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L MacWilliam

Publications and source records attributed to L MacWilliam.

14 recordsLinked to original sources
PubMed1996

Using an alternative data source to examine randomization in the Canadian National Breast Screening Study.

Criticisms of the Canadian National Breast Screening Study (NBSS) assert that reported findings (more deaths in women aged 40-49 allocated to mammography versus no mammography and no difference in mortality between women who had mammography and physical examination versus physical examination alone for those aged 50-59) may be due to more women with prior breast disease being allocated to the mammography arms of the study. The possibility that allocation was not random was examined for NBSS participants in Manitoba, Canada, using health insurance data that were external to and independent of the NBSS. The study design consisted of a retrospective observation study using health insurance (claims) data to construct health histories of breast disease prior to NBSS entry. Self-reported breast disease from the NBSS entry questionnaires was compared to breast disease histories on the basis of health insurance claims. The setting consisted of one NBSS screening center in Winnipeg, Canada. The patient population consisted of 9477 women with at least one health insurance claim in the 24 months prior to NBSS entry. We determined the proportions of women within each study arm who had claims for breast disease, breast disease investigation, or xeromammograms in the 24 months prior to NBSS entry, and compared the proportion of women's self-reports of breast disease or xeromammography with the presence/absence of a claim prior to NBSS entry for breast disease or xeromammography. No significant differences in the proportion of women with prior histories of benign breast disease, investigation, or xeromammograms (p > 0.05) were found across the study arms. Nine women in the mammography group versus one in the no mammography group had one prior health insurance claim for breast cancer, but eight of these women had no subsequent claims for breast cancer. There were no differences across the study arms in the proportion of women who reported a prior history of breast disease or a prior xeromammogram for whom an insurance claim was found. Using data external to the NBSS for Manitoba participants, the study found no definitive evidence to support a nonrandom allocation of women with prior breast disease to the mammography arms of the study. However, generalizability to the other NBSS centers cannot be assured.

Adult↗
PubMed1996

Population health and health care use: an information system for policy makers.

University-based researchers in Manitoba, Canada, have used administrative data routinely collected as part of the national health insurance plan to design a population-based health information system (POPULIS). Decision-makers can use this system to make critical comparisons across regions of residents' health status, socioeconomic risk characteristics, and use of hospitals, nursing homes, and physicians. Policy makers have found this information system useful in providing answers to questions they are often asked: Which populations need more physician services? Which need fewer? Are high-risk populations poorly served or do they have poor health outcomes despite being well served? Does high utilization represent overuse or is it related to high need? Three commentaries follow.

Database Management Systems↗
PubMed1995

Measuring the health of the population.

A set of 102 population-based indicators was developed from multiple administrative data sources; these indicators were used to compare the health status of 1 million Manitoba residents across eight administrative regions for 1 year. Marked variations in health status were shown. Despite theoretically equal access to care in a universally insured system and high rates of utilization of hospital and physician services, residents of Manitoba's two northern, more remote regions scored most poorly--consistently and with statistical significance--across a variety of health status indicators. The strength of the various indicators was evaluated, and premature mortality emerged as the most useful "flagship" indicator for future analyses. Indicators that purport to be sensitive to how well a health care system is performing showed patterns similar to those derived from more classic measures (eg, mortality, low birth weight). Furthermore, the "system sensitive indicators" did not appear to be sufficiently independent of utilization biases.

Adolescent↗
PubMed1995

Stability and trends over 3 years of data.

