Trajectories of Nutritional Risk: The Manitoba Follow-Up Study

OBJECTIVES

To identify patterns of nutritional risk among older men over a four-year period and to project their survival rates over the next two and a half years.

DESIGN

A prospective longitudinal study.

SETTING

Canada.

PARTICIPANTS

Three hundred and thirty-six male survivors of the Manitoba Follow-up Study (MFUS) cohort with an average age of 90 years in 2011.

MEASUREMENTS

Four years of nutritional risk SCREEN II scores (five waves) from the male survivors of the MFUS cohort. The semi-parametric group-based trajectory approach and survival analysis were used to investigate the trajectories of nutritional risk.

RESULTS

Of the participants, 30% lived alone. Five distinct developmental trajectory groups for nutritional risk score were identified. Significant statistical differences were found among the five trajectory groups for SF-36 mental health (p=.02), SF-36 physical health (p=<.001), perception of aging successfully (p=.04) and living alone (p=<.001). Among the five groups, the most pairwise differences were found in appetite, intake of meat and alternatives, and vegetables and fruit, weight change, skipping meals and eating with others. Men in the poorest nutritional risk trajectory group were two times more likely to die within a 2 1/2 year period compared to men in the best nutritional risk trajectory group (hazard rate = 2.33, p=.07).

CONCLUSION

Distinct nutritional risk trajectories were found for older men over a four year period. Poor nutritional risk trajectories are associated with higher risk of mortality for very old men over a short period of time. Timely nutritional assessments by health professionals are needed to identify older men at nutritional risk. Subsequent nutrition education and follow-up may be important in preventing further decline.

Food group consumption and self-rated diets of elderly community-dwelling canadian men. The manitoba followup study

BACKGROUND

Healthy eating perceptions and food group consumption practices of elderly men are largely unexplored. Understanding eating practices of elderly men and how this relates to their quality of life is important for the implementation of practical health promotion strategies.

OBJECTIVE

Examine the frequency of food items consumed (daily, most days, or rarely), and the association of self-rated diet and food group consumption of elderly community-dwelling Canadian men.

DESIGN

Self-reported nutrition data, obtained via mailed questionnaires in spring 2000, from 1,211 Canadian male respondents (mean age 82 years) participating in the Manitoba Follow-up Study were analyzed.

RESULTS

Respondents consumed vegetables/fruit (64%) and grain products (58%) daily, and meat/alternatives (81%) most days. Milk products were equally consumed daily (47%) or most days (47%). Using multiple logistic regression models, controlling for demographic variables, a positive relationship was found between the increasing consumption of vegetables/fruit and grain products and healthier self-rated diets. Daily consumption of vegetables/fruit or grain products significantly predicted healthier self-rated diets compared to men consuming those food categories most days, OR=2.42 (95%CI=1.88, 3.11) and OR=2.18 (95%CI=1.70, 2.79), respectively. Those consuming meat/alternatives or milk products "daily" or "rarely" rated their diets as healthier than those consuming these items "most days".

CONCLUSION

Daily consumption of fruits, vegetables, and grain products is viewed as important for overall health and is positively associated with healthier self-rated diets among elderly Canadian men.

The relationship of the transcutaneous oxygen tension, pulse waves and systolic pressures to the risk for limb amputation in patients with peripheral arterial disease and skin ulcers or gangrene

AIM

Our aim was to determine how the risk associated with presence of low transcutaneous oxygen tension (tcPO2) for subsequent major amputation in patients with skin ulcers or gangrene and peripheral arterial disease, compares with the risks associated with low peripheral pressures and low amplitude of pulse waves. Secondly, we determined whether combination of measurements of oxygen tension with that of the pressures or pulse wave amplitude predicts amputation better than pressure, wave or oxygen tension measurements alone.

METHODS

Measurements were carried out to obtain foot tcPO2, ankle and toe pressures, pressure indices, and toe pulse wave amplitude in 75 limbs with skin lesions and arterial disease of 66 patients referred to the vascular laboratory. These variables were related to the risk of a subsequent major amputation during a median time of 4.2 years, using Cox proportional hazards model.

RESULTS

Low oxygen tension was associated with increased risk of amputation (relative risks 2.16 and 2.55 for tcPO2 < or = 10 mmHg and < or = 20 mmHg, respectively, P<0.05; relative risk 2.22 for tcPO2 < or = 30 mmHg, P=0.07). The relative risks associated with cutoff values of ankle and toe pressures and pressure indices varied from 2.53 (toe < or = 20 mmHg, P<0.05) to 5.83 (ankle < or = 50 mmHg, P<0.001) and the relative risk associated with low wave amplitude (< or = 4 mm) was 3.41, P<0.01. The cutoff values of tcPO2 became insignificant when included in the models together with each pressure variable or pulse amplitude separately. In contrast, wave amplitude remained significantly associated with increased risk of amputation after controlling for each pressure variable (P<0.05).

CONCLUSIONS

TcPO2 < or = 10 mmHg and < or = 20 mmHg are related significantly to increased risk of amputation in patients with skin lesions and arterial disease, but these relative risks are similar in magnitude or smaller than those associated with low cutoff values of pressures, pressure indices or pulse wave amplitude. Low wave amplitude does provide significant information in addition to peripheral pressures with respect to the risk of amputation. On the other hand, low tcPO2 does not provide significant information in addition to peripheral pressures or pulse wave amplitude.

Effectiveness of overhead lifting devices in reducing the risk of injury to care staff in extended care facilities

Patient and/or resident handling is a major cause of injury to healthcare workers. The effectiveness of an overhead ceiling lift programme at mitigating the risk of injury from resident handling was evaluated by comparing injury data and staff perceptions before and after implementation of the programme, and by comparison with a similar unit that did not implement an overhead ceiling lift programme. A questionnaire was used to assess perceived risk of injury and discomfort, preferred resident handling methods, frequency of performing designated resident handling tasks, perceived physical demands, work organization, and staff satisfaction. Staff preferred overhead ceiling lifts to other methods of transfer (manual or floor lifts) when lifting or transferring residents. A significant reduction was observed in the perceived risk of injury and discomfort to the neck, shoulders, back, hands, and arms of care staff. Compensation costs due to lifting and transferring tasks were reduced by 68% for the intervention unit and increased by 68% for the comparison unit. Overhead ceiling lifts were not beneficial in reducing the perceived risk of injury, pain or discomfort, or compensation costs when used to reposition residents. The study demonstrated an overall cost-savings associated with the installation of the overhead lifts, and highlighted areas for further improvement.

