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Biomedical subjects

L Joseph

Publications and source records attributed to L Joseph.

At least 55 records · Page 3Linked to original sources
PubMed2001

Comparison of methods to analyse imprecise faecal coliform count data from environmental samples.

Imprecise values arise when bacterial colonies are too numerous to be counted or when no colonies grow at a specific dilution. Our objective was to show the usefulness of multiple imputation in analysing data containing imprecise values. We also indicate that interval censored regression, which is faster computationally in situations where it applies, can be used, providing similar estimates to imputation. We used bacteriological data from a large epidemiological study in daycare centres to illustrate this method and compared it to a standard method which uses single exact values for the imprecise data. The data consisted of numbers of FC on children's and educators' hands, from sandboxes and from playareas. In general, we found that multiple imputation and interval censored regression provided more conservative intervals than the standard method. The discrepancy in the results highlights both the importance of using a method that best captures the uncertainty in the data and how different conclusions might be drawn. This can be crucial for both researchers and those who are involved in formulating and regulating standards for bacteriological contamination.

Child Day Care Centers↗
PubMed2001

Cost of prescribed NSAID-related gastrointestinal adverse events in elderly patients.

AIMS: It is well established that nonsteroidal anti-inflammatory drugs (NSAIDs) have gastrointestinal (GI) side-effects. However, the cost of health care resources spent on preventing and managing these side-effects is not clear. The objective of this study was to estimate the direct cost of NSAID-related GI events in an elderly population. METHODS: From the Régie de l'assurance-maladie du Québec (RAMQ) database, we obtained medical, pharmaceutical and demographic records of a 10% random sample (n = 49 033) of seniors who, between January 1, 1993 and December 31, 1997, had a dispensed prescription of a NSAID. Patients who did not have any GI events during the year prior to their first dispensed prescription were included in the cohort. All patients were followed-up for 2 years. The daily direct Canadian dollar costs of GI events that were incurred by these patients while they were on NSAID therapy were compared with those of GI events that were incurred by these same patients while they were not on NSAID therapy. The difference in these daily costs was attributed to NSAIDs. RESULTS: A total of 12 082 new NSAID users were included in the study. Two hundred and seventeen (1.8%) were hospitalized for GI-related problems; of these, 130 (60%) had their GI hospitalization as their first GI event; 3257 (27.0%) used gastroprotective agents (GPAs), and 857 (26.3%) took GPAs without any apparent prior GI symptoms; 801 (6.6%) had GI diagnostic tests; and 661 (5.5%) died. The average direct costs of GI side-effects per patient-day on NSAIDs were 3.5 times higher than those of a patient-day not on NSAIDs. The direct cost of GI side-effects per patient-day on NSAIDs was $1.34, of which more than 70% ($0.94) was attributed to GI events resulting from NSAID treatment. CONCLUSIONS: Approximately one Canadian dollar was added to patient costs for every day he/she was on NSAID therapy. Safer therapies and appropriate patient risk management may potentially reduce NSAID-related health care resource use.

Aged↗
PubMed2001

Predictors of quality of life 6 months and 1 year after acute myocardial infarction.

