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Biomedical subjects

I McDowell

Publications and source records attributed to I McDowell.

At least 37 records · Page 2Linked to original sources
PubMed1998

Multidimensionality in instrumental and basic activities of daily living.

Although the use of self-reported ADL (activity of daily living) scales has a long history, the Katz-based assumptions of unidimensionality and hierarchy are increasingly found lacking, and ADLs alone are found to underestimate dysfunction and disability. Data from nearly 8900 elderly respondents in the community sample of the 1991 Canadian Study of Health and Aging were used to examine the measurement properties of a modified version of the Older Americans Research Survey (OARS) ADL and IADL items combined. A multidimensional factor structure was revealed, with three levels of functional ability possessing internal consistency. We conclude that assumptions regarding ADL/IADL unidimensionality and hierarchy are not always valid, and that ADL and IADL items should be considered in combination to capture a greater range of functional disability prevalence. We also suggest that expectations of precise measurement of functional dependence by (I)ADL scales should perhaps be relaxed to the goal of simply differentiating broad levels of self-reported functioning (such as basic, intermediate, and complex), within which some tasks are roughly equivalent. Because these scales are widely used as screening tools and in shaping policy, we suggest that employing a more empirically grounded measurement standard has the potential to reduce bias due to item complexity and task specificity, facilitate standardization, and more reliably predict outcomes.

Activities of Daily Living↗
PubMed1998

Hypokalaemia during insulin-induced hypoglycaemia in hypopituitary adults with and without growth hormone deficiency.

OBJECTIVE: We have investigated plasma potassium changes during insulin-induced hypoglycaemia (IIH) in adult patients with growth hormone deficiency (GHD) who have low total body potassium and may also have a vulnerable myocardium due to an increased prevalence of atherosclerosis. DESIGN: Hypoglycaemia was induced through the administration of intravenous soluble insulin (0.1 U/Kg, i.v.). SUBJECTS: 23 consecutive adult patients undergoing routine biochemical evaluation for hypopituitarism. MEASUREMENTS: GH, cortisol glucose, sodium and potassium levels were measured at 0, 30, 60, 90 and 120 min after insulin administration. Pituitary function was also assessed through measurement of TSH, thyroid hormones, LH/FSH, testosterone and 17-oestradiol. IGF-I concentrations were also analysed. RESULTS: All patients achieved adequate hypoglycaemia (nadir glucose < 2 mmol/l). 15 patients had GHD (peak GH < 10 mU/l) either in isolation or as part of a spectrum of pituitary hormone deficiencies. The remaining 8 patients had normal pituitary function. Plasma potassium concentrations (mean +/- SEM) fell from 3.8 +/- 0.3 mmol/l (normals) and 3.8 +/- 0.2 mmol/l (GHDs) to nadir concentrations of 3.0 +/- 0.2 mmol/l and 3.1 +/- 0.3 mmol/l, respectively (P < 0.005). Overt hypokalaemia (< 3.5 mmol/l) occurred in 13/15 GHDs and all normals. There were no significant differences between the groups. CONCLUSIONS: Insulin-induced hypoglycaemia causes similar degrees of significant hypokalaemia in patients with normal pituitary function and in those with GH deficiency, either alone or in combination with other pituitary hormone deficiencies. Therefore, insulin-induced hypoglycaemia does not appear to be associated with any greater risk of hypokalaemia in hypopituitary adults with GHD compared to those with normal anterior pituitary function.

Adult↗
PubMed1998

Prevalence of diabetes mellitus in elderly people in Canada: report from the Canadian Study of Health and Aging.

AIMS: to estimate the age-specific prevalence of diabetes mellitus in elderly people in Canada, and to examine the effect of method of ascertainment on the estimation of prevalence. METHOD: three measures of diabetes were used in a secondary analysis of the Canadian Study of Health and Aging--a 1991 nation-wide cross-sectional study of the prevalence of dementia in a sample of 10,263 elderly subjects (aged 65-106 years). RESULTS: of community-dwelling subjects, 10.3% reported diabetes. Supplementing this information with clinical reports and random plasma glucose measurements increased the prevalence to 12.0% in the community, 17.5% in institutions and 12.4% overall. CONCLUSION: diabetes is common in elderly people, although the prevalence falls in the very elderly. The method of ascertainment influences estimation of prevalence.

Aged↗
PubMed1997

Implementation of the Ottawa Knee Rule for the use of radiography in acute knee injuries.

