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1.
J Nutr Health Aging ; 27(1): 1-9, 2023.
Article in English | MEDLINE | ID: mdl-36651481

ABSTRACT

OBJECTIVES: To examine the association between metabolic syndrome (MetS) and frailty, and determine whether co-existent MetS and frailty affect disability-free survival (DFS), assessed through a composite of death, dementia or physical disability. DESIGN: Longitudinal study. SETTING AND PARTICIPANTS: Community-dwelling older adults from Australia and the United States (n=18,264) from "ASPirin in Reducing Events in the Elderly" (ASPREE) study. MEASUREMENTS: MetS was defined according to American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines (2018). A modified Fried phenotype and a deficit accumulation Frailty Index (FI) were used to assess frailty. Association between MetS and frailty was examined using multinomial logistic regression. Cox regression was used to analyze the association between MetS, frailty and DFS over a median follow-up of 4.7 years. RESULTS: Among 18,264 participants, 49.9% met the criteria for MetS at baseline. Participants with Mets were more likely to be pre-frail [Relative Risk Ratio (RRR): 1.22; 95%Confidence Interval (CI): 1.14, 1.30)] or frail (RRR: 1.66; 95%CI: 1.32, 2.08) than those without MetS. MetS alone did not shorten DFS while pre-frailty or frailty alone did [Hazard Ratio (HR): 1.68; 95%CI: 1.45, 1.94; HR: 2.65; 95%CI:1.92, 3.66, respectively]. Co-existent MetS with pre-frailty/frailty did not change the risk of shortened DFS. CONCLUSIONS: MetS was associated with pre-frailty or frailty in community-dwelling older individuals. Pre-frailty or frailty increased the risk of reduced DFS but presence of MetS did not change this risk. Assessment of frailty may be more important than MetS in predicting survival free of dementia or physical disability.


Subject(s)
Dementia , Frailty , Metabolic Syndrome , Humans , Aged , Frailty/complications , Metabolic Syndrome/complications , Independent Living , Frail Elderly , Longitudinal Studies , Geriatric Assessment
3.
Aust J Prim Health ; 27(4): 304-311, 2021 Aug.
Article in English | MEDLINE | ID: mdl-33653510

ABSTRACT

Although there is growing recognition of the effects of living with sleep disorders and the important role of primary care in their identification and management, studies indicate that the detection of sleep apnoea (OSA) and insomnia may still be low. This large representative community-based study (n=2977 adults) used logistic regression models to examine predictors of self-reported OSA and current insomnia and linear regression models to examine the association of these sleep conditions with both mental and physical components of health-related quality of life (HRQoL) and health service use. Overall, 5.6% (95% confidence interval (CI) 4.6-6.7) and 6.8% (95% CI 5.7-7.9) of subjects self-reported OSA (using a single-item question) and current insomnia (using two single-item questions) respectively. Many sociodemographic and lifestyle predictors for OSA and insomnia acted in different directions or showed different magnitudes of association. Both disorders had a similar adverse relationship with physical HRQoL, whereas mental HRQoL was more impaired among those with insomnia. Frequent consultations with a doctor were associated with a lower physical HRQoL across these sleep conditions; however, lower mental HRQoL among those frequently visiting a doctor was observed only among individuals with insomnia. The adverse relationship between sleep disorders and physical and mental HRQoL was substantial and should not be underestimated.


Subject(s)
Sleep Apnea, Obstructive , Sleep Initiation and Maintenance Disorders , Adult , Health Services , Humans , Patient Acceptance of Health Care , Quality of Life , Sleep Apnea, Obstructive/epidemiology , Sleep Apnea, Obstructive/therapy , Sleep Initiation and Maintenance Disorders/epidemiology , Sleep Initiation and Maintenance Disorders/therapy
4.
Vaccine ; 39(2): 332-342, 2021 01 08.
Article in English | MEDLINE | ID: mdl-33279317