BACKGROUND: Quality of life (QOL) is an increasingly important outcome measure after hospital admission for acute myocardial infarction (AMI). However, the ability to adjust these outcomes for differences between compared groups of patients is limited because the predictors of QOL after AMI are unknown. METHODS: To identify any clinical, demographic, and psychosocial characteristics of patients at admission that were independent predictors of QOL 6 months and 1 year after AMI, we measured physical and mental QOL (Short Form-36 Physical and Mental Component summary scores) and overall QOL (EuroQol health perception scale) in a prospective cohort of 587 patients admitted at 10 hospitals in Quebec. A set of plausible multivariate linear regression models was created for each outcome measure with use of the Bayesian Information Criterion. RESULTS: Mean physical, mental, and overall QOL scores corresponding to the time immediately before admission (baseline) were 45 (95% confidence interval [CI] 44-46), 47 (95% CI 46-48), and 70 (95% CI 68-72), respectively. By 1 year, mean physical, mental, and overall QOL scores were close to baseline (45 [95% CI 44-46], 48 [95% CI 47-49], and 73 [95% CI 71-74], respectively). The predictors of physical, mental, and overall QOL were similar at 6 months and 1 year. Important predictors of physical QOL were the corresponding score at baseline, age, and previous bypass surgery (beta coefficients at 1 year: 5 [per 10-point difference in baseline score], -1 [per 10-year age difference], 5.3; 95% CIs 4 to 5, -2 to -1, -9.2 to -1.3, respectively). Predictors of mental QOL were the corresponding score at baseline and depression (beta coefficients at 1 year: 3 [per 10-point difference in baseline score], -3 [per 10-point difference in depression score]; 95% CIs 2 to 4, -5 to -2, respectively). Predictors of overall QOL included the corresponding score at baseline and age (beta at 1 year: 2 [per 10-point score difference], -3 [per 10-year age difference]; 95% CIs 1 to 3, -4 to -1, respectively). Depression was also a predictor of impaired physical and overall QOL at 6 months (beta at 6 months: -1.6 [per 10-point score difference], -5.4 [per 10-point score difference]; 95% CIs -2.9 to -0.4, -7.7 to -3.2, respectively). No variables related to treatments received in-hospital were found in the most clinically relevant models. CONCLUSIONS: These results suggest that age and psychosocial characteristics at baseline are the most important predictors of QOL after AMI. Other clinical characteristics and treatments received in-hospital do not appear to strongly affect patients' long-term perceptions of QOL.

Activities of Daily Living↗
PubMed2001

Frequency-dependent open-circuit acoustic sensitivity of fluid-filled, coated, radially polarized piezoelectric ceramic cylindrical shells of arbitrary thickness and infinite length.

The frequency-dependent free-field open-circuit voltage generated by radially polarized piezoelectric ceramic fluid-filled shells of infinite length coated with an elastic layer and excited by a plane acoustic wave is studied. The shell and the coating are of arbitrary thickness and are anisotropic. It is shown that the charge density in the piezoelectric shell is zero by using the electrostatic and open-circuit conditions. General expressions for the pressures and radial velocities in the interior and exterior fluids are obtained by using the finiteness and radiation conditions, respectively. General expressions for the radial stresses and velocities in the piezoelectric shell and elastic coating are also determined by using two-dimensional equations of state and axisymmetric equations of motion. The coefficients in the general expressions are then determined by using the continuity conditions at the various interfaces. Finally, an expression for the open-circuit sensitivity is obtained by using a piezoelectric equation of state. Numerical results are presented for air, water, and vacuum in the interior, two types of elastic coating, and piezoelectric shells with various thicknesses. The effect of neglecting anisotropy on the sensitivity is also illustrated.

Journal Article↗
PubMed2001

Bayesian approaches to modeling the conditional dependence between multiple diagnostic tests.

Many analyses of results from multiple diagnostic tests assume the tests are statistically independent conditional on the true disease status of the subject. This assumption may be violated in practice, especially in situations where none of the tests is a perfectly accurate gold standard. Classical inference for models accounting for the conditional dependence between tests requires that results from at least four different tests be used in order to obtain an identifiable solution, but it is not always feasible to have results from this many tests. We use a Bayesian approach to draw inferences about the disease prevalence and test properties while adjusting for the possibility of conditional dependence between tests, particularly when we have only two tests. We propose both fixed and random effects models. Since with fewer than four tests the problem is nonidentifiable, the posterior distributions are strongly dependent on the prior information about the test properties and the disease prevalence, even with large sample sizes. If the degree of correlation between the tests is known a priori with high precision, then our methods adjust for the dependence between the tests. Otherwise, our methods provide adjusted inferences that incorporate all of the uncertainty inherent in the problem, typically resulting in wider interval estimates. We illustrate our methods using data from a study on the prevalence of Strongyloides infection among Cambodian refugees to Canada.

Bayes Theorem↗
PubMed2001

Gastrointestinal-related healthcare resource usage associated with a fixed combination of diclofenac and misoprostol versus other NSAIDs.

