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Biomedical subjects

Teresa To

Publications and source records attributed to Teresa To.

At least 19 recordsLinked to original sources

Effect of subspecialty training on outcome after pediatric appendectomy.

BACKGROUND/PURPOSE: There have been few studies documenting the effect of subspecialty training on outcomes after appendectomy in children. Some studies have suggested a better outcome in patients managed by pediatric surgeons as compared with general surgeons. METHODS: We studied the effect of subspecialty training on clinical outcome and negative appendectomy rate after pediatric appendectomy. Children less than 19 years in Ontario who underwent appendectomy were identified. Outcomes were compared between pediatric and general surgeons. Subanalyses were conducted for the age groups 0 to 5, 6 to 12, and 13 to 18 years. RESULTS: Over 8 years, 24,019 children underwent appendectomy with a preoperative diagnosis of appendicitis. Of these, 21,027 had appendicitis. General surgeons performed 81.2% of the operations. Negative appendectomy rates were 8.3% and 13.4% (P < .0001) in the pediatric and general surgeon groups, respectively. Children operated on by pediatric surgeons were younger (10.5 +/- 3.6 vs 12.8 +/- 3.8; P < .05), more likely to be perforated (36.6% vs 32.0%; P < .0001), and had a longer postoperative stay (3.8 vs 3.0 days; P < .0001). There was no difference between groups with respect to wound infection or readmission rate when age and perforation status were accounted for. CONCLUSIONS: Pediatric surgeons performed significantly fewer negative appendectomies than general surgeons. Although pediatric surgeons kept their patients longer in the hospital, their patients' wound infection and readmission rates were not different from that of the patients of general surgeons.

Adolescent↗

Occurrence and impact of unanticipated variation in intravenous methotrexate dosing.

BACKGROUND: Studies using direct measurement suggest that the doses of up to 65% of drug infusions are outside industry standards. These preparation-associated errors occur despite routine safety procedures. As of April 5, 2006, the clinical impact of these errors had not been evaluated. OBJECTIVE: To measure the occurrence and associated clinical outcomes of variations in intravenous methotrexate dosing. METHODS: A prospective observational study was performed on 47 methotrexate infusions of 800 mg/m2 that were administered to 19 children with acute lymphoblastic leukemia. Serum methotrexate concentrations were measured at the end of the infusions, which were administered over 24 hours. The total methotrexate dose was determined by direct measurement of the concentration and the volume of each infusion. RESULTS: Dosing errors greater than or equal to 10% occurred in 11 (23%) infusions and ranged from -61% to 55% of the ideal dose. Repeated measures regression analysis found the measured total methotrexate dose was not significantly associated with the serum methotrexate concentration (p = 0.58) or with clinical toxicities. The methotrexate dose administered over the last hours of infusion (p = 0.006) and the serum creatinine level at diagnosis (p = 0.05) were the most significant predictors of the methotrexate concentration. High methotrexate concentrations were significantly associated with increased hepatic aminotransferase levels; however, the degree of elevation was of limited clinical relevance. CONCLUSIONS: While unexpected errors in drug dosing are more common than is suggested by other methods, the clinical impact observed in this model of methotrexate infusion was not demonstrably greater than medication errors described by other methods. Subsequent studies in this model of dosing error will require larger sample sizes, and other drugs should be evaluated.

Antimetabolites, Antineoplastic↗

Development of pediatric comorbidity prediction model.

OBJECTIVE: To develop a comorbidity model for children that can be used with hospital discharge administrative databases. DESIGN: Retrospective study using administrative data obtained from the Canadian Institute for Health Information Discharge Abstract Database and the Deaths File to develop a logistic regression model. Hosmer-Lemeshow chi2 test was used to examine model fit. The C statistic was used to assess model discrimination. Bootstrapping was used to determine the stability of regression coefficients. SETTING: We used linked administrative databases to compile 339,077 hospital discharge abstracts from April 1, 1991, through March 31, 2002. PARTICIPANTS: Children between ages 1 and 14 years in Ontario, Canada. MAIN OUTCOME MEASURE: Death within 1 year of hospital discharge. RESULTS: The 27-variable pediatric comorbidity model predicted 1-year mortality with a C statistic of 0.83 in the Ontario data set from which it was derived. The presence of brain cancer (odds ratio, 76.38 [95% confidence interval, 53.40-109.27]) at hospital admission was the strongest predictor, followed by diabetes insipidus (odds ratio, 39.23 [95% confidence interval, 20.75-74.17]). CONCLUSION: Using clinical judgment and empirical modeling strategies, we were able to identify 27 diagnoses highly predictive of death for children between 1 and 14 years of age within 1 year of hospital discharge.

