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Biomedical subjects

M Szklo

Publications and source records attributed to M Szklo.

At least 91 records · Page 5Linked to original sources
PubMed1991

Carotid atherosclerosis measured by B-mode ultrasound in populations: associations with cardiovascular risk factors in the ARIC study.

To assess whether carotid atherosclerosis measured by B-mode ultrasound is related to cardiovascular risk factors, 386 cases with carotid artery wall thickening and an equal number of controls free of arterial intima-media thickening were drawn from the cohort of the Atherosclerosis Risk in Communities (ARIC) Study examined in four communities in the United States between 1988 and 1990. Cases and controls were individually matched on sex, race, age group, study center, and date of examination. The mean values of total cholesterol, low density lipoprotein (LDL) cholesterol, total triglyceride, blood pressure, and pack-years of cigarette smoking were higher in cases than controls. Mean high density lipoprotein (HDL) cholesterol was lower in cases than controls. Case-control differences were all statistically significant. Multivariable-adjusted odds ratios point to differences of considerable magnitude in the risk of carotid atherosclerosis between groups defined by clinical and public health-oriented risk factor cut-points.

Arteriosclerosis↗
PubMed1991

Mammographic densities and risk of breast cancer.

To determine the relation of mammographic densities to subsequent breast cancer risk, a case-control study was undertaken using prediagnostic mammograms of screening program participants. Mammograms of cases (n = 266) and controls (n = 301) were blindly assessed for mammographic densities, which were measured by planimetry. The odds of breast cancer increased steadily with increasing breast density (test for trend, P less than 0.0001). Breast cancer odds was 1.7 for densities between 5% and 24.9%, 2.5 for 25% through 44.9%, 3.8 for 45% through 64%, and 4.3 for densities of 65% and greater (referent = less than 5% densities). Odds ratios also increased with increasing densities among women with the P2 and DY mammographic patterns. These findings suggest that the percentage of mammographic densities in the breast can predict breast cancer risk more accurately than a qualitative assessment of mammographic patterns.

Adult↗
PubMed1991

Population correlates of plasma fibrinogen and factor VII, putative cardiovascular risk factors.

Recent prospective investigations have reported that higher plasma fibrinogen concentrations and higher factor VII coagulant activity are associated with greater risk of cardiovascular disease. To discover what characteristics may influence fibrinogen and factor VII, we analyzed data from the Atherosclerosis Risk in Communities Study obtained from over 12,000 men and women, aged 45-64 years, from four communities in December 1986 to June 1989. Fibrinogen was higher in blacks than whites and in women than men; in general, it increased with age, smoking, body size, diabetes, fasting serum insulin, LDL cholesterol, lipoprotein(a), leukocyte count, and menopause, and it decreased with ethanol intake, physical activity, HDL cholesterol, and female hormone use. Factor VII was higher in women than men and, in women, increased with age; in both sexes, it increased with body size, triglycerides, LDL cholesterol, and HDL cholesterol, and it decreased with ethanol intake. These findings indicate that elevations in fibrinogen and factor VII may be modifiable through appropriate lifestyle changes.

Body Constitution↗
PubMed1990

The value of immunotherapy with venom in children with allergy to insect stings.

BACKGROUND: The treatment of patients allergic to insect stings with insect-venom injections has been shown to be 97 percent effective in reducing the risk of sting-induced anaphylaxis. However, the frequency of systemic reactions to subsequent stings in unimmunized adults with previous reactions is approximately 60 percent. To determine which factors, in addition to a history of reaction and evidence of venom-specific IgE antibody, predispose patients to future insect-sting reactions, we studied a venom-sensitive group of children who were deemed to be at relatively low risk for severe reactions; 28 percent of them received venom therapy. METHODS: We studied 242 children, 2 through 16 years of age, each of whom had had a systemic allergic reaction, affecting only the skin, to an insect sting. Each child had a positive skin-test reaction to one or more of five hymenopteran venoms. Sixty-eight children received immunotherapy with insect venom and 174 did not; about half were randomly assigned to treatment groups, and the rest were assigned on the basis of the patient's (or the parents') choice. The results of accidental stings during four years of observation were evaluated. RESULTS: In the treated group, 84 stings in 36 patients resulted in one systemic reaction (1.2 percent of stings). In contrast, 196 stings in 86 untreated children resulted in 18 systemic reactions (9.2 percent of stings, P less than 0.001). Sixteen of these 18 reactions were judged to be milder than the patient's reaction to the first sting, 2 were similar in severity, and none were more severe. CONCLUSIONS: These data confirm that immunotherapy with insect venom prevents recurrences of systemic reactions after subsequent insect stings. Because of the surprisingly low rate of reactions among untreated children, we could not identify any characteristics that were predictive of repeat reactions. Since only 9.2 percent of stings in the untreated children led to a systemic reaction and since there was no progression to a more severe reaction, we conclude that venom immunotherapy is unnecessary for most children who are allergic to insect stings.

