PubMed Health⌕ Search

Biomedical subjects

C Frost

Publications and source records attributed to C Frost.

At least 19 recordsLinked to original sources
PubMed2006

Improved reliability of hippocampal atrophy rate measurement in mild cognitive impairment using fluid registration.

MRI-derived rates of hippocampal atrophy may serve as surrogate markers of disease progression in mild cognitive impairment (MCI). Manual delineation is the gold standard in hippocampal volumetry; however, this technique is time-consuming and subject to errors. We aimed to compare regional non-linear (fluid) registration measurement of hippocampal atrophy rates against manual delineation in MCI. Hippocampi of 18 subjects were manually outlined twice on MRI scan-pairs (interval+/-SD: 2.01+/-0.11 years), and volumes were subtracted to calculate change over time. Following global affine and local rigid registration, regional fluid registration was performed from which atrophy rates were derived from the Jacobian determinants over the hippocampal region. Atrophy rates as derived by fluid registration were computed using both forward (repeat onto baseline) and backward (baseline onto repeat) registration. Reliability for both methods and agreement between methods was assessed. Mean+/-SD hippocampal atrophy rates (%/year) derived by manual delineation were: left: 2.13+/-1.62; right: 2.36+/-1.78 and for regional fluid registration: forward: left: 2.39+/-1.68; right: 2.49+/-1.52 and backward: left: 2.21+/-1.51; right: 2.42+/-1.49. Mean hippocampal atrophy rates did not differ between both methods. Reliability for manual hippocampal volume measurements (cross-sectional) was high (intraclass correlation coefficient (ICC): baseline and follow-up, left and right, >0.99). However, the resulting ICC for manual measurements of hippocampal volume change (longitudinal) was considerably lower (left: 0.798; right: 0.850) compared with regional fluid registration (forward: left: 0.985; right: 0.988 and backward: left: 0.975; right: 0.989). We conclude that regional fluid registration is more reliable than manual delineation in assessing hippocampal atrophy rates, without sacrificing sensitivity to change. This method may be useful to quantify hippocampal volume change, given the reduction in operator time and improved precision.

Aged↗
PubMed2006

Combining short interval MRI in Alzheimer's disease: Implications for therapeutic trials.

Cerebral atrophy calculated from serial MRI is a marker of Alzheimer's disease (AD) progression, and a potential outcome measure for therapeutic trials. Reducing within-subject variability in cerebral atrophy rates by acquiring more than two serial scans could allow for shorter clinical trials requiring smaller patient numbers. Forty-six patients with AD and 23 controls each had up to 10 serial MR brain scans over two years. Whole brain atrophy was calculated for each subject from every scan-pair. 708 volumetric MRI scans were acquired: 2199 measures of atrophy were made for patients, and 1182 for controls. A linear mixed model was used to characterise between and within-individual variability. These results were used to investigate the power of combining multiple serial scans in treatment trials of varying lengths. In AD, the mean whole brain atrophy rate was 2.23%/year (95% CI: 1.90-2.56%/year). The linear mixed model was shown to fit the data well and led to a formula (0.99(2) + (0.82/t)2) for the variance of atrophy rates calculated from two scans "t" years apart. Utilising five optimally timed scans with repeat scans at each visit reduced the component of atrophy rate variance attributable to within-subject variability by approximately 56%, equating to a approximately 40% sample size reduction (228 vs 387 patients per arm to detect 20% reduction in atrophy rate) in a six-month placebo-controlled trial. This benefit in terms of sample size is relatively reduced in longer trials, although adding extra scanning visits may have benefits when patient drop-outs are accounted for. We conclude that sample sizes required in short interval therapeutic trials using cerebral atrophy as an outcome measure may be reduced if multiple serial MRI is performed.

Aged↗
PubMed2006

Automatic calculation of hippocampal atrophy rates using a hippocampal template and the boundary shift integral.