Adolescent↗

Postasphyxial hypoxic-ischemic encephalopathy in neonates: outcome prediction rule within 4 hours of birth.

OBJECTIVES: To construct and validate a model and derive a simple rule that is usable in any birth location for the prediction of outcome of term infants with severe asphyxia. DESIGN: Retrospective cohort study. SETTING: Regional outborn neonatal intensive care unit. PARTICIPANTS: Infants with postintrapartum asphyxial hypoxic-ischemic encephalopathy (n = 375). MAIN EXPOSURES: Clinical and laboratory predictors available at age 4 hours. MAIN OUTCOME MEASURES: A logistic regression model was developed and internally validated (with random sampling and based on the year of birth) for severe adverse outcome, which was defined as death or severe disability (severe cerebral palsy, severe developmental delay, sensorineural deafness, or cortical blindness singly or in combination). A simple prediction rule was derived from 3 variables. RESULTS: Complete data were available for 302 (92%) of the 345 infants with known outcomes (204 infants with severe adverse outcome). Six independent predictors of outcomes were identified. Using the 3 most significant predictors (chest compressions, age at onset of respiration, and base deficit), severe adverse outcome rates were 46% (95% confidence interval, 33%-58%) with none of the 3 predictors, 64% (95% confidence interval, 54%-73%) with any 1 predictor, 76% (95% confidence interval, 66%-85%) with any 2 predictors, and 93% (95% confidence interval, 81%-99%) with all of the 3 predictors present. The internal validations revealed a robust model. CONCLUSIONS: This predictive model for neonatal hypoxic-ischemic encephalopathy provides a sliding scale of probabilities that could be used for prognostication and to design eligibility criteria for decision making including neuroprotective therapy.

Age Factors↗

Determinants of survival in children with congenital abnormalities: a long-term population-based cohort study.

BACKGROUND: Today more children with birth defects survive early childhood because of improved medical care; however, little information is available about patterns of long-term mortality and survival in this population. In particular, it is not clear whether other birth characteristics, apart from birth defects, have any role in their mortality. METHODS: Two large cohorts of children with and without birth defects were followed for up to 17 years. More than 45,000 children with birth defects, and 45,000 matched children without birth defects born in Ontario between 1979 and 1986 were followed. Throughout the study period long-term survival rates and the risk of death were compared between the 2 cohorts. Birth characteristics were also examined to determine their effect on the risk of death. RESULTS: During the study the deaths of 3620 and 301 children with and without birth defects, respectively, were recorded, indicating that those with birth defects had a 13 times higher rate of mortality (relative risk [RR], 12.9, 95% confidence interval [CI], 12.1-13.7). Mortality rates in the birth-defects cohort remained higher even after 10-15 years. In both groups children of low gestational age and low birth weight had a higher risk of death. There was a strong dose-response relationship between the number of defects and the risk of death. CONCLUSIONS: Children born with abnormalities face many challenges throughout their lifetimes. If they survive the high mortality risk of the first year of life, they still have to face the considerably higher risk of death in the years to come. In addition to birth defects, other birth characteristics play an independent role in their mortality. These indicators could be used to identify high-risk children.

Adolescent↗

Factors determining the need for operative reduction in children with intussusception: a population-based study.

