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Biomedical subjects

M T Schechter

Publications and source records attributed to M T Schechter.

197 records · Page 11Linked to original sources
PubMed1985

The Vancouver Lymphadenopathy-AIDS Study: 3. Relation of HTLV-III seropositivity, immune status and lymphadenopathy.

In a study of 394 homosexual men recruited at the primary care level the prevalence of antibody to human T-lymphotropic retrovirus (HTLV-III) was higher among those with lymph node enlargement than among controls. The degree of abnormal immune function, as shown by abnormalities in immunoglobulin levels, immune complex activity and T-lymphocyte subsets, was correlated with the extent of lymphadenopathy. A similar pattern of immunologic abnormality was associated with seropositivity for HTLV-III antibody. However, HTLV-III seropositivity was the major determinant of immune function after adjustment for lymph node status. The results suggest that the immune dysfunction seen in patients with lymphadenopathy is due for the most part to the high prevalence of HTLV-III seropositivity in these populations. Lymphadenopathy, in many subjects, may in fact represent a physical sign of a stabilized compensated homeostatic host response. Factors responsible for severe immune decompensation associated with acquired immune deficiency syndrome (AIDS) may best be sought by prospective study of HTLV-III seropositive asymptomatic patients or those with stable persistent generalized lymphadenopathy and relatively normal immune function.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The Vancouver Lymphadenopathy-AIDS Study: 2. Seroepidemiology of HTLV-III antibody.

Testing for antibody to human T-lymphotropic retrovirus (HTLV-III) was carried out in 448 participants in the Vancouver Lymphadenopathy-AIDS (acquired immune deficiency syndrome) Study. The overall prevalence rate of seropositivity was 34%. Of 130 seronegative subjects followed for an average of 8.5 months, 14 became seropositive; thus, the approximate annual seroconversion rate was 15%. More than 100 male sexual partners in one's lifetime, frequent receptive anal intercourse, fisting, a history of gonorrhea or hepatitis, and frequent sexual contact in clubs were found to be independent risk factors for HTLV-III seropositivity.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The Vancouver Lymphadenopathy-AIDS Study: 1. Persistent generalized lymphadenopathy.

The Vancouver Lymphadenopathy-AIDS (acquired immune deficiency syndrome) Study is an ongoing prospective study of over 700 homosexual men attending six primary care practices in central Vancouver. A case-control study of risk factors for persistent generalized lymphadenopathy in homosexual men was conducted in five of the practices. The participants completed a questionnaire and underwent a complete physical examination at the time of enrollment and at a subsequent visit not less than 3 months later, and laboratory tests were performed after both visits. Persistent generalized lymphadenopathy was defined as the presence of lymph nodes greater than 1 cm in diameter at two or more extrainguinal sites for more than 3 months. Of the 519 patients who had completed both visits by February 1984, 126 (24%) were found to have the disease, and two controls without lymphadenopathy were frequency-matched on the basis of age and practice to each subject. More than 100 male sexual partners during one's lifetime, frequent receptive anal intercourse, a history of gonorrhea, use of illicit drugs and sexual contact in Los Angeles were identified as independent risk factors for persistent generalized lymphadenopathy. The similarity of these risk factors to those established for AIDS supports the hypothesis of a common etiology for the two diseases, and the high prevalence rate of persistent generalized lymphadenopathy further supports the hypothesis that AIDS is an uncommon response to a relatively common agent.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Booster immunisation for diphtheria and tetanus: no evidence of need in adults.

Recommendations to give adults diphtheria and tetanus toxoid every ten years have been based on serological surveys that have shown lower antibody levels in older populations. The purpose of an immunisation programme, however, is to prevent disease and not merely to produce antibodies. In Canada, although an immunisation programme against diphtheria has been in operation for nearly sixty years, age-specific morbidity and mortality rates for diphtheria do not show an increase with age. Similarly, age-specific death rates from tetanus do not show any increase. From Canadian surveillance data, there is no evidence to suggest that people are leaving the immune pool and entering the susceptible pool. Immunisation programmes do not need to include routine administration of booster doses of diphtheria and tetanus toxoids to adults since the benefits of the procedure do not justify the risks or costs. Continuing case-surveillance will bring to light any increase in incidence of disease justifying a need for an adult programme.

Adult↗
PubMed1985

Diagnostic testing revisited: pathways through uncertainty.

To aid physicians who may be having difficulty applying the principles of decision analysis to diagnostic data according to the methods published in the past several years, the authors of this paper set out a few principles and schemes for using and interpreting diagnostic data obtained from dichotomous tests. They also present a simple BASIC program for calculating post-test probabilities from likelihood ratios and pretest probabilities that a particular disease is present in a particular patient; the program can be adapted for use on microcomputers.

Clinical Laboratory Techniques↗
PubMed1985

Cigarette smoking and breast cancer: a case-control study of screening program participants.

