Biomedical subjects

S Suissa

Publications and source records attributed to S Suissa.

At least 127 records · Page 7Linked to original sources

PubMed1988

Working disability due to occupational back pain: three-year follow-up of 2,300 compensated workers in Quebec.

A cohort of 2,342 cases constituting a random sample of all occupational back injuries compensated in Quebec (Canada) during 1981 was observed prospectively for 3 years to study associations between cumulative duration of absence from work and sex, age, site of symptoms (cervical, thoracic, and lumbar), and occupation. Of the cohort members, 227 (9.7%) cumulated 6 months of absence or more. A logistic regression model showed age and site of symptoms to be the two most important risk factors associated with absences of 6 months or more. No association was found with sex or occupation. The results showed discrepancies between measures of frequency distribution of back injuries and duration of absence from work, an important finding in terms of identifying health priorities.

Absenteeism↗

PubMed1987

Proliferative characteristics of chronic crypt cells in C57BL/6J and A/J mice as predictors of subsequent tumor formation.

It has been proposed that the number and extent of tumors formed after chronic exposure to dimethylhydrazine (DMH) can be predicted by the indigenous number and distribution of DNA-synthesizing cells in the murine colonic mucosa, and that this sensitivity to DMH is genetically determined. In order to test this hypothesis we studied two genetically distinct inbred strains of mice; the DMH-sensitive A/J (A) mouse, and the relatively DMH-resistant C57BL/6J (B) mouse before and after a single exposure to DMH. The untreated A strain had the longer crypt column [33.2 +/- 0.8 (SD) cells versus 28.8 +/- 0.9 cells], a higher absolute number of labeled cells per crypt column (4.4 +/- 0.6 versus 2.6 +/- 0.9), a greater labeling index (13.4 +/- 1.6% versus 9.1 +/- 2.9%), a wider proliferative compartment, and a greater number and percentage of labeled cells in the middle and upper thirds of the crypt than the untreated B strain. After acute exposure to DMH the A strain lost 14 +/- 3% of their total body weight, while the B strain lost 0.5 +/- 2% total body weight 48 h post-DMH. There was an initial loss of cryptal cells, a drop in the labeling index, and a subsequent increase and overshoot in the number of labeled cells and the labeling index. This pattern of cell loss and recovery over time was parallel in both strains, and thus cannot explain the differences in ultimate tumor formation after chronic exposure to the carcinogen. The data are consistent with the theory that the susceptibility to DMH carcinogenesis can be predicted by the indigenous proliferative characteristics of the murine colonic mucosa. The acute proliferative response to DMH in these strains is similar and parallel; thus ultimate tumor load may depend on long term effects such as the establishment of stable transmissible mutations.

1,2-Dimethylhydrazine↗

PubMed1987

Predicting nocturnal hypoglycemia in patients with type I diabetes treated with continuous subcutaneous insulin infusion.

The incidence of low nocturnal blood glucose values (i.e., less than 65 mg/dl) was assessed in 20 insulin-dependent diabetic patients treated with continuous subcutaneous insulin infusion supported by capillary blood glucose monitoring before each meal and the evening snack. Patients were randomly assigned to a control or experimental group. Both groups followed an identical protocol for the first part of the study (baseline). Patients were instructed to determine capillary blood glucose measurements five times during the night for three consecutive nights. The same procedure was repeated one week later, but this time the subjects in the experimental group were instructed to have an extra snack if capillary blood glucose levels at 10:30 P.M. were 120 mg/dl or less. The control group continued with the usual routine of one evening snack at 9 P.M. At baseline, the incidence of capillary blood glucose values of less than 65 mg/dl was 13 percent. The ingestion of an extra snack at bedtime resulted in the absence of capillary blood glucose values of less than 65 mg/dl in the experimental group, whereas the incidence of capillary blood glucose values of less than 65 mg/dl in the control group remained 13 percent (p = 0.038). The capillary blood glucose concentration at 10:30 P.M. was highly predictive of the risk of nocturnal blood glucose values below 65 mg/dl (p = 0.015) and fasting capillary blood glucose values above 140 mg/dl (p = 0.0001). These data show that nocturnal hypoglycemia may be a considerable problem during continuous subcutaneous insulin infusion therapy even if the basal infusion rate is adjusted in the hospital on the basis of nocturnal blood glucose concentrations. The ingestion of an extra snack at bedtime for capillary blood glucose values below 120 mg/dl has the potential to minimize this risk. The capillary blood glucose concentration at 10:30 P.M. is a significant predictor of nocturnal hypoglycemia.

