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Carl van Walraven

Publications and source records attributed to Carl van Walraven.

36 records · Page 2Linked to original sources
PubMed2003

Prevalence of information gaps in the emergency department and the effect on patient outcomes.

BACKGROUND: Information gaps occur when previously collected information is unavailable to a physician who is currently treating a patient. In this study we measured the prevalence of physician-reported information gaps for patients presenting to an emergency department at a teaching hospital. METHODS: For 1002 visits to the emergency department made by 983 patients, we recorded all information gaps identified by the emergency physician immediately after the patient was assessed. When an information gap was present, the physician was asked to identify the required information, why it was required and how important it was to the patient's care. We reviewed the patient charts to measure severity of illness and to determine whether the patient was referred to the emergency department by a community physician. Multiple linear regression analysis was used to determine whether information gaps were associated with length of stay in the emergency department. RESULTS: At least 1 information gap was identified in 323 (32.2%) of the 1002 visits (95% confidence interval 29.4%-35.2%). Information gaps were associated with severity of illness, being significantly more common in patients who had serious chronic illnesses, those who arrived by ambulance, those who had visited the emergency department or had been in hospital recently, patients in monitored areas in the emergency department and older patients. Information gaps most commonly comprised medical history (58%) and laboratory test results (23.3%) and were felt to be essential to patient care in 47.8% of the cases. The presence of information gaps was not associated with admission to hospital. After adjusting for important confounders, including patient sex, previous hospital admissions, diagnosis and severity of illness, we found that stays in the emergency department were 1.2 hours longer on average for patients with an information gap than for those without one. INTERPRETATION: Information gaps were present in almost one-third of the visits to our emergency department. They were more common in sicker patients and were independently associated with a prolonged stay in the emergency department.

Confidence Intervals↗
PubMed2003

A clinical prediction rule to identify patients with atrial fibrillation and a low risk for stroke while taking aspirin.

BACKGROUND: We sought to derive and internally validate a simple and easily applied clinical prediction rule to identify patients with nonvalvular atrial fibrillation (AF) whose stroke risk while taking aspirin is, irrespective of age, low enough that oral anticoagulation therapy is unnecessary. METHODS: We included 2501 patients with AF treated with aspirin during participation in 6 clinical trials. Patients were randomly divided into derivation and validation sets. Recursive partitioning was used to identify patients in the derivation set whose risk for stroke (ischemic or hemorrhagic) or transient ischemic attack was comparable to that observed in an age- and sex-matched cohort from the Framingham Heart Study. The derived prediction rules were tested on the validation set. RESULTS: Overall, 166 patients (6.6%) had an event during 4688.6 person-years (PYs) of observation for an incident rate of 3.5 events per 100 PYs. Patients in the derivation set classified as low risk (no previous stroke or transient ischemic attack, no treated hypertension or systolic blood pressure equal to or exceeding 140 mm Hg, no symptomatic coronary artery disease, and no diabetes) experienced 1.0 events per 100 PYs, compared with an age- and sex-matched rate of 1.2 events per 100 PYs. In the validation set, low-risk patients experienced 1.1 events per 100 PYs (expected rate of 1.2 events per 100 PYs). Low-risk patients made up 24% of the cohort and 16% of patients older than 75 years. Low-risk patients who were randomized to therapeutic oral anticoagulation therapy experienced 1.5 events per 100 PYs. CONCLUSION: Irrespective of age, patients with AF and none of these 4 clinical features and who take aspirin have stroke rates comparable to those of age-matched community cohorts and would not benefit substantially from anticoagulation.

Aspirin↗
PubMed2003

Oral anticoagulants vs. aspirin for stroke prevention in patients with non-valvular atrial fibrillation: the verdict is in.

There is an increased risk of stroke and other cardiovascular events in patients with atrial fibrillation (AF). Three meta-analyses of randomized clinical trials (RCTs) comparing oral anticoagulants (OAC) with aspirin (ASA) arrived at different conclusions regarding the relative efficacy of these agents to prevent ischemic stroke in AF patients. This article summarizes a recently published individual patient meta-analysis of all published RCTs comparing OAC and ASA in AF. In total, 4052 patients randomized to OAC or ASA were similar regarding important prognostic factors. Patients receiving OAC had a significantly lower risk of any stroke (hazard ratio [HR] 0.54 [95% CI 0.43-0.71]), ischemic stroke (HR 0.48 [0.37-0.63]), or cardiovascular events (HR 0.71 [0.59-0.85]). Patients receiving OAC were more likely to experience major bleeding (HR 1.71 [1.21-2.41]). The benefit of OAC was most prominent in patients at a high risk of stroke and other cardiovascular events, such as patients with hypertension, diabetes, or previous cerebrovascular events. Overall, OAC improves outcomes for cardiovascular events in AF patients but modestly increases the absolute risk of major bleeding. Since high-risk AF patients appear to benefit most from OAC, determining stroke risk in AF patients is very important.

