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Lawrence Joseph

Publications and source records attributed to Lawrence Joseph.

At least 55 records · Page 3Linked to original sources
PubMed2003

A Bayesian A-optimal and model robust design criterion.

Suppose that the true model underlying a set of data is one of a finite set of candidate models, and that parameter estimation for this model is of primary interest. With this goal, optimal design must depend on a loss function across all possible models. A common method that accounts for model uncertainty is to average the loss over all models; this is the basis of what is known as Läuter's criterion. We generalize Läuter's criterion and show that it can be placed in a Bayesian decision theoretic framework, by extending the definition of Bayesian A-optimality. We use this generalized A-optimality to find optimal design points in an environmental safety setting. In estimating the smallest detectable trace limit in a water contamination problem, we obtain optimal designs that are quite different from those suggested by standard A-optimality.

Bayes Theorem↗
PubMed2003

Do traditional Gail model risk factors account for increased breast cancer in women with lupus?

OBJECTIVE: To determine to what extent the observed experience of breast cancer in a combined cohort of patients with systemic lupus erythematosus (SLE) could be explained by the profile of breast cancer risk factors. METHODS: Data were pooled from 2 centers, the Montreal General Hospital and the Feinberg School of Medicine at Northwestern University in Chicago. For each female cohort member, the probability of developing breast cancer during followup was estimated based on factors (including the individual's age, parity, age at first live birth, age of menarche, personal history of benign breast disease, and family history) using the Gail model, an established model for predicting breast cancer risk. The actual occurrence of cancer cases was determined by linkage with regional cancer registries. RESULTS: Of the 583 women in the combined cohort, 5 had been diagnosed with breast cancer prior to cohort entry, and 14 declined participation. In those remaining, 12 cases of breast cancer occurred compared to 5.6 predicted by the Gail model (standardized incidence ratio 2.1, 95% confidence interval: 1.1, 3.7). Thus, after controlling for risk factors, the incidence of breast cancer was elevated. CONCLUSION: Our data suggest that the risk of breast cancer in our SLE cohort is not completely explained by traditional factors found in the Gail model. Other factors, such as carcinogenic exposures (i.e., alkylating agents and immunosuppressive drugs) or the immunologic dysregulation of SLE itself, may be contributory.

Age Factors↗
PubMed2003

Thromboembolic risk in patients with high titre anticardiolipin and multiple antiphospholipid antibodies.

Asymptomatic antiphospholipid antibody (aPL) carriers with high risk for thrombosis may benefit from preventive anticoagulation. It was our objective to test whether the risk of thrombosis increases with: 1). increasing titres of anticardiolipin antibodies (aCL) after adjustment for other cardiovascular risk factors and 2). the number of aPL detected. In a cross-sectional study, blood was collected from clinics in two teaching hospitals. The study included 208 individuals suspected of having an aPL and 208 age- and sex-matched controls having blood drawn for a complete blood count. Clinical variables included history of previous arterial (ATE) or venous (VTE) thrombotic events, traditional risk factors for cardiovascular disease, and systemic lupus erythematosus (SLE). Laboratory variables included IgG/IgM aCL, lupus anticoagulant, and IgG/IgM anti-beta2-glycoprotein I. Mean age was 46.5 years and 83% were female. Seventy-five of the 416 participants had >or= 1 aPL, and 69 had confirmed >or= 1 ATE or VTE. Family history was positive in 48% of participants, smoking in 28%, hypertension in 16%, diabetes in 6%, and SLE in 20%. A 10-unit increase in aCL IgG titre was associated with an odds ratio (OR) [95% CI] of 1.07 [1.01-1.13] for ATE and 1.06 [1.02-1.11] for VTE. The odds of a previous thrombosis increased with each additional aPL detected: 1.5 [0.93-2.3] for ATE and 1.7 [1.1-2.5] for VTE. These results indicate that increased titres of aCL and multiple aPL were associated with an increased risk of a previous thrombotic event.

Adult↗
PubMed2003

Adherence to ophthalmologic monitoring for antimalarial toxicity in a lupus cohort.