CONTEXT: The Ottawa Knee Rule is a previously validated clinical decision rule that was developed to allow physicians to be more selective and efficient in their use of plain radiography for patients with acute knee injuries. OBJECTIVE: To assess the impact on clinical practice of implementing the Ottawa Knee Rule. DESIGN: Controlled clinical trial with before-after and concurrent controls. SETTING: Emergency departments of 2 teaching and 2 community hospitals. PATIENTS: All 3907 consecutive eligible adults seen with acute knee injuries during two 12-month periods before and after the intervention. INTERVENTION: During the after period in the 2 intervention hospitals, the Ottawa Knee Rule was taught to all house staff and attending physicians who were encouraged to order knee radiography according to the rule. MAIN OUTCOME MEASURES: Referral for knee radiography, accuracy and reliability of the rule, mean time in emergency department, and mean charges. RESULTS: There was a relative reduction of 26.4% in the proportion of patients referred for knee radiography in the intervention group (77.6% vs 57.1 %; P<.001), but a relative reduction of only 1.3% in the control group (76.9% vs 75.9%; P=.60). These changes over time were significant when the intervention and control groups were compared (P<.001). The rule was found to have a sensitivity of 1.0 (95% confidence interval [CI], 0.94-1.0) for detecting 58 knee fractures. The K coefficient for interpretation of the rule was 0.91 (95% CI, 0.82-1.0). Compared with nonfracture patients who underwent radiography during the after-intervention period, those discharged without radiography spent less time in the emergency department (85.7 minutes vs 118.8 minutes) and incurred lower estimated total medical charges for physician visits and radiography (US $80 vs US $183). CONCLUSIONS: Implementation of the Ottawa Knee Rule led to a decrease in use of knee radiography without patient dissatisfaction or missed fractures and was associated with reduced waiting times and costs. Widespread use of the rule could lead to important health care savings without jeopardizing patient care.

Acute Disease↗
PubMed1997

Caring for elderly people at home: the consequences to caregivers.

The emphasis on home-based care is one important aspect of health services restructuring initiatives in Canada. Fundamental to the preference for home-based care over institutional care is the expectation that family caregivers will be available in the home to support patients who would otherwise be in an institution. The authors explore the potential impact of this devolution of services from institutions to the home in 2 vulnerable patient populations--elderly patients with dementia and elderly patients with terminal illnesses. Community-based surveillance strategies are needed to determine the true health, quality-of-life and economic outcomes of these restructuring initiatives.

Aged↗
PubMed1997

Prevalence and severity of cognitive impairment with and without dementia in an elderly population.

BACKGROUND: Not all cognitively impaired people have dementia, but those who do not meet current criteria for dementia have received little study. We report a comprehensive estimate of the prevalence of "cognitive impairment, no dementia" (CIND) in an elderly population. METHODS: The Canadian Study of Health and Aging gathered population representation information about elderly Canadians aged 65 and over from 36 cities and surrounding areas in five regions. In each region, the sample size was 1800 people in the community and 250 people in institutions. Patients in the community were screened for cognitive impairment by means of the modified mini-mental state examination. Those who scored below the cut-off point (n = 1106) and a randomly selected sample of those who scored above the cut-off point (n = 494) were referred for clinical examination. 59 individuals unable to take the screening test were also assessed clinically. We selected 17 long-term care institutions in each region, and then randomly selected consenting residents of these institutions for clinical assessment (n = 1255). RESULTS: The prevalence of CIND was 16.8%, which was more than all types of dementia combined (8.0%). The prevalence of all types of cognitive impairment, including dementias, increased with age. Patients with CIND were three times more likely to be living in institutions than were cognitively unimpaired patients (odds ratio 3-1 [95% CI 2.4-3.9]). Circumscribed memory loss has a prevalence of 5.3% in the elderly Canadian population, and was the most common category. CIND was related to some degree of functional impairment in elderly patients. INTERPRETATION: CIND is commonly associated with functional disability and a need for institutional care. This diagnostic category includes a costly group of disorders that merit further study.

Aged↗
PubMed1997

Community screening for dementia: the Mini Mental State Exam (MMSE) and Modified Mini-Mental State Exam (3MS) compared.

The objectives of this study were to assess whether Teng's modification of the Mini-Mental State Examination (MMSE) improves its performance as a screening test for cognitive impairment and dementia, and to replicate this comparison in French and English language groups, and for differing assumptions concerning the relative importance of false negative and false positive errors. Screening interviews were conducted with representative samples of people aged 65 or over, set in 36 communities in 10 Canadian provinces. There were 8900 community participants in the Canadian Study of Health and Aging, of whom 1600 also underwent an extensive clinical and neuropsychological examination. Sensitivity, specificity and areas under the receiver operating characteristic (ROC) curve for the original MMSE and modified version (the 3MS) were the main outcome measures. Results are reported for French and English versions of the tests. The results indicate the alpha internal consistency for the 3MS was 0.87, compared to 0.78 for the MMSE. The area under the ROC curve in identifying dementia was 0.93 for the 3MS and 0.89 for the MMSE (p < 0.001). There was less difference between the two tests in identifying all levels of cognitive impairment (AUC 0.80 versus 0.77, p < 0.01). The superiority of the 3MS appears more due to its extended scoring system than to its additional questions. The validity of the MMSE was comparable in English and French samples; results for the 3MS were inconsistent between the two samples, suggesting possible translation problems. In conclusion, the 3MS was superior to the MMSE, justifying the slightly greater burden for its administration and scoring. Neither test worked well in identifying lower levels of cognitive impairment.