Analysis of nursing assessments in a cohort patients with ruptured cerebral aneurysms

Patients admitted with subarachnoid hemorrhage are monitored for symptoms of vasospasm. A prospective study was designed to compare two monitoring instruments: a standard neurological tool (SNR) and the National Institutes of Health Stroke Scale (NIHSS). The two assessment tools were compared to evaluate their concordance and to identify areas where efficiency in recording assessments might be improved. We found no statistical difference between the two tools in detecting symptomatic cerebral vasospasm. Substantial discrepancies in the documentation of observations were noted, particularly in the assessment of limb drift. Avoidance of these discrepancies may require further definition in the SNR tool. A qualitative component consisting of a review of the nurses' notes regarding neurological status in the patients' charts was conducted. It was demonstrated that nurses commonly document information in the progress notes that is already captured in the SNR. Further education of nurses in the use of assessment tools is therefore recommended to avoid redundancies and increase efficiency in recording clinical observations.

Comparison of a standard neurological tool with a stroke scale for detecting symptomatic cerebral vasospasm

The purpose of this study was to critically analyze the effectiveness of two tools used by nurses to assess neurological status of individuals at risk of developing cerebral vasospasm following aneurysmal subarachnoid hemorrhage due to aneurysm rupture. Early detection of vasospasm provides an opportunity for prompt treatment so that further ischemia or infarction can be prevented. We hypothesized that the National Institutes of Health Stroke Scale would detect symptomatic vasospasm earlier than the standard neurological record currently used in the practice setting of a tertiary care teaching hospital. Thirty participants were entered into the study, and a differential diagnostic process identified 15 with symptomatic vasospasm. Quantitative prospective and retrospective analysis showed that there was no statistical difference between the two scales in early detection of vasospasm. This finding may partially be explained by the clinical similarities between the vasospasm and nonvasospasm groups and by the challenges experienced by nurses in administering the stroke scale. Clinically relevant observations suggested the stroke scale was more effective in the assessment of focal symptoms. Qualitative content analysis of nursing notes also provided insight into clinical findings not captured on either scale regarding generalized changes such as restlessness, impulsiveness, and unusual behavior. This study demonstrates the need to develop a more appropriate tool for early detection of vasospasm.

A comparison of the Canadian Occupational Performance Measure and the Health Assessment Questionnaire

The Canadian Occupational Performance Measure (COPM) is receiving international attention as an important assessment for directing occupational therapy interventions and measuring client-centred outcomes. The COPM measures individuals' perceptions of disability by identifying those tasks that are important to them and difficult to perform. The Health Assessment Questionnaire (HAQ) has been used extensively with persons with arthritis and measures individuals' perceived difficulty in performing predetermined tasks of daily living. The HAQ has been shown to correlate with actual performance and has reported concurrent validity with a number of similar scales. In this study, 13 participants diagnosed with rheumatoid arthritis were assessed with the COPM and the disability dimension of the HAQ. Participants scored performance limitations on both the COPM and the HAQ; the correlation coefficient between the scores was not statistically significant. However, when the COPM and the HAQ scores for similar activities were compared, a statistically significant correlation was found. These findings support the use of the COPM as a valid measure of self-reported performance.

A randomized controlled trial to prevent patient lift and transfer injuries of health care workers

STUDY DESIGN

Randomized controlled trial (RCT).

OBJECTIVES

To compare the effectiveness of training and equipment to reduce musculoskeletal injuries, increase comfort, and reduce physical demands on staff performing patient lifts and transfers at a large acute care hospital.

SUMMARY OF BACKGROUND DATA

Back injury to nursing staff during patient handling tasks is a major issue in health care. The value of mechanical assistive devices in reducing injuries to these workers is unclear.

METHODS

This three-armed RCT consisted of a "control arm," a "safe lifting" arm, and a "no strenuous lifting" arm. A medical, surgical, and rehabilitation ward were each randomly assigned to each arm. Both intervention arms received intensive training in back care, patient assessment, and handling techniques. Hence, the "safe lifting" arm used improved patient handling techniques using manual equipment, whereas the "no strenuous lifting" arm aimed to eliminate manual patient handling through use of additional mechanical and other assistive equipment.

RESULTS

Frequency of manual patient handling tasks was significantly decreased on the "no strenuous lifting" arm. Self-perceived work fatigue, back and shoulder pain, safety, and frequency and intensity of physical discomfort associated with patient handling tasks were improved on both intervention arms, but staff on the mechanical equipment arm showed greater improvements. Musculoskeletal injury rates were not significantly altered.

CONCLUSIONS

The "no strenuous lifting" program, which combined training with assured availability of mechanical and other assistive patient handling equipment, most effectively improved comfort with patient handling, decreased staff fatigue, and decreased physical demands. The fact that injury rates were not statistically significantly reduced may reflect the less sensitive nature of this indicator compared with the subjective indicators.

Prevalence of asthma symptoms among adults aged 20-44 years in Canada

BACKGROUND

Reported prevalence rates of asthma vary within and between countries around the world. These differences suggest environmental factors in addition to genetic factors in the cause of the disease and may provide clues for preventive strategies. We examined the variability of asthma-related symptoms and medication use among adults in 6 sites across Canada (Vancouver, Winnipeg, Hamilton, Montreal, Halifax and Prince Edward Island) and compared our findings with those from sites that had participated in a recent European survey.

METHODS

We used the same sampling strategy and standardized questionnaire as those used in the European Community Respiratory Health Survey (ECRHS). The 6 Canadian sites were selected to represent different environments with respect to climate, air pollution and occupational exposure. Community-based samples of 3000 to 4000 people aged 20-44 years were randomly selected in each site. Subjects were asked to complete the questionnaire by mail between March 1993 and November 1994. Prevalence rates (and 95% confidence intervals [CIs]) of asthma symptoms, self-reported asthma attacks and use of asthma medication were compared across the Canadian sites and with sites that had participated in the ECRHS.

RESULTS

The overall response rate of those selected to receive the questionnaire was 86.5% (range 74.5%-92.8%). The prevalence rates of most asthma symptoms varied significantly among the Canadian sites. For instance, 21.9% (Montreal) to 30.4% (Halifax) of the men and 24.0% (Vancouver) to 35.2% (Halifax) of the women reported wheezing in the year before the survey. Depending on the site, 4.4% to 6.3% of the men and 5.2% to 9.5% of the women reported an asthma attack in the last year, and 4.0% to 6.1% of the men and 4.9% to 9.7% of the women were currently using asthma medication. Prevalence rates of symptoms, asthma attacks and medication use did not change with age, but they were higher among women than among men. Compared with the results from the ECRHS sites, those from the Canadian sites were among the highest.

INTERPRETATION

Significant variation in the prevalence of asthma symptoms, asthma attacks and use of asthma medication between Canadian sites and international sites suggests environmental influences. Different combinations of factors in different sites may be responsible for the high prevalence rates and should be the subject of further research to guide clinical management and public health intervention.