Adolescent↗

PubMed1987

Metaiodobenzylguanidine [131I] scintigraphy detects impaired myocardial sympathetic neuronal transport function of canine mechanical-overload heart failure.

In heart failure secondary to chronic mechanical overload, cardiac sympathetic neurons demonstrate depressed catecholamine synthetic and transport function. To assess the potential of sympathetic neuronal imaging for detection of depressed transport function, serial scintigrams were acquired after the intravenous administration of metaiodobenzylguanidine [131I] to 13 normal dogs, 3 autotransplanted (denervated) dogs, 5 dogs with left ventricular failure, and 5 dogs with compensated left ventricular hypertrophy due to a surgical arteriovenous shunt. Nine dogs were killed at 14 hours postinjection for determination of metaiodobenzylguanidine [131I] and endogenous norepinephrine content in left atrium, left ventricle, liver, and spleen. By 4 hours postinjection, autotransplanted dogs had a 39% reduction in mean left ventricular tracer accumulation, reflecting an absent intraneuronal tracer pool. Failure dogs demonstrated an accelerated early mean left ventricular tracer efflux rate (26.0%/hour versus 13.7%/hour in normals), reflecting a disproportionately increased extraneuronal tracer pool. They also showed reduced late left ventricular and left atrial concentrations of tracer, consistent with a reduced intraneuronal tracer pool. By contrast, compensated hypertrophy dogs demonstrated a normal early mean left ventricular tracer efflux rate (16.4%/hour) and essentially normal late left ventricular and left atrial concentrations of tracer. Metaiodobenzylguanidine [131I] scintigraphic findings reflect the integrity of the cardiac sympathetic neuronal transport system in canine mechanical-overload heart failure. Metaiodobenzylguanidine [123I] scintigraphy should be explored as a means of early detection of mechanical-overload heart failure in patients.

3-Iodobenzylguanidine↗

PubMed1987

Importance and economic burden of occupational back pain: a study of 2,500 cases representative of Quebec.

The objectives of the study were to estimate the rate of 1-year incidence of occupational back pain, describe the duration of absence from work, and assess medical and economic aspects of this problem. A total of 2,523 files of occupational back pain, representative of the Province of Quebec for the year 1981, were examined by a multidisciplinary team. Census data from 1981 were used for the denominators. The overall 1-year incidence in 1981 was 1.37%. The age-specific incidence rates show an increase-decrease pattern that could be interpreted as a "healthy worker effect". The male to female relative risks by age range from 5.6 (20 to 24 years old) to 1.8 (55 to 64 years old). In the 1-year follow-up, 74% of the workers were absent for less than 1 month. The 7.4% of cases who were absent from work for more than 6 months accounted for nearly 75% of lost days, medical costs, and indemnity payments. We pinpoint some methodologic issues of studies on occupational back pain.

Absenteeism↗

PubMed1986

Last days: a study of the quality of life of terminally ill cancer patients.

Behavior of a number of Quality of Life measures gathered from two samples of terminal cancer patients over the last weeks of their lives are reported. Samples represent patients in the 26 hospices participating in a nationwide U.S. demonstration project and patients in the palliative care units of two Montreal hospitals. The U.S. data reported are quality of life measures made by a lay principal care person (PCP) or trained interviewer; the Montreal measures were made by both an attending doctor and an attending nurse. The general finding, as expected, is one of increasing deterioration in quality of life, with accelerated deterioration between 3 and 1 week of death. Pain follows a somewhat different pattern than other measures. More patients are in either of the extreme categories at an earlier point in time than found for other measures, and there are fewer changes as death is approached. Finally, about 20% of the patients do not fall into extremely low quality of life categories, even in the week prior to death.

Activities of Daily Living↗

PubMed1986

Brain stem tumors in children: results of a survey of 62 patients treated with radiotherapy.