ABSTRACT

INTRODUCTION: Passive surveillance is recommended globally for the detection of adverse events following immunisation (AEFI) but this has significant challenges. Use of Mobile health for vaccine safety surveillance enables a consumer-centred approach to reporting. The Stimulated Telephone Assisted Rapid Safety Surveillance (STARSS) a randomised control trial (RCT) sought to evaluate the efficacy and acceptability of SMS for AEFI surveillance. METHODS: Multi-centre RCT, participants were adult vaccinees or parents of children receiving any vaccine at a trial site. At enrolment randomisation occurred to one of two SMS groups or a control group. Prompts on days 2, 7 and 14 post-immunisation, were sent to the SMS group, to ascertain if a medical event following immunisation (MEFI) had occurred. No SMS's were sent to the control participants. Those in the SMS who notified an MEFI were pre-randomised to complete a computer assisted telephone interview or a web based report to determine if an AEFI had occurred whilst an AEFI in the controls was determined by a search for passive reports. The primary outcome was the AEFI detection rate in the SMS group compared to controls. RESULTS: We enrolled 6,338 participants, who were equally distributed across groups and who received 11,675 vaccines. The SMS group (4,225) received 12,675 surveillance prompts with 9.8% being non-compliant and not responding. In those that responded 90% indicated that no MEFI had been experienced and 184 had a verified AEFI. 6 control subjects had a reported AEFI. The AEFI detection rate was 13 fold greater in the SMS group when compared with controls (4.3 vs 0.3%). CONCLUSION: We have demonstrated that the STARSS methodology improves AEFI detection. Our findings should inform the wider use of SMS-based surveillance which is particularly relevant since establishing robust and novel pharmacovigilance systems is critical to monitoring novel vaccines which includes potential COVID vaccines.


Subject(s)
COVID-19 , Telemedicine , Adult , Adverse Drug Reaction Reporting Systems , Child , Humans , Immunization , Infant , Population Surveillance , SARS-CoV-2 , Telephone
5.
Vaccine ; 39(2): 237-246, 2021 01 08.
Article in English | MEDLINE | ID: mdl-33309486

ABSTRACT

INTRODUCTION: Monitoring for adverse events following immunisation (AEFI) is critical for vaccine pharmacovigilance. Given the global and expanding availability of mobile phones their utility for consumer-based vaccine safety surveillance is of interest but little is known about consumer acceptability. This study nested within the Stimulated Telephone Assisted Rapid Safety Surveillance (STARSS) randomised control trial sought to evaluate the acceptability of SMS for AEFI surveillance. METHODS: The primary STARSS study was a multi-centre RCT evaluating the efficacy of repeated SMS prompts for AEFI surveillance with participants being adult vaccinees or parents of children receiving any vaccine. This nested study enrolled primary RCT participants who completed a detailed computer assisted telephone interview to determine their attitudes towards SMS-based surveillance and ascertain their knowledge and attitudes toward vaccine safety, efficacy, data privacy and use of electronic health records. Attitudes to surveillance and related behaviour were used as measures of acceptability. RESULTS: 20% (1200/6555) of the participants were enrolled and 1139 completed the full-length questionnaire. 96% indicated that SMS-based surveillance after immunisation to check the safety of the vaccine "should be done" but 62% of all respondents said it should be done but consent should be sought first. Neither vaccine safety attitudes nor attitudes toward privacy were associated with opposition to SMS-based surveillance. In terms of SMS related behaviour demographic rather than attitudinal factors were associated with non-compliance. CONCLUSION: Overall, the attitude towards SMS-based surveillance was very favourable. Experiencing the SMS surveillance has the effect of reducing opposition to an SMS surveillance system, and at the same time increasing the likelihood of a preference for prior consent. Detection of a vaccine safety signal could be impeded in particular demographic groups who are non-compliant and we should undertake further research to understand why these groups are non-compliant and how this can be improved.