We describe a method of automatically calculating hippocampal atrophy rates on T1-weighted MR images without manual delineation of hippocampi. This method was applied to a group of Alzheimer's disease (AD) (n=36) and control (n=19) subjects and compared with manual methods (manual segmentation of baseline and repeat-image hippocampi) and semi-automated methods (manual segmentation of baseline hippocampi only). In controls, mean (S.D.) atrophy rates for manual, semi-automated, and automated methods were 18.1 (53.5), 15.3 (50.2) and 11.3 (50.4) mm3 loss per year, respectively. In AD patients these rates were 174.6 (106.5) 159.4 (101.2) and 172.1 (123.1) mm3 loss per year, respectively. The automated method was a significant predictor of disease (p=0.001) and gave similar group discrimination compared with both semi-automated and manual methods. The automated hippocampal analysis in this small study took approximately 20 min per hippocampal pair on a 3.4 GHz Intel Xeon server, whereas manual delineation of each hippocampal pair took approximately 90 min of operator-intensive labour. This method may be useful diagnostically or in studies where analysis of many scans may be required.

Aged↗
PubMed2006

Increased rate of whole-brain atrophy over 6 months in early Huntington disease.

The authors measured the rate of whole-brain atrophy over 6 months in 13 patients with early Huntington disease (HD) and seven matched controls. Patients with early HD had significantly increased rates of whole-brain atrophy vs controls (mean [SD] HD, 1.10 [0.88]%/year; controls, 0.26 [0.54]%/year). The measurement of cerebral change over short time periods (e.g., 6 months) may be relevant for trials designed to assess effects on neurodegeneration or atrophy.

Adult↗
PubMed2006

MRS shows abnormalities before symptoms in familial Alzheimer disease.

BACKGROUND: Pathologic change in Alzheimer disease (AD) begins some years before symptoms. MRS has the potential to detect metabolic abnormalities reflecting this early pathologic change. Presenilin 1 (PS1) and amyloid precursor protein (APP) mutation carriers have a nearly 100% risk of developing AD and may be studied prior to symptom onset. METHODS: Short echo time proton MR spectra were acquired from a midline posterior cingulate voxel in presymptomatic carriers of PS1 or APP mutations ("presymptomatic mutation carriers" [PMCs]; n = 7) and age- and sex-matched control subjects (n = 6). Ratios of N-acetyl aspartate (NAA), myo-inositol (MI), and choline-containing compounds (Cho) to creatine (Cr) were measured and NAA/MI calculated. Regression analyses and t tests were performed after log transformation. RESULTS: PMC and control subjects were matched for age and sex. PMC subjects were 1.7 to 21.6 years (mean 9.8 years) before expected symptom onset, predicted from family-specific mean age at onset. Age did not significantly affect metabolite ratios. Geometric mean ratios in control subjects were as follows: NAA/Cr = 1.75, MI/Cr = 0.59, and NAA/MI = 2.95. NAA/Cr and NAA/MI were significantly reduced in PMC relative to controls (NAA/Cr mean decrease 10% [95% CI 2 to 18%]; NAA/MI mean decrease 25% [95% CI 3 to 44%]). MI/Cr was increased in PMC, but the differences did not achieve significance (19% increase [95% CI 1% decrease to 41% increase]; p = 0.07)). In PMCs, reduction in NAA/MI (p = 0.001) and MI/Cr (p = 0.002) were related to proximity of expected age at onset. CONCLUSIONS: Metabolic changes are detectable in presymptomatic mutation carriers years before expected onset of Alzheimer disease. Their magnitude is related to proximity of expected age at onset.

Adolescent↗
PubMed2006

Do symptoms of memory impairment correspond to cognitive impairment: a cross sectional study of a clinical cohort.

