Biomedical subjects

Rollin Brant

Publications and source records attributed to Rollin Brant.

26 records · Page 2Linked to original sources

PubMed2003

Bias in estimates of confidence intervals for health outcome report cards.

Health researchers commonly use logistic regression when profiling health providers. Data from the patients treated by the providers are used to construct models predicting the expected number of outcomes for providers and the ratio of observed to expected outcomes (O/E ratio) used as a risk-adjusted measure of provider performance. Typically, when calculating the standard deviation (SD) of O/E ratios, only O is treated as a random variable. We used the propagation of errors (Pe) to derive a SD estimate that accounted for variability in O and the estimate of E. Using data previously used to profile Canadian cardiac surgery providers, we compared Pe-SD estimates with typical SD (SDT) estimates. The SDT estimates and confidence intervals were always larger than the Pe estimates, most notably when one or more providers treated a large proportion of the patients. This was confirmed using computer simulations. SDT estimates should be abandoned in favor of more sophisticated estimates.

Bias↗

PubMed2003

The frequency of complications associated with the use of multiple-dose activated charcoal.

STUDY OBJECTIVE: The objective of this study was to determine the frequency of complications associated with the use of multiple-dose activated charcoal. METHODS: The study population was drawn from 8 tertiary care hospitals in 4 North American cities. Medical records of all inpatients between March 1993 and March 1998 with a discharge diagnosis of poisoning (International Classification of Diseases, 9th edition, Clinical Modification codes 960-989.9) were reviewed to select patients who had received multiple-dose activated charcoal (defined as > or =2 doses administered within 12 hours). Medical records of patients who received multiple-dose activated charcoal were reviewed for patient demographics and clinical information regarding the occurrence of pulmonary aspiration, gastrointestinal obstruction, hypernatremia, hypermagnesemia, corneal abrasion, and other complications associated with the use of multiple-dose activated charcoal. RESULTS: We reviewed 6,258 medical records, identifying 878 patients who received multiple-dose activated charcoal. We judged 5 (0.6%; 95% confidence interval [CI] 0.1% to 1.1%) patients to have had clinically significant pulmonary aspiration and none (0%; upper 95% CI 0.3%) to have had gastrointestinal obstruction. None of the patients with pulmonary aspiration died or had residual sequelae recorded. Hypernatremia (peak serum sodium >145 mEq/L [145 mmol/L]) was documented in 53 (6.0%; 95% CI 4.4% to 7.6%) patients, of whom 5 (0.6%; 95% CI 0.1% to 1.1%) had a serum sodium concentration of greater than 155 mEq/L (155 mmol/L). Hypermagnesemia (peak serum magnesium >2.5 mg/dL [1.0 mmol/L]) was documented in 27 (3.1%; 95% CI 2.0% to 4.2%) patients, of whom 3 (0.3%; 95% CI 0.1% to 1.0%) had peak values that were greater than 3.75 mg/dL (1.5 mmol/L). One patient had a corneal abrasion (0.1%; 95% CI 0% to 0.6%). No other complications were identified. CONCLUSION: Clinically significant complications associated with the use of multiple-dose activated charcoal occur infrequently.

Adolescent↗

PubMed2003

Temporal trends in antihypertensive drug prescriptions in Canada before and after introduction of the Canadian Hypertension Education Program.

OBJECTIVE: Poor control of hypertension is a world-wide health issue. In 1999, the Canadian Hypertension Education Program (CHEP) was launched to annually develop and implement evidence-based hypertension guidelines in an effort to improve hypertension control rates. This study was designed to examine temporal trends in antihypertensive drug prescribing and to explore whether drug prescriptions changed after initiation of the new CHEP guideline process. DESIGN AND METHODS: We used longitudinal Canadian dispensing data (from the IMS CompuScript database; IMS Health, Pointe-Claire, Quebec) to examine antihypertensive prescriptions in the 3 years prior to and the 3 years following introduction of the new CHEP process. To control for temporal changes in the incidence of other cardiovascular conditions for which antihypertensive agents may be prescribed for their non-blood pressure-lowering effects (for example, angiotensin-converting enzyme (ACE) inhibitors for heart failure or coronary artery disease), prescription rates for digoxin, loop diuretics, and nitrates were also examined. RESULTS: Prescriptions for all antihypertensive agents increased significantly between 1996 and 2001 [11% for thiazides, 45% for beta-blockers, 68% for ACE inhibitors, 19% for calcium channel blockers, and 4332% for angiotensin receptor blockers (ARBs)]. Loop diuretic prescriptions increased 27%, but prescriptions for digoxin (-19%) and nitrates (-8%) declined over this time frame. Time series analyses demonstrated increases in the prescription growth rate for all four antihypertensive drug classes recommended in CHEP for the period 1999-2001 compared with 1996-1998, which were statistically significantly and of substantial magnitude (absolute annual increase in prescription growth rate of 4.6% (95% confidence interval 3.5-5.9%) for thiazides, 3.0% (1.8-4.2%) for beta-blockers, 8.2% (6.7-9.7%) for ACE inhibitors, and 6.1% (4.4-7.8%) for calcium channel blockers). The growth rate in nitrate prescriptions did not significantly change [1.1% (-0.6 to +3.0%)] and, although the changes in growth rate for loop diuretics [4.7% (3.2-6.3%)] and digoxin [2.1% (0.6-3.5%)] were statistically significant, they were of smaller magnitude than the changes in the four recommended antihypertensive agents. Similar results were observed when analysis was restricted to new prescriptions only. CONCLUSIONS: Prescriptions for all antihypertensive drugs increased substantially in Canada between 1996 and 2001; the rate of increase was significantly greater after 1999 for all four drugs recommended as first-line therapy in the annual CHEP guidelines. This preliminary data is encouraging, but a national survey of blood pressure control is needed to fully evaluate the impact of the new Canadian guideline process.