Subject(s)
Adverse Drug Reaction Reporting Systems , Telemedicine , Adult , Child , Humans , Immunization , Telephone , Vaccination
6.
Epidemiol Infect ; 146(5): 619-626, 2018 04.
Article in English | MEDLINE | ID: mdl-29463336

ABSTRACT

Acute respiratory infections cause significant morbidity and mortality accounting for 5.8 million deaths worldwide. In Australia, influenza-like illness (ILI), defined as cough, fever and fatigue is a common presentation in general practice and results in reduced productivity and lost working days. Little is known about the epidemiology of ILI in working-age adults. Using data from the ASPREN influenza surveillance network in Australia (2010-2013) we found that working-age adults made up 45.2% of all ILI notifications with 55% of samples positive for at least one respiratory virus. Viruses most commonly detected in our study included influenza A (20.6%), rhinovirus (18.6%), influenza B (6.2%), human meta-pneumovirus (3.4%), respiratory syncytial virus (3.1%), para-influenza virus (2.6%) and adenovirus (1.3%). We also demonstrated that influenza A is the predominant virus that increases ILI (by 1.2% per month for every positive influenza A case) in working-age adults during autumn-winter months while other viruses are active throughout the year. Understanding the epidemiology of viral respiratory infections through a year will help clinicians make informed decisions about testing, antibiotic and antiviral prescribing and when the beginning of the 'flu season' can be more confidently predicted.


Subject(s)
Respiratory Tract Infections/epidemiology , Virus Diseases/epidemiology , Viruses/isolation & purification , Adult , Australia/epidemiology , Female , Humans , Male , Middle Aged , Respiratory Tract Infections/virology , Seasons , Virus Diseases/virology , Viruses/classification , Young Adult
7.
Acta Psychiatr Scand ; 136(2): 147-155, 2017 08.
Article in English | MEDLINE | ID: mdl-28419425

ABSTRACT

OBJECTIVE: Although findings suggest that binge eating is becoming increasingly normative, the 'clinical significance' of this behaviour at a population level remains uncertain. We aimed to assess the time trends in binge-eating prevalence and burden over 18 years. METHOD: Six cross-sectional face-to-face surveys of the Australian adult population were conducted in 1998, 2005, 2008, 2009, 2014, and 2015 (Ntotal = 15 126). Data were collected on demographics, 3-month prevalence of objective binge eating (OBE), health-related quality of life, days out of role, and distress related to OBE. RESULTS: The prevalence of OBE increased six-fold from 1998 (2.7%) to 2015 (13.0%). Health-related quality of life associated with OBE improved from 1998 to 2015, where it more closely approximated population norms. Days out of role remained higher among participants who reported OBE, although decreased over time. Half of participants who reported weekly (56.6%) and twice-weekly (47.1%) OBE reported that they were not distressed by this behaviour. However, the presence of distress related to OBE in 2015 was associated with greater health-related quality-of-life impairment. CONCLUSION: As the prevalence of binge eating increases over time, associated disability has been decreasing. Implications for the diagnosis of disorders associated with binge eating are discussed.


Subject(s)
Bulimia Nervosa/epidemiology , Feeding Behavior , Quality of Life , Adult , Australia , Body Image , Body Weight , Female , Humans , Male , Prevalence , Residence Characteristics , Young Adult
8.
Clin Rheumatol ; 36(5): 1201-1208, 2017 May.
Article in English | MEDLINE | ID: mdl-26861032

ABSTRACT

Chronic nonspecific musculoskeletal pain (CNMP) is an idiopathic condition often seen in general practice and rheumatology clinics, the aetiology of which may include vitamin D deficiency. The objective of the present study is to evaluate the effectiveness of vitamin D supplementation in the management of CNMP through a systematic review and meta-analysis. According to PRISMA guidelines, PubMed, Embase, Web of Science, Cochrane and Scopus electronic databases were searched for randomised controlled trials comparing vitamin D supplementation to a control or placebo in CNMP patients; the search was not limited by language or date. Meta-analysis was performed using the mean and standardised mean difference which was computed with 95 % confidence intervals, and overall effect size was calculated. Both fixed and random effects models were used in meta-analysis to account for heterogeneity in the studies. The initial search identified 107 studies, of which 10 were potentially relevant, with 7 studies excluded because they did not meet selection criteria. Three studies were included in the meta-analysis. We found no effect of vitamin D supplementation (standardised mean difference (SMD) 0.004; 95 % confidence interval (CI) -0.248 to 0.256) on pain in CNMP patients. Forest plot is used to present the results from meta-analysis. Contrary to a widespread clinical view, there is a moderate level of evidence that vitamin D supplementation is not helpful for treating CNMP patients.