BACKGROUND: Symptoms of memory loss are a common complaint within the general population and a frequent reason for seeking medical advice. However, the clinical relevance of these symptoms to future development of neurodegenerative disease is uncertain. The aim of this study is to characterise a cohort of individuals with symptoms of memory loss and varying memory impairment, who will be followed longitudinally with serial neuropsychology and neuroimaging to evaluate the clinical relevance of symptoms of memory loss. METHOD: Fifty-eight subjects with symptoms of memory loss were recruited from the National Hospital for Neurology and Neurosurgery. All subjects underwent clinical assessment, APOE4 genotyping, neuroimaging and neuropsychological tests. RESULTS: Those with mild cognitive impairment (MCI) had an increased prevalence of the APOE4 allele, impaired performance on tests of memory, measures of IQ and naming compared to controls. Baseline brain volumes were decreased and ventricular size increased. Those with symptoms of memory loss but no cognitive impairment (SNCI) performed significantly worse on tests of memory than the control group. CONCLUSIONS: The MCI represent a group with multiple risk factors for progression to AD. The SNCI group may represent a heterogeneous group with some individuals in the early stages of AD whilst others' memory complaints are more likely linked to anxiety or personality traits.

Aged↗
PubMed2005

Measuring atrophy in Alzheimer disease: a serial MRI study over 6 and 12 months.

BACKGROUND: Global brain atrophy rate calculated from serial MRI scans may be a surrogate marker of Alzheimer disease (AD) progression. Few studies have assessed atrophy in AD over short intervals. METHODS: Thirty-eight patients with AD and 19 control subjects had MRI scans at baseline, 6 months, and 1 year. Ventricular change and whole-brain volume loss were calculated directly from the regions manually outlined on registered scans and using the automated (boundary shift integral [BSI]) technique. Sample sizes required to power placebo-controlled treatment trials over 6 months and 1 year were calculated using these techniques. RESULTS: Increased rates of ventricular expansion and whole-brain atrophy were seen in AD compared with control subjects at both 6 and 12 months using manual and automated techniques (p < 0.001). Using the BSI consistently reduced measurement variability especially for whole-brain change. In clinical trials, at 6 months, significantly fewer patients would be required using the ventricular BSI (VBSI) compared with the brain BSI (BBSI) (e.g., 165 vs 410 per arm to provide 90% power to detect a 20% reduction in rate of change). At 1 year, sample size estimates were smaller than at 6 months, and the advantage of using VBSI instead of BBSI was less marked. CONCLUSIONS: In short-interval studies, using the ventricular boundary shift integral instead of the brain boundary shift integral may allow for disease-modifying effects to be demonstrated using significantly smaller sample sizes. This potential benefit must be balanced against the possibility that ventricular volumes may be more likely to be affected by factors other than neurodegeneration.

Aged↗
PubMed2005

How much variation in CS rates can be explained by case mix differences?

OBJECTIVE: To quantify the amount of variation in caesarean section (CS) rates between maternity units explained by case mix differences. DESIGN: Cross-sectional study. SETTING: All 216 maternity units in England and Wales. POPULATION: Women giving birth at these maternity units between May and July 2000. METHODS: Logistic regression models were developed to investigate the relationship between case mix characteristics, and odds of (i) CS before labour, (ii) CS in labour. Using these results, overall CS rates standardised for case mix were calculated for each maternity unit. Random-effects meta-analysis was used to examine heterogeneity between maternity units. MAIN OUTCOME MEASURES: CS before labour and CS during labour. RESULTS: Adjustment for case mix differences between maternity units explained 34% of the variance in CS rates. Odds of CS (before and in labour) increased with maternal age. Women from ethnic minority groups had lower odds of CS before labour, and increased odds of CS in labour. Women with a previous vaginal delivery had lower odds of CS, although the magnitude of this for CS before and in labour is markedly different. CONCLUSIONS: Case mix adjustment is important to enable understanding of the factors that influence the CS rate. These include organisational and staffing levels as well as women's preferences for childbirth and clinician's attitudes. An understanding of how these factors influence the CS rate is essential for evaluation of quality and appropriateness of obstetric care provided to women.