OBJECTIVE: Antimalarial agents (hydroxychloroquine and chloroquine) are important in the treatment of various rheumatic diseases, including systemic lupus erythematosus (SLE). Although these agents may lead to ocular complications, little is known about adherence to policies for ophthalmologic monitoring. We investigated adherence to the 1996 American College of Rheumatology (ACR) guidelines (recommending yearly ophthalmologic assessments) at our clinic, and determined the factors associated with nonadherence. METHODS: Chart review of the Montreal General Hospital lupus clinic cohort. RESULTS: Of 195 subjects with at least one full year of antimalarial exposure during 1996-2001, 5 refused participation and data on ophthalmology monitoring was incomplete for 42. Of the remaining 148 patients, 47 (32%) had missed at least one annual ophthalmology assessment (were nonadherent) during the interval; almost half of these had missed </= 2 assessments. Nonadherence was present in 50% of the 52 patients who had been taking an antimalarial agent for </= 5 years. In adjusted logistic regression models, cumulative damage (measured by the Systemic Lupus International Collaborating Clinics/ACR Damage Index) and antimalarial exposure </= 5 years were predictive of nonadherence. Adjusted estimates indicated a 1.2-fold increase (95% CI 1.0, 1.5) in the odds of nonadherence for every point increase in the total Damage Index score. The adjusted OR for individuals exposed to an antimalarial for </= 5 years was 5.2 (95% CI 2.1, 13.8). CONCLUSION: Our results indicate incomplete adherence to ACR guidelines at our center. Because patients with higher Damage Index scores were more likely to have missed ophthalmology appointments, even after adjusting for pertinent covariates, it suggests that sicker patients may be more at risk of nonadherence. The association of nonadherence with duration of antimalarial exposure, while not surprising, is still an important reminder that adherence to ophthalmologic monitoring may decrease as risk for retinal toxicity is increasing.

Adult↗
PubMed2002

Quality of life after acute myocardial infarction among patients treated at sites with and without on-site availability of angiography.

BACKGROUND: Previous studies have compared the treatment and outcome of patients with acute myocardial infarction (AMI) admitted at sites with and without availability of angiography. Although mortality rates do not differ, it is unknown if quality of life (QOL) and functional status differ. METHODS: We measured QOL and functional status in patients with AMI treated within Québec at 5 sites with (n = 253) and 5 sites without (n = 334) angiography. RESULTS: At admission, clinical characteristics, complication rates, and baseline measures of QOL and functional status were similar at sites with and without angiography. During hospitalization, patients treated at sites with angiography were more likely to undergo an invasive cardiac procedure than patients admitted at sites without angiography (angiography, 63% vs 26%; percutaneous transluminal coronary angioplasty, 33% vs 13%; and coronary artery bypass graft, 12% vs 5%). At 30 days and 6 months after AMI, QOL was slightly superior at sites with angiography, but by 1 year, most measures of QOL were back to baseline at both types of sites and were similar between the 2 groups. At 6 months, most standard health-related QOL components were similar; only physical and emotional role limitations were higher at sites with angiography. Return to work occurred earlier (at 30 days, 23% vs 12%), and a lower proportion of patients was readmitted for angina (within 1 year after AMI, 12% vs 18%) at sites with angiography. CONCLUSIONS: In the early post-AMI period, the QOL of patients admitted at sites with angiography was higher than that of patients admitted at sites without angiography. However, by 1 year, the QOL and functional status of patients was similar in both groups. Differences in QOL were greatest when differences in treatment were greatest, lending support to a positive albeit small association between an early invasive approach to post-AMI care and improved QOL.

Activities of Daily Living↗
PubMed2002

Timing of total joint replacement affects clinical outcomes among patients with osteoarthritis of the hip or knee.

OBJECTIVE: To determine the predictors of outcome in patients with osteoarthritis 2 years after receiving total hip or knee replacement. METHODS: A prospective cohort study of 222 osteoarthritis patients undergoing total hip or knee replacement in Boston and Montreal was done. Their postoperative outcomes at 6 months were previously reported. This followup reports on the outcomes after 2 years among the 165 patients (74%) who remained. The subjects were divided into 2 groups according to the median value of their preoperative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function score. The Short Form 36-item physical function subscale and the WOMAC pain and function subscale scores were collected at baseline and at 3, 6, and 24 months postoperatively. Clinical outcomes were analyzed at 2 years, using descriptive and multiple regression analyses. RESULTS: Improvements in pain and function at 2 years were similar to those observed at 6 months. Those subjects with the worst function and pain at the time of surgery (baseline) had comparatively worse function 2 years after surgery. CONCLUSION: In this comparison, the poor outcomes observed at 6 months following total joint replacement in patients with worse baseline functional status persisted after 2 years. Although there are no validated indications for when a patient should optimally have total joint replacement, these data suggest that timing of surgery may be more important than previously realized and, specifically, that performing surgery earlier in the course of functional decline may be associated with better outcome.