Subject(s)
Musculoskeletal Pain/drug therapy , Vitamin D/administration & dosage , Chronic Disease , Dietary Supplements , Humans , Treatment Outcome , Vitamins/administration & dosage
9.
Epidemiol Infect ; 144(11): 2317-28, 2016 08.
Article in English | MEDLINE | ID: mdl-27125368

ABSTRACT

Data were pooled from three Australian sentinel general practice influenza surveillance networks to estimate Australia-wide influenza vaccine coverage and effectiveness against community presentations for laboratory-confirmed influenza for the 2012, 2013 and 2014 seasons. Patients presenting with influenza-like illness at participating GP practices were swabbed and tested for influenza. The vaccination odds of patients testing positive were compared with patients testing negative to estimate influenza vaccine effectiveness (VE) by logistic regression, adjusting for age group, week of presentation and network. Pooling of data across Australia increased the sample size for estimation from a minimum of 684 to 3,683 in 2012, from 314 to 2,042 in 2013 and from 497 to 3,074 in 2014. Overall VE was 38% [95% confidence interval (CI) 24-49] in 2012, 60% (95% CI 45-70) in 2013 and 44% (95% CI 31-55) in 2014. For A(H1N1)pdm09 VE was 54% (95% CI-28 to 83) in 2012, 59% (95% CI 33-74) in 2013 and 55% (95% CI 39-67) in 2014. For A(H3N2), VE was 30% (95% CI 14-44) in 2012, 67% (95% CI 39-82) in 2013 and 26% (95% CI 1-45) in 2014. For influenza B, VE was stable across years at 56% (95% CI 37-70) in 2012, 57% (95% CI 30-73) in 2013 and 54% (95% CI 21-73) in 2014. Overall VE against influenza was low in 2012 and 2014 when A(H3N2) was the dominant strain and the vaccine was poorly matched. In contrast, overall VE was higher in 2013 when A(H1N1)pdm09 dominated and the vaccine was a better match. Pooling data can increase the sample available and enable more precise subtype- and age group-specific estimates, but limitations remain.


Subject(s)
Influenza A Virus, H1N1 Subtype/immunology , Influenza A Virus, H3N2 Subtype/immunology , Influenza B virus/immunology , Influenza Vaccines/immunology , Influenza, Human/prevention & control , Adolescent , Adult , Aged , Aged, 80 and over , Australia/epidemiology , Child , Child, Preschool , Female , Humans , Infant , Infant, Newborn , Influenza Vaccines/administration & dosage , Influenza, Human/epidemiology , Logistic Models , Male , Middle Aged , Retrospective Studies , Seasons , Sentinel Surveillance , Vaccination , Young Adult
10.
J Theor Biol ; 382: 386-96, 2015 Oct 07.
Article in English | MEDLINE | ID: mdl-26141642

ABSTRACT

To evaluate coding strategies for cochlear implants a model of the human cochlear nerve is required. Nerve models based on voltage-clamp experiments, such as the Frankenhaeuser-Huxley model of myelinated nerve, can have over forty parameters and are not amenable for fitting to physiological data from a different animal or type of nerve. Phenomenological nerve models, such as leaky integrate-and-fire (LIF) models, have fewer parameters but have not been validated with a wide range of stimuli. In the absence of substantial cochlear nerve data, we have used data from a toad sciatic nerve for validation (50 Hz to 2 kHz with levels up to 20 dB above threshold). We show that the standard LIF model with fixed refractory properties and a single set of parameters cannot adequately predict the toad rate-level functions. Given the deficiency of this standard model, we have abstracted the dynamics of the sodium inactivation variable in the Frankenhaeuser-Huxley model to develop a phenomenological LIF model with a dynamic threshold. This nine-parameter model predicts the physiological rate-level functions much more accurately than the standard LIF model. Because of the low number of parameters, we expect to be able to optimize the model parameters so that the model is more appropriate for cochlear implant simulations.


