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Biomedical subjects

R Foy

Publications and source records attributed to R Foy.

17 recordsLinked to original sources
PubMed2003

Introduction of photodynamic therapy for the treatment of neovascular age-related macular degeneration: tracking a moving target.

OBJECTIVES: To identify changes in referral and treatment patterns of neovascular age-related macular degeneration with photodynamic therapy (PDT) within ophthalmology units in NHS hospitals and assess how beliefs about what would constitute a worthwhile level of clinical benefit had altered over a 12-month period. METHODS: Two questionnaire surveys (October 2000 and October 2001) to all clinical directors or lead consultants in UK NHS eye units. These sought data on which (if any) patients were referred or treated with PDT and the threshold of clinical benefit, in terms of numbers needed to treat, at which they would support the use of PDT. RESULTS: Response rates were 82% in the first survey and 79% in the second. The availability of PDT had significantly increased (P=0.0001). The proportion of units routinely providing PDT for patients with more than 50% classic subfoveal choroidal neovascularization (CNV) increased from 8 to 23%. Between the 2 surveys, there was a significant reduction in the threshold of effectiveness at which respondents would support the use of PDT (P=0.012). The proportion of respondents requiring further evidence before supporting the use of PDT decreased from 33 to 17% (P=0.009). There was a significant association between the threshold of support and the level of service provision for both surveys (P=0.01). CONCLUSIONS: Although substantial variations exist, availability of PDT has increased over the 12-month period. The differing thresholds at which introduction of PDT would be considered justifiable varied widely. PDT is being introduced into the NHS in a fragmented manner. In common with other new health technologies, factors other than the strength of evidence appear to be influencing beliefs about the effectiveness of PDT and its subsequent provision. While it is unlikely that such an action alone will lead to evidence-based practice, the variations in beliefs identified by this survey suggest that sufficient clinical uncertainty exists to support the need for further clinical trials.

Follow-Up Studies↗
PubMed2003

How evidence based are recruitment strategies to randomized controlled trials in primary care? Experience from seven studies.

BACKGROUND: Failure to recruit adequate numbers of participants represents a major barrier to the completion of randomized controlled trials in primary care and is associated with substantial opportunity costs. However, uncertainty exists regarding the relative effectiveness of different methods to promote recruitment. OBJECTIVES: The purpose of this study was to estimate the proportion of strategies used to promote patient recruitment to randomized controlled trials in primary care that are evidence based. METHODS: Investigators from seven primary care-based clinical trials of dyspepsia management aiming to recruit a total of 6070 patients participated. Following a survey of trial organization, a Delphi technique was used to reach consensus on levels of evidence on the effectiveness of interventions or organizational characteristics in influencing recruitment. The main outcome measures were the proportions of interventions or organizational characteristics for influencing patient recruitment that are based upon randomized controlled trials, on convincing non-experimental evidence or meeting neither of these criteria. RESULTS: Out of a total of 56 interventions used across the trials, 35 (63%) were judged as evidence based. Out of a total of 29 organizational characteristics possessed by the trials, five (17%) were judged as evidence based. Across the seven dyspepsia trials, the presence of 'favourable' organizational characteristics appeared to be important contributors towards successful recruitment. CONCLUSIONS: A wide range of interventions and organizational characteristics with the potential to promote recruitment were used or possessed by seven primary care trials. Many were not evidence based. Our experience suggests that organizational characteristics could be more influential in trial recruitment than the use of specific interventions. Given the costs of primary care-based trials, researchers need more rigorous evidence to inform recruitment strategies.

Dyspepsia↗
PubMed2003

About time: diagnostic guidelines that help clinicians.

Clinical guidelines often make recommendations on the use of diagnostic tests. Compared with sensitivity and specificity, the use of pre- and post-test probabilities allows a more explicit and rational selection and interpretation of diagnostic tests. Ideally, clinical guidelines relating to diagnosis should routinely incorporate this information to enhance individualised decision making. We report our experience of incorporating pre- and post-test probabilities into a guideline on the investigation of women with postmenopausal bleeding developed by the Scottish Intercollegiate Guidelines Network. Issues relating to their application are highlighted, including the limitations of available evidence on diagnostic tests and prevalence of disease, acceptability to guideline users, and the uncertain impact on actual clinical decision making. Despite these potential difficulties, the incorporation of data on pre- and post-test probabilities into the development and presentation of guideline recommendations may offer an important opportunity to make clinical decision making more transparent for both clinicians and patients.

Decision Making↗
PubMed2002

A new health technology: where is the consensus on a clinically worthwhile benefit?

AIM: New therapies are often introduced into the NHS prior to full evaluation, leading to inequities in provision. Uncertainty exists regarding the value of photodynamic therapy in the treatment of neovascular age-related macular degeneration. We ascertained the availability of this treatment and the information used to inform clinical policy. METHODS: A postal survey of all clinical directors/lead consultants in the UK sought data on which (if any) patients were referred or treated with PDT by their unit, the sources of evidence informing clinical policy and the threshold of clinical benefit at which respondents would support the use of PDT. RESULTS: 123/152 questionnaires were returned. 42% of units make some provision for PDT on the NHS, including routine provision by 9%. 14.5% of units offer the option of care in the private sector, whilst 26.5% treated or referred no patients. The threshold at which respondents considered introduction of PDT would be justifiable varied widely. Respondents cited local literature review, advice from clinicians, guidance from the Royal College and information from the pharmaceutical industry as most influential in determining current policy. However, the National Institute for Clinical Excellence (NICE) and the Cochrane Library were anticipated as playing a greater role in shaping future practice. CONCLUSIONS: Substantial variation exists in the availability of PDT. Advocates of PDT may interpret our data as an indication of the NHS failing to provide an effective therapy equitably, whilst others may deduce that patients are receiving an under-evaluated treatment in routine clinical practice. The differing thresholds at which clinicians believe treatment would be justified may further exacerbate variations and the priority given to PDT.