The value of toe pulse waves in determination of risks for limb amputation and death in patients with peripheral arterial disease and skin ulcers or gangrene

OBJECTIVES

The purpose of this study was to determine whether the presence of low amplitude of pulse waves recorded from the toes is related to the risk of subsequent amputation and death in patients with skin ulcers or gangrene and peripheral arterial disease, and how the risk of low wave amplitude relates to the risk associated with low peripheral pressures.

METHODS

A total of 309 patients with 346 limbs with skin lesions and arterial disease referred to the vascular laboratory were followed up for an average of 5 years (range, 1-8 years). Measurements were carried out to obtain ankle and toe pressures, pressure indices, and toe pulse wave amplitude. These variables were related to the risks of major amputation and total and cardiovascular death by means of the Cox proportional hazards model.

RESULTS

Low toe pulse wave amplitude (< or = 4 mm) was associated with increased risk of amputation (relative risks 4.20 in all limbs and 2.63 in those with toe pressure < or = 30 mm Hg; P <.01). Wave amplitude remained significantly associated with increased risk of amputation after controlling for each pressure variable (P <.01). Low pulse wave amplitude and toe/brachial index were associated with increased risks of both total and cardiovascular death in all patients (relative risks ranged from 1.43-1.73; P <.05) and in those with toe pressure of 30 mm Hg or less (relative risks 1.56-1.90; P <.05).

CONCLUSIONS

Low toe pulse wave amplitude is related significantly to increased risks of amputation and death in patients with skin lesions and arterial disease. The presence of low wave amplitude provides significant information in addition to peripheral pressures with respect to the risk of amputation.

Health-risk perception in the inner city community of Centro Habana, Cuba

Perceptions of health risks were surveyed in the inner city of Centro Habana, Cuba. A questionnaire developed by community leaders and experts was administered to 348 residents to determine the level of perceived risk for each of 41 risk items. Ecologic-level data on morbidity, mortality, and environmental indicators were also gathered. Using factor analysis to reduce the dimensionality of the data, five factor groupings accounted for 60% of the variance, as follows: social environment (40.8%); infectious agents and other health-risk factors of immediate concern (6.1%); lifestyle risks (4. 9%); environmental sanitation (4.1%); and living conditions (3.3%). A relationship between the perception of risk and the ecologic data was found, with inconsistencies largely attributable to factors known to influence risk perception. The greatest concern identified throughout the municipality was housing conditions, highest in the neighborhood that had already begun to address this problem. The analysis was useful in planning targeted health promotion campaigns and prioritizing further interventions. Repeat evaluation of risk perception will be conducted following the completion of interventions.

Predictors of time loss after back injury in nurses

STUDY DESIGN

A 2-year prospective inception cohort study of back injury in nurses.

OBJECTIVES

To determine the extent to which characteristics of nurses, of the injury, and of the workplace predict occurrence and duration of time loss from work after back injury.

SUMMARY OF BACKGROUND DATA

During 2 years, 320 nurses incurred 416 back injuries at a large teaching hospital in Winnipeg, Canada. Nurses injured on preselected wards were targeted for early intervention, including provision of modified work, whereas nurses injured on other wards received the usual care.

METHODS

Time loss attributable to the back injury during the 6 months after injury was analyzed. Three statistical models were used to examine occurrence of time loss (logistic regression), duration of time loss (Tobit regression), and duration of time loss once an injury incurring time loss had been documented (least-squares regression).

RESULTS

In 218 of the 416 injuries, the injured nurse consented to interview. Whereas perceived disability was related to whether a time loss injury would ensue, self-reported pain was strongly related to the duration of time loss once an injury had become a time loss injury. Duration of time loss was reduced by participation in the return-to-work program. Mechanism of injury, specifically injury occurring while lifting patients, resulted in greater time loss.

CONCLUSIONS

Focusing on reducing the perception of disability at the time of injury is critical to preventing time loss, but once time loss has occurred, offer of modified work and attention to pain reduction are warranted. The findings add to the evidence that workplace-based intervention programs can be effective in reducing the morbidity resulting from back injury.

Satisfaction of women attending the Manitoba breast screening program

BACKGROUND

This study evaluated the satisfaction of women who attended the Manitoba Breast Screening Program (MBSP) during the first 17 months of operation and examined differences in satisfaction by screening location and screening result. The setting was the province of Manitoba, Canada.

METHODS

A breast screening program satisfaction questionnaire comprising six subscales was mailed to 1,331 randomly chosen women in five different categories who attended the MBSP. Four categories were based on location of screen (city of Brandon vs city of Winnipeg) and screen result (normal vs abnormal) and one category comprised women who were screened at a mobile unit. Eighty-eight percent of all questionnaires were returned. Data analyses included analyses of variance to examine the effect of location and result on satisfaction scores and logistic regression to explore the variables associated with reported satisfied and not satisfied responses to each satisfaction subscale.

RESULTS

All satisfaction scores were above 80 of 100, indicating high levels of satisfaction. A significant difference in satisfaction scores between women in Winnipeg and women in Brandon was found for the convenience and accessibility (P = 0.0153) and the information transfer subscales (P = 0.0150). A significant difference was found between women with abnormal and women with normal screen results for all subscales (P < 0.01). Women were 4.5 times more likely to be dissatisfied on the general satisfaction subscale if they had an abnormal screen result (95% CI 1.9,10.4).

CONCLUSIONS

High levels of satisfaction were reported for all aspects of screening at the MBSP. However, women were less likely to be satisfied with program convenience and accessibility. Women with an abnormal result reported lower levels of satisfaction on all subscales. Some women with an abnormal screening result were confused about what their results meant and why they were sent for additional diagnostic tests. As a result of these findings, numerous changes were made to the MBSP.

The effect of age on risk factors for ischemic heart disease: the Manitoba Follow-Up Study, 1948-1993

PURPOSE

The purpose of this paper is to determine the age-specific relationships between risk factors at age 40 through 75 years and ischemic heart disease (IHD), and to determine the effects of aging on these relationships in a cohort of 3983 Canadian males.

METHODS

The Manitoba Follow-Up Study is the prospective investigation of cardiovascular disease as it develops in a cohort of 3983 young men. Over a period of 45 years, from 1948 to 1993, 1094 study members (27%) developed clinical evidence of IHD. Blood pressure, body weight, smoking, and presence of diabetes mellitus have been recorded at regular intervals throughout the follow-up period. Using measurements from examinations every 5 years between ages 40 and 75 years, age-specific Cox proportional hazard models were fit to relate these risk factors to IHD.

RESULTS

The adjusted relative risk of IHD for systolic blood pressure, diastolic blood pressure and smoking were found to significantly (p < 0.001) decline with advancing age. The adjusted relative risk for body mass index and presence of diabetes mellitus for ischemic heart disease did not vary with age (p > 0.05). After age 65 years, these risk factors were of little value for the prediction of IHD.

