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Biomedical subjects

S Shiboski

Publications and source records attributed to S Shiboski.

31 records · Page 2Linked to original sources
PubMed1994

Risk factors for anal human papillomavirus infection and anal cytologic abnormalities in HIV-positive and HIV-negative homosexual men.

Men with advanced human immunodeficiency virus (HIV) disease have a high prevalence of anal human papillomavirus (HPV) infection and potentially precancerous anal disease. To characterize prevalence of and risk factors for anal HPV infection and anal cytologic abnormalities, 37 HIV-positive and 28 HIV-negative participants in the San Francisco General Hospital Cohort Study were studied. A questionnaire was administered, followed by an anal examination consisting of two consecutive anal swabs for cytology and HPV DNA hybridization, and anoscopy with biopsy of visible lesions. Ten of 28 (36%) HIV-negative men and 19 of 37 (51%) HIV-positive men had anal HPV infection (p = 0.32). Risk factors for anal HPV infection included HIV positivity with a CD4 count < 200/mm3 (p = 0.03) and a history of smoking (p = 0.03). Abnormal anal cytology was found in 2 of 26 (8%) HIV-negative men and 10 of 36 (28%) HIV-positive men with cytology adequate for interpretation (p = 0.09). Risk factors for abnormal anal cytology included HIV positivity with a CD4 count < 200/mm3 (p = 0.006) and current smoking (p = 0.03). We conclude that the risk of development of anal disease and HPV infection was highest among HIV-positive men with a CD4 count of < 200/mm3, and that smoking may play a role in the pathogenesis of anal disease.

Adult↗
PubMed1993

Use of T lymphocyte subset analysis in the case definition for AIDS.

Infection with HIV-1 and < 200 CD4+ lymphocytes/mm3 has been proposed as an AIDS-defining condition. We have evaluated the effects of using this and other T-cell subset measurements, in the diagnosis of AIDS in two cohorts of homosexual/bisexual men in San Francisco. Among 762 HIV-1 infected men, 200 CD4+ lymphocytes/mm3 corresponded to 13 percent CD4+ lymphocytes and a CD4+/CD8+ ratio of 0.23. If these AIDS-defining criteria had been implemented in mid-1991, the number of living AIDS cases would have increased by 106 (212%), 133 (266%), and 136 (272%), respectively. When these criteria were first met, either before or in the absence of a clinical AIDS diagnosis, about half of the subjects were asymptomatic and the median clinically AIDS-free interval was approximately 2 years. Using two consecutive tests or pair-wise combinations of criteria reduced the number of cases identified by testing error or transient biological variation, but the number of living AIDS cases would still be increased more than twofold. Finally, any AIDS case definition using a specific T-cell subset value will be compromised by the inherent variability in these measurements and the substantial overlap in the results for those with and without clinical manifestations of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Factors associated with human immunodeficiency virus seroconversion in homosexual men in three San Francisco cohort studies, 1984-1989.

A total of 83 HIV seroconversions occurred between 1984 and 1989 in three San Francisco cohorts of homosexual and bisexual men. A nested case-control analysis was performed to assess the risk of seroconversion associated with sexual practices. Strong associations were found with total number of intercourse partners and receptive anal intercourse. Weaker, but significant associations were found with receptive oral intercourse. Individuals reporting condom use with some partners were more likely to become infected than those reporting no condom use. Some of this difference was due to increased numbers of sexual partners among those reporting some condom use, but the association remained significant in multivariate analyses. This observation indicates there is some unmeasured risk associated with those using condoms, such as more HIV seropositive partners.

Cohort Studies↗
PubMed1993

Lack of effect of prophylactic aerosolized pentamidine on the detection of Pneumocystis carinii in induced sputum or bronchoalveolar lavage specimens.

Two independent studies were undertaken to determine the effect of prophylactic treatment with aerosolized pentamidine on the laboratory diagnosis of Pneumocystis carinii pneumonia in individuals at risk for or with the acquired immunodeficiency syndrome. The first study was a retrospective analysis to determine the effect of prophylactic treatment with aerosolized pentamidine on the diagnostic yield and sensitivity of detection of P carinii in induced sputum specimens. The results of examinations of 110 induced sputum specimens from patients who had not received aerosolized pentamidine were compared with the findings in 57 specimens from patients who had. There was no statistically significant difference between the two groups for the diagnostic yield in induced sputum specimens (48% vs 47%) or in bronchoalveolar lavage fluid specimens subsequently obtained from patients with nondiagnostic induced sputum examinations (33% vs 37%). The sensitivity of induced sputum specimens for identifying P carinii was 76% to 78% for patients who had not received aerosolized pentamidine and 71% to 75% for patients who had received the drug. The second study was a prospective comparison of 118 bronchoalveolar lavage fluid specimens to determine the effect of prophylactic treatment with aerosolized pentamidine on the number of organisms present. One hundred eighteen bronchoalveolar lavage fluid specimens were quantitatively examined and scored according to the number of clumps of P carinii present. No statistically significant difference was seen in the number of clumps of P carinii found in specimens from patients who had received aerosolized pentamidine vs the number of clumps found in specimens from patients who had not. In conclusion, prophylactic treatment with aerosolized pentamidine had no effect on (1) the diagnostic yield and sensitivity of detection of P carinii in induced sputum specimens or (2) the number of organisms detected in bronchoalveolar lavage fluid specimens obtained from individuals at risk for or with the acquired immunodeficiency syndrome.

