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Biomedical subjects

N M Lefcoe

Publications and source records attributed to N M Lefcoe.

At least 19 recordsLinked to original sources
PubMed1998

Pulmonary uptake of technetium-99m-sestamibi induced by dipyridamole-based stress or exercise.

UNLABELLED: On poststress images with 99mTc-sestamibi (MIBI), increased lung uptake of the radiotracer may reflect severe or multivessel coronary artery disease. METHODS: We measured pulmonary/myocardial ratios of MIBI at standardized times on immediate poststress acquisitions and on delayed tomographic acquisitions. In 1500 sequential patients referred for rest and stress myocardial tomography, ancillary planar images were obtained 4 min postinjection at peak stress with exercise, either alone (exercise, n = 674), or after intravenous dipyridamole (dipyridamole, n = 826). RESULTS: Based on 95% confidence limits in the angiographic normals, high values for immediate acquisitions were found in 17% of dipyridamole studies and 15% of exercise studies. High values for delayed acquisitions were found in 10% of dipyridamole studies and 9% of exercise studies. For both stress modes, increased values were related (p < 0.001) to ischemic perfusion defects for immediate images, to fixed defects for delayed images, and to ventricular dilation in both cases. By logistic regression analysis, body weight and history of infarction were also minor independent determinants (p < 0.01) of delayed acquisitions. In a subset of 250 cases with angiographic correlation (163 with dipyridamole; 87 with exercise), immediate lung uptake was highly correlated with ventricular dysfunction and with coronary stenoses (p < 0.0001). Relationships were similar to those in a historic control series imaged with 201TI. Values for delayed poststress images, and for corresponding rest images, showed strong relationships to ventricular dysfunction but not to stenosis severity. CONCLUSION: The relationships of immediate lung uptake to scintigraphic and angiographic disease patterns suggest its possible diagnostic use as an indicator of stress-induced ventricular decompensation.

Cardiac Catheterization↗
PubMed1993

An evaluation of the workplace smoking bylaw in the city of Toronto.

Random-digit dialing surveys were conducted before (n = 1543) and 8 to 9 months after (n = 1430) implementation of the city of Toronto workplace smoking bylaw. Compared with workers in the rest of metropolitan Toronto and persons not working outside the home, city workers evidenced more positive changes in regard to knowledge of the bylaw, its requirements, and enforcement provisions. City workers reported more changes in workplace restrictions and satisfaction with such restrictions. Patterns of smoking at work changed.

Health Knowledge, Attitudes, Practice↗
PubMed1992

Does cigarette smoking affect the fitness of young adults? Rationale and protocol for future research.

While there is considerable evidence of the direct effects of cigarette smoking upon the cardiovascular and respiratory systems, one result of impaired function, that is how cigarette smoking affects fitness and athletic performance, has not been well documented. Because of the potential impact that exercise might have as a substitute for smoking, it is important to delineate relationships, particularly for those who are just beginning to smoke. Literature is presented as a rationale for research in this area and results of a pilot study on smokers and non-smokers are reported. A number of trends in the fitness and pulmonary function tests emerged, suggesting this line of research be pursued.

Adult↗
PubMed1991

The effects of counseling on smoking cessation among patients hospitalized with chronic obstructive pulmonary disease: a randomized clinical trial.

Seventy-four cigarette-smoking patients admitted with COPD to the Chest Unit of a 600-bed teaching hospital served as subjects for a randomized trial of smoking cessation counseling. All patients were advised to quit smoking and smoking in the unit was not allowed. One-half of the patients were, in addition, provided with a self-help manual and three to eight 15- to 20-min counseling sessions on alternate days while in hospital. Self-reports of smoking status were obtained at 3 and 6 months, a sample of which were validated with serum COHb. The results were disappointing. Differences between the counseled group and the controls both in rates of cessation at 6 months (33.3% vs 21.4%) and, for patients still smoking, reductions in amount smoked would have lacked practical significance even if statistical significance had been obtained. Some alternative treatment approaches are suggested for this group of patients.

Adult↗
PubMed1990

A study of the mechanism of the antiasthmatic action of inhaled budesonide.