Aged↗
PubMed2002

Predicting which patients can undergo upper endoscopy comfortably without conscious sedation.

BACKGROUND: Eliminating conscious sedation for diagnostic endoscopy may be advantageous for patient safety and cost containment. The aim of this study was to identify and validate independent predictors of a comfortable, technically adequate, unsedated diagnostic upper endoscopy in Canadian patients. METHODS: Patients were consecutively enrolled in a prospective fashion. Data collected on an initial cohort of 268 patients included demographics, a validated anxiety questionnaire, use of sedatives/analgesics, upper endoscopy experience, pharyngeal sensitivity, technical adequacy, and patient assessment of comfort after the procedure. The main outcome measure was "satisfactory upper endoscopy," a composite of optimal scores for patient comfort and technical adequacy. Univariate and multivariate analyses were performed to identify the optimal predictive model of a satisfactory unsedated diagnostic upper endoscopy. Once identified, 68 additional patients were enrolled in a similar fashion from an independent prospective sample for purposes of outcome validation. Multivariate analysis was then repeated with the total cohort (N = 336). These results were then compared for concordance with those obtained from the initial cohort. RESULTS: Among the initial 268 patients (54.3% women; mean age 51 +/- 17 years), 49% were anxious, 15% regularly used sedatives and analgesics, 28% experienced increased pharyngeal sensitivity, and 41% had previously undergone upper endoscopy. Endoscopy was completed in 94.7% of patients without sedation and was technically adequate in 97%, and 80.1% were willing to repeat the procedure under similar conditions. Satisfactory upper endoscopy was achieved in only 59% of the initial cohort. The only independent and significant predictors of a satisfactory upper endoscopy were advancing age (OR 1.2: 95% CI [1.1, 1.4]) and decreased pharyngeal sensitivity (OR 0.5: 95% CI [0.27, 0.93]). Concordance of results were noted after validation with the second cohort. Satisfactory endoscopy was achieved in only 59.5% of the total cohort (n = 336); only 61% reported a comfortable procedural experience. CONCLUSIONS: The proportion of patients who can comfortably undergo technically adequate unsedated upper endoscopy is modest. Unsedated upper endoscopy is most likely to be successful under these procedural conditions in patients of advancing age with decreased pharyngeal sensitivity. The generalizability of these findings to an American population requires further study and may assist in identifying a subgroup of patients in whom it is cost-effective to perform upper endoscopy comfortably without sedation.

Adult↗
PubMed2002

Field triage of trauma patients: improving on the Prehospital Index.

The purpose of the present study was to evaluate the predictive ability of the Prehospital Index (PHI) in identifying injury severity and to develop a trauma triage scale that incorporates, along with the PHI, a subset of time independent variables to improve the predictive ability of the PHI-based triage instrument. This study included 1,291 trauma patients treated in Montreal, Canada. The developed trauma triage protocol was based on logistic regression analysis, in which the model that predicts the data best was selected by using Bayesian information criterion. The selected regression model included the variables age, body region injured, mechanism of injury, comorbidity, and PHI. This algorithm was a substantial improvement in detecting major versus non-major injuries (major injury defined based on death, intensive care unit admission, and surgery intervention) over the PHI alone (area under the receiver operating characteristic curve: 0.76 v 0.66, P <.05). Considering time independent variables could lead to better injury triage decisions.

Adolescent↗
PubMed2002

Antibiotics against Chlamydia pneumoniae and prognosis after acute myocardial infarction.