Adolescent↗
PubMed1990

The epidemiology of idiopathic dilated cardiomyopathy in a biracial community.

An epidemiologic study of idiopathic dilated cardiomyopathy was carried out in order to identify possible risk factors for this often fatal cause of heart failure in young adults. Possible associations with black race and other genetic and environmental factors were examined by comparing newly diagnosed cases ascertained from four Baltimore hospitals (n = 95) with neighborhood controls (n = 95), matched on sex and 5-year age intervals. Matched and unmatched relative odds and conditional logistic regression coefficients were obtained to describe the associations. Statistically significant, independent associations were observed between idiopathic dilated cardiomyopathy and black race, low annual income, and history of asthma (p less than 0.05). The black predominance (relative odds = 2.7, 95% confidence interval 2.0-3.4) was not explained by income, alcohol consumption, cigarette usage, body mass index, hypertension, or asthma. A possible interactive effect was observed between black race and history of asthma and other atopic diseases. Thus, blacks, especially those with a history of hypersensitivity, may represent a high-risk subgroup in need of preventive care or early intervention.

Adolescent↗
PubMed1989

Epidemiology of insect venom sensitivity.

The prevalence of insect sting reaction and of venom sensitization in adults is unknown. We report the results of intake evaluation of a stratified random sample of a large adult population previously studied for the determinants of atopic disease. In 269 subjects, the prevalence of systemic allergic sting reactions was 3.3% and 26.5% had IgE antibodies to venom demonstrated by skin test or radioallergosorbent test. Asymptomatic sensitization (positive venom skin test) was observed in 15% of subjects with no history of an allergic sting reaction. Positive venom skin tests were more frequent in men, in those with positive skin tests to inhalant allergens, and in subjects aged 20 through 29 years. A positive venom skin test or radioallergosorbent test was more frequent in subjects who had been stung within the previous 3 years (35%) than in those stung more than 3 years before (20%). We conclude that both systemic allergic reactions to insect stings and asymptomatic sensitivity to venom are common and that most affected persons never seek medical advice. The significance of asymptomatic venom sensitization is unknown.

Adult↗
PubMed1989

Idiopathic dilated cardiomyopathy and atopic disease: epidemiologic evidence for an association with asthma.

Because of recent evidence from in vitro studies suggesting that immediate hypersensitivity or other autoimmune mechanisms may play a role in the initiation or progression of idiopathic dilated cardiomyopathy (DCM), an epidemiologic study was carried out to examine possible associations with atopic diseases and other immunologic disorders. Newly diagnosed cases were ascertained from four Baltimore hospitals and were interviewed along with neighborhood controls identified using a random digit dialing technique. The cases and controls (N = 190) were matched on sex and 5-year age intervals and were compared in the analysis using matched and unmatched estimates of the relative odds and conditional logistic regression methods. A statistically significant, independent association was observed between idiopathic DCM and a history of asthma (p less than 0.05). The association was most pronounced among individuals who were less than 55 years of age (relative odds = 20.3, p less than 0.05), with 31.1% (14 of 45) of the patients who were under the age of 55 having a reported history of asthma. These findings support the theory that hypersensitivity mechanisms may be important in the development of idiopathic DCM. A treatment effect associated with asthma is an alternative possibility.

Adolescent↗
PubMed1989

A case-control study of aplastic anemia.

A case-control interview study of aplastic anemia was conducted to evaluate suspected risk factors. Cases (N = 59) newly diagnosed during 1975-82 at 25 Baltimore area hospitals were compared with 59 individually matched (on age, sex and race) controls selected by random digit dialing. The average educational level was less for cases than controls. The major job-related findings were a significant excess for occupational exposure to paint (OR = 6.1; 95% C.I. = 1.2-29.7), further substantiated by a positive dose-response relationship, although painters were not at excess risk. An increased risk of occupational exposure to viruses (OR = 9.0; 95% C.I. = 0.8-105.6) was noted. Additional evidence implicating viral factors included a significant association with prior history of hepatitis (OR = 9.0; 95% C.I. = 1.0, 84.2) and an elevated risk for pre-diagnostic receipt of blood transfusions (OR = 7.1; 95% C.I. = 0.7-68.4). Risks were not increased for other occupational, residential, personal, or medical treatment exposures or for other viral infections, medical conditions, smoking or alcohol consumption prior to diagnosis. Because of the small number of subjects studied and the multiple comparisons examined, these findings should be interpreted cautiously and confirmation should be undertaken in larger, population-based studies.