Inhaled antiasthmatic steroids have been assumed and yet never proved to exert their antiasthmatic effect by topical action in the airways. We tested the hypothesis that the efficacy of inhaled budesonide (BUD) might be due instead to its systemic activity after absorption. We compared inhaled and oral BUD with doses selected to ensure higher peak plasma levels and a greater area under the plasma concentration curve with the oral treatment. After pretreatment with beclomethasone to maximize asthma control, 47 adults with asthma were randomized to receive 0.4 mg of inhaled BUD per day (n = 16) or 1.4 mg of oral BUD per day (n = 15), or placebo (n = 16) in double-blind fashion and then followed weekly until asthma relapsed or for 8 weeks if no relapse occurred. "Relapse" was defined as a drop in the mean peak expiratory flow rate greater than 2 SEM below the mean during the baseline week before switching to the test drugs. The time to relapse was the primary outcome variable. Time to relapse was longer with inhaled than with oral BUD (medians, 22 versus 7.9 days; p = 0.003) or placebo (medians, 22 versus 9 days; p = 0.004). Oral BUD and placebo did not differ (p = 0.41). The morning serum cortisol levels remained normal during all three treatments. Thus, at conventional dosage the antiasthmatic effect of inhaled BUD may be fully explained by a local intrapulmonary action.

Administration, Inhalation↗
PubMed1989

Bioequivalent doses of budesonide and prednisone in moderate and severe asthma.

We determined the relative antiasthmatic and systemic glucocorticoid potencies of inhaled budesonide (BUD) versus morning-dose oral prednisone (PRED) in 34 adult patients with asthma over a dose range extending from conventional to high and potentially toxic levels, 3.2 mg of BUD or 40 mg of PRED per day. Changes in symptom frequency and severity, FEV1, and peak expiratory flow rate were measured during a double-blind, double-dummy controlled, crossover protocol. The drugs proved equally effective, provided a sufficient dosage was administered. The dose required to eliminate recurrently disabling asthma relapses in these patients was about 2.0 mg of BUD per day or greater than 40 mg of PRED per day. On the average, BUD doses greater than or equal to 1.84 mg/day/70 kg adult (26.3 micrograms/kg/day) exhibited systemic effects on the 8 AM serum cortisol level and blood eosinophil count equivalent to greater than or equal to 15 mg of PRED per day. The latter doses are known to be associated with steroid-induced complications, such as osteoporosis. However, the level of systemic glucocorticoid activity produced by any particular dose of BUD in these patients was consistently much lower than that produced by the dose of PRED needed to achieve an equivalent level of antiasthmatic response. Thus, the use of high-dose inhaled BUD appears clinically reasonable and ethically acceptable in patients with severe asthma in whom the alternative is their continuing dependency on PRED.

Administration, Inhalation↗
PubMed1988

Self-reported long-term smoking cessation in patients with respiratory disease: prediction of success and perception of health effects.

Smoking status of 372 patients with respiratory disease, who had been advised to quit smoking by a respiratory specialist, was assessed six months after the advice. A multiple logistic regression model was developed for prediction of successful abstinence. The patients were again followed four to seven years later. Questionnaires were returned by 160 patients (43.0%). Of the remaining patients, 27 (7.3%) had died, 12 (3.2%) refused to participate, 53 (14.2%) had no current address available and 120 (32.3%) did not return questionnaires mailed to them. Among the respondents, 31.9% reported at least one year of abstinence from cigarettes, 63.1% were still smoking and 5.0% had quit smoking for periods of less than one year. While the original logistic model was not very useful for predicting long-term success (69.7% accuracy of classification), a model that included, as predictors, six-month smoking status and reasons for smoking other than addiction, was more useful (78.9% accuracy). At follow-up, successful abstainers reported improvement in their respiratory condition but no differences were found in reported symptoms or emotional well-being when they were compared to those who continued to smoke. Treatment implications of these results are discussed and include offers of alternative treatments if short-term abstinence is not achieved following physician advice.

Attitude to Health↗
PubMed1988

Intensity of follow-up. Effects on estimates in a population telephone survey with an extension of Kish's (1965) approach.

Information from a population telephone survey of attitudes of residents of the Province of Ontario, Canada, toward legislation to restrict smoking was used to examine the effects of intensity of follow-up on population estimates. It was found that the bias introduced to the attitude estimates by less intensive follow-up was smaller than the bias introduced to estimates of sociodemographic characteristics and smoking status. An algebraic determination of the components contributing to the bias in the attitude estimates was used to investigate how the relation between smoking status and certain attitudes influenced the relation between attitude and intensity of follow-up. This required an extension of the approach described by Kish (Survey Sampling. New York: John Wiley and Sons, 1965.)

Adult↗
PubMed1987

Short- and long-term prediction of self-reported cigarette smoking in a cohort of late adolescents: report of an 8-year follow-up of public school students.

The purpose of this study was to assess accuracy in predicting adolescent smoking status using attitude, knowledge, behavioral, and sociodemographic variables. A cohort of 4,641 schoolchildren was tested in 1975 (grades 4-6), in 1978 (grades 6-8), and, finally, in 1983 (grades 10-12). From 1978 to 1983, eight variables were used to account for 25% of the variance in smoking status. Over the 8-year period, six variables accounted for 13% of the variance. In both models, prior experience with cigarettes, peer and parental smoking, sex, and student intention were used. Tests of the Ajzen-Fishbein model and social learning theory indicate that social factors were more important than attitudinal ones in predicting future smoking, but these relationships were relatively weak. However, for both long- and short-term prediction, previous behavior proved to be the best predictor. Implications for the design of prevention programs are discussed.