Subject(s)
Cochlear Nerve/physiology , Models, Neurological , Myelin Sheath/metabolism , Electric Stimulation , Humans
11.
J Theor Biol ; 382: 397-404, 2015 Oct 07.
Article in English | MEDLINE | ID: mdl-26187096

ABSTRACT

Phenomenological neural models, such as the leaky integrate-and-fire model, normally have a fixed refractory time-course that is independent of the stimulus. The recovery of threshold following an action potential is typically based on physiological experiments that use a two-pulse paradigm in which the first pulse is suprathreshold and causes excitation and the second pulse is used to determine the threshold at various intervals following the first. In such experiments, the nerve is completely unstimulated between the two pulses. This contrasts the receptor stimuli in normal physiological systems and the electrical stimuli used by cochlear implants and other neural prostheses. A numerical study of the Frankenhaeuser-Huxley conductance-based model of nerve fibre was therefore undertaken to investigate the effect of stimulation on refractoriness. We found that the application of a depolarizing stimulus during the later part of what is classically regarded as the absolute refractory period could effectively prolong the absolute refractory period, while leaving the refractory time-constants and other refractory parameters largely unaffected. Indeed, long depolarizing pulses, which would have been suprathreshold if presented to a resting nerve fibre, appeared to block excitation indefinitely. Stimulation during what is classically regarded as the absolute refractory period can therefore greatly affect the temporal response of a nerve. We conclude that the classical definition of absolute refractory period should be refined to include only the initial period following an action potential when an ongoing stimulus would not affect threshold; this period was found to be about half as long as the classical absolute refractory period. We further conclude that the stimulus-dependent nature of the relative refractory period must be considered when developing a phenomenological nerve model for complex stimuli.


Subject(s)
Models, Neurological , Refractory Period, Electrophysiological , Action Potentials , Electric Stimulation , Numerical Analysis, Computer-Assisted , Time Factors
12.
J Clin Pharm Ther ; 39(4): 383-9, 2014 Aug.
Article in English | MEDLINE | ID: mdl-24702306

ABSTRACT

WHAT IS KNOWN AND OBJECTIVE: The elderly are at increased risk of adverse effects resulting from drug interactions due to decreased drug clearance and polypharmacy. This study examines the prevalence of the co-administration of clinically relevant cytochrome P450 (CYP) enzyme inhibitors with drugs that are substrates for these enzymes, in the community-dwelling elderly in Australia. METHODS: Participants aged 75 years or older (n = 1045) were recruited via their general practitioners at four Australian sites (Newcastle, Sydney, Melbourne and Adelaide). A research nurse visited the home of each patient to compile a list of all prescription medications (including doses) currently used by the patient, and to complete assessments for depression, quality of life and cognitive status. The medication data were searched for the co-prescription of clinically relevant CYP inhibitor and corresponding substrate drugs. RESULTS AND DISCUSSION: Potentially inappropriate CYP inhibitor-substrate combinations were found in 6·2% (65/1045) of patients. These patients were on significantly more medications (6·1 ± 3·0 vs. 3·9 ± 2·5; P = 0·001) and had a significantly lower physical quality of life (P = 0·047) than those who were not on any CYP inhibitor-substrate combinations. The most commonly prescribed inhibitor-substrate combinations involved the CYP 3A4 inhibitors, diltiazem and verapamil, with the substrates simvastatin or atorvastatin. Only 1 of 41 patients on a CYP3A4 inhibitor and a statin was prescribed a non-CYP 3A4 metabolized statin. Metoprolol was another substrate commonly co-prescribed with a CYP2D6 inhibitor. In many cases, the risks and benefits of potential interactions may have been considered by the GP as the prescribed doses of both the inhibitor and substrate were relatively low. There were, however, some notable exceptions, also involving the substrates simvastatin, atorvastatin and metoprolol. There were no GP factors that were associated with co-prescription of CYP inhibitors and substrates. WHAT IS NEW AND CONCLUSION: There is not a particular GP demographic that should be targeted for education regarding CYP interactions, but a focus on particular medications such as the statins may reduce the potential for clinically significant drug-drug interactions. As CYP drug-drug interactions are more common in patients on higher number of medications, particular vigilance is required at the time of prescribing and dispensing medications for elderly patients with multiple conditions.