CONCLUSIONS

The relative risk and statistical significance of blood pressure and smoking, as risk factors for IHD, decline with age.

Components of initial and residual disability after back injury in nurses

STUDY DESIGN

A pre- versus postintervention with concurrent control group design was used to investigate the effect of a workplace-based early intervention program on perception of disability in nurses with low back injury.

OBJECTIVES

This report examines changes over time in the components of the Oswestry Low Back Pain and Disability Questionnaire in two groups of back-injured nurses-those who received the early intervention program (study) and those who were not offered the program (control).

SUMMARY OF BACKGROUND DATA

Early intervention programs can decrease morbidity, time lost from work, and compensation costs. Although perception of disability decreases, some residual disability remains, the nature of which is not clear.

METHODS

The Oswestry Low Back Pain and Disability Questionnaire scores of 40 study nurses and 118 control nurses at time of injury and at 6 months after injury were examined. Analysis of variance was used to compare changes in mean overall scores over time. The proportion of nurses reporting disability on individual components of the Oswestry Low Back Pain and Disability Questionnaire at each time period was compared with the results of a chi-square test.

RESULTS

Overall Oswestry Low Back Pain and Disability Questionnaire scores were similar between study and control nurses at time of injury, but were significantly lower in study nurses at 6 months after injury. However, scores of individual Oswestry Low Back Pain and Disability Questionnaire components that related to job demands increased over time; this was most apparent in lifting, particularly in study nurses.

CONCLUSIONS

Although overall perception of disability decreased 6 months after injury, particularly in study nurses, disability in job-related activities persisted. Residual disability after back injury should be addressed in workplace-based prevention programs.

Respiratory symptoms in a susceptible population due to burning of agricultural residue

STUDY OBJECTIVES

To identify characteristics associated with respiratory symptoms due to an episode of air pollution.

DESIGN

Mail survey.

SETTING

In October 1992, the population of the city of Winnipeg was exposed to elevated levels of particulate matter (total and <10 microm size), carbon monoxide, nitrogen dioxide, and volatile organic compounds due to smoke from adjacent fields where farmers were burning agricultural residue (straw and stubble).

PARTICIPANTS

We surveyed 428 participants in the ongoing Lung Health Study (35 to 64 years old, both sexes) with mild to moderate airways obstruction (mean FEV1 percent predicted 73+/-12%), and a high level of airways hyperreactivity (23% of men and 37% of women).

RESULTS

While 37% of subjects were not bothered by smoke at all, 42% reported that symptoms (cough, wheezing, chest tightness, shortness of breath) developed or became worse due to the air pollution episode and 20% reported that they had breathing trouble. Those with symptoms were more likely to be female than male and were more likely to be ex-smokers than smokers. Subjects with asthma and chronic bronchitis were also more likely affected. The degree of airways obstruction and the level of bronchial hyperresponsiveness were not associated with increased susceptibility.

CONCLUSIONS

Gender, smoking habit, and respiratory symptoms but not bronchial hyperresponsiveness or the degree of airways obstruction are factors influencing susceptibility to symptoms due to air pollution in adult smokers and former smokers.

Cardiac structure and exercise blood pressure in urban and rural Canadian men of Icelandic descent

The objective of the study was to determine the relationship between exercise systolic blood pressure (ESBP), during bicycle ergometry, and echocardiographically determined left ventricular structure in rural and urban Canadian men of Icelandic descent. The study was cross-sectional in design. The settings were urban Winnipeg and the rural Interlake District in the province of Manitoba, Canada. Subjects were adult male volunteers from families of wholly Icelandic descent. The subjects were 30 to 60 years of age and had supine blood pressure < 160/95 mm Hg. Anthropomorphic measurements, echocardiography and sphygmomanometry, at rest and during bicycle ergometry, were performed on all subjects. Prevalence of exaggerated ESBP (> or = 200 mm Hg) and left ventricular hypertrophy (LVH) was not significantly different in the two groups. In all but one individual LVH was classified as eccentric hypertrophy. In both urban and rural subjects with exaggerated ESBP, left ventricular mass index (LVMI) was greater than in those subjects without exaggerated ESBP. The LVMI correlated with ESBP at the highest workloads (> or = 150 W). Multivariate analysis of all subjects showed that cardiac index, ESBP, body mass index, and low exercise heart rate were predictive of LVMI. There was no significant difference in prevalence of ESBP or LVH between urban and rural Manitobans of Icelandic descent. However, LVMI levels were lower, and values for ESBP greater, in the rural group compared with the urban group. Within each of the two groups there was a positive association between ESBP and LVMI; hence, the study supports findings of our previous investigation showing evidence of early target organ effects in normotensive men with an exaggerated ESBP.

Effect of an early intervention program on the relationship between subjective pain and disability measures in nurses with low back injury

STUDY DESIGN

The effect of a workplace-based early intervention program on perceptions of pain and disability in nurses with low back injury was studied using a preintervention versus postintervention design with concurrent control group.

OBJECTIVES

To examine the relationship and changes over time between pain and disability measures in two groups of back-injured nurses--those who received the early intervention program (study) and those who were not offered the program (control).

SUMMARY OF BACKGROUND DATA

The relationship between back pain and disability is not straightforward. The effects of an intervention program on changes in perceptions of pain and disability over time have not been widely reported.

METHODS

The Oswestry Low Back Disability Questionnaire and a visual analog pain scale were administered to 46 study nurses and 137 control nurses at time of injury and at 6 months after injury. Correlation and regression analyses were used to explore the relationships between the two measures. Changes over time were compared with analyses of variance.

RESULTS

Pain and disability were positively correlated in both groups at time of injury and at follow-up evaluation. Mean scores for pain and disability were lower at follow-up evaluation than at initial injury in both groups; study nurses had significantly (P < 0.01) lower scores at 6 months than nurses in the control group. Disability at time of injury predicted disability at 6 months only for nurses in the control group.

CONCLUSIONS

This workplace-based early intervention program decreased levels of pain and disability in back-injured nurses and altered the relationship between these two variables over a 6-month time interval.

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.

Value of toe pulse waves in addition to systolic pressures in the assessment of the severity of peripheral arterial disease and critical limb ischemia

PURPOSE

Although pressure measurements are useful in the assessment of the severity of the arterial obstruction, they do not completely identify limbs with and without critical limb ischemia. Our objective was to test whether addition of the measurements of toe pulse waves (PW), which depend on distal perfusion, to pressure measurements could improve the determination of the severity of arterial disease and the presence of critical limb ischemia.

METHODS

We measured toe pressure (TSP) and ankle/brachial index (ABI) and recorded PW with photoplethysmography in 358 limbs of 182 patients.