Adolescent↗
PubMed2004

An investigation into the biological activity of the selected histidine-containing diketopiperazines cyclo(His-Phe) and cyclo(His-Tyr).

Although cyclic diketopiperazines have been known since the beginning of the century, only now have they attracted considerable interest with respect to their biological activity. The aim of this study was to determine if the diketopiperazines cyclo(L-histidyl-L-phenylalanyl) (cyclo(His-Phe)) and cyclo(L-histidyl-L-tyrosyl) (cyclo(His-Tyr)) have significant biological activity relevant to the treatment of cardiovascular-related disease states, cancer and infectious diseases. Haematological studies were performed, including thrombin substrate binding, blood clotting time, platelet adhesion, platelet aggregation and fibrinolysis assays. A cytotoxicity screening utilizing a tetrazolium-based assay on the cell lines HeLa, WHCO3, and MCF-7 was performed. The whole-cell patch-clamp technique was used to investigate ion-channel activity in ventricular myocytes of rats, and isolated rat heart studies were performed to investigate the cardiac effects involving heart rate and coronary flow rate. Cyclo(His-Tyr) produced a significant prolongation of blood clotting time, slowing of clot lysis and inhibition of ADP-induced platelet adhesion and aggregation (P < 0.05). Cyclo(His-Phe) showed significant (P < 0.05) anti-tumour activity, causing greatest reduction of cell viability in cervical carcinoma cells. Preliminary results from patch-clamp studies indicate that both diketopiperazines caused blocking of sodium and calcium ion channels, but opening of inward rectifying potassium ion channels. In the rat isolated heart studies, cyclo(His-Phe) caused a gradual reduction in heart rate (P = 0.0027) and a decrease in coronary flow rate (P = 0.0017). Cyclo(His-Tyr) significantly increased the heart rate (P = 0.0016) but did not cause any significant change of coronary flow rate (P > 0.05). Cyclo(His-Tyr) showed notable (P < 0.05) antibacterial activity and both diketopiperazines showed excellent antifungal activity (P < 0.05). These observations reveal diketopiperazines to be ideal lead compounds for the rational design of an agent capable of preventing metastasis, inhibiting tumour growth, and as potential chemotherapeutic, antiarrhythmic and antihypertensive agents, as well as potential antibacterial and antifungal agents.

Animals↗
PubMed2003

Expression and function of neuronal nicotinic ACh receptors in rat microvascular endothelial cells.

The expression and function of nicotinic ACh receptors (nAChRs) in rat coronary microvascular endothelial cells (CMECs) were examined using RT-PCR and whole cell patch-clamp recording methods. RT-PCR revealed expression of mRNA encoding for the subunits alpha(2), alpha(3), alpha(4), alpha(5), alpha(7), beta(2), and beta(4) but not beta(3). Focal application of ACh evoked an inward current in isolated CMECs voltage clamped at negative membrane potentials. The current-voltage relationship of the ACh-induced current exhibited marked inward rectification and a reversal potential (E(rev)) close to 0 mV. The cholinergic agonists nicotine, epibatidine, and cytisine activated membrane currents similar to those evoked by ACh. The nicotine-induced current was abolished by the neuronal nAChR antagonist mecamylamine. The direction and magnitude of the shift in E(rev) of nicotine-induced current as a function of extracellular Na(+) concentration indicate that the nAChR channel is cation selective and follows that predicted by the Goldman-Hodgkin-Katz equation assuming K(+)/Na(+) permeability ratio of 1.11. In fura-2-loaded CMECs, application of ACh, but not of nicotine, elicited a transient increase in intracellular free Ca(2+) concentration. Taken together, these results demonstrate that neuronal nAChR activation by cholinergic agonists evokes an inward current in CMECs carried primarily by Na(+), which may contribute to the plasma nicotine-induced changes in microvascular permeability and reactivity induced by elevations in plasma nicotine.

Acetylcholine↗
PubMed2003

Area-wide traffic calming for preventing traffic related injuries.