OBJECTIVE: To compare gastrointestinal (GI) healthcare resource use (HCRU) and associated costs in patients taking a fixed combination of diclofenac and misoprostol versus other nonsteroidal anti-inflammatory drugs (NSAIDs). METHODS: We analysed a sample (49,033 patients) of the Government of Quebec Health Insurance Agency database. Patients were included in the study if they did not have GI events during the year preceding the date of their first NSAID prescription dispensing (the index date). Patients were followed up for 2 years. A 3-stage model was used to determine the factors that influenced the direct medical costs of GI HCRU: (i) a logistic regression model (model 1) to estimate the risk of GI HCRU; (ii) a linear regression model (model 2) to estimate the direct costs of GI HCRU for those who had such events; (iii) multiplying the estimated risks from model 1 by the estimated costs from model 2 gave the estimated direct costs of GI HCRU for all patients. STUDY PERSPECTIVE: Provincial government of Quebec, Canada. RESULTS: 1,533 patients were prescribed diclofenac/misoprostol at the index date and 10,540 another NSAID. Comorbidity markers were not significantly different between the 2 groups. Of the diclofenac/misoprostol patients, 23 (1.5%) were hospitalised for GI problems compared with 194 (1.8%) of the NSAID group; 403 (26.3%) of diclofenac/misoprostol patients used gastroprotective agents compared with 2,849 (27.0%) of the NSAID patients; 118 (7.7%) of diclofenac/misoprostol patients had GI diagnostic tests compared with 682 (6.5%) of the NSAID patients. The average direct medical cost of GI HCRU was 310.52 Canadian dollars ($Can)/patient (1997 values) in the diclofenac/misoprostol group compared with $Can231.19/patient (1997 values) in the NSAID group. When adjusted for baseline factors, the ratio of the total direct medical cost of GI HCRU in the diclofenac/misoprostol group to that of the NSAID group was 1.15 (95% confidence interval: 0.89, 1.48). CONCLUSIONS: Our data showed no significant differences in GI HCRU among patients taking diclofenac/misoprostol compared with those taking NSAIDs.

Aged↗
PubMed2001

Wheat germ supplement reduces cyst and trophozoite passage in people with giardiasis.

The protozoan parasite Giardia lamblia is a major cause of waterborne enteric disease worldwide. Lectins are proteins that bind to carbohydrate (sugar) moieties. Potential targets for lectins are found on the surface of most single-celled organisms. Modest concentrations of wheat germ agglutinin (WGA) have been shown to inhibit G. lamblia excystation and trophozoite growth in vitro and can reduce cyst passage in mice infected with the closely related protozoan parasite, G. muris. Commercial preparations of wheat germ (WG) contain 13-53 microg of WGA per gram. We performed a double-masked, placebo-controlled study of dietary supplementation with WG in 63 subjects with giardiasis in Montreal and Lima (25 asymptomatic patients passing cysts; 38 patients with symptoms). Asymptomatic subjects received WG (2 g, 3 times a day) or placebo (cornstarch, 2 g, 3 times a day) for 10 days, followed by metronidazole (250 mg 3 times a day) for 7 days. Symptomatic subjects received metronidazole (250 mg 3 times a day) plus either WG or placebo for 7 days. Stool specimens were collected every day (Montreal) or every other day (Lima) for 10 days and on Day 35 for microscopic examination and coproantigen determination. Subjects kept a diary of symptoms for 10 days after recruitment. In asymptomatic subjects, both cyst passage and coproantigen levels were reduced by approximately 50% in those taking WG compared with the placebo group (P < 0.01 and P = 0.06, respectively). In symptomatic subjects, cyst passage and coproantigen levels fell precipitously in response to metronidazole therapy, and there were no clinically important differences between those receiving supplemental WG or placebo. However, symptoms appear to have resolved more rapidly in the subjects taking WG in addition to metronidazole. The WG supplement was well tolerated in both symptomatic and asymptomatic subjects. These data suggest that components of WG, possibly WGA, either alone or in combination with antiprotozoal agents, can influence the course of human giardiasis.

Adult↗
PubMed2001

Radiographic damage in rheumatoid arthritis correlates with functional disability but not direct medical costs.