A survey was conducted by the Radiation Oncology Discipline Committee of the Pediatric Oncology Group to provide an estimate of the outcome of treatment with modern radiotherapy of brain stem tumors in children. Thirteen of thirty-eight institutions submitted data for 62 patients who had been diagnosed between 1972 and 1981, who had completed planned treatment with radiotherapy, and for whom follow-up information was available. The results were poor. Fourteen patients were alive with no evidence of recurrence between 11 and 154 (median 50.5) months post-treatment, two were alive with disease at 22 and 24 months, and forty-six died of disease at intervals ranging from 2 to 30 (median 8.7) months from initiation of treatment. Actuarial survival was 50% at 1 year, 29% at 2 years, and 23% at 5 years. The age of the patient, the surgical approach, and the volume and dose of radiotherapy all appeared to correlate with outcome on univariate analysis; but on multivariate analysis a statistically significant survival advantage was found only for patients greater than 5 years of age who had undergone surgery as part of their treatment. Possible explanations for these findings are discussed, and the roles of surgery, radiotherapy, and chemotherapy are reviewed.

Adolescent↗

PubMed1986

Radiation response of haematopoietic cell lines of human origin.

Six human haematopoietic cell lines, five of leukaemic origin, including cells with myeloid, lymphoid and undifferentiated phenotype have been studied with respect to radiation response. The intrinsic radiosensitivity of the cells varied widely, the D0s ranging from 0.53 to 1.39 Gy. Five of the cell lines showed some capacity to accumulate sublethal damage; in three of these, enhanced survival was demonstrated in split-dose experiments. One cell line (HL-60) was anomalous in that although little accumulation of sublethal damage was demonstrable, survival was enhanced by fractionation of the dose. Five of the six cell lines studied were of leukaemic origin. The results support the belief that, in contrast to the almost constant radiosensitivity of normal haematopoietic cell progenitors, leukaemic cell progenitors may show a wide range of radiosensitivites.

Cell Line↗

PubMed1986

Further examination of the reliability of the Modified Rathus Assertiveness Schedule.

The reliability of the 30-item Modified Rathus Assertiveness Schedule (MRAS) was examined using the test-retest method over a three-week period. The MRAS, which was administered to 103 white middle-class seventh graders, yielded correlations of .74 using the Pearson product and Spearman Brown correlation coefficient. The correlations for males yielded .77 and .72 using the Pearson Product and Spearman Brown techniques, respectively. For females the correlations for both tests were .72. Paired t tests by sex indicated no significant change in MRAS scores between test administrations. These findings add to the existing information on the reliability of the MRAS.

Adolescent↗

PubMed1986

Sex-specific criteria for interpretation of thallium-201 myocardial uptake and washout studies.

A study was undertaken to determine the effect of gender on criteria for the quantitative analysis of exercise-redistribution 201Tl myocardial scintigraphy. The studies of 26 normal females and 23 normal males were subjected to bilinear interpolative background subtraction and horizontal profile analysis. Significant sexual differences were found in both regional uptake ratios and washout rates. These differences primarily reflected a proportionately decreased anterior and upper septal uptake in females, and faster washout in females. Faster myocardial 201Tl washout rates in females could not be clearly ascribed to either a physiological or artifactual explanation. It is concluded that since important differences exist between males and females in the detected pattern of 201Tl myocardial uptake and washout, sex-specific criteria may enhance the predictive accuracy of exercise-redistribution 201Tl myocardial scintigraphy.

Adult↗

PubMed1986

Four-year results of a youth smoking prevention program using assertiveness training.

Assertiveness training and its relationship to smoking behavior and how young adolescent boys and girls differ with respect to assertion was investigated. A total of 161 seventh-grade students from six health education classes participated. Two classes received an innovative smoking education program, two classes received assertiveness training plus an innovative smoking education program, and two classes received only the smoking education program usually offered by the school. Locus of control and levels of assertion and smoking behavior were assessed at pre- and posttest. The results indicate that boys are significantly more assertive than girls at age 12 (p = .0018), and this assertiveness increases equally over the next four years (p less than .0001). There were no significant differences in smoking behavior among the three groups; however, trends in smoking behavior in the desired direction were observed. There is no significant difference in smoking behavior between boys and girls. In this respect the sexes have reached equality, that is, girls are initiating cigarette smoking as frequently as are boys. Finally, there were no significant changes in assertion among the groups. It is concluded that the utility of assertiveness training for young adolescents is questionable.

Adaptation, Psychological↗

PubMed1983

Weight changes of male dairy calves following zeranol implants.