Adolescent↗
PubMed1989

Mammographic parenchymal patterns as indicators of breast cancer risk.

Mammographic parenchymal patterns have been suggested as indicators of breast cancer risk. However, few well-controlled studies have used prediagnostic mammograms to determine the pattern classification. The authors studied 266 cases of breast cancer and 301 controls from 25 screening centers of the Breast Cancer Detection and Demonstration Project, a nationwide screening program conducted between 1973 and 1980 to evaluate the risk associated with mammographic patterns using mammograms taken four years before the detection of breast cancer. Mammograms of the cancerous breast of cases and of the ipsilateral breast in the control matched to each case were blindly assessed by one of the investigators (J.N.W.), originator of the mammographic pattern classification. The breast cancer odds ratio among women with the combined P2 + DY patterns, compared with women with the N1 pattern, was 2.8 (95% confidence interval (CI): 1.6-5.1). This estimate of relative risk was comparable with the risk associated with other recognized breast cancer risk factors. The odds ratio among P2 + DY women with a first-degree family history of breast cancer was 5.5 (95% CI: 2.6-11.8) compared with N1 women without a family history. These data provide additional evidence that mammographic patterns are indicators for subsequent development of breast cancer, particularly among women with a first-degree family history of this malignancy.

Adult↗
PubMed1989

Familial cancer history and chronic lymphocytic leukemia. A case-control study.

In a population-based case-control study carried out in the Baltimore, Maryland metropolitan area, family cancer history for 342 chronic lymphocytic leukemia cases diagnosed in 1969-1982 revealed significantly higher risks of leukemia as well as other hematolymphoproliferative neoplasms and breast cancer among their first-degree relatives compared with reported occurrence of these neoplasms in first-degree relatives of 342 matched cancer controls and 342 matched controls without cancer. Siblings of case subjects also had a significant elevation of kidney cancer compared with siblings of controls. Only one of the affected case families (and no control family) included more than one additional member with leukemia. The results suggest a genetic component for leukemia occurrence in several case families, although the majority of cases of chronic lymphocytic leukemia appeared to be sporadic. The similarity of findings between the two comparisons (cases vs. cancer controls and cases vs. controls without cancer) diminishes the likelihood of recall bias as an explanation for the observed excess risks.

Adult↗
PubMed1988

Poverty, race, and hospitalization for childhood asthma.

This study uses Maryland hospital discharge data for the period 1979-82 to determine whether Black children are more likely to be hospitalized for asthma and whether this difference persists after adjustment for poverty. The average annual asthma discharge rate was 1.95/1000 children aged 1-19; 3.75/1000 for Black children, and 1.25/1000 for White. Medicaid-enrolled children of both races had increased discharge rates for asthma compared to those whose care was paid for by other sources: 5.68/1000 vs 2.99/1000 for Blacks, and 3.10/1000 vs 1.11/1000 for Whites. When ecologic analyses were performed, populations of Black and White children had nearly equal asthma discharge rates after adjustment for poverty. The statewide adjusted rate was 2.70/1000 (95% CL = 1.93, 3.78) for Black children and 2.10/1000 (1.66, 2.66) for White children. Among Maryland counties and health planning districts, variation in asthma discharge rates was not associated with the supply of hospital beds or the population to primary-care physician ratio. We conclude that Black children are at increased risk of hospitalization for asthma, but that some or all of this increase is related to poverty rather than to race.

Adolescent↗
PubMed1987

Acquired disorders affecting the immune system and non-Hodgkin's lymphoma.

A case-control study was undertaken to determine whether a prior history of a variety of acquired disorders affecting the immune system was associated with an increased risk of non-Hodgkin's lymphoma. Cases were identified over a 4-year period (1976-1979) at the Johns Hopkins Hospital and individually matched to hospital controls on age, sex, race, and year of diagnosis. For the 109 cases and matched controls who were traced and interviewed, positive associations suggesting an increase in risk were not detected. Instead, there was a suggestion of an inverse relationship. Odds ratios (ORs) were consistently less than 1 for associations between non-Hodgkin's lymphoma and several chronic infectious diseases (OR = 0.65, 95% CI = 0.35, 1.20), chronic inflammatory diseases (OR = 0.88, 95% CI = 0.43, 1.79), autoimmune disorders (OR = 0.80, 95% CI = 0.19, 3.76), and allergic disorders (OR = 0.77, 95% CI = 0.45, 1.32). A statistically significant protective association was found for surgical removal of lymphoid tissue (OR = 0.50, 95% CI = 0.27, 0.91). Adjustment for potentially confounding variables did not change these results. These findings do not support the previously anecdotally reported impression that disorders producing a chronic antigenic stimulus are associated with the development of non-Hodgkin's lymphoma.