OBJECTIVE: Few longitudinal data exist on the relationship between radiographic damage and self-reported functional disability and direct medical costs in rheumatoid arthritis (RA). We assessed these relationships. METHODS: One hundred thirty patients with RA (at time of the first available radiograph, mean age 56.6 yrs, 16.9% male, mean disease duration 16.8 yrs) were followed for up to 13.4 years. Semiannually, they reported on functional disability (0 = no difficulty, 3 = unable to do), global severity (0 = very well, 100 = very poor), pain (0 = no pain, 3 = severe pain), and health services utilization through completion of the Stanford Health Assessment Questionnaire (HAQ). Concurrent hand radiographs were scored for erosions and joint space narrowing using the Genant method and a single score summing both erosions and joint space narrowing for both hands was calculated (0 = no damage, 200 = maximum damage). The univariate association of functional disability, global severity, pain, or direct medical costs with concurrent radiographic damage was assessed through Spearman correlations and hierarchical regression models. The hierarchical models permit exploitation of the between-patient and within-patient variation present in our longitudinal data. RESULTS: At the time of the first available radiograph, mean (SD) levels of functional disability, global severity, and pain were 1.3 (0.7), 39.4 (21.0), and 1.1 (0.7), respectively. At entry into the study, the average radiograph score was 49.7 and upon leaving the study it was 66.9. Patients were followed an average of 6.7 years, with radiograph scores increasing at an average rate of 2.5 units/yr. The Spearman correlation [95% confidence interval (CI)] between average per-patient radiograph score and average per-patient HAQ disability index, average per-patient global severity, average per-patient pain score, and average per-patient direct medical costs was, respectively, 0.42 (0.26, 0.55), 0.23 (0.06, 0.39), 0.20 (0.03, 0.36), and 0.06 (-0.11, 0.23). The mean slope (95% CI) for disability on radiograph score was 0.0186 (0.0132, 0.0226), for severity on radiographs 0.1889 (0.1295, 0.2498), and for pain on radiographs 0.0057 (0.0027, 0.0084). As an example, over 10 years, a 25 unit (i.e., 50%) increase in radiograph scores would, on average, be associated with a 0.46 unit (i.e., 35%) increase in disability, a 4.72 unit (12%) increase in global severity score, and a 0.14 unit (13%) increase in pain, all expressed on the HAQ scales. There was little association between radiograph score and direct medical costs. CONCLUSION: A clinically meaningful association exists between radiographic damage and self-reported functional disability, suggesting that interventions that slow radiographic progression may improve the patient's health status. Such a relationship was not observed between radiographic damage and direct medical costs.

Aged↗
PubMed2001

Selection of subjects for hospital-based epidemiologic studies based on outward manifestations of disease.

Selection of controls with the same outward manifestations of disease as the case group has been proposed as a means of avoiding selection bias in hospital-based case-control studies. The same strategy, however, can lead to selection bias in registry-based case-control studies that use control diseases with similar manifestations whose diagnoses might have been associated with the exposure. Matching exposed and unexposed subjects by outward manifestation of disease can be used in cohort and cross-sectional studies aiming at decreasing selection bias. This strategy in these study designs may lead to overmatching, but this will not bias the relative-risk estimates. Efficiency considerations in applying this strategy require further investigation.

Bias↗
PubMed2000

Canadian normative data for the SF-36 health survey. Canadian Multicentre Osteoporosis Study Research Group.

BACKGROUND: The Medical Outcomes Study 36-item Short Form (SF-36) is a widely used measure of health-related quality of life. Normative data are the key to determining whether a group or an individual scores above or below the average for their country, age or sex. Published norms for the SF-36 exist for other countries but have not been previously published for Canada. METHODS: The Canadian Multicentre Osteoporosis Study is a prospective cohort study involving 9423 randomly selected Canadian men and women aged 25 years or more living in the community. The sample was drawn within a 50-km radius of 9 Canadian cities, and the information collected included the SF-36 as a measure of health-related quality of life. This provided a unique opportunity to develop age- and sex-adjusted normative data for the Canadian population. RESULTS: Canadian men scored substantially higher than women on all 8 domains and the 2 summary component scales of the SF-36. Canadians scored higher than their US counterparts on all SF-36 domains and both summary component scales and scored higher than their UK counterparts on 4 domains, although many of the differences are not large. INTERPRETATION: The differences in the SF-36 scores between age groups, sexes and countries confirm that these Canadian norms are necessary for comparative purposes. The data will be useful for assessing the health status of the general population and of patient populations, and the effect of interventions on health-related quality of life.