In a trial to determine the effect of zeranol implants on weight gains from birth to 180 days of age, 269 male Holstein calves were assigned randomly to one of three groups: a) 56 intact calves, b) 106 castrated calves implanted at birth and again at 90 days with 36 mg zeranol, and c) 107 castrated controls. All calves were weighed at 0, 28, 56, 90, and 180 days of age. Zeranol-implanted steers averaged 9.2% greater average daily gain at 90 days and 9.5% greater at the end of the trial than control steers. Intact male calves' weight gains were intermediate between the two steer groups. There was no correlation between implant status, total protein of blood serum, mortality, birth weight, or parity of the dam. During the first 180 days of age, implanting the first 180 days of age, implanting Holstein calves with zeranol at birth and reimplanting at 90 days can return upwards of $14.89 per dollar invested.

Animals↗

PubMedDate not supplied

Antihypertensive drug therapy in Saskatchewan: patterns of use and determinants in hypertension.

BACKGROUND: The benefits of continuous treatment of hypertension have been extensively documented in randomized controlled trials. However, clinical trials may not reflect actual drug use in the population. OBJECTIVE: To examine the distribution and determinants of patterns of use of antihypertensive agents in the first 5 years of hypertension treatment in Saskatchewan. METHODS: Patterns of use and modifications to therapy were derived from a careful examination of medication use in a cohort of 19 501 subjects aged 40 to 79 years, without recognized cardiac disease and initiating therapy with an angiotensin-converting enzyme inhibitor, a calcium antagonist, or a beta-blocker in Saskatchewan between 1990 and 1993. RESULTS: Angiotensin-converting enzyme inhibitors (37.4%), followed by calcium antagonists (27.5%) and beta-blockers (26.4%), were the most commonly prescribed agents to initiate treatment in our study population. Patients with diabetes were less likely to be dispensed a beta-blocker, as were younger and female patients. Previous visits to a cardiologist decreased the likelihood of receiving combination therapy or angiotensin-converting enzyme inhibitors but increased that of using calcium antagonists. Apart from dose adjustment, 89% of study subjects underwent at least 1 modification to their initial regimen, at a median time of 134 days. After 1 year, only 33.8% of patients were still using their initial drug. An early decrease in the proportion of patients continuing to receive initial therapy was noted, especially among beta-blocker users. CONCLUSIONS: Erratic drug-taking behaviors were observed in this Saskatchewan population. In addition, initial drug use does not seem to be in accordance with the stepped-care approach to hypertension therapy recommended in the Canadian guidelines.

Adrenergic beta-Antagonists↗

PubMedDate not supplied

Antihypertensives and myocardial infarction risk: the modifying effect of history of drug use.

PURPOSE: Confounding by indication is common in observational studies of outcomes that treatment is intended to affect. In light of the stepped-care approach to hypertension management, we reexamined the controversy around myocardial infarction (MI) risk in relation to antihypertensive agents by considering past drug history both as a confounder and as an effect modifier. METHODS: Case-control design nested within a cohort of 19,501 adults initiating therapy with angiotensin-converting enzyme inhibitors (ACEI), calcium channel blockers (CCB) or beta-blockers in Saskatchewan (1990-93) and followed up to 1997. MI cases were identified using death certificates and hospital discharge diagnoses (ICD-9,410). Four controls were matched to each case to account for duration and timing of follow-up. RESULTS: 812 MI cases were identified, of which 26% were fatal. At first, current use of CCB and ACEI (versus beta-blockers) appeared to be associated with an increased risk of MI (RR = 2.2; 95% CI = 1.8-2.7 and RR = 1.3; CI = 1.0-1.6 respectively). Adjustment for drug use history attenuated both associations (RR = 1.6; CI = 1.1-2.2 and RR = 1.0; CI = 0.7-1.4). Moreover, the risk for CCB use disappeared when restricted to patients who had already used these agents in the past (RR = 1.1; CI = 0.77-1.7) whereas a high risk of MI for ACEI was found in digoxin users (RR = 9.4; CI = 3.2-27.5). CONCLUSION: Past drug history can be both a confounder and an effect modifier in observational studies. We found adjustment for medication history to attenuate the associations between antihypertensive agents and MI risk. In addition, the estimates significantly varied across drug history profiles thus suggesting the presence of preferential prescribing of specific drug classes to high-risk patients.

Adrenergic beta-Antagonists↗

PubMedDate not supplied

Statistical methods in pharmacoepidemiology. Principles in managing error.