Adolescent↗
PubMed1987

A population survey in Ontario regarding restrictive measures on smoking: relationship of smoking status to knowledge, attitudes and predicted behaviour.

A population survey of Ontario residents regarding knowledge of the health effects of smoking, attitudes towards restrictive measures, and predicted behaviour was carried out. Telephone responses of 490 current, 290 former, and 581 never smokers were compared. For both active and passive smoking, never smokers were most knowledgeable about health effects, former smokers being less knowledgeable, and current smokers least so. While a majority of each smoking status group supported some restriction on smoking in all 13 settings examined, there were consistent differences among the groups as to degree. Never and former smokers were in close agreement and were more restrictive in their attitudes than current smokers. Prohibition was more strongly favoured by all groups for health and day care facilities, schools, stores, and local transit systems than for other settings. While a majority of smokers thought there would be compliance with restrictions, non-smokers were less optimistic. Smokers were less likely than non-smokers to see a role for governments in enactment; municipal involvement was favoured over other levels by all groups. No group indicated much support for enforcement by police. These findings remained when multivariate analyses controlling for inter-group differences in sociodemographic characteristics were carried out.

Adult↗
PubMed1986

Change in smoking status among a cohort of late adolescents: prediction and explanation of initiation, maintenance and cessation.

This study examined the degree and type of changes in adolescent smoking status that occurred over an eight-year period, when the group was in grades four to six, to late adolescence and early adulthood. Where changes in smoking occurred, they were more likely to be in the direction of increased (57.7%), as compared to decreased (4.1%) involvement with smoking, particularly among females. Discriminant function models were developed and resulted in 60% accuracy of classification. Variables measured in 1975 found to be related to change in status (from 1975 to 1983) were early smoking, sex, age, peer and parental smoking, prediction of future smoking, attitude and knowledge. Changes in some of the independent variables were examined and found to be related to changes in smoking. Implications for prevention and cessation programmes are discussed.

Adolescent↗
PubMed1984

Use of spacers to facilitate inhaled corticosteroid treatment of asthma.

Budesonide, a topically active corticosteroid, was administered in doses of 400 and 1,600 micrograms/day to 35 asthmatic adults, using a standard inhalation device or a tube or cone spacer. The spacers reduced oropharyngeal candidiasis by an amount equivalent to a 90% reduction in drug dose (p = less than 0.005) and doubled the drug's overall antiasthmatic potency (delta FEV1, p = 0.05) without significantly increasing its overall effect on blood eosinophils (p = 0.14) or the A.M. serum cortisol (p = 0.12). Steroid-induced neutrophilia increased by an amount approximating that produced by an extra half tablet of prednisone per day (p = 0.002). Both the airways and systemic effects of the spacers were greater in patients who had small airways dysfunction present prior to the study. The data suggest an increase in intrapulmonary drug deposition during spacer treatment without a material shift in regional delivery within the lung. Spacers should be particularly useful for patients whose response to inhaled steroid is compromised by by dose-limiting oropharyngeal complications. They can also reduce drug costs. They should be used selectively in children until their effect on regional intrapulmonary drug deposition has been more clearly defined.

Administration, Topical↗
PubMed1984

Personal observations on the use of inhaled corticosteroid drugs for chronic asthma.

Topically active inhaled corticosteroid (IC) drugs are highly effective for chronic asthma. Formalized conceptions of "high, low or safe" dosages of these drugs may be less appropriate than one of "optimal dosage". It seems reasonable to formulate a specific goal of treatment, and then fit dosage to the individual needs and tolerances of the patient rather than to a conventionalized "safe" limit, based on averaged data from different and perhaps quite dissimilar subjects. The studies reviewed here illustrate some principles applicable to the effective use of IC drugs.

Aerosols↗
PubMed1983

Use of a self-help smoking cessation manual as an adjunct to advice from a respiratory specialist.

The purpose of the present study was to determine the effectiveness of a self-help smoking cessation manual for patients with pulmonary disease. All patients were advised to quit smoking by a respiratory specialist. Thirty-five patients were then provided with a manual detailing techniques for quitting; the remaining 40 patients served as a control and were given no additional information or instruction following advice. The cessation rate in the treatment group was 16.7%; and in the control group, 25.6%. This difference was not statistically significant. Approximately half of the patients who received the manual used it, and only 12.5% of the users found it helpful. It was concluded that providing patients with the specific instructions on quitting smoking as presented in the manual did not appear to be useful.

Adult↗