Activities of Daily Living↗
PubMed2000

Gastrointestinal health care resource use and costs associated with nonsteroidal antiinflammatory drugs versus acetaminophen: retrospective cohort study of an elderly population.

OBJECTIVE: To estimate gastrointestinal (GI) health care resource use and direct costs associated with prescription nonsteroidal antiinflammatory drugs (NSAIDs) in an elderly population. METHODS: Using the Government of Quebec's health insurance database, we obtained the medical, pharmaceutical, and demographic records of 73,850 senior citizens who, between 1993 and 1997, had either an NSAID or an acetaminophen prescription dispensed. The date of their first dispensed prescription for an NSAID or acetaminophen was termed their index date. Patients who were not taking oral corticosteroids or anticoagulants at their index date, were not diagnosed with cancer at their index date, and were not hospitalized and did not have any GI events during the year prior to their index date were included in the study. Patients who had a dispensed NSAID prescription at their index date formed the NSAID cohort; the others formed the acetaminophen cohort. All patients were followed up for 2 years. The daily direct costs of GI events incurred during NSAID therapy by the NSAID cohort were compared with those incurred during a similar followup period by the acetaminophen cohort. The difference in these average daily costs was attributed to NSAID use. RESULTS: The NSAID cohort included 5,268 senior citizens and the acetaminophen cohort 2,245. More GI adverse events were observed in the NSAID cohort (odds ratio 2.48, 95% confidence interval 2.06, 3.00). The average daily direct cost of GI events for a day of NSAID therapy attributed to the NSAIDs was $0.84 (Canadian). On average, for each Canadian dollar spent on NSAIDs, an additional $0.66 was spent on their side effects. CONCLUSION: Safer alternatives to NSAIDs would significantly reduce medical care costs for patients in need of NSAID therapy.

Acetaminophen↗
PubMed2000

The use of alternative medical therapies in patients with systemic lupus erythematosus. Trination Study Group.

OBJECTIVE: As part of an ongoing study of health resource utilization and diminished productivity in patients with systemic lupus erythematosus (SLE), the use of alternative medical therapies was assessed. METHODS: A cohort of 707 patients with SLE from 3 countries completed questionnaires on demographics, social support, health status (using the Short Form 36 health survey), satisfaction with health care, health resource utilization (conventional resources and alternative therapies), and time losses in labor market and non-labor market activities. Annual direct and indirect costs (1997 Canadian dollars) were calculated and compared for users and nonusers of alternative medical therapies. RESULTS: Among the 707 patients, 352 (49.8%) were found to use alternative therapies and at similar rates across Canada, the United States, and the United Kingdom. Users were younger and better educated than nonusers, exhibited poorer levels of self-rated health status and satisfaction with medical care, and had minimal to no objective evidence of worse disease (according to the revised Systemic Lupus Activity Measure instrument). The mean of log direct medical costs for conventional resources was higher for users of select alternative therapies compared with nonusers. In a logistic regression, neither the number of alternative therapies used nor the individual therapy increased the probability of incurring indirect costs. CONCLUSION: The use of alternative medical therapies is common in patients with SLE. Users of many alternative medical therapies accrue greater conventional medical costs compared with nonusers. The use of alternative medical therapy may be a marker for care-seeking behavior associated with higher consumption of conventional medical resources in the absence of demonstrable additional morbidity and should be considered in future cost analyses of patients with SLE.

Adult↗
PubMed2000

Estimation of the prevalence of low bone density in Canadian women and men using a population-specific DXA reference standard: the Canadian Multicentre Osteoporosis Study (CaMos).