To successfully appraise the significance of epidemiological data on drug risk and safety requires a good understanding of the errors involved in the design and analysis of pharmacoepidemiological studies. A proper comprehension of the repercussions of these errors and of the strengths and limitations of the tools used to measure their magnitude are essential to sound decision making by the regulatory, industry or clinical consumers of these data. In this paper, we examine the role of statistics in managing the quantifiable errors present in pharmacoepidemiological data analysis and interpretation. Some epidemiological principles on the measurement of risk are first introduced. The influences of controllable systematic error and random error on our assessment of epidemiological data are then presented, along with the prevailing statistical principles and measures necessary to control these errors. To illustrate the various issues addressed, published data on the risks of NSAIDs, focusing particularly on upper gastrointestinal bleeding (UGIB), the risks of replacement estrogens for endometrial cancer and the safety of allopurinol for cataracts are used as examples throughout.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMedDate not supplied

Risk of fatal and near-fatal asthma in relation to inhaled corticosteroid use.

OBJECTIVE: To examine the relationship between patterns of use of inhaled beclomethasone dipropionate and the risk of fatal and near-fatal asthma. DESIGN: Nested case-control analysis of a historical cohort; a further analysis. SETTING: The 12,301 residents of Saskatchewan aged 5 to 54 years who were dispensed 10 or more asthma drugs from 1978 to 1987. PATIENTS: The 129 persons who experienced asthma death (n = 44) and near-death (n = 85) and their 655 controls matched as to age and date of entry into the cohort, with the additional matching criteria of at least one hospitalization for asthma in the prior 2 years, region of residence, and having received social assistance. MAIN OUTCOME: Life-threatening attacks of asthma defined as death due to asthma or the occurrence of hypercarbia, intubation, and mechanical ventilation during an acute attack of asthma. RESULTS: After accounting for the risk associated with use of other medications and adjustment for markers of risk of adverse events related to asthma, subjects who had been dispensed, on average, one or more metered-dose inhalers of beclomethasone per month over a 1-year period had a significantly lower risk of fatal and near-fatal asthma (odds ratio, 0.1; 95% confidence interval, 0.02 to 0.6). CONCLUSION: These data support recent guidelines from several countries that recommend the use of inhaled corticosteroids in moderate and severe asthma.

Administration, Inhalation↗

PubMedDate not supplied

Determinants of preventive practices of general practitioners in Torino, Italy.

We conducted a study of general practitioners in Torino, Italy, to determine their patterns of preventive practice. We examined a set of primary and secondary preventive interventions and their determinants. We explored the determinants of primary preventive interventions (antismoking and alcohol abuse counseling, counseling for prevention of accidents at home among the elderly, flu vaccination for the elderly, and counseling on contraceptive use) and cancer early detection techniques (chest x rays and sputum cytology for lung cancer; mammography, physical examination, teaching of breast self-examination, and Papanicolaou [Pap] smear for gynecological cancers). Grouping determinants in cognitive, sociodemographic, and organization factors, we found different patterns for each maneuver. Cognitive factors played an important role, but their importance varied for each intervention. We found that smoking behavior of physicians predicted antismoking counseling. Further, the availability of other primary care services is an important factor in the early detection of gynecological cancers.

Accident Prevention↗

PubMedDate not supplied

A study of mortality near sour gas refineries in southwest Alberta: an epidemic unrevealed.

Concerns about excesses in a wide array of adverse health outcomes have been expressed for over 25 years by a rural population in southwestern Alberta, living downwind from natural gas refineries. Among these has been the perception that deaths have occurred more frequently than ought to have been expected. As part of a large field epidemiologic study undertaken during the summer of 1985 to investigate possible health effects in this area, a residential cohort study was carried out to study mortality. The cohort was defined as all those individuals who resided in the area in 1970. A total of 30,175 person-years of risk within Alberta were experienced by this cohort during 1970-84. The deaths during this period were enumerated by resident reports and by manual record linkage with the death records of the Alberta Bureau of Vital Statistics. Age- and sex-standardized mortality ratios, based on expected rates from 2 pre-specified demographically similar, non-metropolitan Southern Alberta populations, were 0.88 and 0.84 respectively, neither of which was significantly different from unity. These data cannot address the question of etiology but they can do much to allay the anxieties of a community convinced it had experienced an epidemic of death.

Adult↗