BACKGROUND: It is estimated that by 2020 road traffic crashes will have moved from ninth to third in the world disease burden ranking, as measured in disability adjusted life years, and second in developing countries. The identification of effective strategies for the prevention of traffic related injuries is of global health importance. Area-wide traffic calming schemes that discourage through traffic on residential roads is one such strategy. OBJECTIVES: To evaluate the effectiveness of area-wide traffic calming in preventing traffic related crashes, injuries, and deaths. SEARCH STRATEGY: We searched the following electronic databases: Cochrane Injuries Group's Specialised Register, Cochrane Controlled Trials Register, MEDLINE, EMBASE and TRANSPORT (NTIS, TRIS, TRANSDOC). We searched the web sites of road safety organisations, handsearched conference proceedings, checked reference lists of relevant papers and contacted experts in the area. The search was not restricted by language or publication status. SELECTION CRITERIA: Randomised controlled trials, and controlled before-after studies of area-wide traffic calming schemes. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data on type of study, characteristics of intervention and control areas, and length of data collection periods. Before and after data were collected on the total number of road traffic crashes, all road user deaths and injuries, pedestrian-motor vehicle collisions and road user deaths. The statistical package STATA was used to calculate rate ratios for each study, which were then pooled to give an overall estimate using a random effects model. MAIN RESULTS: We found no randomised controlled trials, but 16 controlled before-after trials met our inclusion criteria. Seven studies were done in Germany, six in the UK, two in Australia and one in the Netherlands. There were no studies in low or middle income countries. Eight trials reported the number of road traffic crashes resulting in deaths. The pooled rate ratio was 0.63 (0.14, 2.59 95% CI). Sixteen studies reported the number of road traffic crashes resulting in injuries (fatal and non fatal). The pooled rate ratio was 0.89 (0.80, 1.00 95% CI). Nine studies reported the total number of road traffic crashes. The pooled rate ratio was 0.95 (0.81, 1.11 95% CI). Thirteen trials reported the number of pedestrian-motor vehicle collisions. The pooled rate ratio was 1.00 (0.84, 1.18). There was significant heterogeneity for the total number of crashes and deaths and injuries. REVIEWER'S CONCLUSIONS: The results from this review suggest that area-wide traffic calming in towns and cities may be a promising intervention for reducing the number of road traffic injuries, and deaths. However, further rigorous evaluations of this intervention are needed.

Accident Prevention↗
PubMed2003

Outcome after treatment of coronary in-stent restenosis; results from a systematic review using meta-analysis techniques.

AIMS: To evaluate the clinical outcome after treatment of coronary in-stent restenosis. METHODS AND RESULTS: For identification of the relevant literature a specific search strategy was conducted and explicit inclusion criteria were defined to avoid selection bias. Based on the selected literature, a systematic review using descriptive statistics and meta-analysis methods regarding the outcome after treatment of coronary in-stent restenosis was performed. The proportion of patients experiencing a major adverse cardiac event (MACE) as defined by death, myocardial infarction, and target lesion revascularization was the main outcome measure. A total of 1304 citations were identified. Among these, 28 studies (six different treatment modalities) including a total of 3012 patients met the inclusion criteria and were incorporated into this analysis. The estimated average probability of experiencing a major cardiac adverse event after treatment for in-stent restenosis with a follow-up period of 9+/-4 months was 30.0% (25.0-34.9%, 95% confidence interval) with strong evidence for heterogeneity between study specific results (P=0.0001). The clinical outcome was not significantly different between treatment modalities. After adjustment for confounding factors (i.e. lesion length), however, patients undergoing intracoronary radiation showed an estimated advantage of 16.9% (-37.7+/-4.0%, 95% confidence interval) in MACE free survival, as compared to balloon angioplasty. The post-interventional diameter stenosis was the only independent predictor for the long-term outcome after treatment of in-stent restenosis. CONCLUSIONS: Treatment of in-stent restenosis is associated with an overall 30% rate of major adverse cardiac events. Currently, repeat angioplasty is the treatment option of choice, especially when a sufficient acute procedural result can be achieved. Intracoronary radiation should be considered in cases with therapy refractory forms of diffuse in-stent restenosis.

