigate the association between methodological quality and the magnitude of estimates of effectiveness by comparing systematically estimates of effectiveness derived from RCTs and QEO studies. Quantifying any such association should help healthcare decision-makers to judge the strength of evidence from non-randomised studies. Two strategies were used to minimise the influence of differences in external validity between RCTs and QEO studies: a comparison of the RCT and QEO study estimates of effectiveness of any intervention, where both estimates were reported in a single paper a comparison of the RCT and QEO study estimates of effectiveness for specified interventions, where the estimates were reported in different papers. The authors also sought to identify study designs that have been proposed to address one or more of the problems often found with conventional RCTs. METHODS DATA SOURCES: Relevant literature was identified from: The Cochrane Library, MEDLINE, EMBASE, DARE, and the Science Citation Index. References of relevant papers already identified experts. Electronic searches were very difficult to design and yielded few papers for the first strategy and when identifying study designs. CHOICE OF INTERVENTIONS TO REVIEW FOR STRATEGIES 1 AND 2: For strategy 1, any intervention was eligible. For strategy 2, interventions for which the population, intervention and outcome investigated were anticipated to be homogeneous across studies were selected for review: Mammographic screening (MSBC) of women to reduce mortality from breast cancer. Folic acid supplementation (FAS) to prevent neural tube defects in women trying to conceive. DATA EXTRACTION AND QUALITY ASSESSMENT: Data were extracted by the first author and checked by the second author. Disagreements were negotiated with reference to the paper concerned. For strategy 1, study quality was scored using a checklist to assess whether the RCT and QEO study estimates were derived from the same populations, whether the assessment of outcomes was 'blinded', and the extent to which the QEO study estimate took account of possible confounding. For strategy 2, a more detailed instrument was used to assess study quality on four dimensions: the quality of reporting, the generalisability of the results, and the extent to which estimates of effectiveness may have been subject to bias or confounding. All quality assessments were carried out by three people. DATA SYNTHESIS AND ANALYSIS: For strategy 1, pairs of comparisons between RCT and QEO study estimates were classified as high or low quality. Seven indices of the size of discrepancies between estimates of effect size and outcome frequency were calculated, where possible, for each comparison. Distributions of the size and direction of discrepancies were compared for high- and low-quality comparisons. FOR STRATEGY 2, THREE ANALYSES WERE CARRIED OUT: Attributes of the instrument were described by k statistics, percentage agreement, and Cronbach's a values. Regression analyses were used to investigate -variations in study quality. (ABSTRACT TRUNCATED)

Breast Neoplasms↗
PubMed1999

Glaucoma screening: the importance of combining test data.

The objective of this study was to evaluate the effectiveness of screening tests for primary open angle glaucoma, both singly and in combination, using a decision analysis approach. A range of screening tests were carried out on 145 nonglaucomatous patients and 67 cases of previously undiagnosed glaucoma. Receiver operator characteristic curves were constructed for single test data to show the trade-off between sensitivity and specificity for varying cut-off criteria. The best discriminators of glaucoma were, in rank order: (1) a multiple stimulus static visual field screening test, (2) optic disc cupping, and (3) intraocular pressure. Decision curves were also constructed for various combinations of screening tests, where the inclusion of the tests were based on discriminant analyses. Sensitivities and specificities of more than 0.90 were obtained when visual field screening, optic disc cupping, and intraocular pressure were combined. Data from other tests when combined with these three variables failed to provide a significant improvement in discrimination.

Adult↗
PubMed1998

A randomised trial of calcium alginate swabs to control blood loss in 3-5-year-old children.

OBJECTIVE: To compare the effectiveness of calcium alginate swabs and traditional cotton swabs in the control of blood loss after extraction of deciduous teeth from healthy children, aged 3-5 years, under general anaesthetic. DESIGN: Prospective, randomised clinical trial. SETTING: General anaesthetic suite in a dental teaching hospital. SUBJECTS: 101 patients were recruited to the study, comprising 50 randomised to be treated with cotton swabs and 51 with alginate swabs. INTERVENTIONS: Teeth were extracted under general anaesthesia and blood collected for measurement in order to compare blood loss using the two systems. MAIN OUTCOME MEASURES: The number of teeth extracted ranged from 1-14. The total blood loss ranged from 0.53-78.13 ml with a median of 12.9 ml. CONCLUSION: Calcium alginate swabs were not found to produce any clinical or statistical advantage over traditional cotton swabs in this surgical setting.