Subject(s)
Cytochrome P-450 Enzyme Inhibitors/administration & dosage , Hydroxymethylglutaryl-CoA Reductase Inhibitors/administration & dosage , Polypharmacy , Practice Patterns, Physicians'/statistics & numerical data , Aged , Aged, 80 and over , Australia/epidemiology , Cognition Disorders/epidemiology , Cytochrome P-450 Enzyme Inhibitors/pharmacology , Depression/epidemiology , Drug Interactions , Female , Humans , Hydroxymethylglutaryl-CoA Reductase Inhibitors/adverse effects , Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacokinetics , Male , Prevalence , Quality of Life
13.
Eur J Clin Nutr ; 67(1): 64-70, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23169470

ABSTRACT

BACKGROUND/OBJECTIVES: Hypertension affects about 30% of adults worldwide. Garlic has blood pressure-lowering properties and the mechanism of action is biologically plausible. Our trial assessed the effect, dose-response, tolerability and acceptability of different doses of aged garlic extract as an adjunct treatment to existing antihypertensive medication in patients with uncontrolled hypertension. SUBJECTS/METHODS: A total of 79 general practice patients with uncontrolled systolic hypertension participated in a double-blind randomised placebo-controlled dose-response trial of 12 weeks. Participants were allocated to one of three garlic groups with either of one, two or four capsules daily of aged garlic extract (240/480/960 mg containing 0.6/1.2/2.4 mg of S-allylcysteine) or placebo. Blood pressure was assessed at 4, 8 and 12 weeks and compared with baseline using a mixed-model approach. Tolerability was monitored throughout the trial and acceptability was assessed at 12 weeks by questionnaire. RESULTS: Mean systolic blood pressure was significantly reduced by 11.8±5.4 mm Hg in the garlic-2-capsule group over 12 weeks compared with placebo (P=0.006), and reached borderline significant reduction in the garlic-4-capsule group at 8 weeks (-7.4±4.1 mm Hg, P=0.07). Changes in systolic blood pressure in the garlic-1-capsule group and diastolic blood pressure were not significantly different to placebo. Tolerability, compliance and acceptability were high in all garlic groups (93%) and highest in the groups taking one or two capsules daily. CONCLUSIONS: Our trial suggests aged garlic extract to be an effective and tolerable treatment in uncontrolled hypertension, and may be considered as a safe adjunct treatment to conventional antihypertensive therapy.


Subject(s)
Antihypertensive Agents/therapeutic use , Dietary Supplements , Garlic/chemistry , Hypertension/diet therapy , Plant Extracts/therapeutic use , Plant Roots/chemistry , Adult , Aged , Aged, 80 and over , Antihypertensive Agents/administration & dosage , Antihypertensive Agents/adverse effects , Antihypertensive Agents/chemistry , Capsules , Combined Modality Therapy/adverse effects , Cysteine/administration & dosage , Cysteine/adverse effects , Cysteine/analogs & derivatives , Cysteine/analysis , Cysteine/therapeutic use , Dietary Supplements/adverse effects , Dietary Supplements/analysis , Double-Blind Method , Female , Humans , Hypertension/drug therapy , Intention to Treat Analysis , Male , Middle Aged , Patient Compliance , Patient Dropouts , Plant Extracts/administration & dosage , Plant Extracts/adverse effects , Plant Extracts/chemistry
14.
Eye (Lond) ; 25(6): 784-93, 2011 Jun.
Article in English | MEDLINE | ID: mdl-21436849

ABSTRACT

AIMS/PURPOSE: To determine the prevalence of age-related maculopathy (ARM) and age-related macular degeneration (AMD) in men aged 65-83 years living in the Speedwell region of Bristol, United Kingdom and identify modifiable risk factors. METHODS: A total of 2348 men recruited to the Speedwell prospective cohort study in 1979 were followed up in 1997 with an eye questionnaire and had retinal photographs that were assessed using the International Classification System for ARM. RESULTS: In all, 934 men (66.8% response rate) attended with a mean of 17.9 years (15.3-20.6 years) follow-up. Early ARM (grades 2-3) was found in 9.2% (95% confidence interval (CI) 7.4%, 11.4%) and late age-related maculopathy (grade 4, AMD) in 0.5% (95% CI 0.2%, 1.2%). The risk of ARM (grades 2-4) was increased with raised C-reactive protein and consumption of lard and solid fats, whereas triglyceride levels were associated with a lower risk. The latter were confirmed in multivariable analyses and in addition, haemodynamic measures also predicted risk (eg mean arterial pressure odds ratio (OR) per z-score 1.37, 95% CI 1.04, 1.79). CONCLUSIONS: In a representative cohort of men aged 65-83 from Bristol, United Kingdom, many had macular changes that put them at higher risk of developing AMD. Various modifiable exposures were associated with an increased risk ARM/AMD. Opportunities for screening and undertaking secondary prevention interventions need to be explored to prevent progression of the disease and blindness.