AIM: The objective of this study is to determine if children presenting to a nonteaching hospital were at greater risk for operative reduction of intussusception than those presenting to a teaching hospital. METHODS: This population-based 8-year study included all children younger than 6 years with intussusception in the province of Ontario, Canada. Multiple logistic regression was used to model markers for operative reduction including age, sex, coexisting conditions, hospital type, and interhospital transfers. RESULTS: Of the 961 children with intussusception, 25.4% had operative reduction. Risk factors for operative reduction were a diagnosis of Meckel's diverticulum and transfer from one institution to another after the initial diagnosis. One hundred forty-eight (15.4%) were transferred. Of those transferred and initially admitted to a nonteaching hospital, 87.4% (125/143) were transferred to a teaching hospital. Risk of operative reduction was higher in children transferred more than 1 day after admission (52.0% vs 39.0%). Odds ratios after adjusting for age, sex, and hospital type were 1.95 (95% confidence interval, 1.28-2.98; P < . 001) for those transferred on the same day and 3.31 (95% confidence interval, 1.34-7.28; P < .01) for those transferred after 24 hours. CONCLUSION: Children who were presented to a nonteaching hospital and later transferred to a teaching hospital were at greater risk for operative reduction of intussusception, in particular, those who were transferred more than 1 day after admission. These data underline the importance of early diagnosis and timely management of intussusception.

Child, Preschool↗

Saccadic adaptation in Chiari type II malformation.

BACKGROUND: Saccadic adaptation corrects errors in saccadic amplitude. Experimentally-induced saccadic adaptation provides a method for studying motor learning. The cerebellum is a major participant in saccadic adaptation. Chiari type II malformation (CII) is a developmental deformity of the cerebellum and brainstem that is associated with spina bifida. We investigated the effects of CII on saccadic adaptation. METHOD: We measured eye movements using an infrared eye tracker in 21 subjects with CII (CII group) and 39 typically developing children (control group), aged 8-19 years. Saccadic adaptation was induced experimentally using targets that stepped horizontally 120 to the right and then stepped backward 3 degrees during saccades. RESULTS: Saccadic adaptation was achieved at the end of the adaptation phase in participants in each group. Saccadic amplitude gain decreased by 6.9% in the CII group and 9.3% in the control group. The groups did not differ significantly (p = 0.27). Amplitude gain reduction was significantly less in the CII participants who had multiple shunt revisions. Regression analyses revealed no effects of spinal lesion level, presence of nystagmus, or cerebellar vermis dysmorphology on saccadic adaptation. CONCLUSION: The neural circuits involved in saccadic adaptation appear to be functionally intact in CII.

Adaptation, Physiological↗

Case verification of children with asthma in Ontario.

Asthma is an important chronic childhood illness. A population-based surveillance program could measure the burden of illness, but first, the validity of an administrative diagnosis of asthma must be confirmed. The objective was to evaluate the accuracy of population-based outpatient administrative data in identifying children with asthma for the purpose of on-going asthma surveillance and research. Twenty-one primary care physician (PCP) clinics in Ontario participated. Patients under 18 yr old were categorized into three diagnosis categories according to administrative data diagnosis codes: asthma, asthma-related, and non-asthma. In each PCP clinic, for each diagnosis category, 10 charts were randomly selected for abstraction. A panel of experts (blind to the code) reviewed the abstracted charts and identified them as asthma or non-asthma. The reviewers' diagnosis was considered the gold standard. The accuracy of the administrative data diagnosis coding was analyzed using the concepts of diagnostic test evaluation. Six hundred and thirty patient charts were abstracted and reviewed. Overall agreement between the diagnosis provided by expert chart review and the administrative data diagnosis code was 84.8% (p < 0.001), and was 60.2%, 94.8% and 99.5% for the asthma, asthma-related, and non-asthma categories, respectively. Additionally, the sensitivity and specificity were 91.4% and 82.9%, respectively. Agreement between the administrative data diagnosis code and the PCP chart diagnosis was 99.4% (p < 0.001). An administrative data diagnosis code of asthma is sensitive and specific for identifying asthma. By using the results of this study as a starting point, future research will create a cohort of children with asthma to be used for population-based surveillance and research.

Asthma↗

Correlates of methylphenidate use in Canadian children: a cross-sectional study.