Because the health status of a population does not usually respond immediately to interventions, whether social or medical, the ability to analyze change over time is important. Therefore, patterns of change and stability in health status and health care use of Manitoba residents during a 3-year period from 1990 to 1992 were analyzed using the Population-based Health Information System. This article presents summary findings and discusses methodological and policy issues arising from the analyses. A small but significant decrease in premature mortality (the primary health status indicator) was observed in most regions of the province, but two remote, northern regions, those whose residents scored at high socioeconomic risk, remained distinguished for their poor health status. These "poor health" regions also had the highest contact rates with primary caregivers, raising questions about the role of the health care system in improving the health of the population. A persistent increase in surgery was observed in several regions, led by increases in outpatient surgery over and above increases in the elderly population and beyond substitution for inpatient procedures. This trend (not obvious before these analyses) is important as hospitals move to expand their outpatient facilities in response to restraints on inpatient care.

Adolescent↗
PubMed1992

The Canadian four-centre study of anaesthetic outcomes: II. Can outcomes be used to assess the quality of anaesthesia care?

Since anaesthesia, unlike medical or surgical specialties, does not constitute treatment, this study sought to determine if methods used to assess medical or surgical outcomes (that is the determination of adverse outcome) are applicable to anaesthesia. Anaesthetists collected information on patient, surgical and anaesthetic factors while data on recovery room and postoperative events were evaluated by research nurses. Data on 27,184 inpatients were collected and the analysis of outcomes determined for the intraoperative, post-anaesthetic care unit and postoperative time periods. Logistic regression was used to control for differences in patient populations across the four hospitals. In addition, a random selection of 115 major events was classified by a panel of anaesthetists into anaesthesia, surgical and patient-disease contributions. Across the three time periods, large variations in minor outcomes were found across the four hospitals; these variations ranged from two- to five-fold after case-mix adjustment (age, physical status, sex, emergency versus elective and length of anaesthesia). The rates of major events and deaths were similar across three hospitals; one hospital had a lower mortality rate (P less than 0.001) but had a higher rate of all major events (P less than 0.0001). Of major events assessed by physician panels, 18.3% had some anaesthetic involvement and no deaths were attributable partially or wholly to anaesthesia. Possible reasons to account for these variations in outcome include compliance in recording events, inadequate case-mix adjustment, differences in interpretation of the variables (despite guidelines) and institutional differences in monitoring, charting and observation protocols. The authors conclude that measuring quality of care in anaesthesia by comparing major outcomes is unsatisfactory since the contribution of anaesthesia to perioperative outcomes is uncertain and that variations may be explained by institutional differences which are beyond the control of the anaesthetist. It is suggested that minor adverse events, particularly those of concern to the patient, should be the next focus for quality improvement in anaesthesia.

Anesthesia↗
PubMed1992

Assessing physicians' compliance with guidelines for Papanicolaou testing.

In this study, population-based data were used to examine the appropriateness of Papanicolaou (Pap) testing from the perspective of the women being tested and their physicians. The approach used is unique in its assessment of overtesting and undertesting in the primary care setting. From the data base of the province of Manitoba's universal health insurance plan, 4-year health histories (1981 to 1984) were constructed for each woman from a random sample of the population of women who, in 1982, were between the ages of 25 to 64 years (n = 22,287). At the last visit to a general practitioner, gynecologist, or general surgeon in 1984 (termed the current visit), the authors determined whether a Pap test was given for each woman. Using decision rules from a Canadian task force report on cervical screening and previous health history, the authors evaluated the appropriateness of screening by determining whether a Pap test was given and was needed, or whether a women who had not received a Pap test required one. Overall, 55.7% of women were tested appropriately. Of the 5352 women who received a Pap test at the current visit, 62.8% were overtested. Of the 16,935 women not tested at the current visit, 38.5% required screening (i.e. were undertested). Characteristics of a physician's practice that were significantly related to compliance with the guidelines included having a high proportion of patients visiting for obstetric or gynecologic reasons. Variables that were associated with negative compliance were 1) being a gynecologist; and 2) having a high proportion of patients who lived in inner city or rural areas. Because physicians are paid a fee for every Pap smear taken and the guidelines were well disseminated, these results should be reasonably representative of fee-for-service practice in North America, where preventive care is not subject to user charges. This study supports previous findings that a passive approach to dissemination of guidelines is insufficient to effect practice.

