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Biomedical subjects

R Foy

Publications and source records attributed to R Foy.

13 recordsLinked to original sources
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↗
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↗