OBJECTIVES: This study aimed to estimate the prevalence of methylphenidate (MPH) use among Canadian children aged 2 to 11 years, from 1994-1995 to 1998-1999 and to identify sociodemographic, child, and parent-family correlates are identified. METHODS: Cross-sectional data collections from the National Longitudinal Survey of Children and Youth (NLSCY) for 1994-1995, 1996-1997, and 1998-1999 were used and samples weighted up to population levels (n=17,814 in 1994-1995, 13,575 in 1996-1997, and 18,980 in 1998-1999). Logistic regression identified correlates of parent-reported MPH use in each time period. RESULTS: MPH use by Canadian children increased from 1.33% (95% confidence interval [CI], 1.17% to 1.50%) in 1994-1995 to 1.60% (95% CI, 1.42% to 1.78%) in 1998-1999. Use among school children aged 6 to 11 years increased from 1.94% (95% CI, 1.68% to 2.20%) in 1994-1995 to 2.42% (95% CI, 2.14% to 2.71%) in 1998-1999. Use of MPH increased among girls, from 0.52% (95% CI, 0.32% to 0.67%) in 1994-1995 to 0.97% (95% CI, 0.77% to 1.17%) in 1998-1999. For a child with parent-reported hyperactivity, the odds ratios for using MPH were 6.30 (95% CI, 4.94 to 8.90) in 1994-1995 and 12.54 (95% CI, 9.74 to 16.16) in 1998-1999. Age 6 to 11 years, male sex, and absence of parental alcohol use were significant correlates of MPH use in all time periods. Parental smoking correlated with MPH use in 1994-1995 and in 1998-1999. CONCLUSIONS: Less than 2% of Canadian children used MPH between 1994 and 1999. Some increase in use occurred among school-aged children and girls. Parent-reported hyperactivity was the most important correlate of MPH use.

Attention Deficit Disorder with Hyperactivity↗

Saccadic adaptation in children.

Saccades are fast-orienting eye movements. Saccadic adaptation, a form of motor learning, is a corrective change in the amplitude of saccades in response to error. The aim of the study was to ascertain whether saccadic adaptation occurs in typically developing children. We recorded saccades with an infrared eye tracker in 39 children, aged 8 to 19 years, at baseline to 12-degree horizontal target steps and after an adaptive task. During the adaptive task, a saccadic hypometric error was induced. This task consisted of 200 12-degree target steps that stepped backward 3 degrees during the initial saccade and without the participants' awareness. The initial saccade triggered the back-step. This paradigm required a corrective reduction of the amplitude of the initial saccades in response to the induced error. Saccadic adaptation was achieved in 26 participants, whose mean saccadic amplitudes decreased by 13% (P < .05). Saccadic adaptation was not influenced by age. We conclude that children as young as 8 years old have established functions of the neural circuits responsible for the motor learning required for saccadic adaptation.

Adaptation, Physiological↗

The Ontario Asthma Regional Variation Study: emergency department visit rates and the relation to hospitalization rates.

BACKGROUND: Hospitalization rates for asthma vary more than threefold across regions of Ontario. It is not known whether this variation is primarily due to regional differences in the rate of emergency department (ED) visits or hospital admissions. OBJECTIVE: To determine the variation in ED visit rates for asthma in Ontario, and the relation between ED visit rates and hospitalization rates. DESIGN, SETTING, AND PATIENTS: We studied patients with an ED disposition diagnosis of asthma in a stratified sample of 16 hospitals (pediatric facilities, 13; adult facilities, 14) over a 1-year period. Pediatric patients were defined as those patients who were </= 19 years of age. MEASUREMENTS: Direct age-standardized and sex-standardized ED visit and hospitalization rates, and the percentages of patients presenting to EDs and subsequently admitted to the hospital were calculated for each site. High/low ratios (ie, extremal quotients [EQ]), weighted coefficients of variation (CVs), and the systematic component of variation (SCV) were used to summarize the variation among hospitals. RESULTS: The total number of ED visits for asthma at participating sites was 12,518 (7,825 children and 4,693 adults). A total of 847 children (10.8%) and 322 adults (6.9%) were admitted to the hospital. Age-standardized and sex-standardized ED visit rates ranged from 8.7 to 25.2 per 1,000 population for children (EQ, 2.9; CV, 30.9%; SCV, 173; p < 0.001) and 1.7 to 10.1 per 1,000 population for adults (EQ, 5.9; CV, 52.9; SCV, 445; p < 0.001). The proportion of pediatric and adult ED visits resulting in admission to the hospital varied significantly by site (p < 0.001) and was inversely related to ED visit rates in children (p < 0.001) but not in adults. ED visit rates were related to hospitalization rates in children (p = 0.042) and adults (p < 0.0001), but only accounted for 4% and 27%, respectively, of the variation in hospitalization rates. CONCLUSION: Hospitalization rates for asthma in Ontario are primarily influenced by the variation in the percentage of ED visitors admitted to the hospital rather than the ED visit rate.

