David Jerwood

Pelvic Floor Muscle Assessment: The PERFECT Scheme

Summary Aims of study 1. To develop a digital technique to assess pelvic floor muscles (PFM). 2. To validate the technique and test for validity and reliability. 3. To translate the assessment into an exercise-based regimen. Method and Results PERFECT is an acronym with P representing power (or pressure, a measure of strength using a manometric perineometer), E = endurance, R = repetitions, F = fast contractions, and finally ECT = every contraction timed. The scheme was developed to simplify and clarify PFM assessment. The pressure (referred to hereafter as power, although actually a surrogate measure of muscular strength) of a contraction was validated by examining perineal lift and perineometric pressure during a maximum voluntary contraction (MVC). Data analysis demonstrated significant positive correlations between power and both lift (r = 0.864; p = 0.031) and perineometric pressure (r = 0.786; p = 0.001); digitally assessed endurance correlated with the area under the pressure curve of a sophisticated perineometer (r = 0.549; p = 0.001). A study of inter-examiner reliability demonstrated highly significant positive correlations between two examiners for power (r = 0.947; p Test-retest reliability produced highly significant correlations (p Conclusions The PERFECT scheme has demonstrated reliability and validity as an assessment tool. Furthermore, it is proposed that this scheme provides guidelines for the planning of patient-specific exercise programmes which satisfy the principles of muscle training.

Does Pre-modulated Interferential Therapy Cure Genuine Stress Incontinence?

Summary This article reports the findings of two independent randomised, prospective, clinical trials specifically designed to investigate the effect of pre-modulated interferential therapy (IFT) on women with genuine stress incontinence (GSI). The first trial (n = 46) compared IFT with pelvic floor exercises (PFE) and cones, and the second (n = 30) compared IFT with placebo treatment. The effectiveness of treatment was assessed objectively with a standard pad test before and after treatment, and subjectively using an ordinal scale. A total of 43.5% of women receiving IFT in the first study were objectively cured or improved, and 73.3% in the second study. Subjectively, 60.9% were classified as cured or improved in the first trial, and 33.3% in the second trial. The long-term effect of treatment was investigated using a postal questionnaire which showed that 30% of patients receiving IFT in study 1 and 20% in study 2 demonstrated a lasting effect of treatment. It is concluded that pre-modulated IFT has a place in the conservative management of GSI.

Prescribing of lipid lowering drugs to South Asian patients: ecological study.

Coronary heart disease is the major cause of morbidity and mortality in the South Asian population in the United Kingdom, and its incidence is higher than in the white population.1 This excess risk seems to be determined by a combination of metabolic factors leading to the insulin resistance syndrome, psychosocial factors, and established risk factors.2 Ten out of 15 coronary risk factors measured were reported to be higher in South Asian patients than in their European counterparts, and several of these factors are believed to reflect relative deprivation. South Asian people are also at risk owing to high triglyceride concentrations and low concentrations of high density lipoprotein cholesterol. Although substantial evidence shows the value of lowering cholesterol in people at risk, studies have shown that many patients are not receiving appropriate treatment.3 We investigated the relation …

Development of the Bradford perineometer

Summary A new pressure-sensitive perineometer is described which enables the dynamic characteristics of the pelvic floor musculature to be examined. When attached to standard water-filled urodynamics equipment (or other similar pressure-sensitive measuring device), a visual display and hard copy are generated simultaneously to facilitate monitoring, data storage and subsequent statistical analysis. A number of different pressure parameters and pressure-time profiles have been identified which are thought to provide information on the contractility of the fast-and slow-twitch pelvic floor muscle fibres during a ten-second maximum voluntary contraction. This equipment can be used to evaluate and compare the dynamic characteristics of the pelvic floor musculature of continent and incontinent women.

Comparing and unifying slope estimates across psychometric function models.