BACKGROUND: There is mounting pathologic and immunologic evidence that Chlamydia pneumoniae plays a role in the atherogenic pathway. However, very few clinical studies have supported these findings. METHODS: Using the administrative data of all patients > or =65 years of age who had an acute myocardial infarction (AMI) in Quebec between 1991 and 1995 (n = 26,195), we studied the relationship between the intake of antichlamydial antibiotics and post-AMI prognosis. Three groups were compared: patients exposed to (1) antichlamydial antibiotics, (2) sulfa-derivative antibiotics, to which C pneumoniae is not sensitive, and (3) neither of the above classes of antibiotics. Two periods of antibiotic exposure were explored: (1) during the first 3 months after AMI and (2) during the 6 months before AMI. RESULTS: Patients in the 3 exposure groups were similar except for a slightly lower proportion of men in the sulfa-derivative antibiotics group. Among all patients who were exposed during the 3 months after AMI and who survived at least 3 months, the 1-year mortality rate was similar across the 3 groups (10.1%, 11.1%, and 10.4% for the antichlamydial, sulfa-derivative, and nonexposed group, respectively) but favored the antichlamydial group at 2 years (15.9%, 23.0%, and 20.0%). In adjusted survival analysis, patients in the sulfa-derivative and nonexposed groups were slightly more likely to die than patients in the antichlamydial group (relative risk [RR], 1.38; 95% confidence interval [CI], 1.04 to 1.82 and 1.29; 95% CI, 1.05 to 1.59, respectively). Among individuals treated during the 6 months before AMI, the adjusted risk of dying was similar in the sulfa-derivative and nonexposed groups compared with the antichlamydial group (RR 1.03, 95% CI 0.90 to 1.18 and 1.08, 95% CI 0.99 to 1.19, respectively). CONCLUSIONS: Exposure to antichlamydial antibiotics during the 3 months after AMI is associated with a small survival benefit, whereas exposure during the 6 months before AMI does not affect survival.

4-Quinolones↗
PubMed2002

Effects of hospital volume on long-term outcomes after percutaneous transluminal coronary angioplasty after acute myocardial infarction.

BACKGROUND: Volume of procedures has been associated with short-term outcome after percutaneous transluminal coronary angioplasty. However, the effect of hospital procedural volume on long-term outcome after PTCA is unknown. METHODS AND RESULTS: We analyzed the physician claims and discharge data of 6635 patients who underwent PTCA after acute myocardial infarction (AMI) between 1991 and 1995 in the province of Quebec, Canada. For each administrative year, hospitals in which PTCA was performed were classified into 3 groups: low-volume, <200 procedures per year; medium-volume, 200 to 399 procedures per year; and high-volume, > or =400 procedures per year. Compared with patients in medium-volume and high-volume hospitals, patients in low-volume hospitals were older, had more recent AMI, and were less likely to have been transferred for PTCA. After adjustment for baseline differences, patients in the low-volume and medium-volume groups were more likely to undergo CABG within 6 months compared with patients in the high-volume group (odds ratio [OR] 2.1, 95% CI 1.3-3.3, and OR 1.5, 95% CI 1.2-1.9, respectively). In contrast, patients in the low-volume and medium-volume groups were less likely than patients in the high-volume group to undergo repeat PTCA within 6 months (OR 0.37, 95% CI 0.24-0.58, and OR 0.8, 95% CI 0.70-0.92, respectively). At 6 months, adjusted rates of repeat revascularization, recurrent AMI, or death did not differ between the 3 groups. CONCLUSION: Overall adverse event rates at 6 months after PTCA do not differ between hospital volume groups. The higher rate of CABG in low-volume hospitals and the higher rate of repeat PTCA in high-volume hospitals may represent different physician preferences for the treatment of failed PTCA rather than higher complication rates.

Age Factors↗
PubMed2002

Multiple imputation to account for missing data in a survey: estimating the prevalence of osteoporosis.

BACKGROUND: Nonresponse bias is a concern in any epidemiologic survey in which a subset of selected individuals declines to participate. METHODS: We reviewed multiple imputation, a widely applicable and easy to implement Bayesian methodology to adjust for nonresponse bias. To illustrate the method, we used data from the Canadian Multicentre Osteoporosis Study, a large cohort study of 9423 randomly selected Canadians, designed in part to estimate the prevalence of osteoporosis. Although subjects were randomly selected, only 42% of individuals who were contacted agreed to participate fully in the study. The study design included a brief questionnaire for those invitees who declined further participation in order to collect information on the major risk factors for osteoporosis. These risk factors (which included age, sex, previous fractures, family history of osteoporosis, and current smoking status) were then used to estimate the missing osteoporosis status for nonparticipants using multiple imputation. Both ignorable and nonignorable imputation models are considered. RESULTS: Our results suggest that selection bias in the study is of concern, but only slightly, in very elderly (age 80+ years), both women and men. CONCLUSIONS: Epidemiologists should consider using multiple imputation more often than is current practice.