The Canadian Multicentre Osteoporosis Study (CaMos) is a prospective cohort study which will measure the incidence and prevalence of osteoporosis and fractures, and the effect of putative risk factors, in a random sample of 10,061 women and men aged > or = 25 years recruited in approximately equal numbers in nine centers across Canada. In this paper we report the results of studies to establish peak bone mass (PBM) which would be appropriate reference data for use in Canada. These reference data are used to estimate the prevalence of osteoporosis and osteopenia in Canadian women and men aged > or = 50 years. Participants were recruited via randomly selected household telephone listings. Bone mineral density (BMD) of the lumbar spine and femoral neck were measured by dual-energy X-ray absorptiometry using Hologic QDR 1000 or 2000 or Lunar DPX densitometers. BMD results for lumbar spine and femoral neck were converted to a Hologic base. BMD of the lumbar spine in 578 women and 467 men was constant to age 39 years giving a PBM of 1.042 +/- 0.121 g/cm2 for women and 1.058 +/- 0.127 g/cm2 for men. BMD at the femoral neck declined from age 29 years. The mean femoral neck BMD between 25 and 29 years was taken as PBM and was found to be 0.857 +/- 0.125 g/cm2 for women and 0.910 +/- 0.125 g/cm2 for men. Prevalence of osteoporosis, as defined by WHO criteria, in Canadian women aged > or = 50 years was 12.1% at the lumbar spine and 7.9% at the femoral neck with a combined prevalence of 15.8%. In men it was 2.9% at the lumbar spine and 4.8% at the femoral neck with a combined prevalence of 6.6%.

Absorptiometry, Photon↗
PubMed2000

Iron stores and coronary artery disease: a clinical application of a method to incorporate measurement error of the exposure in a logistic regression model.

Rates of coronary artery disease (CAD) increase sharply after menopause. We examined the hypotheses that high iron stores, as measured by plasma ferritin levels, are a risk factor for CAD and that the increase in iron stores after menopause is at least in part responsible for the rise in CAD in women. We also investigated measurement error of plasma ferritin using a Bayesian conditional independence model and incorporated it into the estimation of the odds ratio (OR) for males. Cases had >/=1 coronary artery stenosis >/=70%. Controls had no visible coronary lesions on angiography. The median plasma ferritin level was 48 mg/L (interquartile range: 28 to 86) among 244 cases and 45 mg/l (24 to 85) among 140 controls. The multivariate analyses among females, males, and females and males combined did not support an association between plasma ferritin levels and CAD (OR for one unit change in log ferritin 1.01, 95% CI 0.71-1.44, OR 0.95, 95% CI 0.66-1.37 and OR 0.95, 95% CI 0.75-1.21, respectively). Accounting for the measurement error of ferritin in males slightly improved the precision of the estimate of the OR but did not unmask an association (OR: 0.94, 95% CI 0.69-1.30). We conclude that high ferritin levels before or after menopause are not associated with CAD. Measurement error might be considered in situations where a one-time measurement is assumed to be representative of long-term exposure.

Aged↗
PubMed2000

Predictors of physical outcomes in pediatric bone marrow transplantation.

The purpose of the present study was to investigate the hypothesis that family factors, in conjunction with clinical factors, are associated with physical outcomes in pediatric BMT. A prospective study of 68 pediatric patients (mean age = 7.5 years; ranging from 4 months to 18 years) undergoing BMT was carried out over a 6.5 year period. Physicians rated initial prognosis on a (0-5) scale which incorporated the child's diagnosis, known risk factors, and type of donor. Both parents individually completed two psychometrically sound questionnaires assessing family well-being and marital satisfaction. Cox proportional hazards survival analyses were performed to determine predictors of death (44% of the patients died). Potential predictor variables included were: initial prognosis, type of transplant, patient's age, socioeconomic status, marital satisfaction and family status, and family stress. Initial prognosis, as estimated by the physician, (RR = 0.62, 95% CI = 0.40, 0.97) was the best predictor of survival. Initial clinical factors are clearly critical in outcomes for pediatric BMT patients.

Actuarial Analysis↗