Antihypertensive Agents↗

PubMed2002

Multiple imputation versus data enhancement for dealing with missing data in observational health care outcome analyses.

The problem of missing data is frequently encountered in observational studies. We compared approaches to dealing with missing data. Three multiple imputation methods were compared with a method of enhancing a clinical database through merging with administrative data. The clinical database used for comparison contained information collected from 6,065 cardiac care patients in 1995 in the province of Alberta, Canada. The effectiveness of the different strategies was evaluated using measures of discrimination and goodness of fit for the 1995 data. The strategies were further evaluated by examining how well the models predicted outcomes in data collected from patients in 1996. In general, the different methods produced similar results, with one of the multiple imputation methods demonstrating a slight advantage. It is concluded that the choice of missing data strategy should be guided by statistical expertise and data resources.

Alberta↗

PubMed2002

Evaluation of satisfaction with midwifery care.

OBJECTIVE: to determine if there were differences in women's satisfaction with maternity care given by doctors and midwives. In addition a simple, six-question, satisfaction questionnaire was to be tested. DESIGN: a randomised controlled trial comparing two models of maternity care. SETTING: a tertiary referral centre in Alberta, Canada. PARTICIPANTS: one hundred and ninety four women with a low-risk pregnancy were randomly assigned to either the midwife care, experimental group (n = 101), or the doctor care, control group (n = 93). INTERVENTIONS: a pilot midwifery programme was introduced into a maternity services delivery system that did not have established midwifery. MEASUREMENTS: women's satisfaction was measured, at two weeks postpartum, with the Labour and Delivery Satisfaction Index (LADSI), general attitudes toward the birth experience, also at two weeks postpartum; with the Attitudes about Labour and Delivery Experience (ADLE) questionnaire. Fluctuations in satisfaction were measured with a Six Simple Questions (SSQ) questionnaire at 36 weeks gestation and 48 hours, two and six weeks postpartum. FINDINGS: women in the midwife group reported significantly greater satisfaction and a more positive attitude toward their childbirth experience than women in the doctor group (p < 0.001). The SSQ demonstrated scores similar to the LADSI. Satisfaction in both groups was lowest at 36 weeks gestation and highest immediately postpartum. KEY CONCLUSIONS: women experiencing low-risk pregnancies were more satisfied with care by midwives than with care provided by doctors. Satisfaction scores were high for both groups and may have been lower for women in the doctor group as a result of disappointment with caregiver assignment as all women had sought midwifery care. The SSQ measures similar dimensions to the LADSI but the agreement is not strong enough to recommend its use as a substitute at this time. IMPLICATIONS FOR PRACTICE: the significantly higher satisfaction of the women with the care provided by the midwives together with better clinical outcomes reported elsewhere suggest that the option of midwifery care should be accessible as an option for all women in Canada. Further research is suggested to determine the usefulness of the SSQ.

Female↗

PubMed2002

Systematic error in the determination of nocturnal blood pressure dipping status by ambulatory blood pressure monitoring.