The psychometric function relating stimulus intensity to response probability generally presents itself as a monotonically increasing sigmoid profile. Two summary parameters of the function are particularly important as measures of perceptual performance: the threshold parameter, which defines the location of the function over the stimulus axis (abscissa), and the slope parameter, which defines the (local) rate at which response probability increases with increasing stimulus intensity. In practice, the psychometric function may be modeled by a variety of mathematical structures, and the resulting algebraic expression describing the slope parameter may vary considerably between different functions fitted to the same experimental data. This variation often restricts comparisons between studies that select different functions and compromises the general interpretation of slope values. This article reviews the general characteristics of psychometric function models, discusses three strategies for resolving the issue of slope value differences, and presents mathematical expressions for implementing each strategy.

On the unimodality of present-value distributions

Abstract Financial literature in the past appears to have concentrated on developing present-value models, which were essentially deterministic. Even when stochastic formulations are presented, they are often directed towards the establishment of explicit formulate for mean value, variance and, in some cases, semi-variance. Alternative procedures, based on modal values or exact interval estimates for example, require more detailed analytical information regarding the structure of the underlying distribution function. The existence of a unique mode and its associated precision are two important aspects of this problem and both these questions can be addressed by a generalised concept of unimodality. Discounting random cash flows under exponential timing will inevitably lead to a present value, whose distribution is α-unimodal.

A stochastic model for proactive risk management decisions

The analysis of stochastic discounting models provides one of the more powerful tools available for decision-making under conditions of uncertainty. This paper is mainly devoted to the establishment of properties and applications of a particular stochastic discounting model. More precisely, the paper investigates some of the theoretical problems encountered in a stochastic discounting model when assessing mutually exclusive options, and establishes the advantages of considering risk retention in proactive risk-management programs.

Analytical and simulation techniques for discounting binomial random sums

Present-value models have often proved invaluable within the financial decision-making process. Such models are becoming increasingly more complex in their stochastic formulation and more sophisticated in their statistical objectives. Recent articles attempt to make exact inferences regarding the probability distribution of the present value. This paper establishes the result that whenever exponential timing is associated with the investment, then @a-unimodality is automatically induced into the present-value distribution irrespective of the selection criteria of the components of that investment. Furthermore, the conditions leading to the familiar (0) unimodality are determined, whereby it often appears to be financially more prudent to delay the timing mechanism than to exercise caution in the selection of the components.

A transformed geometric distribution in stochastic modelling

The analytical concepts of infinite divisibility and (0) unimodality are fundamental to the study of probability distributions in general and to discrete distributions in particular. In this paper, a one-one correspondence is established between these two important properties which will permit any infinitely divisible discrete distribution (with finite mean value) to be transformed into a (0) unimodal discrete distribution. When this transformation is applied specifically to the geometric distribution, the result is a novel distribution, which can be fully and explicitly specified and whose factorial moments can be expressed in closed forms. This transformed geometric distribution is found to apply to underreported geometrically distributed decision processes, embedded renewal processes with logarithmically distributed components, and M/M/1 queues in which the service mechanism has been uniformly improved.

Analytical and computer simulation techniques for a stochastic model arising in discounting continuous uniform cash flows

Present-value models are currently available for both single cash flows and continuous uniform cash flows under uncertain timing. Recent work by the authors has concentrated mainly on establishing theoretical results concerning the conditions under which unimodality will be introduced into the present-value distribution, particularly under exponential timing. Apart from the conventional (0) unimodality, there are two other forms of unimodality available which refer more to the nature of the unimodal behaviour rather than its location. When the timing mechanism operating for a continuous uniform cash flow is modelled by a geometrically distributed sum of exponential inter-assessment times, this paper establishes that the present-value distribution adopts a form of unimodality which is conceptually and structurally distinct from that form of unimodality adopted within the single cash flow analogue. Each present-value distribution will therefore become (0) unimodal under different prevailing economic conditions. One financial implication of these results is that it should be possible to develop coherent funding strategies for selecting a single cash flow option or a continuous uniform cash flow option having due regard to the current financial climate.