Aged↗
PubMed2002

Counterbalancing patient demands with evidence: results from a pan-Canadian randomized clinical trial of brief supportive-expressive group psychotherapy for women with systemic lupus erythematosus.

OBJECTIVE: To evaluate the effect of Brief Supportive-Expressive Group Psychotherapy as an adjunct to standard medical care in reducing psychological distress, medical symptoms, and health care costs and improving quality of life in women with systemic lupus erythematosus (SLE). METHODS: A randomized clinical trial was conducted with 133 SLE female patients from 9 clinics across Canada. Clinical and psychosocial measures were taken at baseline, posttreatment, and 6 and 12 months posttreatment. Outcomes assessed were psychological distress, quality of life, disease activity, health service utilization, and diminished productivity. RESULTS: Intention-to-treat analyses revealed that there were no clinically important group differences on any of the outcome measures. CONCLUSION: Although both groups improved over time on several measures (e.g., decreases in psychological distress, stress, and emotion-oriented coping), these changes could not be attributed to the psychotherapeutic intervention. Thus, evidence does not support the referral of these patients to this type of intervention.

Adaptation, Psychological↗
PubMed2002

Cost-minimization analysis of genetic testing versus clinical screening of at-risk relatives for familial adenomatous polyposis.

OBJECTIVE: Familial adenomatous polyposis (FAP) is a well-known hereditary colorectal cancer-predisposing syndrome. Genetic testing for colorectal cancer risk is now part of standard medical practice, but very little is known about the economic impact of this technology. The aim of this study was to assess, from a healthcare system perspective, the direct costs of two strategies for screening at-risk relatives of FAP patients: clinical screening versus genetic testing for FAP. METHODS: A systematic review of the literature was carried out. Additional information was gathered from experts in research and clinical laboratories and in hospital departments. A decision tree was constructed to compare per-person and per-family costs of the two strategies for screening at-risk relatives of FAP patients. Sensitivity analysis was performed to assess the stability of the model across the full range of plausible values for all key parameters. RESULTS: According to the decision analysis, with FAP screening starting at puberty, the average screening costs are $3,181 and $2,259 (Canadian dollars), respectively, for the clinical screening and the genetic testing strategies. Genetic screening is cost saving up to a first screening age of 36. Sensitivity analysis shows that the results of the baseline analysis hold across a variety of assumptions concerning the parameter values. CONCLUSIONS: The genetic testing strategy is cost saving relative to the clinical screening alternative. Apart from its lower costs, it is associated with many other benefits. Accordingly, under predefined conditions, predictive genetic testing seems to be the optimal screening strategy for FAP.

Adenomatous Polyposis Coli↗
PubMed2002

Use of complementary and alternative therapies by patients self-reporting arthritis or rheumatism: results from a nationwide canadian survey.

OBJECTIVE: Arthritis or rheumatism (A/R) often leads patients to experiment with complementary and alternative medicine (CAM); we investigated the factors associated with use of CAM. METHODS: The source of the data is the cross sectional household component of the 1996-97 National Population Health Survey of the health status and behaviors of Canadians. The survey sample is based on 66,000 persons aged 20 years and older, representing 21 million adults. Cross tabulations were used to estimate the percentage of adults with A/R who used CAM. Multivariate logistic regression was used to identify those characteristics associated with the use of CAM in the year preceding the survey. RESULTS: In 1996-97, among the 3.3 million Canadian adults aged 20 years or older who self-reported arthritis, 22% utilized CAM in the past year. CAM users tended to be younger and with higher education and household income. They reported more pain, consumed more analgesics, and tended to be more depressed. The coexistence of back or bowel disorders, cancer, sinusitis, or food allergies with arthritis was also related to CAM use. Moreover, CAM users also used more traditional health resources. CONCLUSION: Our results indicate that patients with A/R consulting CAM providers self-report more intense symptoms than nonusers and often have other chronic conditions. They do not seem to reject the traditional health care system, but supplement it with CAM, possibly to fulfill needs insufficiently satisfied by traditional health care providers.