BACKGROUND: Vertical displacement of the arm relative to the heart causes inverse changes in blood pressure of approximately 0.8 mmHg for every centimetre change in arm position. Therefore a potential confounding issue in assessing diurnal variation in blood pressure during ambulatory blood pressure monitoring (ABPM) is arm position during sleep. An increase in the number of patients with 'excessive' nocturnal dipping (> 20% decrease in night/day blood pressure) was observed following the creation of an instructional videotape in which patients were advised to muffle the noise of the monitor with a pillow at night. This raised the possibility that patients were placing their arm on top of the pillow reducing nocturnal blood pressure readings. DESIGN: Ambulatory blood pressure monitoring data from 184 patients prior to and from 193 patients following specific instructions not to put their arm on top of the pillow was examined. RESULTS: Following the instructions, the percentage of patients with 'excessive' nocturnal dipping in blood pressure decreased (excessive systolic dipping 17.4 versus 8.8%, P = 0.014; excessive diastolic dipping 37 versus 24.4%, P = 0.01). Consistent with an increase in the ratio of nocturnal/day pressures, there was an increase in the percentage of patients with inadequate nocturnal dipping (< 10% decrease in night/day blood pressure; systolic dipping 33.7 versus 45.6%, P = 0.02; diastolic dipping 13.0 versus 31.6%, P < 0.001) CONCLUSION: Instructing patients to avoid resting their arm on a pillow at night has a substantial effect on the classification of nocturnal dipping status. Patients need clear instructions not to place their arm on a pillow at night during blood pressure monitoring.

Arm↗

PubMed2002

Differences in admission rates of children with bronchiolitis by pediatric and general emergency departments.

OBJECTIVE: It is uncertain whether pediatric and general emergency departments have different admitting practices regarding children with bronchiolitis. The objective of this study was to quantify the differences in admission practices between pediatric and general emergency departments of children with bronchiolitis in 1 North American metropolitan area, controlling for various factors such as clinical severity, comorbid conditions, and socioeconomic status. DESIGN: Retrospective cohort review of emergency department visits from April 1992 to March 1997. SETTING: Five emergency departments (1 pediatric and 4 general) serving the Calgary Health Region, which encompasses approximately 850 000 people. PATIENTS: All children residing within the region who visited a regional emergency department and were diagnosed to have bronchiolitis (International Classification of Diseases, Ninth Revision code 466.1, primary or secondary diagnosis). MAIN OUTCOME MEASURE: Population-standardized estimates of admission rates. RESULTS: The medical charts of 3091 children diagnosed to have bronchiolitis during the study period were reviewed. Of this number, 2496 children were evaluated at the pediatric emergency department, and 629 (25%) were admitted. The remaining 595 (19%) were evaluated at the general emergency departments, and 221 (37%) were admitted. Controlling for age, gender, estimated family income based on postal code, medical comorbidity, and clinical severity estimated by presenting respiratory rate and room air oxygen saturation, population-standardized estimates for admission rates at the pediatric and general emergency departments were 24% (standard error: 1%) and 43% (standard error: 2%), respectively. CONCLUSION: Children diagnosed to have bronchiolitis at the Calgary Health Region's pediatric emergency department were about half as likely to be admitted to the hospital as children diagnosed at the region's general emergency departments.

Alberta↗

PubMedDate not supplied

Chelation therapy for ischemic heart disease: a randomized controlled trial.

CONTEXT: Chelation therapy using EDTA is an unproven but widely used alternative therapy for ischemic heart disease. OBJECTIVE: To determine if current EDTA protocols have a favorable impact on exercise ischemia threshold and quality of life measures in patients with stable ischemic heart disease. DESIGN: Double-blind, randomized, placebo-controlled trial conducted between January 1996 and January 2000. SETTING: Participants were recruited from a cohort of cardiac catheterization patients and the practices of cardiologists in Calgary, Alberta. PARTICIPANTS: We screened 3140 patients, performed a qualifying treadmill test in 171, and enrolled 84. Entry criteria included age at least 21 years with coronary artery disease proven by angiography or a documented myocardial infarction and stable angina while receiving optimal medical therapy. The required treadmill test used a gradual ramping protocol and patients had to demonstrate at least 1-mm ST depression. INTERVENTIONS: Patients were randomly assigned to receive infusion with either weight-adjusted (40 mg/kg) EDTA chelation therapy (n = 41) or placebo (n = 43) for 3 hours per treatment, twice weekly for 15 weeks and once per month for an additional 3 months. Patients in both groups took oral multivitamin therapy as well. MAIN OUTCOME MEASURE: Change from baseline to 27-week follow-up in time to ischemia (1-mm ST depression). RESULTS: Thirty-nine patients in each group completed the 27-week protocol. One chelation patient had therapy discontinued for a transient rise in serum creatinine. The mean (SD) baseline exercise time to ischemia was 572 (172) and 589 (176) seconds in the placebo and chelation groups, respectively. The corresponding mean changes in time to ischemia at 27 weeks were 54 seconds (95% confidence interval [CI], 23-84 seconds; P<.001) and 63 seconds (95% CI, 29-95 seconds; P<.001), for a difference of 9 seconds (95% CI, -36 to 53 seconds; P =.69). Exercise capacity and quality of life scores improved by similar degrees in both groups. CONCLUSION: Based on exercise time to ischemia, exercise capacity, and quality of life measurements, there is no evidence to support a beneficial effect of chelation therapy in patients with ischemic heart disease, stable angina, and a positive treadmill test for ischemia.

Aged↗