Coronary Restenosis↗
PubMed2003

Traffic calming for the prevention of road traffic injuries: systematic review and meta-analysis.

OBJECTIVE: To assess whether area-wide traffic calming schemes can reduce road crash related deaths and injuries. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Cochrane Injuries Group Specialised Register, Cochrane Central Register of Controlled Trials, Medline, EMBASE, Sociological Abstracts Science (and social science) citation index, National Technical Information service, Psychlit, Transport Research Information Service, International Road Research Documentation, and Transdoc, and web sites of road safety organisation were searched; experts were contacted, conference proceedings were handsearched, and relevant reference lists were checked. INCLUSION CRITERIA: Randomised controlled trials, and controlled before/after studies of area-wide traffic calming schemes designed to discourage and slow down through traffic on residential roads. METHODS: Data were collected on road user deaths, injuries, and traffic crashes. For each study rate ratios were calculated, the ratio of event rates before and after intervention in the traffic calmed area divided by the corresponding ratio of event rates in the control area, which were pooled to give an overall estimate using a random effects model. FINDINGS: Sixteen controlled before/after studies met our inclusion criteria. Eight studies reported the number of road user deaths: pooled rate ratio 0.63 (95% confidence interval (CI) 0.14 to 2.59). Sixteen studies reported the number of injuries (fatal and non-fatal): pooled rate ratio 0.89 (95% CI 0.80 to 1.00). All studies were in high income countries. CONCLUSION: Area-wide traffic calming in towns and cities has the potential to reduce road traffic injuries. However, further rigorous evaluations of this intervention are needed, especially in low and middle income countries.

Accidents, Traffic↗
PubMed2001

Correcting for measurement error in binary and continuous variables using replicates.

Measurement error in exposures and confounders leads to bias in regression coefficients. It is possible to adjust for this bias if true values or independent replicates are observed on a subsample. We extend a method suitable for quantitative variables to the situation where both binary and quantitative variables are present. Binary variables with independent replicates introduce two extra problems: (i) the error is correlated with the true value, and (ii) the measurement error probabilities are unidentified if only two replicates are available. We show that - under plausible assumptions - adjustment for error in binary confounders does not need to address these problems. The regression coefficient for a binary exposure is overadjusted if methods for continuous variables are used. Correct adjustment is possible either if three replicates are available, or if further assumptions can be made; otherwise, bounds can be put on the correctly adjusted value, and these bounds are reasonably close together if the exposure has prevalence near 0.5.

Bias↗
PubMed2001

Inequalities in availability of National Health Service general dental practitioners in England and Wales.

AIM: To model the inequalities in availability of National Health Service general dental practitioners in England and Wales in relation to key socio-demographic factors. METHODS: Current estimates of the numbers of NHS general dental practitioners for each health authority were related to data from the 1991 census using Poisson regression models, and generalised estimating equations to allow for correlation between results for neighbouring health authorities. RESULTS: An 'average' health authority, without a dental school, would be expected to have 2,138 residents for every NHS dentist. Controlling for relevant factors, health authorities with higher proportions of the following are associated with lower (better) population to dentist ratios by the amounts shown: each 1% higher female population (-11.8%; 95%CI -19.1%, -3.9% P = 0.004); each 1% greater South Asian population (-1.4%; 95%CI -2.1%, -0.7% P <0.001). A health authority with a dental school is associated with a more favourable ratio compared with one without such a facility (-9.2%; 95%CI -16.2%, -1.6% P = 0.019). Each additional 1% of the following are associated with a worse ratio by the amounts shown: children aged 0 to 14 years old (+5.2%; 95% CI +2.4%, +8.1% P < 0.001); adults aged over 65 years old (+2.8%, 95%CI +1.0%, +4.7% P =0.002); households without a car (+0.8%; 95%CI 0.0%, +1.6% P =0.042). CONCLUSIONS: Ensuring access to dental care may be a more complex issue than simply providing adequate numbers of dentists at a national level. Any manpower planning exercise should additionally consider local factors that may act as incentives or disincentives to those professionals who provide care.