RESULTS

TSP, ABI, and PW amplitude were lower in 67 limbs with rest pain, skin lesions, or both, with mean differences of 29 mm Hg, 0.12, and 16 mm, respectively (p < 0.01). Similarly, in the subgroup of 107 limbs with TSP < or = 30 mm Hg, TSP, and PW amplitude, but not ABI, were lower in 53 limbs with rest pain, skin lesions, or both, with mean differences of 10 mm Hg and 7 mm (p < 0.01). Multiple logistic regression showed that after controlling was done for TSP and ABI, the odds ratio for the presence of rest pain, skin lesions, or both associated with PW amplitude < or = 4 mm was 4.3 (95% confidence interval 1.7, 11.0; p < 0.01). In the subgroup with TSP < or = 30 mm Hg, this odds ratio was 3.5 (95% confidence interval 1.0, 11.6; p < 0.05).

CONCLUSIONS

The findings indicate that addition of PW recording to pressure measurements is likely to increase the accuracy of assessment for critical limb ischemia.

Tracking of blood pressure over a 40-year period in the University of Manitoba Follow-up Study, 1948-1988

High blood pressure is a well-recognized, modifiable, cardiovascular disease risk factor. Tracking of blood pressure was examined in the University of Manitoba Follow-up Study, a cohort of 3,983 men followed over a 40-year period, between 1948 and 1988. Blood pressure measurements recorded over time in these men, prior to the development of ischemic heart disease, were used in this analysis. Two approaches to tracking were used; correlation analysis and the quantification of the likelihood for a man whose blood pressure was in either the top or bottom quintile to remain in the extreme end of the distribution at later measurement. For ages 25-75 years and for intervals between blood pressure measurement ranging from 5 to 35 years, significant evidence for tracking was found. The strongest evidence for tracking was in middle age, 45-55 years. Strength of tracking decreased with increasing time between measurements. This analysis suggests that men at highest risk for hypertension can be identified at a young age. Hence, strategies for prevention of cardiovascular complications can be targeted in early adulthood.

The natural history of atrial fibrillation: incidence, risk factors, and prognosis in the Manitoba Follow-Up Study

PURPOSE

Atrial fibrillation is a common arrhythmia associated with increased cardiovascular morbidity and mortality. This study was undertaken to identify the natural history of this condition, including risk factors for its development, and outcome.

PATIENTS AND METHODS

The incidence of atrial fibrillation among 3,983 male air crew recruits observed continuously for 44 years was calculated based on person-years of observation. Age and 23 variables were examined to identify risk factors for atrial fibrillation. Controlling for age and 9 prognostic variables, the effect of atrial fibrillation on 8 outcomes was examined. Analysis of risk factors for atrial fibrillation and outcome after atrial fibrillation was based on a Cox proportional hazard model using time-dependent covariates.

RESULTS

Of the 3,983 study members, 299 (7.5%) developed atrial fibrillation during 154,131 person-years of observation. The incidence rose with age from less than 0.5 per 1,000 person-years before age 50 to 9.7 per 1,000 person-years after age 70. Risk for atrial fibrillation was increased with myocardial infarction (relative risk [RR] 3.62), angina (RR 2.84), and ST-T wave abnormalities in the absence of ischemic heart disease (RR 2.21). The RR for atrial fibrillation was strongest at the onset of ischemic heart disease and diminished over time. The rate of atrial fibrillation was 1.42 times increased in men with a history of hypertension. Congestive heart failure, valvular heart disease, and cardiomyopathy were important but uncommon risk factors. Atrial fibrillation independently increased the risk for stroke (RR 2.07) and congestive heart failure (RR 2.98). Total mortality rate was increased 1.31 times; cardiovascular mortality including and excluding fatal stroke were also increased (RR 1.41 and 1.37, respectively).

CONCLUSIONS

The incidence of atrial fibrillation in men increases with advancing age. Clinical cardiac abnormalities, particularly recent ischemic heart disease and hypertension, are strongly associated with increased risk for atrial fibrillation. Atrial fibrillation increases morbidity and mortality, but the magnitude of the increase may be less than previously reported.

A population-based approach to monitoring adverse outcomes of medical care

A population-based approach to monitoring quality of care combining small-area analysis and outcomes assessment is proposed. While adverse outcomes due to poor surgical technique have long been targeted for quality-of-care review, in this study, giving similar attention to adverse outcomes produced by high rates of interventions is proposed. A population-based approach will strengthen traditional review efforts that currently begin and end at the hospital door. Excluded from these reviews have been questions such as the following: Should the procedure have been performed in the first place? Did the benefits outweigh the risks? Were there other patients not operated on who might have benefited more? Traditional approaches can identify less competent hospitals or practitioners: population-based approaches can identify the surgical enthusiasts who may pose equal risks to the populations of the areas they serve. Applying a population-based approach to review of coronary artery bypass graft surgery for Medicare patients in five cities in the United States demonstrates that at least as many deaths could have been prevented by decreasing surgical rates to the U.S. average as by improving the technical quality of care with which the procedure was performed. A similar population-based analysis of complications (as judged by re-admissions within 30 days of surgery) associated with hysterectomy across regions of Manitoba, Canada, is presented. In summary, negligent acts in the delivery of health care in institutions are rare and are difficult to detect because medicine is an inexact science and because adverse outcomes are more likely in high-risk patients, regardless of the quality of care. However, from a population perspective, adverse events are predictable, occur relatively frequently, and are directly related to the frequency of a population's exposure to surgical intervention. Efforts to improve quality of care could be made more effective by including the rates at which populations are exposed to treatments and the technical quality of care delivered.

Acute epiglottitis in adults: diagnosis and treatment in 43 patients

Epiglottitis (supraglottitis) is an acute infection involving the supraglottic larynx that usually occurs in children, but can also affect adult patients. The purpose of this study was to retrospectively analyze diagnostic and treatment methods in adults with epiglottitis seen over a 10-year period at the Winnipeg Health Sciences Centre. Forty-three epiglottitis patients over the age of 16 were treated between 1982 and 1992. Treatment was individualized according to airway status at presentation, and not based on clinical staging protocols. A total of 29 patients were treated conservatively, whereas 14 patients were intubated immediately. One expectantly managed patient had to be intubated on the ward, and one patient died from septicemia. No presenting symptom or sign reliably predicted the need for intubation. Epiglottitis is seen in adults and can be easily and safely diagnosed by either indirect or flexible laryngoscopy. Endotracheal intubation is the safest and most direct means of securing the airway in severely affected patients. Staging systems are useful for retrospective data analysis, but should not be relied on to predict the course of patients with an inherently unpredictable disease.