Subject(s)
Macular Degeneration/epidemiology , Aged , Aged, 80 and over , Cohort Studies , Follow-Up Studies , Humans , Macular Degeneration/etiology , Male , Multivariate Analysis , Prevalence , Risk Factors , United Kingdom/epidemiology
15.
Phys Rev E Stat Nonlin Soft Matter Phys ; 76(4 Pt 1): 041138, 2007 Oct.
Article in English | MEDLINE | ID: mdl-17994967

ABSTRACT

In this, the fourth of a series of papers [the first three papers were Phys. Rev. E 68, 016103 (2003), 68, 036133 (2003), and Phys. Lett. A 334, 12 (2005)] on the response of overdamped noisy bistable systems subject to an asymmetrizing constant signal superimposed on a time-sinusoidal driving signal, we obtain analytic expressions for the power spectral density of the response, including a detailed theoretical analysis of the power spectrum. The results are valid for any two-state system, however the specific case of the Duffing (or standard quartic) potential is considered in detail. The stochastic dynamics are confined to the weak noise limit (periodic signal amplitude much greater than noise intensity), i.e., when the response of the system to the external periodic field is strongly nonlinear.

16.
Phys Rev E Stat Nonlin Soft Matter Phys ; 75(2 Pt 1): 021121, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17358327

ABSTRACT

We have investigated information transmission in an array of threshold units that have signal-dependent noise and a common input signal. We demonstrate a phenomenon similar to stochastic resonance and suprathreshold stochastic resonance with additive noise and show that information transmission can be enhanced by a nonzero level of noise. By comparing system performance to one with additive noise we also demonstrate that the information transmission of weak signals is significantly better with signal-dependent noise. Indeed, information rates are not compromised even for arbitrary small input signals. Furthermore, by an appropriate selection of parameters, we observe that the information can be made to be (almost) independent of the level of the noise, thus providing a robust method of transmitting information in the presence of noise. These result could imply that the ability of hair cells to code and transmit sensory information in biological sensory systems is not limited by the level of signal-dependent noise.

17.
Climacteric ; 7(2): 143-52, 2004 Jun.
Article in English | MEDLINE | ID: mdl-15497903

ABSTRACT

OBJECTIVES: To investigate the impact of the Women's Health Initiative (WHI) on the use and perception of hormone therapy (HT) in well-informed and altruistic women who had volunteered for a similar long-term study of HT (Women's International Study of long Duration Oestrogen after Menopause, WISDOM). METHODS: A total of 840 South Australian WISDOM participants were sent questionnaires asking about their source of information about the WHI, interpretation of the 2002 WHI findings, perception of HT as a risk factor for breast cancer, attitudes towards doctors and the media and intent to use HT in the future. RESULTS: Altogether, 618 participants (74%) responded. Written and verbal information provided by WISDOM were rated as the most helpful sources of information about the WHI. Participants were aware of the increase in breast cancer and decrease in fractures seen with combined estrogen/progestogen hormone therapy (EPT) but were less convinced about the other major findings, including cardiovascular disease and dementia. HT was rated as an important risk factor for breast cancer. Participants valued medical research and were more likely to question therapies without evidence. After WHI and WISDOM, most were willing to participate in a subsequent trial and most past HT users resumed therapy. CONCLUSIONS: There are sufficient recruits for future long-term HT studies if they are given sufficient quality information and individual counselling. Our study also suggests that women who are appropriately informed may choose to take long-term HT despite a more conservative approach advised by some agencies.