Adolescent↗
PubMed2001

Nonlinear behavior of certain optic nerve head parameters and their determinants in normal subjects.

OBJECTIVE: To investigate the relationship between the absolute area of certain optic disc parameters and a number of ocular dimensional characteristics and demographic factors in young, healthy subjects. DESIGN: Cross-sectional study. PARTICIPANTS: One hundred twenty-one subjects, aged 16.5 to 35.4 years participated, encompassing a wide range of refractive error from +4 diopters (D) to -25.75 D. One eye from each subject was randomly selected for examination. MAIN OUTCOME MEASURES: Absolute size of the optic disc parameters: optic disc area (DA), neuroretinal rim area (NRA), optic cup area (CA), and peripapillary atrophy area (PA). METHODS: Absolute sizes of optic disc parameters were determined from digitized photographic color transparencies, taking into consideration the magnification of the fundus camera and human eye. Relationships between the absolute size of the optic disc features and axial length, crystalline lens thickness, anterior chamber depth, ocular refraction, front surface keratometry, age, and gender were examined. RESULTS: Axial length, lens thickness, front surface keratometry, and age demonstrated positive associations with all optic disc parameters, and anterior chamber depth and ocular refraction demonstrated negative associations in all cases. Multiple regression analysis revealed that the associations observed univariately for age, anterior chamber depth, lens thickness, front surface keratometry, and ocular refraction were confounded by axial length for all disc parameters. After taking logs, DA and NRA exhibit an exponential relationship with axial length, whereas PA and CA exhibit a linear relationship with axial length. DA and NRA increase by approximately 3% per millimeter increase in axial length at 20 mm and up to 40% for DA and 50% for NRA at an axial length of 35 mm. PA and CA are estimated to increase by 26% (10%-44%) and 10% (5%-16%), respectively, per millimeter increase in axial length. Females have approximately 5% smaller DA and 7% smaller NRA than males, but these effects are not statistically significant (P > 0.2). From the multiple regression analysis, females have 31% larger optic cup areas (1%-57%, P = 0.03) and 24% smaller PA (42% smaller to 5% larger P = 0.06) than males, but these effects are of borderline statistical significance at 5%. CONCLUSIONS: Of the ocular biometric factors considered, axial length seems to be the most important predictor of the absolute area of the optic disc parameters. No association exists between any disc parameter and age in this sample of subjects less than 40 years of age. Females exhibited smaller values for DA, NRA, and PA than did males, differences that were not statistically significant, and larger CA (P = 0.03).

Adolescent↗
PubMed2001

Total costs and predictors of costs in patients with systemic lupus erythematosus.

OBJECTIVE: To determine the annual direct, indirect and total costs and predictors of costs in patients with systemic lupus erythematosus (SLE). METHODS: One hundred and five patients with SLE completed questionnaires on health-care utilization and employment history. Predictors of costs were determined by multiple regression analyses using direct, indirect and total costs as outcome variables. Demographics, health status, disease activity, end-organ damage, social support and satisfaction with care were used as predictor variables. RESULTS: The mean annual total cost per patient was pounds sterling 7913. Direct costs were a third and indirect costs two-thirds of the total cost. Higher education level, greater disease activity and lower physical functioning were associated with higher direct, indirect and total costs. Higher direct costs were also associated with greater damage and younger age. CONCLUSION: SLE has a considerable impact on the health-care system and society. Improvement in disease activity and physical health and prevention of end-organ damage may reduce costs in SLE.

Adolescent↗