A case-control study of Canadian women aged 40-59 years (n = 123; 369) has been conducted on the relationship of cigarette-smoking and initial visit breast cancer detection within a multicenter screening program. Among premenopausal women, a relative risk of 2.1 (1.1, 4.0) was found for ever-smokers versus never-smokers. There was a dose-response gradient with relative risks of 1.0, 1.3, 2.5, and 3.5 among women with 0, 1-200, 201-500, and greater than 500 cigarette-years of exposure, respectively. No overall association was detected among postmenopausal women but a significant interaction with parity was present in this group. When menopausal status was ignored, there was a nonsignificantly elevated risk of 1.4 (0.9, 2.1) for ever- versus never-smokers but the dose-response was significant with relative risks of 1.0, 0.9, 1.7, and 2.0 in the above four exposure categories, respectively. These results persisted despite adjustment for several important variables. These data are consistent with an interaction of smoking and participation in the screening study or with a possible etiologic role for smoking. Even if smoking is not related to breast cancer etiologically, these data still suggest that smokers who visit screening centers have an elevated risk of breast cancer detection on initial visit, especially among premenopausal women. They do not support the hypothesis of a protective effect of smoking and underscore the need for further study into this important relationship.

Adult↗
PubMed1985

Breast cancer risk factors: can we select women for prophylactic mastectomy?

Prophylactic procedures to prevent disease in women at high risk for breast cancer should be considered only when the benefits of prophylaxis outweigh its costs. The rational prophylactic use of mastectomy in these circumstances must await answers to several questions. First, accurate estimates of the true risk associated with these lesions must be obtained, as current estimates are imprecise and potentially biased. Second, large ongoing trials of breast cancer screening and treatment may provide effective methods of distinguishing those women at exceptionally high risk in whom such procedures may be warranted. Finally, the question of conservative surgery as an acceptable treatment for breast cancer must be settled; otherwise, the prophylactic procedure may be more invasive and disfiguring than the treatment of the disease it seeks to prevent.

Adult↗
PubMed1984

The assessment of diagnostic tests. A survey of current medical research.

To study current diagnostic test evaluation, 129 recent articles were assessed against several well-known methodological criteria. Only 68% employed a well-defined "gold standard." Test interpretation was clearly described in only 68% and was stated to be "blind" in only 40%. Approximately 20% used the terms sensitivity and specificity incorrectly. Predictive values were considered in only 31% and the influence of disease prevalence and study setting was considered in only 19%. Overall, 74% failed to demonstrate more than four of seven important characteristics and there was an increased proportion of high specificities reported in this group. Articles assessing new tests reported high sensitivities and specificities significantly more often than articles assessing existing tests. These results indicate a clear need for greater attention to accepted methodological standards on the part of researchers, reviewers, and editors.

Diagnosis↗
PubMedDate not supplied

The assessment of diagnostic tests: a comparison of medical literature in 1982 and 1985.

To determine whether improvements have occurred since a survey of the 1982 literature assessing diagnostic tests, the authors evaluated all English-language articles that assessed clinical diagnostic tests in abridged Index Medicus journals in 1985, and that had the terms sensitivity and specificity in the title, abstract, or key words. The 89 articles were assessed against seven methodologic criteria, including use of a well-defined "gold standard," clearly defined test interpretation, blinding, clear data presentation, correct use of sensitivity and specificity, calculation of predictive values, and consideration of prevalence. In comparisons of 1985 vs. 1982 articles, there were significant improvements in five of the seven criteria. For example, the proportion of articles using a well-defined "gold standard" rose from 68% to 88%. Overall, the frequency of papers demonstrating five or more of the seven criteria increased from 26% to 47%. However, predictive values were discussed in only 54% of the articles without, necessarily, consideration of the influence of prevalence as well. This study raises the concern that while the concepts of sensitivity and specificity are now accepted, predictive values remain less well understood. Although there has been an improvement in the assessment of diagnostic tests in published research, attention to accepted methodologic standards is still needed on the part of researchers, reviewers, and editors.

Clinical Laboratory Techniques↗
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↗
PubMedDate not supplied

Sociodemographic correlates for risk-taking behaviour among HIV seronegative homosexual men.

The aim of this paper is to determine the sociodemographic characteristics of seronegative men engaging in behaviours at high risk for HIV transmission within a cohort of homosexual men. Eligible subjects in the cohort (n = 139) were those who were HIV negative and who completed an index visit between October 1989 and September 1990 and reported having sexual contact with casual partners during the previous 12-month period. Risk-takers (n = 31) were those who reported having unprotected anal receptive or insertive intercourse with casual partners; while the remaining subjects (controls) (n = 108) were those who reported either not engaging in anal intercourse with casual partners or using condoms when they did. Risk-takers were significantly younger and were more likely than controls to have incomes below $10,000, to smoke cigarettes and to use nitrite inhalants. Our findings suggest the importance of targeting AIDS prevention activities to specific subgroups within the gay community who are more at risk of HIV infection.

Adult↗