Adolescent↗

Volume matters: physician practice characteristics and immunization coverage among young children insured through a universal health plan.

OBJECTIVES: We studied the association between immunization coverage for a cohort of 2-year-old children covered by a universal health insurance plan and pediatric provider and other health services characteristics. METHODS: We assembled a cohort of 101,570 infants born in urban areas in Ontario, Canada, between July 1, 1997, and June 31, 1998. Children were considered to have up-to-date (UTD) immunization coverage if they had > or =5 immunizations by 2 years of age, ie, the recommended 3 doses and 1 booster of diphtheria-polio-tetanus-pertussis/Haemophilus influenzae type b vaccine and 1 dose of measles-mumps-rubella vaccine. Provider practice characteristics were derived from outpatient billing records, and 1996 census data were used to derive neighborhood income quintiles. The association between UTD immunization status and provider characteristics was assessed with multilevel regression models, controlling for patient characteristics. RESULTS: Overall, the rate of complete UTD immunization coverage was low (66.3%) despite a large number of primary care visits (median: 19 visits). Children whose usual provider had a low volume of pediatric primary care were less than one half as likely to be UTD. Other factors associated with not being UTD included very low continuity of care, low continuity of care, and usual provider in practice for <5 years. With adjustment for patient and provider characteristics, there was no difference in immunization coverage for general practitioners versus pediatricians. Children from low-income neighborhoods were less likely to be UTD. CONCLUSIONS: Despite universal access to primary care services, rates of complete immunization coverage among 2-year-old children in Ontario are low. Because visit rates are high, primary care reform should include interventions directed at provider immunization practices to reduce missed opportunities.

Child, Preschool↗

Saccades in children.

Saccades are necessary for optimal vision. Little is known about saccades in children. We recorded saccades using an infrared eye tracker in 39 children, aged 8-19 years. Participants made saccades to visual targets that stepped 10 degrees or 15 degrees horizontally and 5 degrees or 10 degrees vertically at unpredictable time intervals. Saccadic latency decreased significantly with increasing age, while saccadic gain and peak velocity did not vary with age. Saccadic gains and peak velocities in children are similar to reported adult values. This implies maturity of the neural circuits responsible for making saccades accurate and fast. Saccade latency decreases as the brain matures.

Adolescent↗

Congenital abnormalities and childhood cancer.

BACKGROUND: The examination of specific characteristics of neoplasms diagnosed in children have suggested that a significant proportion can be attributed to a genetic mutation or genetic predisposition. Although the study of a genetic predisposition to cancer in children remains in the early stages, congenital abnormalities could provide essential information for mapping predisposing lesions in children with cancer. METHODS: In the current study, 2 large cohorts of children with and without congenital abnormalities were followed for the occurrence of cancer and death up to 18 years. Through this study, the risk of developing cancer by age at diagnosis, effects of birth characteristics on cancer risk, and possible associations between specific anomalies and tumor types were examined. RESULTS: Based on the follow-up of 90,400 children, the risk of developing cancer during the first year of life was found to be nearly 6 times higher in children with anomalies (rate ratio [RR] of 5.8; 95% confidence interval [95% CI], 3.7-9.1). Children with birth defects were found to be at a higher risk for developing leukemia (RR of 2.7; 95% CI, 2.1-3.6), tumors of the central nervous system (RR of 2.5; 95% CI, 1.8-3.4), sympathetic nervous system tumors (RR of 2.2; 95% CI, 1.4-3.4), and soft tissue sarcomas (RR of 1.9; 95% CI, 1.0-3.5). Among children with birth defects, children with Down syndrome, nervous system anomalies, and anomalies of the urinary system had the highest incidence rates of cancer. In the presence of birth defects, other factors such as birth weight, gestational age, age of the mother, and birth order were not found to be associated significantly with the risk of cancer. CONCLUSIONS: The significant relative risks found in the current study provided evidence of links between the presence of abnormalities and the development of cancer. Some "cancer-prone" abnormalities were identified in the current study. Such anomalies may be markers of other exposures or processes that increase the risk of developing cancer.

Adult↗

Population demographic indicators associated with incidence of pyloric stenosis.