Alginates↗
PubMed1997

A review of data-derived methods for assigning causes of death from verbal autopsy data.

BACKGROUND: Verbal autopsy (VA) is an indirect method for estimating cause-specific mortality. In most previous studies, cause of death has been assigned from verbal autopsy data using expert algorithms or by physician review. Both of these methods may have poor validity. In addition, physician review is time consuming and has to be carried out by doctors. A range of methods exist for deriving classification rules from data. Such rules are quick and simple to apply and in many situations perform as well as experts. METHODS: This paper has two aims. First, it considers the advantages and disadvantages of the three main methods for deriving classification rules empirically; (a) linear and other discriminant techniques, (b) probability density estimation and (c) decision trees and rule-based methods. Second, it reviews the factors which need to be taken into account when choosing a classification method for assigning cause of death from VA data. RESULTS: Four main factors influence the choice of classification method: (a) the purpose for which a classifier is being developed, (b) the number of validated causes of death assigned to each case, (c) the characteristics of the VA data and (d) the need for a classifier to be comprehensible. When the objective is to estimate mortality from a single cause of death, logistic regression should be used. When the objective is to determine patterns of mortality, the choice of method will depend on the above factors in ways which are elaborated in the paper. CONCLUSION: Choice of classification method for assigning cause of death needs to be considered when designing a VA validation study. Comparison of the performance of classifiers derived using different methods requires a large VA dataset, which is not currently available.

Algorithms↗
PubMed1996

Vision defects in patients with peri-chiasmal lesions.

BACKGROUND: Patients with chiasmal lesions frequently suffer loss of vision, but some may be visually asymptomatic and have little, if any, visual field loss. This study addressed two questions about the nature of such loss: (1) which tests are best able to detect visual loss and (2) what is the relation between the size of a lesion and the degree and type of visual loss. METHODS: Visual acuity (VA), Goldmann perimetry, pattern evoked potentials, contrast sensitivity (CS), and color vision (CV) were assessed, in addition to a full ophthalmologic examination. Thirty-five patients were recruited from neurology, endocrinology, and ophthalmology departments; 31 had pituitary tumors and 4 had tumors of other origin (1 secondary) close to the chiasm. For analysis, patients were classified (1) according to whether they had visual symptoms on presentation and (2) according to lesion size. RESULTS: Seventeen patients had visual symptoms; all had visual field defects and all but one had two or more additional abnormal test results. Of the 18 visually asymptomatic patients, 12 had visual field defects and 14 had at least 2 abnormal test results; 7 had tumors with less than 5 mm of suprasellar extension, of whom 5 had field loss or at least 2 abnormal test results. CS was abnormal most often (85% of patients), followed by Goldmann perimetry (80%), visual evoked potentials (VEPs) (57%), CV (49%), and VA (26%). CONCLUSION: Our results support previous reports that asymptomatic patients and those with intrasellar tumors or only small amounts of suprasellar extension may have demonstrable visual dysfunction. Perimetry did not appear to be significantly worse than other more recently developed tests, which have often been regarded as being more sensitive, for detecting vision loss. However, VA and clinical observation of pupil reactions had poor sensitivity.

Adolescent↗
PubMed1994

Effectiveness of unsupervised oculokinetic perimetry for detecting glaucomatous visual field defects.

Oculokinetic perimetry (OKP) is a simple, inexpensive technique which was introduced primarily to promote more widespread use of visual field screening for glaucoma. The effectiveness of unsupervised OKP screening was evaluated using 145 non-glaucomatous patients and 64 patients with previously undiagnosed primary open angle glaucoma. Glaucoma cases were validated by the extended 132 point program on the Henson CFS2000 instrument. Both sample populations were representative of patients presenting for primary vision care. The effectiveness of the 26 point OKP test was compared with the 26 point Henson screening program. The results suggest that, in contrast to the Henson screening test (sensitivity = 85.1%, specificity = 93.8%), unsupervised OKP screening (sensitivity = 25.0%, specificity = 93.6%) has limited effectiveness for detecting glaucomatous visual field defects.