Aged↗
PubMed1997

Reported activities of daily living: agreement between elderly subjects with and without dementia and their caregivers.

OBJECTIVES: to determine how accurately information on disability provided by a caregiver (proxy respondent) reflected the opinion of subjects themselves, and if this agreement varied by severity of dementia or relationship of the caregiver to the subject. SETTING AND PARTICIPANTS: the study was based on data from the Canadian Study of Health and Aging, a multicentre study of dementia and health of Canadians age 65 and over. Eight hundred study subjects and their caregivers were independently interviewed regarding the subjects' activities of daily living (ADL). MEASUREMENTS: the percentage of subjects who were independent for individual ADL items and the agreement in these reports between subjects and caregivers were investigated using three-level kappa statistics. RESULTS: index subjects with caregivers other than spouses or offspring required more assistance with ADL. The reported percentage of independence decreased with increasing severity of dementia. There was more agreement between self- and proxy-reported level of independence for physical ADL than for instrumental ADL items. Agreement decreased with increasing severity of dementia. Few statistically significant differences were noted between level of agreement and caregiver relationship. CONCLUSION: satisfactory levels of agreement on ADL between cognitively normal subjects and their caregivers indicate that proxy respondents are a reasonable source of information on ADL when data collection from the subjects themselves is not feasible. Since agreement decreases as the severity of dementia increases, caregiver reports may be preferred for elderly patients even with mild dementia in order to facilitate longitudinal assessment of ADL ratings as the dementia progresses.

Activities of Daily Living↗
PubMed1996

Prospective validation of a decision rule for the use of radiography in acute knee injuries.

OBJECTIVE: To validate a previously derived decision rule for the use of radiography in patients with acute knee injury. DESIGN: Prospectively administered survey. SETTING: Emergency departments of two university hospitals serving adults. PATIENTS: Convenience sample of 1096 of 1251 eligible adults with acute knee injuries; 124 patients were examined by two physicians. MAIN OUTCOME MEASURES: Attending emergency physicians assessed each patient for standardized clinical variables and determined the need for radiography according to the decision rule. Patients who did not have radiography underwent a structured telephone interview at day 14 to determine the possibility of a fracture. The rule was assessed for ability to correctly identify the criterion standard, fracture of the knee. An attempt was made to refine the rule by means of univariate and recursive partitioning analyses. RESULTS: The decision rule had a sensitivity of 1.0 (95% confidence interval [CI], 0.94 to 1.0) for identifying 63 clinically important fractures. Physicians correctly interpreted the rule in 96% of cases, and the k value for interpretation was 0.77 (95% CI, 0.65 to 0.89). The potential relative reduction in use of radiography was estimated to be 28%. The probability of fracture, if the decision rule were "negative," is estimated to be 0% (95% CI, 0% to 0.4%). Attempts to refine the rule led to a model with improved specificity but with an unacceptable loss of sensitivity. CONCLUSION: Prospective validation has shown this decision rule to be 100% sensitive for identifying fractures of the knee, to be reliable and acceptable, and to have the potential to allow physicians to reduce the use of radiography in patients with acute knee injury.

Adult↗
PubMed1996

Optimal cut-points when screening for more than one disease state: an example from the Canadian Study of Health and Aging.

A method is described for choosing optimal cut-points in screening test with a continuous score in order to divide people into any number of disease categories. The cut-points are chosen to minimize the overall expected loss, given a matrix of losses incurred by misclassifications. It is shown that the optimal cut-points depend on the column differences of the loss matrix. The effect of changing the loss matrix is examined. For the error counting matrix, where misclassifications are given equal weight, it is shown that the relationship between the minimal loss cut-point and the receiver operating characteristic (ROC) curve for two disease categories extends to the general case. The results of a study in which elderly people were screened for cognitive impairment and dementia are used to illustrate the method.

Aged↗
PubMed1996

Factors associated with institutionalization of older people in Canada: testing a multifactorial definition of frailty.