OBJECTIVES: To calculate incidence rates of pyloric stenosis (estimated by the rate of pyloromyotomy) among infants in Ontario and determine their association with population sociodemographic indicators. METHODS: Pyloromyotomy rates were calculated from hospital discharge data from 1993 through 2000. Four-year data (1993-1996 and 1997-2000) were combined to ensure the stability of the rates. Small-area variations in pyloromyotomy rates and correlations between sociodemographic indicators were studied. RESULTS: Approximately 84.0% of the patients were male infants (younger than 1 year). The sex-adjusted pyloromyotomy rates were 1.57 and 1.86 per 1000 with a 3.4-fold and 3.0-fold regional variation in 1993-1996 and 1997-2000, respectively. Urban areas consistently had the lowest pyloromyotomy rate (1.04 and 1.11 per 1000 in Metropolitan Toronto), but the highest rates were from more rural areas (3.30 and 3.38 per 1000 in Quinte, Kingston, Rideau). After adjusting for socioeconomic status and availability of surgeons in the region, living in a rural area remained a significant factor associated with a higher incidence of pyloromyotomy. The risk of pyloromyotomy for an infant who lives in a region with more than two thirds of its area classified as rural was 1.79 (95% confidence interval, 1.23-2.61; P<.005). CONCLUSIONS: The observed changes in incidence and a higher rate among male infants are consistent with results from previous comparative studies conducted in North America and Sweden. The rural/urban differences suggest that environmental influences related to living in these areas may have a role in the etiology of pyloric stenosis. Further research is needed to evaluate these differences.

Demography↗

The development of a comorbidity index with physical function as the outcome.

BACKGROUND AND OBJECTIVES: Physical function is an important measure of success of many medical and surgical interventions. Ability to adjust for comorbid disease is essential in health services research and epidemiologic studies. Current indices have primarily been developed with mortality as the outcome, and are not sensitive enough when the outcome is physical function. The objective of this study was to develop a self-administered Functional Comorbidity Index with physical function as the outcome. METHODS: The index was developed using two databases: a cross-sectional, simple random sample of 9,423 Canadian adults and a sample of 28,349 US adults seeking treatment for spine ailments. The primary outcome measure was the SF-36 physical function (PF) subscale. RESULTS: The Functional Comorbidity Index, an 18-item list of diagnoses, showed stronger association with physical function (model R(2) = 0.29) compared with the Charlson (model R(2) = 0.18), and Kaplan-Feinstein (model R(2) = 0.07) indices. The Functional Comorbidity Index correctly classified patients into high and low function, in 77% of cases. CONCLUSION: This new index contains diagnoses such as arthritis not found on indices used to predict mortality, and the FCI explained more variance in PF scores compared to indices designed to predict mortality.

Adolescent↗

Antibiotic prescribing for upper respiratory tract infection: the importance of diagnostic uncertainty.

OBJECTIVES: Antibiotic misuse for viral upper respiratory tract infections (URI) in children is a significant problem. We determined the influence on antibiotic prescribing of clinical features that may increase concern about possible bacterial infection (age, appearance, fever) in children with URI. STUDY DESIGN: We created 16 scenarios of children with URI and distributed them by mail survey to 540 pediatricians and family practitioners in Ontario, Canada. The association of patient clinical features, parental pressure, and physician characteristics with antibiotic prescribing was determined through the use of logistic regression analysis. RESULTS: A total of 257 physicians responded (48%). Poor appearance (OR, 6.50; 95% CI, 5.06 to 3.84), fever above 38.5 degrees C (OR, 1.48; 95% CI, 1.21 to 1.82), and age older than 2 years (OR, 2.27; 95% CI, 1.85 to 2.78) were associated with prescribing, whereas parental pressure was not. Physician characteristics associated with antibiotic use were family practitioner (OR, 1.54; 95% CI, 1.22 to 1.96), increasing number of patients seen per week (OR, 1.05; 95% CI, 1.01 to 1.08 for every 20-patient increase), and increasing physician age (OR, 1.17; 95% CI, 1.11 to 1.24, 5-year increments). CONCLUSIONS: Clinical factors, which may lead physicians to be concerned about possible bacterial infection in children, are associated with antibiotic use for pediatric URI.

Anti-Bacterial Agents↗