Adolescent↗
PubMed1987

Design and conduct of epidemiologic studies.

This article reviews the advantages and disadvantages of the experimental vis-a-vis the nonexperimental (observational) epidemiologic approach in the assessment of causal relationships. Nonexperimental epidemiologic strategies, including the study of ecologic correlations, concurrent and nonconcurrent prospective designs, as well as case-control and cross-sectional designs, are briefly discussed. Among the case-control designs, reference is made to matched and to "nested" case-control studies. These different design approaches are discussed in relation to issues of external validity, bias, confounding, interaction, and precision.

Cross-Sectional Studies↗
PubMed1987

A case-control study of breast cancer stratified by estrogen receptor status.

A population-based case-control study was conducted to examine whether tumor estrogen receptor status differentiated risk factor patterns for breast cancer. From December 1980 to December 1982, 458 women with newly diagnosed breast cancer and 568 control women, aged 20-54 years, from the Atlanta, Georgia, metropolitan area were interviewed. On the basis of tumor estrogen receptor results, cases were classified as receptor-positive or receptor-negative. Intercase analysis showed that age was positively and significantly associated with estrogen receptor-positive breast cancer (p = 0.001); the relative risk for an estrogen receptor-positive as opposed to an estrogen receptor-negative tumor was elevated threefold among women aged 50-54 years compared with those aged less than 35 years. In the case-control analysis, race was the only individual factor that demonstrated a significant difference in the risk for estrogen receptor-positive versus estrogen receptor-negative cancer (p less than 0.05), with blacks being at a 25% excess risk for estrogen receptor-negative cancer compared with whites. Although a history of benign breast disease was a risk factor for both positive and negative tumors, the association was stronger for the estrogen receptor-positive tumors. Postmenopausal women were at a lower risk for both cancer subtypes compared with premenopausal women. Compared with non-users, women who had ever taken oral contraceptives had a 16% decrease in the risk for receptor-positive cancer and a 22% increase in the risk for receptor-negative cancer. These results are consistent with the notion that certain exposure variables may relate to hormonal status, possibly by augmentation or suppression of estrogen receptor activity.

Adult↗
PubMed1987

Comparison of methods for determining occupational exposure in a case-control interview study of chronic lymphocytic leukemia.

A comparison was made between two indirect methods for linking reported lifetime occupations and industries of employment with specific exposures and with directly reported exposure information, using data from a population-based case-control interview study of chronic lymphocytic leukemia (CLL). Exposures previously suspected of being associated with CLL were examined using a job-exposure matrix developed by Hoar et al and a linkage between observed occupational exposures and specific occupations, by industry, based on data collected in the National Occupational Hazard Survey (NOHS). In general, concordance on exposure for the two occupation-exposure linkage methods was fairly poor, although it was better for some of the exposures studied (butadiene and asbestos, for which most kappas were between 0.40 and 0.60) than for others (carbon tetrachloride and benzene with kappas ranging from 0.01 to 0.12). Higher proportions of cases and controls directly reported exposure to benzene and asbestos than was determined using the two more indirect methods, neither of which showed consistently greater agreement with direct reporting.

Epidemiologic Methods↗
PubMed1986

Risk factors for definite hypertension: cross-sectional and prospective analyses of two Italian rural cohorts.

Risk factors for definite hypertension were examined using data from two Italian rural cohorts from the Seven Countries Study, originally composed of 1,712 men ages 40-59 at entry. Two approaches were used: cross-sectional examination of baseline exposure/outcome measurements; and prospective examination of data, correlating baseline measurements with subsequent definite hypertension, diagnosed at the 10-year follow-up exam. Hypertension was defined as diastolic blood pressure greater than or equal to 95 mm Hg or systolic blood pressure greater than or equal to 160 mm Hg. Included in the cross-sectional analysis were 1,437 subjects free from other cardiovascular diseases at baseline. Of these, 590 were included in the prospective analysis. Using a multiple logistic function that did not include baseline (normal) blood pressure, age, pulse rate, and weight were confirmed as risk factors for hypertension both cross-sectionally and prospectively, thus suggesting that bias cannot explain the relationship of hypertension to these factors. Although proteinuria and vital capacity were associated with hypertension in the cross-sectional analysis, no such relationships were detected prospectively, thus implying that these factors are effects, rather than determinants, of definite hypertension. Smoking had a negative prospective (but not cross-sectional) association with hypertension, which can probably be explained by survival bias at 10 years after ascertainment of smoking habits. When mean baseline blood pressure was added to the prospective multiple logistic function, it became the only factor significantly associated with hypertension (P less than 0.001), again confirming the importance of "tracking" in the determination of hypertension.

Age Factors↗