Adult↗
PubMed2002

Prevalence of factors influencing cancer risk in women with lupus: social habits, reproductive issues, and obesity.

OBJECTIVE: There is mounting evidence that hematological malignancies are increased in systemic lupus erythematosus (SLE), and the risk of certain solid tumors may also be increased. The pathogenesis may be different for the 2 processes: risk of hematological malignancies in SLE may be due to chronic lymphocyte stimulation, while risk of solid tumors may be influenced by factors such as obesity and reproductive habits. We aimed to determine prevalence in a lupus cohort of selected factors that influence the risk of cancer, and to compare this prevalence to that of the general population. METHODS: Subjects were women followed in the Montreal General Hospital Lupus Clinic. We administered a postal survey of factors known to be associated with lung and aerodigestive cancers (smoking, alcohol use) as well as factors associated with breast and gynecologic cancers (nulliparity, use of oral contraceptives, and hormone replacement therapy). For patients who had died or been lost to followup, data were abstracted from clinic records. Information about nonsteroidal antiinflammatory drug (NSAID) use (a potentially protective factor for colorectal cancer) was also collected. Obesity prevalence was established from the clinic database. Comparison figures were obtained from the 1996-1997 National Population Health Survey data for Quebec women and age adjusted, where possible. RESULTS: Compared to the general population, the lupus population had lower prevalence of current use of oral contraceptives, and greater prevalence of obesity and nulliparity. The average number of pack-years among smokers was also greater in the lupus cohort. CONCLUSION: Solid cancer incidence in SLE may be influenced by established cancer risk factors such as smoking, obesity, and reproductive history.

Adult↗
PubMedDate not supplied

A hierarchical Bayesian meta-analysis of randomised clinical trials of drug-eluting stents.

BACKGROUND: Drug-eluting stents (DES) are associated with lower restenosis rates than bare-metal stents (BMS), but the benefits and safety of the new devices have not been systematically quantified across different trials. We undertook a meta-analysis of randomised trials comparing BMS and stents eluting sirolimus or paclitaxel. METHODS: A systematic literature search aimed to identify all randomised clinical trials with 6-12 months of clinical follow-up. Results were pooled by a hierarchical Bayesian random-effects model with prespecified stratification for drug and the presence of carrier polymer. The primary outcomes examined were rates of death, myocardial infarction, target-lesion revascularisation, major adverse cardiac events (death, myocardial infarction, and target-vessel revascularisation), and angiographic restenosis. FINDINGS: We identified 11 eligible trials involving 5103 patients. The pooled mortality rates were low for both DES and BMS with no evidence of any difference between them (odds ratio 1.11 [95% credible interval 0.61-2.06]). Pooled rates of myocardial infarction showed no between-group difference (0.92 [0.65-1.25]). The rate of major adverse cardiac events was 7.8% with DES and 16.4% with BMS (0.42 [0.32-0.53]), and the angiographic restenosis rates were also lower for DES (8.9% vs 29.3%; 0.18 [0.06-0.40]). The pooled rates of major adverse cardiac events for each DES type and the respective BMS were: for sirolimus, 6.8% versus 21.0% (0.28 [0.17-0.41]); for polymer-based paclitaxel 8.7% versus 16.7% (0.47 [0.25-0.71]); and for non-polymer-based paclitaxel 7.7% versus 9.5% (0.64 [0.42-1.00]). We did not observe higher rates of edge restenosis, stent thrombosis, or late incomplete stent apposition with DES, although the credible intervals were wide. INTERPRETATION: Sirolimus-eluting and polymeric paclitaxel-eluting stents are effective at decreasing rates of angiographic restenosis and major adverse cardiac events compared with BMS. However, there is no evidence that they affect mortality or myocardial-infarction rates. They also appear to be safe in the short to medium term, although definitive conclusions are not possible. Larger studies with longer follow-up are needed to define better the role of these new devices.

Angioplasty, Balloon, Coronary↗