Adult↗
PubMed1993

Reliability of high- and low-contrast letter charts.

The aim of this study was to measure the reliability, in test score units, of several clinical tests which use high- and low-contrast letters, and to provide an estimate of what constitutes a significant change in performance over time. Patients with normal vision and with early or subtle eye disease were recruited so that the results would be representative of the population likely to present for primary vision screening. Patients were tested on the Bailey-Lovie logMAR chart, the Regan low-contrast letter charts and the Pelli-Robson low-contrast letter chart on two occasions; the two test sessions were separated by at least four weeks to give an estimate of reliability appropriate for the conditions under which the tests are likely to be used. A 'significant change', i.e. one which would be observed in only about 5% of patients with stable visual performance, was about +/- 2 'steps' of the measurement scale, i.e. +/- 2 lines for the Bailey-Lovie and Regan charts and +/- 2 letter groups for the Pelli-Robson chart.

Adult↗
PubMed1992

Visual recovery using small dilating eye drops.

It is well established that reduced size dilating eye drops of 1% tropicamide and 10% phenylephrine (micro drops) are effective for clinical purposes. Excellent pupil dilatation (mydriasis) is achieved and pupil constriction does not occur in response to light. In this study, the effect of micro drops of 1% tropicamide on distance and near visual recovery was compared with standard drops in a group of 20 healthy volunteers. For each person studied, one eye was selected at random to be tested first with the standard drop size, and then after a minimum of one week, the same eye was again tested using a drop of the same drug one fifth standard size. An iris photograph, Snellen visual acuity at 6 m, and reading visual acuity was obtained for each test procedure: before drop instillation and at 30 min, 1, 2 and 4 h after drug instillation. Use of the micro drops caused a small but statistically significant improvement in the rate of recovery of distance and near visual acuity. These findings, allied to the known beneficial effects of reduced systemic absorption using micro drops, lend further weight to the argument that mydriasis may be achieved more safely, with fewer side effects, and with earlier return of normal vision when reduced size drops are used. It is hoped that practical micro drop dispensers will be developed.

Adult↗
PubMed1992

Evaluation of two infrared autorefractors in pseudophakia.

We investigated the viability of using an objective infrared autorefractor to identify high corneal astigmatism (> 3.00 D) in a pseudophakic population. The eyes of 91 patients, who had recently undergone cataract extraction and intraocular lens implanation, were refracted manually and using two infrared autorefractors, a Canon RK-1 and a Nikon NR-2000. Autorefractor measurements were repeated to provide estimates of reliability for each instrument. LogMAR visual acuities were also recorded with both the manual and autorefractor corrections. Approximately 75% of repeat autorefractor measurements were within 0.50 D of the initial readings, and about 75% of measurements were within 1.00 D of the manual refractions. Visual acuities with manual corrections were, on average, one line better than with autorefractor corrections. By validating the autorefractors against manual refraction, the efficiency of the autorefractors for detecting astigmatism > 3.00 D was calculated. Setting the cut-off criterion to ensure high sensitivity (95%), so that almost all patients with > 3.00 D were detected, resulted in both instruments having a poor specificity of about 40%.

Adult↗
PubMed1991

Vistech VCTS 6500 charts--within- and between-session reliability.

The aim of the study was to measure the reliability of the Vistech VCTS 6500 charts, in test score units, in order to allow clinicians to derive estimates of what constitutes a clinically meaningful change in performance over time. The reliability of a more familiar test, Bailey-Lovie high contrast visual acuity, was also measured to provide a comparison. Patients with normal vision and with early or subtle eye disease were recruited so that the results would be representative of the population likely to present for primary vision screening. Patients were tested on all three VCTS charts on two separate occasions at least 3 weeks apart to give estimates of within- and between-session reliability. Reliability was found to be low in all circumstances; between-session reliability could be improved by using the mean score for the three charts, but the 95% range of difference scores still encompassed at least one-half of the total performance range of the test. It was concluded that Vistech charts are unlikely to be of use for clinical measurements or for research studies.

Adult↗