The effect of body heating and cooling on the ankle and toe systolic pressures in arterial disease

Although changes in body temperature alter limb blood flow, little information exists on the effect of body heating and cooling on systolic pressures in limbs with arterial disease. Ten patients with stable claudication were studied. Mean ankle systolic pressure index during body cooling (0.79 +/- 0.04) exceeded (p less than 0.01) both the value during routine test (0.69 +/- 0.03) and during heating (0.65 +/- 0.04). The individual, paired difference in ankle systolic pressure index between cooling and heating exceeded 0.15 in seven limbs and between cooling and routine test in five. Mean toe systolic pressure index during heating, but not during cooling, was lower than during routine test (p less than 0.01). There was no significant difference in the mean toe systolic pressure index between heating and cooling. However, compared with heating, toe systolic pressure index increased with cooling in 12 limbs and decreased in eight, including three with loss of measurable pressure. The paired difference in toe systolic pressure index between cooling and heating exceeded 0.15 in 10 limbs and between cooling and routine test in eight; whereas between heating and routine test the paired difference was within 0.15 in all but three limbs. The results indicate that changes in body temperature have significant effects on distal pressures in arterial disease. Preliminary warming in routine tests should improve reproducibility.

Waiting times for nursing-home placement: the impact of patients' choices

OBJECTIVE

To identify patient characteristics and characteristics of long-term care facilities that significantly affect the waiting time for transfer from hospital to nursing home.

DESIGN

Cohort study.

PARTICIPANTS

All patients designated to be transferred from four Winnipeg hospitals between June 1, 1988, and May 31, 1989. The patients were followed up until placement, death or May 31, 1990.

MAIN OUTCOME MEASURE

Length of time waiting for nursing-home placement and relative rates of placement.

RESULTS

The variable found to shorten the waiting time the most was the patient's choice of a for-profit or nonprofit secular facility; other significant variables were male sex, age of 75 to 84 years and occupancy of an acute care bed during the wait.

CONCLUSION

The province has three policy options: it can increase the proportion of secular nursing-home beds when new facilities are built; it can require that hospital patients accept an interim nursing-home placement pending transfer to the nursing home of their choice; or it can tie the sponsorship of new facilities to a formula based on the ethnoreligious distribution of the population currently aged 55 to 64 years.

The natural history of electrocardiographic preexcitation in men. The Manitoba Follow-up Study

OBJECTIVE

To examine the natural history of preexcitation occurring on the routine electrocardiogram (ECG).

DESIGN

A longitudinal cohort study of 3983 originally healthy men followed prospectively for 40 years.

SETTING

Free-living (community-dwelling) study members residing predominantly in Canada.

PARTICIPANTS

Nineteen male study members with preexcitation occurring during routine examination in the 40-year follow-up of the Manitoba Follow-up Study.

MEASUREMENTS

Routinely requested clinical examinations and ECGs, supplemented by information supplied by the study member or his physician.

MAIN RESULTS

Ten study members were found to have preexcitation at enrollment, for a prevalence of 2.5 per 1000 (95% CI, 1.2 to 4.6). A delta wave was first detected during follow-up in an additional nine study members. Seventeen of 19 study members did not have the delta wave at some later time, and preexcitation was intermittently present in most of these members. Over time there was a loss of preexcitation, with 15 of 19 study members no longer exhibiting a delta wave by the end of follow-up. Five of 11 study members with symptoms had physician confirmation of an arrhythmia. Fourteen study members remain alive, and none of the five deaths was attributed to preexcitation.

CONCLUSIONS

Preexcitation found on routine ECG in our originally healthy male study group did not confer excess morbidity or mortality, even in those study members who developed symptomatic arrhythmias. Most preexcitation was intermittent and disappeared over time.

Regular narrow QRS complex tachycardias in the Manitoba Follow-up Study (1948-88)

OBJECTIVE

To determine the incidence, risk factors and prognosis of regular narrow QRS complex tachycardia (NQT), which develops in the absence of pre-excitation in subjects free from ischemic heart disease in the Manitoba Follow-up Study.

DESIGN AND SETTING

The Manitoba Follow-up Study is a longitudinal cardiovascular study of 3983 initially healthy men (primarily living in Canada) followed prospectively for 40 years. Risk factors and prognosis were assessed in a nested case-control study.

MAIN RESULTS

Twenty-two individuals were diagnosed with NQT before clinical and/or electrocardiographic manifestation of ischemic heart disease (145,408 person-years of observation). Between the ages of 30 and 80, the incidence of NQT was one per 6000 person-years and increased with age. History of childhood diseases, valvular disease, smoking, elevated blood pressure and body mass index did not increase the likelihood for NQT development. NQT was diagnosed concurrently with a serious noncardiac condition in seven cases; excess mortality resulted as six of these subjects died within one year of NQT diagnosis while only two subjects without concurrent disease at NQT diagnosis died during follow-up. In comparison with 2% of control subjects, 27% of subjects with NQT subsequently developed electrocardiographical evidence of atrial fibrillation (relative risk was 12 with lower 95% confidence limit of 1.8).

CONCLUSIONS

NQT in an otherwise healthy individual is a benign condition and increases the likelihood of atrial fibrillation development.

The association between exercise blood pressure and the prevalence of ECG abnormalities

The relationship between atrial and ventricular electrocardiographic abnormalities and exercise systolic blood pressure was studied in 246 male and 183 female subjects, of whom 199 males and 158 females were normotensive (resting blood pressure below 140/90 mmHg) and 47 males and 25 females were borderline hypertensive (resting systolic blood pressure 140 to 159 and/or diastolic blood pressure 90 to 99 mmHg). Subjects were classified into three groups according to systolic blood pressure during treadmill exercise (less than or equal to 180 mmHg, 180 to 199 mmHg and greater than or equal to 200 mmHg). With respect to atrial electrocardiographic abnormalities, the prevalence of abnormal values of the P-terminal force in lead V1 increased significantly with increased levels of resting exercise systolic blood pressure in males and females. The prevalence of electrocardiographic left ventricular hypertrophy, as reflected in abnormal values of one or more RS voltage indices, increased significantly with exercise systolic blood pressure in males but not in females. Males did not show a trend of increasing electrocardiographic left ventricular hypertrophy with increased resting systolic blood pressure means. In females, the significant difference between resting systolic blood pressure means and electrocardiographic left ventricular hypertrophy did not reflect a linear progression across resting systolic blood pressure categories. The significant association of the P-terminal force in lead V1 with exercise systolic blood pressure has not previously been reported. Although an association between left ventricular hypertrophy and exercise systolic blood pressure in hypertensives has been reported by others, the association seen in normotensive and borderline hypertensive males has not been reported previously.(ABSTRACT TRUNCATED AT 250 WORDS)

Is health care use changing? A comparison between physician, hospital, nursing-home, and home-care use of two elderly cohorts

This study used log-linear survival analysis, and log-rank tests to compare 1) the characteristics of two elderly cohorts; 2) their use of physician, hospital, nursing-home and home-care services over 8.5 years; and 3) physician and bed supplies during the two periods. Both cohorts were similar in health status and in their use of hospital, nursing-home, and home-care resources despite a steady decrease in hospital beds during both periods and a shrinking supply of nursing-home beds for the later cohort. Although physician supply increased more rapidly for the first (1971) than for the second (1976) cohort, the later cohort used significantly more ambulatory care than the earlier cohort. Home care appears to substitute for year-to-year variations in nursing-home admissions but not for variations in hospital lengths of stay.