OBJECTIVES: To test a model of frailty by examining factors associated with institutionalization of older people in Canada; to assess whether diagnostic data provided information about risk beyond that provided by data on functional capacity and demographic variables. METHODS: Cross-sectional study of 1258 institutional subjects and 9113 community-dwelling older adults from the Canadian Study of Health and Aging. RESULTS: Multiple logistic regression analysis showed that female gender, being unmarried, absence of a caregiver, presence of cognitive impairment (including all types of dementia), functional impairment, diabetes mellitus, stroke, and Parkinson's disease were independently associated with being in a long-term care facility. CONCLUSION: Frailty appears to be a multidimensional construct, and not simply a synonym for dependence in Activities of Daily Living. Studies of health outcomes in older people should include diagnostic data as well as demographic information and data on functional capacity.

Activities of Daily Living↗
PubMed1996

Standardization of the diagnosis of dementia in the Canadian Study of Health and Aging.

Standardization of diagnostic procedures for cognitive impairment in large epidemiologic surveys remains difficult. This paper reports results of diagnostic standardization in a subsample of 2,914 elderly (age 65 years+) Canadians from the Canadian Study of Health and Aging (CSHA; n = 10,263). The objectives were to measure the consistency of the CSHA diagnosis as a test of validity; to assess inter-rater reliability, and to assess the impact of neuropsychological data on the diagnosis of dementia. The CSHA clinical assessment included a nurse's examination, Modified Mini-Mental Status (3MS) exam and Cambridge Mental Disorders Examination, neuropsychological tests, medical history and examination, and laboratory investigations. A final diagnosis was reached in a consensus conference which incorporated preliminary diagnoses from both physicians and neuropsychologists. Computer algorithms, which were developed to check consistency between the clinical observations and the final diagnosis, demonstrated 98% concordance with DSM-III-R criteria for dementia and 92% with NINCDS-ADRADA (National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association) criteria for probable Alzheimer's disease. Inter-rater agreement was high: kappa = 0.81 for dementia/no dementia; kappa = 0.74 for normal/cognitive impairment, not dementia/ dementia. Comparisons of diagnoses between raters by clinical specialty revealed few systematic differences. The impact of neuropsychological input on the physician's diagnosis was most marked in the borderline cases between diagnostic categories.

Aged↗
PubMed1996

Development standards for health measures.

The growing demand for subjective measurements of health in clinical studies has encouraged the rapid creation of many new scales, leading to compromises in the quality of some instruments. Quality control standards are desirable to guide the development of measures and subsequent data interpretation. The limitations in existing measures may be classified under three broad topic areas: 1) shortcomings in the design of the instrument, 2) methodological limitations in the process of its development, and 3) shortcomings in the way that the instrument is described following its initial development. We outline examples of common problems in these areas and propose guidelines for the design, development and presentation of health measurement methods. The guidelines represent a preliminary step in formalizing a discipline of health measurement.

Health Services Research↗
PubMed1996

Dementia among seniors.

The prevalence of dementia increases sharply in old age and is higher among women than men. Alzheimer's disease, the most common form of dementia, affects a greater proportion of women. On average, the number of years lived with dementia is longer for women, and women with dementia are more likely to be living in institutions than men with the condition.

Age Distribution↗
PubMed1995

Derivation of a decision rule for the use of radiography in acute knee injuries.

STUDY OBJECTIVE: To derive a highly sensitive decision rule for the selective use of radiography in acute knee injuries. DESIGN: Prospectively administered survey. SETTING: Emergency departments of two university hospitals. PARTICIPANTS: Convenience sample of 1,047 adults with acute knee injuries. RESULTS: Attending emergency physicians assessed each patient for 23 standardized clinical findings, which were recorded on data collection forms. A total of 127 patients was examined independently by two physicians to determine interobserver agreement. The outcome measure was fracture of the knee. Any patients who did not have ED radiography underwent a structured telephone interview to determine the possibility of a missed fracture. Those variables found to be both reliable (highest kappa values) and strongly associated with a fracture (highest chi 2 values) were further analyzed by a recursive-partitioning multivariate technique. The derived decision rule included the following variables: (1) age 55 years or older, (2) tenderness at the head of the fibula, (3) isolated tenderness of the patella, (4) inability to flex to 90 degrees, and (5) inability to bear weight both immediately and in the ED (four steps). The presence of one or more of these findings would have identified the 68 fractures in the study population with a sensitivity of 1.0 (95% confidence interval [Cl], .95 to 1.0) and a specificity of .54 (95% Cl, .51 to .57). Application of the rule would have led to a 28.0% relative reduction in the use of radiography from 68.6% to 49.4% in the study population. CONCLUSION: A practical, highly sensitive, and reliable decision rule for the use of radiography in acute knee injuries has been derived. Clinical application should await prospective validation of the rule.

Adult↗