Adult↗
PubMed1988

Risk factors for hypertension: results from a cross-sectional survey.

A case-control study of hypertension was conducted, using as a sampling frame a cross-sectional survey of Canadian Federal civil servants. Three case groups were selected, based on prior knowledge of hypertensive status and measured blood pressure. A 3-to-1 matching scheme was employed. Data was analysed using a logistic regression model. Statistically significantly elevated odds ratios, in excess of 3.0, were noted for overweight or obese status. Other odds ratios associated with a significantly increased risk of hypertension were maternal and paternal history of hypertension and current cigarette smoking.

Adult↗
PubMed1988

Risk factors for myocardial infarction: the importance of relaxation.

Several risk factors for acute myocardial infarction (AMI) were examined, including history of smoking and hypercholesterolemia, income, education, coronary-prone behaviour by Structured Interview (SI) and the type and quality of stress-reducing relaxing activities, in a case-control study. Our sample included 100 AMI patients (80 males and 20 females, with mean ages 57.3 and 64.1 years, respectively), as well as 100 age- and sex-matched controls. Univariate differences between cases and controls were significant for history of smoking, income level, SI-defined hostility, SI-defined suppression of hostility, amount and type of relaxing activities and history of hypercholesterolemia. Multivariable analyses demonstrated that AMI patients reported significantly lower levels of relaxation and income, but higher levels of suppressed hostility and a higher incidence of hypercholesterolemia. Our findings confirm the significance of hostility and particularly suppressed hostility as AMI risk factors; furthermore, inadequate relaxation was identified as an independent risk factor associated with AMI.

Arousal↗
PubMed1987

Increased rates of illness and death from asthma in Canada.

Recent rates of illness and death from asthma in Canada and rates of hospital admission/separation for asthma were examined by age group and region. The death rates were higher in 1982-84 than in 1970-72, especially among those aged 15 to 34 years. Increases were also noted in hospital admission/separation rates, especially among those less than 15 years of age. Hospital admission/separation rates were highest in the Maritime provinces and Saskatchewan, whereas death rates were highest in Alberta and Saskatchewan. Examination of death certificates for coding errors and recoding of certificates to a single (8th) revision of the International Classification of Diseases indicated that changes in disease coding and errors in coding did not account for the significant increase in rates of death from asthma for those aged 15 to 34 years. These increases in rates of illness and death from asthma are unexplained and warrant further investigation.

Adolescent↗
PubMed1986

Effect of cigarette smoking on nasal mucociliary clearance and ciliary beat frequency.

Despite the in vitro ciliotoxicity of tobacco smoke and the abnormal mucociliary clearance found in smoking related chronic bronchitis, studies of mucociliary clearance in healthy smokers have produced variable results. The nasal mucociliary clearance of saccharin and the in vitro nasal ciliary beat frequency were studied in healthy smokers and non-smokers. One of 29 smokers had a nasal mucociliary clearance time of over 60 minutes; in the remaining 28 the mean (SD) clearance time was 20.8 (9.3) minutes, which was significantly longer (p less than 0.001) than the mean time of 11.1 (3.8) minutes in 27 lifelong non-smokers. There was no significant difference between the mean nasal ciliary beat frequency of 10 smokers and 10 non-smokers. There were no significant differences in mean ciliary beat frequency or mean nasal mucociliary clearance time after 10 healthy non-smoking volunteers had smoked two cigarettes each, exhaling the smoke through their nostrils. Unless there is a prompt reversal of any ciliotoxic effect of tobacco smoke when cilia are removed for in vitro examination, the defective clearance seen in chronic cigarette smokers seems unlikely to be due to slowed ciliary beat frequency. It may be due to reduction in number of cilia or to change in the viscoelastic properties of mucus. The failure to detect any acute effect of tobacco smoke is in keeping with this hypothesis.

Adult↗
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Epidemiologic Methods↗