Does anesthesia contribute to operative mortality?

An anesthesia follow-up program (100,000 anesthetics) and vital statistics data were used to assess the role of anesthesia in operative deaths. Four factor groups (patient, surgical, anesthesia, and "other") were assessed by logistic regression analysis to ascertain which variables were predictive of seven-day mortality. Advanced age, male gender, physical status, major surgery, emergency procedure, procedures performed in 1975 to 1979, intraoperative complications, narcotic techniques, and having one or two anesthetic drugs administered were associated with increased mortality, whereas duration of anesthesia, experience of the anesthesiologist, and inhalation techniques were not. Receiver-operator characteristic curves showed no increment in prediction of operative mortality greater than that for patient plus surgical factors when "other" or anesthetic factors were added. Patient and surgical risk factors were much more important in predicting seven-day mortality than the anesthesia factors we studied.

Haemophilus influenzae meningitis in Manitoba and the Keewatin District, NWT: potential for mass vaccination

A community-based surveillance study of all central nervous system infections was carried out in Manitoba and the Keewatin District, NWT, between Apr. 1, 1981, and Mar. 31, 1984. There were 201 cases of bacterial meningitis in Manitoba over the study period, 81 (40%) caused by Haemophilus influenzae; all but one isolate tested were type b (Hib). There were nine cases of H. influenzae meningitis in the Keewatin District. The overall annual incidence rate of H. influenzae meningitis in Manitoba was 2.5/100,000; for children under 5 years the rate was 32.1/100,000. For the Keewatin District the corresponding rates were 69.6/100,000 and 530/100,000. A total of 85% and 100% of the cases of H. influenzae meningitis occurred by 24 months of age in Manitoba and the Keewatin District respectively. The age at onset was earlier in native Indian children (22 cases) and Inuit children (9 cases) than in non-native children (59 cases) (p less than 0.005); thus, vaccine prevention of Hib meningitis will likely be more difficult in native Indian and Métis children. Without evaluating the increased potential of H. influenzae vaccines to prevent nonmeningitic forms of disease, we concluded that mass childhood vaccination with polyribosylribitolphosphate (PRP) vaccine is not warranted in Manitoba or the Keewatin District. Immunogenicity studies suggest that administration of conjugated Hib vaccines such as PRP-D in infancy may prevent approximately one-third to two-thirds of cases of H. influenzae meningitis; these vaccines warrant consideration for use in mass childhood vaccination programs.

Do nursing homes reduce hospital use?

This study applies data from the Manitoba Longitudinal Study on Aging for two purposes. First examined were the hospital-utilization patterns of elderly nursing home admissions during the 2 years before and 2 years after entrance into a facility. In addition, use of the hospital by these new admissions and by long-term nursing home residents was compared with that of the use by the elderly living in the community. When age, sex, and mortality rate are taken into account, the results indicate that, although both new admissions and long-term nursing home residents are sicker than their community counterparts, they are significantly less frequently hospitalized.

The natural history of primary first-degree atrioventricular heart block

The long-term prognosis of first-degree heart block in the absence of organic heart disease has not been clearly defined. We addressed this question in a 30-year longitudinal study of 3983 healthy men. We identified 52 cases that were present on entry into the study and 124 incident cases during follow-up. The incidence rose steadily after age 40 and was 1.13 per 1000 person-years over the entire period. Two thirds of the cases had only moderate prolongation of the PR interval (0.22 to 0.23 second). We compared four age-matched controls with each case for histories of scarlet fever, rheumatic fever, diphtheria, smoking, blood pressure, and body-mass index. No significant differences (P greater than 0.05) were found. Likewise, mortality from all causes did not differ between cases and controls. Although somewhat higher rates of morbidity and mortality from ischemic heart disease were observed in the cases than in the controls, the differences were not significant. Progression to higher grades of heart block occurred in only two cases. In view of the prognostic findings and the rare occurrence of advanced degrees of heart block, we conclude that primary first-degree heart block with moderate PR prolongation is a benign condition. This conclusion may not apply, however, to persons with more marked prolongation of the PR interval, a very rare condition.

Variations in physicians' hospitalization practices: a population-based study in Manitoba, Canada

This paper uses claims data from a universal health care system to describe physicians' hospitalization styles after adjusting for case-mix characteristics of their primary patients. Patients were uniquely assigned to that physician (general or family practitioners, internist, general surgeon, or obstetrician/gynecologist) seen most frequently over each two two-year periods (1972-74 and 1974-76). Four indices were developed including: 1) percentage of primary patients hospitalized; 2) mean number of readmissions for such patients; 3) mean length of stay; and 4) total days of hospitalization per primary care patient (a summary measure combining the first three). Rates of admission, not length of stay, were shown to be strongly related to this summary measure. Marked variations in the hospitalization indices were observed across physicians; these variations cannot be explained by the health or sociodemographic characteristics of a physician's patients. Rural physicians practicing in areas with high bed-to-population ratios and low occupancy rates were particularly high users of hospitals. The economic implications of different practice styles are shown to be large; physicians who were high users of hospitals serve 27 per cent of the patients but their patients consume 42 per cent of the hospital days.

The electrocardiogram in apparently healthy men and the risk of sudden death

The purpose of this study was to determine whether electrocardiographic abnormalities detected on a routine examination in men without clinical evidence of heart disease predicted sudden death in the absence of pre-existing clinical manifestations of heart disease. The Manitoba study consists of a cohort of 3983 men with a mean age at entry of 30.8 years who have been followed with regular examinations including electrocardiograms since 1948. During the 30 year observation period, 70 cases of sudden death have occurred in men without previous clinical manifestations of heart disease. The prevalence of electrocardiographic abnormalities before sudden death was 71.4% (50/70). The frequency of abnormalities was 31.4% (22) major ST segment and T wave abnormalities, 15.7/ (11) ventricular extrasystoles, 12.9% (nine) left ventricular hypertrophy (voltage criteria), 7.1% (five) complete left bundle-branch block, and 5.7% (four) pronounced left axis deviation. When these electrocardiographic findings in men without clinical manifestations of heart disease were related prospectively to incidence of sudden death each one except pronounced left axis deviation was a significant predictor of sudden death. Two of the variables were examined in more detail. Increased severity of primary T wave abnormalities and the association of ST segment and T wave abnormalities with increased QRS voltage further increased sudden death risk. The combination of ventricular extrasystoles with either ST-T abnormalities or left ventricular hypertrophy much increased the risk of sudden death. Thus these data indicate that electrocardiographic abnormalities detected on routine examination in men without clinical evidence of heart disease are significantly related to the occurrence of sudden death.