Administration, Oral↗
PubMed2003

The effect of hospital occupancy on emergency department length of stay and patient disposition.

UNLABELLED: Emergency department (ED) overcrowding is a common problem. Despite a widespread belief that low hospital bed availability contributes to ED overcrowding, there are few data demonstrating this effect. OBJECTIVES: To identify the effect of hospital occupancy on ED length of stay for admitted patients and patient disposition. METHODS: This was an observational study design using administrative data at a 500-bed acute care teaching hospital. All patients presenting to the ED between April 1993 and June 1999 were included in the study. The predictor variable was daily hospital occupancy. Outcome measures included daily ED length of stay for admitted patients, daily consultation rate, and daily admission rate. The models controlled for the average daily age of ED patients and the average daily "arrival density" index, which adjusts for patient volume and clustering of patient arrivals. RESULTS: The average hospital occupancy was 89.7%. On average 155 patients visited the ED daily; 21% were referred to hospital physicians and 19% were admitted. The median ED length of stay for admitted patients was 5 hours 54 minutes (interquartile range 5 hr 12 min to 6 hr 42 min). Daily ED length of stay for admitted patients increased 18 minutes (95% CI = 12 to 24) when there was an absolute increase in occupancy of 10%. The ED length of stay appeared to increase extensively when hospital occupancy exceeded a threshold of 90%. Consultation and admission rates were not influenced by hospital occupancy. CONCLUSIONS: Increased hospital occupancy is strongly associated with ED length of stay for admitted patients. Increasing hospital bed availability might reduce ED overcrowding.

Bed Occupancy↗
PubMed2003

Population-based study of repeat laboratory testing.

BACKGROUND: Test repetition could be a readily modifiable component of laboratory utilization. Laboratory test repetition has not been rigorously studied at a population-based level. Our objective was to determine the prevalence of, and charges associated with, repetition of eight common laboratory tests. METHODS: We performed a cross-sectional study using high-quality, population-based clinical databases that included adults in Eastern Ontario, Canada, between September 1999 and September 2000 for incidence of repeating eight common laboratory tests (hemoglobin, sodium, creatinine, thyrotropin, total cholesterol, HDL-cholesterol, ferritin, and hemoglobin A(1C)). Tests were classified as potentially redundant if repeated within the test's baseline testing interval. For creatinine, sodium, and hemoglobin, only tests repeated in the community were considered. For a sensitivity analysis, we varied the repeat interval by 25%, excluded tests repeated by different physicians, and excluded repeats of normal tests. RESULTS: Almost 4 million tests were conducted during the study year. Most tests (76%) were conducted on patients in the community. More than one-half of all people in the population had at least one laboratory test, with an overall testing rate of 367 tests per 100 people per year. Repeat testing within 1 month accounted for 30% of all utilization (109 repeat tests per 100 people per year). Repetition was more common in hospitalized patients, varied extensively among tests, and was concentrated in a limited number of people. For the eight tests included in the study, charges of potentially redundant repetition in adults totaled between 13.9 and 35.9 million dollars (Canadian) annually. CONCLUSIONS: Laboratory test repetition is very common, makes up a significant component of overall test utilization, and is costly.

Adolescent↗
PubMed2003

Did publication of a clinical practice guideline recommendation to screen for type 2 diabetes in women with gestational diabetes change practice?

OBJECTIVE: To determine whether women with previous gestational diabetes mellitus (GDM) were screened postpartum for type 2 diabetes according to the Canadian Diabetes Association (CDA) guidelines. RESEARCH DESIGN AND METHODS: The 1998 CDA guidelines recommend that all women diagnosed with GDM be screened postpartum for type 2 diabetes using a 2-h 75-g oral glucose tolerance test (OGTT). The impact of and compliance with this expert opinion-based recommendation is unknown. All women who delivered at the Ottawa Hospital in 1997 (pre-guideline) and 2000 (post-guideline) with confirmed GDM were identified. Using population-based administrative databases, we determined the proportion of these women who had an OGTT, serum glucose test, or glycated hemoglobin (GHb) test in the first postpartum year. Women who had not undergone any blood work were excluded. RESULTS: There were 131 women in 1997 and 123 women in 2000 with confirmed GDM. Of these, only 69 women in 1997 and 52 women in 2000 had blood work recorded in the database. None of these women had an OGTT performed in either period. We found a significant increase in the measurement of serum glucose (50 women pre-guideline [72.1%], 48 women post-guideline [92.3%], P < 0.05) and GHb (8 women pre-guideline [11.6%], 20 women post-guideline [38.5%], P < 0.01). CONCLUSIONS: In our region, physicians are not following the CDA recommendations to screen women with GDM postpartum with an OGTT. However, we did find a significant increase in the measurement of serum glucose and GHb. Publication of expert opinion-based guidelines did not change the postpartum use of an OGTT in these women but may have increased the use of less reliable screening tests for type 2 diabetes.