Subject(s)
Attitude to Health , Estrogen Replacement Therapy/statistics & numerical data , Patient Selection , Randomized Controlled Trials as Topic , Adult , Aged , Communications Media , Female , Healthy People Programs , Humans , Middle Aged , South Australia/epidemiology , Surveys and Questionnaires , Women's Health
18.
Phys Rev E Stat Nonlin Soft Matter Phys ; 68(3 Pt 2): 036133, 2003 Sep.
Article in English | MEDLINE | ID: mdl-14524858

ABSTRACT

We study the problem of detecting a small dc signal by quantifying its effect on the mean difference DeltaT in residence times in the stable steady states of a bistable dynamical measurement device, in the presence of a noise floor and a known time-sinusoidal bias signal. Errors in the measurement process occur due to a finite observation time that is present in most practical scenarios. The error is found to have a nonmonotonic dependence on the noise intensity; at a critical noise intensity, the error is minimized. This phenomenon, reminiscent of the well-known stochastic resonance effect, can also be obtained by adjusting the device tuning parameters for a given noise floor. The effect appears to be most pronounced for subthreshold bias signals in the strongly nonlinear response regime.

19.
Phys Rev E Stat Nonlin Soft Matter Phys ; 68(1 Pt 2): 016103, 2003 Jul.
Article in English | MEDLINE | ID: mdl-12935196

ABSTRACT

A detailed theoretical analysis of the dynamics of a sinusoidally driven noisy asymmetric bistable system is presented. The results are valid for any two-state system, however, the specific case of the Duffing potential is considered in detail. The dynamics are considered in the weak noise limit, i.e., when the response of the system to the external periodic field is strongly nonlinear. The system asymmetry is created by a nonzero dc component of the external force, and manifests itself as an asymmetry between the mean switching times between the potential wells. We obtain explicit analytic expressions for the whole hierarchy of switching time distributions (including the residence time and return time distributions). We also obtain expressions for the average residence times and describe how they depend on asymmetry, together with an explicit expression for the difference between the residence times in the weak noise limit; the results are presented in the context of using the switching dynamics to detect weak dc target signals.

20.
Eye (Lond) ; 16(3): 275-80, 2002 May.
Article in English | MEDLINE | ID: mdl-12032717

ABSTRACT

AIMS: To ascertain the prevalence of cataract in a representative group of men who have been followed since 1979 for cardiovascular disease. METHODS: Of 2348 men aged 45-63 recruited in 1979 to the Speedwell Cardiovascular Study, 1420 were alive and willing to take part in further studies in 1997. They were sent a questionnaire about their eye health and invited to an ophthalmological examination at Bristol Eye Hospital. Cataract was graded using the Lens Opacities Classification System III (LOCS III) method. RESULTS: Of the 1420 men, 26 died before they could be examined. Out of the remaining 1394 men, 949 presented for examination and full information was available for 936. Some information about eye health was obtainable for 394 men and 51 were not contactable. The prevalence of cataract increased with age and 36 men (3.8%) had had previous cataract surgery in either or both eyes. Of the remaining 903 men with no previous history of cataract surgery, cortical cataract was present in the right eye of 75 men (8.3%), nuclear (opalescence) in 128 (14.2%) and posterior subcapsular in 15 (1.7%). Five men (0.6%) had visual acuity of 6/60 or worse attributable to cataract in the right eye and 232 (25%) had visual acuity in one or both eyes of 6/24 or less at least partially attributable to cataract. There was no association between social class and the presence of cataract. CONCLUSIONS: The prevalence of cataract in a representative cohort of men followed since 1979 for cardiovascular disease was comparable to that previously reported in the UK and is consistent with studies from around the world. It appears that substantial amounts of visual loss, attributable to cataract, are present in men. Further studies establishing the reasons for this should be undertaken.


Subject(s)
Cardiovascular Diseases/epidemiology , Cataract/epidemiology , Age Factors , Aged , Aged, 80 and over , Cardiovascular Diseases/complications , Cardiovascular Diseases/physiopathology , Cataract/complications , Cataract/physiopathology , Cataract Extraction , Cross-Sectional Studies , England/epidemiology , Health Surveys , Humans , Male , Prevalence , Regression Analysis , Risk , Social Class , Visual Acuity
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