Attitude of Health Personnel↗
PubMed2001

The impact of national clinical guidelines on obstetricians in Scotland.

OBJECTIVE: To audit reported clinical practice in relation to four national obstetric guidelines on The Preparation of the Foetus for Preterm Delivery, The Management of Mild, Non-proteinuric Hypertension in Pregnancy, The Management of Pregnancy in Women with Epilepsy and The Management of Postpartum Haemorrhage. DESIGN: Questionnaire surveys before and after dissemination of the guidelines. SUBJECTS: One hundred and sixty one consultants and senior specialist registrars in Scotland. RESULTS: The response rates to the baseline and follow-up surveys were 85% and 74% respectively. Over 90% of the obstetricians kept the guidelines for reference and 85% had been prompted to change or reconsider their practice. Reported compliance improved significantly for six out of twenty nine recommendations covering: the use of tocolysis in women at risk of pre-term labour; the use of prophylactic antibiotics or entry to a clinical trial for pre-term, pre-labour rupture of the membranes; the initiation of steroid therapy in women with insulin-dependent diabetes mellitus; and the prescribing of periconceptual folic acid and vitamin K to women with epilepsy. There were no significant improvements in relation to mild, non-proteinuric hypertension or post-partum haemorrhage. CONCLUSIONS: There were significant improvements in the reported management of women at risk of preterm labour and those with epilepsy. However, reported practice in relation to mild, non-proteinuric hypertension and post-partum haemorrhage has improved little. This is possibly because the guidelines for these topics were relatively complicated to understand and apply, and established patterns of practice more resistant to change.

Adult↗
PubMed2000

Photometric observations of a polychromatic laser guide star.

We report the photometric observation of a polychromatic laser guide star (PLGS) using the AVLIS laser at the Lawrence Livermore National Laboratory (LLNL). The process aims at providing a measurement of the tilt of the incoming wave front at a telescope induced by atmospheric turbulence. It relies on the two-photon coherent excitation of the 4D5/2 energy level of sodium atoms in the mesosphere. We used two laser beams at 589 and 569 nm, with a maximum total average output power of approximately 350 W. For the purpose of photometric calibration, a natural star was observed simultaneously through the same instrument as the PLGS at the focus of the LLNL 50-cm telescope. Photometric measurements of the 330-nm return flux confirm our previous theoretical studies that the PLGS process should allow us at a later stage to correct for the tilt at wavelengths as short as approximately 1 microm at good astronomical sites. They show also that, at saturation of two-photon coherent absorption in the mesosphere, the backscattered flux increases by a factor of approximately 2 when the pulse repetition rate decreases by a factor of 3 at constant average power. This unexpected behavior is briefly discussed.

Journal Article↗
PubMed1999

Frontal predominance of a relative increase in sleep delta and theta EEG activity after sleep loss in humans.

The effect of sleep deprivation (40 h) on topographic and temporal aspects of electroencephalographic (EEG) activity during sleep was investigated by all night spectral analysis in six young volunteers. The sleep-deprivation-induced increase of EEG power density in the delta and theta frequencies (1-7 Hz) during nonREM sleep, assessed along the antero-posterior axis (midline: Fz, Cz, Pz, Oz), was significantly larger in the more frontal derivations (Fz, Cz) than in the more parietal derivations (Pz, Oz). This frequency-specific frontal predominance was already present in the first 30 min of recovery sleep, and dissipated in the course of the 8-h sleep episode. The data demonstrate that the enhancement of slow wave EEG activity during sleep following extended wakefulness is most pronounced in frontal cortical areas.

Adult↗
PubMed1998

Testing for Helicobacter pylori in primary care: trouble in store?

STUDY OBJECTIVE: To assess the role of testing for Helicobacter pylori in the management of dyspeptic patients in primary care. DESIGN: Selective review of literature frequently quoted to support use of H pylori testing. MAIN RESULTS: Testing for H pylori and referral of only positive cases for endoscopy aims to reduce the number of "unnecessary" endoscopies. Patients with negative results may receive short-term reassurance and subsequently place fewer demands on health services. However, studies to date have only assessed this practice in secondary care settings. Given the relatively high prevalence of both dyspepsia and H pylori infection, the transfer of this practice to primary care may lead to a paradoxical increase in endoscopy referrals. Identification of H pylori and prescribing of eradication treatment also aims to reduce endoscopy referrals. No primary care trials have yet assessed this approach. Given that fewer than one in four of dyspeptic patients have peptic ulceration, a high proportion may fail to respond to eradication treatment and subsequently require referral for endoscopy. The longer term clinical and psychosocial sequelae of treating or labelling patients with an infection associated with gastric cancer remain unknown. CONCLUSIONS: Given uncertainty concerning the possible adverse effects of H pylori testing in primary care, we suggest a moratorium on its use in this setting until results from relevant clinical trials become available.

Aged↗