Blood Glucose↗
PubMed2002

Oral anticoagulants vs aspirin in nonvalvular atrial fibrillation: an individual patient meta-analysis.

CONTEXT: Patients with nonvalvular atrial fibrillation (AF) have an increased risk of stroke and other vascular events. OBJECTIVE: To compare the risk of vascular and bleeding events in patients with nonvalvular AF treated with vitamin K -inhibiting oral anticoagulants or acetylsalicylic acid (aspirin). DESIGN: Pooled analysis of patient-level data from 6 published, randomized clinical trials. PATIENTS: A total of 4052 patients with AF randomly assigned to receive therapeutic doses of oral anticoagulant or aspirin with or without low-dose oral anticoagulants. MAIN OUTCOME MEASURES: Ischemic and hemorrhagic stroke, other cardiovascular events, all-cause death, and major bleeding events. Person-year incidence rates were calculated to provide crude comparisons. Relative efficacy was assessed using proportional hazards modeling stratified by study. The variation of the oral anticoagulant's relative effect by pertinent patient factors was explored with interaction terms. All analyses were conducted using the intention-to-treat principle. RESULTS: Patients receiving oral anticoagulant and aspirin were balanced for important prognostic factors. There was no significant heterogeneity between trials in the relative efficacy of oral anticoagulant vs aspirin for any outcome. Patients receiving oral anticoagulant were significantly less likely to experience any stroke (2.4 vs 4.5 events per 100 patient-years; hazard ratio [HR], 0.55; 95% confidence interval [CI], 0.43-0.71), ischemic stroke (HR, 0.48; 95% CI, 0.37-0.63), or cardiovascular events (HR, 0.71; 95% CI, 0.59-0.85) but were more likely to experience major bleeding (2.2 vs 1.3 events per 100 patient-years; HR, 1.71; 95% CI, 1.21-2.41). The reduction in ischemic stroke risk was similar in patients with paroxysmal AF (1.5 vs 4.7 events per 100 patient-years; HR, 0.32; 95% CI, 0.16-0.61; P<.001). Treating 1000 patients with AF for 1 year with oral anticoagulant rather than aspirin would prevent 23 ischemic strokes while causing 9 additional major bleeds. Overall all-cause survival did not differ but appeared to improve for oral anticoagulant patients 3 years after therapy was started. CONCLUSIONS: Compared with aspirin, oral anticoagulant significantly decreases the risk of all strokes, ischemic strokes, and cardiovascular events for patients with nonvalvular chronic or paroxysmal AF but modestly increases the absolute risk of major bleeding. The balance of benefits and risks varies by patient subgroup.

Administration, Oral↗
PubMed2002

Restricted driver licensing for medical impairments: does it work?

BACKGROUND: Medical conditions may adversely affect driving ability. Many North American jurisdictions provide restricted driving licences that permit people with certain medical conditions to drive under limited conditions, but the effectiveness of such programs has not yet been determined. The objectives of this study were to evaluate the rates of crashes and traffic violations among drivers with a restricted licence, compared with the rates in the general driving population, and to compare the crash and traffic violation rates before and after driving restrictions were imposed. METHODS: We retrospectively analyzed a cohort of all licensed Saskatchewan drivers registered from Jan. 1, 1992, to Apr. 19, 1999. The cohort was divided into those with a restricted licence and those with an unrestricted general licence. We used multivariate Poisson regression to calculate incidence rate ratios (IRRs) for at-fault crashes and traffic violations, adjusting for age, sex and residence (urban v. rural). We used interventional time series analysis to compare rates of crashes and traffic violations before and after the imposition of driving restrictions. RESULTS: Of the 703,758 drivers in the study, 23,185 (3.3%) had a restricted licence. Restricted licence holders had a higher crash rate than drivers without restrictions (adjusted IRR 1.13, 95% confidence interval [CI] 1.11-1.17). However, this rate was lower than that among male drivers (adjusted IRR 2.01, 95% CI 1.99-2.02) and urban drivers (adjusted IRR 1.38, 95% CI 1.37-1.39). Drivers with restricted licences had a lower traffic violation rate than those without restrictions (adjusted IRR 0.93, 95% CI 0.91-0.95). At-fault crash rates decreased by 12.8% (95% CI 2.4%-23.2%) and adjusted traffic violation rates decreased by 10.0% (95% CI 4.4%-15.7%) after restrictions were imposed. During the study period, licence restrictions likely averted up to 816 crashes and 751 traffic violations. INTERPRETATION: Province-wide population data suggest that a restricted licensing program appears to provide a significant decrease in the rates of crashes and traffic violations.