Relationship of blood pressure in 20-39-year-old men to subsequent blood pressure and incidence of hypertension over a 30-year observation period

The objective of this investigation was to determine the relationship of blood pressure (BP) in young men, ages 20-39 years, to their subsequent BP from the perspective of BP tracking, position in BP distribution and later evidence of hypertensive BP values. Since 1948, the Manitoba Study group has followed 3983 men, 90% of whom were 20-39 years old at entry. BP in persons not prescribed antihypertensive medications was examined at 5-year intervals during the 30-year observation period to 1978. To adjust for age, BP was examined within 5-year age groups at entry. The correlations between entry and subsequent BP at the same length of follow-up were greater for systolic than diastolic BP and increased with older ages. The correlation decreased wtih every 5-year examination after entry for all ages. Men whose BP was below the mean at entry were less likely to have a BP greater than 1 standard deviation (SD) above the mean at any of the examinations. Men with an entry BP greater than 1 SD above the mean were more likely to have BP greater than 1 SD above the mean later, but the relationship decreased considerably after 20 years, especially in 20-24-year age group. The results were similar for the probability of hypertension values (systolic BP greater than or equal to 140 or 150 mm Hg, diastolic BP greater than or equal to 90 or 95 mm Hg) at later examinations. Thus, BP in later life can be predicted from BP at ages 20-39 years and can identify groups at high or low risk for hypertension.

The natural history of right bundle branch block and frontal plane QRS axis in apparently healthy men

We examined the characteristics, long-term follow-up, and prognosis of right bundle branch block (RBBB) detected on a routine ECG in men with no apparent heart disease. During the 29-year period, 59 cases of RBBB were observed in men with a mean age of 44.4 +/- 1.9 years. Because marked right or left axis deviation may identify cases with concomitant involvement of the left bundle branch system, subsets of frontal plane QRS (A QRS) were examined. Comparisons were made with groups of similar ages who were free of RBBB. Cases with RBBB were observed for 936 person-years (mean 15.9 +/- 1.6 years per case), showing no excess ischemic heart disease incidence, no cases of progression to advanced AV block (second- or third-degree), or sudden death. Right bundle branch block was associated with a greater proportion of both right axis (greater than or equal to +90 degrees) and marked left axis (-45 degrees to -90 degrees) deviation compared with those of the same age without this conduction disturbance. In apparently healthy men, RBBB had no adverse long-term prognosis regardless of frontal plane QRS axis.

Relationship of ventricular ectopy in men without apparent heart disease to occurrence of ischemic heart disease and sudden death

The purpose of this investigation was to determine whether ventricular ectopic beats, or ventricular premature beats (VPBs), on routine electrocardiograms in men without apparent heart disease predict the later occurrence of clinical manifestations of ischemic heart disease (IHD). The Manitoba Study cohort consisted of 3983 men predominantly between 25 and 34 years of age and free of IHD at entry. During the 29-year observation period, 401 persons without clinical evidence of heart disease had VPBs on an electrocardiogram at a routine examination. They were followed 10.8 +/- 0.5 (SEM) years and 13.5% (54 men) later manifested IHD. Age-specific total IHD incidence was significantly (p less than 0.05) greater for men 40 to 59 years of age at VPB occurrence compared to men of the same age without VPBs. The clinical manifestation with the strongest association with VPBs was sudden death. VPB characteristics of frequency, configuration, coupling interval, and postextrasystolic T-wave change did not distinguish those who developed IHD. Prematurity index (R-R'/QT) showed a trend toward an association of late coupled ectopic beats (R-R'/QT greater than 1.6) and IHD risk. However, faster basic ventricular rate plus VPBs significantly correlated with greater IHD probability. Thus ventricular ectopic beats on a routine electrocardiogram in men over 40 years of age without apparent heart disease identify those at high risk for a clinical IHD event, especially sudden death.

The relationship of marked left axis deviation to the risk of ischemic heart disease

The purpose of this study was to examine the value of marked left axis deviation in men without apparent heart disease in the assessment of ischemic heart disease risk. In the Manitoba Study, a cohort of 3983 men who were predominantly between 25 to 34 yr of age at entry in 1948, 247 cases of marked left axis deviation (mean frontal plane QRS vector of -45 degrees to -90 degrees) were identified at a mean age of 46.1 +/- 0.7 (+/- 1 SEM) yr with a mean follow-up of 12.1 +/- 0.6 yr. The results were that the development of left axis deviation in men 40 to 59 yr of age, independent of blood pressure is a significant predictor of ischemic heart disease events that are usually manifest 5 to 10 yr after the onset of this electrocardiographic abnormality. Subsets of QRS variables examined to identify cases with different degrees of ischemic heart disease risk revealed that neither Q waves in leads I or aVL, or QRS duration or actual frontal plane QRS vector identified groups with different ischemic heart disease risk. However, subsets of age (less than 40 and 60 yr or greater) perhaps reflecting different etiologies of marked left axis deviation and previous electrocardiographic findings (S1S2S3 pattern) identify a low risk group.

Chronobiology of cardiac sudden death in men

Daily variation in occurrence of sudden cardiac death was examined in 3,983 men observed since 1948. For men without previous clinical evidence of ischemic heart disease, an excess proportion of sudden cardiac deaths occurred on Mondays. For men with previous clinical evidence of ischemic heart disease, sudden cardiac death occurred more uniformly throughout the week. By comparison there was no significant daily variation in cancer mortality or in day of occurrence of myocardial infarction. Thus, for men without clinically manifest heart disease, the warning "beware on Monday" should stimulate further investigation.

Natural history of left bundle-branch block

The purpose of this study was to examine factors associated with the development of complete left bundle-branch block and the prognosis in a group of people not in hospital, who had no clinical evidence of ischaemic or valvular heart disease. Twenty-nine cases of left bundle-branch block without clinical evidence of ischaemic heart disease were noted in the Manitoba cohort of 3983 men under observation since 1948. The most frequent electrocardiographic finding before development of left bundle-branch block was a normal electrocardiogram; left ventricular hypertrophy though infrequent, was the only abnormality significantly more common than in the rest of the group. The development of left bundle-branch block was associated with distinct leftward shift of the frontal plane mean QRS axis. The most frequent clinical cardiovascular event observed after development of the block was sudden death without previous clinical evidence of ischaemic heart disease. The five-year incidence of sudden death as the first manifestation of heart disease was 10 times greater in men with left bundle-branch block than in those without it.