Accidents, Traffic↗
PubMed2002

Renin-angiotensin system blockade and the risk of hyperkalemia in chronic hemodialysis patients.

BACKGROUND: Blockade of the renin-angiotensin system by angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers can cause hyperkalemia in patients with chronic renal insufficiency who are not on dialysis, but the risk of hyperkalemia in hemodialysis patients is unknown. SUBJECTS AND METHODS: We conducted a prospective study of 251 adult hemodialysis patients to determine if renin-angiotensin system blockade was associated with hyperkalemia, defined as a predialysis serum potassium concentration of 5.5 mmol/L or higher. Medication use was determined by chart review and patient interview. Predialysis serum potassium concentration was measured monthly. RESULTS: There were 367 episodes of hyperkalemia during 1877 person-months of follow-up. After adjustment for potential confounding variables and for clustering of episodes by patient, use of an ACE inhibitor or an angiotensin receptor blocker was associated with a significantly higher risk of hyperkalemia (odds ratio [OR] = 2.2; 95% confidence interval [CI]: 1.4 to 3.4). The increased risk of hyperkalemia with renin-angiotensin system blockade was seen in anuric dialysis patients (OR = 2.3; 95% CI: 1.3 to 4.2), as well as those with residual renal function (OR = 2.1; 95% CI: 1.0 to 4.1). CONCLUSION: The use of ACE inhibitors or angiotensin receptor blockers is independently associated with an increased risk of developing hyperkalemia in chronic hemodialysis patients. The serum potassium concentration should be closely monitored when these medications are prescribed for hemodialysis patients.

Aged↗
PubMed2002

The effect of participation in a weight loss programme on short-term health resource utilization.

Obese people consume significantly greater amounts of health resources. This study set out to determine if health resource utilization by obese people decreases after losing weight in a comprehensive medically supervised weight management programme. Four hundred and fifty-six patients enrolled in a single-centred, multifaceted weight loss programme in a universal health care system were studied. Patient information was anonymously linked with administrative databases to measure health resource utilization for 1 year before and after the programme. Mean body mass index (BMI) decreased by more than 15%. The mean annual physician visits (pre = 9.6, post = 9.4) did not change significantly after the programme. However, patients saw a significantly fewer number of different physicians per year following the programme (pre = 4.5, post = 3.9; P < 0.001). Mean annual number of emergency visits (pre = 0.2; post = 0.2) and hospital admissions (pre = 0.05; post = 0.08) did not change. Neither baseline BMI, nor its change during the programme, influenced changes in health resource utilization. Our study suggests that weight loss in a supervised weight management programme does not necessarily decrease short-term health resource utilization. Further study is required to determine if patients who maintain their weight loss experience a decrease in health utilization.

Adult↗
PubMed2002

The effect of a hepatitis serology testing algorithm on laboratory utilization.

RATIONALE, AIMS AND OBJECTIVES: Laboratory testing algorithms use patient and laboratory data to identify the optimal testing strategy for patients. Studies have shown that these algorithms can decrease test utilization. Since over-utilization of hepatitis serological tests was suspected, a hepatitis serology testing algorithm was initiated in Ontario, Canada. This study determined the effects of this algorithm on utilization. METHODS: Population-based retrospective observational study, involving all patients having viral hepatitis serological testing at private laboratories in Ontario, Canada, between July 1991 and December 1999. Prior to the testing algorithm, physicians listed the required specific antigens and antibodies on the test requisition form. In September 1996, the form was changed so that physicians identified the clinical indication--acute hepatitis, chronic hepatitis or immune status testing--for hepatitis serology testing. Therefore, the algorithm introduced a new 'tick-box' to the requisition form. Tests conducted by the laboratory depended upon which indication was chosen. Rates for hepatitis serological testing were calculated using population-based claims data. RESULTS: Time-series modelling showed that the testing algorithm was associated with a slight but significant increase in the use of hepatitis serology (P < 0.05). The algorithm was associated with an increase of 30 serological tests per 100,000 population per month. CONCLUSIONS: Introducing a testing algorithm for hepatic viral serology in Ontario did not significantly decrease hepatitis serology utilization and may be associated with a slight, but significant, increase in serology utilization rates.

Algorithms↗
PubMed2002

Effect of discharge summary availability during post-discharge visits on hospital readmission.

OBJECTIVE: To determine if the delivery of hospital discharge summaries to follow-up physicians decreases the risk of hospital readmission. SUBJECTS: Eight hundred eighty-eight patients discharged from a single hospital following treatment for an acute medical illness. SETTING: Teaching hospital in a universal health-care system. DESIGN: We determined the date that each patient's discharge summary was printed and the physicians to whom it was sent. Summary receipt was confirmed by survey and phoning each physician's office. Each patient's hospital chart was reviewed to determine their acute and chronic medical conditions as well as their course in hospital. Using population-based administrative databases, all post-hospitalization visits were identified. For each of these visits, we determined whether the summary was available. MAIN OUTCOME MEASURES: Time to nonelective hospital readmission during 3 months following discharge. RESULTS: The discharge summary was available for only 568 of 4,639 outpatient visits (12.2%). Overall, 240 (27.0%) of patients were urgently readmitted to hospital. After adjusting for significant patient and hospitalization factors, we found a trend toward a decreased risk of readmission for patients who were seen in follow-up by a physician who had received a summary (relative risk 0.74, 95% confidence interval 0.50 to 1.11). CONCLUSIONS: The risk of rehospitalization may decrease when patients are assessed following discharge by physicians who have received the discharge summary. Further research is required to determine if better continuity of patient information improves patient outcomes.

Access to Information↗
PubMed2002

How far is the sternal angle from the mid-right atrium?

BACKGROUND: The central venous pressure (CVP) is commonly estimated at the bedside by measuring the height of the jugular venous pressure (JVP) relative to the sternal angle. Determining the CVP from this measure requires that the distance from the sternal angle to the level of the mid-right atrium be known. Classical clinical teaching quotes this distance as 5 cm, invariable between patients, and invariable with changes in the elevation of the patient's head. The validity of these JVP characteristics has been questioned. OBJECTIVES: To measure the distance from the sternal angle to the level of the mid-right atrium (SA-RA) and determine if the SA-RA distance varies with patient position. METHODS: Cross-sectional study conducted at a single-center teaching hospital on ambulatory patients undergoing computed tomography of the chest. RESULTS: One hundred sixty patients were included. The median SA-RA distance with the patient lying supine was 5.4 cm (interquartile range, 4.7 to 6.1). Using geometric calculations to estimate the SA-RA distance when the patient's torso was elevated above the supine position, the median SA-RA distance was calculated to be 8 cm, 9.7 cm, and 9.8 cm at 30, 45, and 60 degrees elevation respectively. The SA-RA distance varied extensively between patients and was independently associated with smoking, age, and antero-posterior chest diameter. CONCLUSIONS: The distance from the sternal angle to the level of the mid-right atrium varies considerably between individuals and with patient position. When using the JVP to calculate the CVP, physicians need to consider specific patient factors and the patient's position.

Aged↗
PubMed2002

Dissemination of discharge summaries. Not reaching follow-up physicians.

OBJECTIVE: To discover how often hospital discharge summaries were available to physicians seeing patients for follow-up visits after hospitalization. DESIGN: Cohort study. SETTING: Teaching hospital in Ottawa, Ont. PARTICIPANTS: We studied 792 patients discharged from an internal medicine service after treatment for acute illness. We determined when and by which physician each patient was seen during the first 6 months after discharge. We also determined the date each patient's discharge summary was printed and the physicians to whom it was sent. We confirmed that summaries were received by means of a survey or by telephoning physicians' offices. Patients were observed for 6 months or until they were readmitted to hospital. MAIN OUTCOME MEASURES: Proportion of follow-up visits to physicians for which discharge summaries were available. RESULTS: During the observation period, patients made 6619 visits (median six per patient, interquartile range [IQR] 2 to 9) to 914 different physicians (median three per patient, IQR 2 to 4). Discharge summaries were available for only 996 (15%) visits. Summaries were available for only 65 initial visits (8.2%); no summaries were available for any visit for 542 (68.4%) patients. Summaries were most commonly unavailable because they were not generated in time for follow-up visits (20.0%) or were not sent to follow-up physicians (50.8%). CONCLUSION: At our institution, discharge summaries often did not get to physicians seeing patients after discharge from hospital.

Aged↗