AIDS-Related Opportunistic Infections↗
PubMed1992

Progression to AIDS in HIV-infected homosexual and bisexual men with hairy leukoplakia and oral candidiasis.

OBJECTIVE: This study was designed to assess the significance of HIV-related oral lesions in predicting the rate of progression to AIDS. DESIGN: Cohorts were investigated prospectively, and oral examinations were performed by clinicians trained in the diagnosis of oral lesions. SETTING: We studied three existing cohorts of homosexual and bisexual men in San Francisco, California, USA. PARTICIPANTS: Of the HIV-infected men who received standardized oral examinations (n = 791), 603 were eligible for analysis of baseline examinations and 448 for analysis of follow-up examinations. MAIN OUTCOME MEASURES: We determined time from presence of oral lesion at baseline or follow-up examination, or from participant self-reported history of the lesion, to diagnosis of AIDS. RESULTS: Using proportional hazard regression and stratifying by CD4 lymphocyte count at the time of baseline oral examination, we found that the rate of development of AIDS was increased among men with hairy leukoplakia [relative hazard, 1.8; 95% confidence interval (CI), 1.2-2.7], oral candidiasis (relative hazard, 7.3; 95% CI, 3.1-17.3), and both lesions (relative hazard, 3.1; 95% CI, 1.6-6.1) compared with men with normal findings. On follow-up examination, stratifying for CD4 count, the rate of progression to AIDS was similar for those with hairy leukoplakia compared with those with oral candidiasis. The progression rate from oral candidiasis to AIDS was faster from presence on baseline examination than from presence on follow-up examination or from self-reported history of the lesion. CONCLUSION: The presence of oral candidiasis and/or hairy leukoplakia on baseline examination confers independent prognostic information and should be incorporated into HIV-staging schemes.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Immune activation markers and AIDS prognosis.

Four assays for serum levels of cellular products of immune activation were examined as prognostic markers for AIDS in a prospective study of asymptomatic HIV-seropositive homosexual men. Baseline serum values of beta 2-microglobulin (beta 2M), neopterin, soluble CD8 (sCD8), and soluble interleukin-2 receptor (sIL-2R) for 185 men were examined univariately and multivariately as predictors of AIDS during 36 months of follow-up. Thirty-three cases of AIDS (18%) were diagnosed during the follow-up period. All four assays correlated highly with each other (r = 0.48-0.63), and all four were good univariate predictors of AIDS and comparable to CD4 lymphocyte count. beta 2M, neopterin, and sCD8 predicted AIDS independently of both CD4 count and HIV p24 antigen or p24 antibody in multivariate analysis. Within the range of CD4 count 200-499 x 10(6) cells/l, an immune activation marker used in combination with an assay for p24 antigen identifies those at 3-6% risk of AIDS over 36 months (low risk on both assays) and those at 63-86% risk (high risk on both assays). These results can be used to guide physicians and patients making decisions about treating asymptomatic HIV infection with zidovudine in individuals with CD4 lymphocyte count of 200-499 x 10(6) cells/l.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Log-linear models for cancer risk among migrants.

Epidemiological studies of migrants have played an important role in separating the environmental and genetic components of cancer aetiology. The statistical analyses of these studies have typically involved calculating age- and sex-adjusted rates by country of birth. We describe methods which permit the effect of duration of residence in the host country to be estimated after adjusting for other temporal effects such as age, and period or cohort. The methods, which are based on log-linear modelling, can also be applied in a case-control manner if appropriate denominator populations are unavailable. Examples are given in which the more traditional methods of analysis may have yielded misleading results.

Adolescent↗
PubMed1990

Use of beta 2-microglobulin level and CD4 lymphocyte count to predict development of acquired immunodeficiency syndrome in persons with human immunodeficiency virus infection.

Serum beta 2-microglobulin (beta 2M) levels were measured by radioimmunoassay in 962 unmarried men recruited by probability sampling from areas in San Francisco, Calif, most severely affected by the epidemic of acquired immunodeficiency syndrome (AIDS). From July 1984 to December 1987, 65 incident AIDS cases occurred in 388 homosexual/bisexual men infected by the human immunodeficiency virus (HIV) at the time of recruitment. The mean level of beta 2M in uninfected individuals at entry was 170 nmol/L. In HIV-seropositive patients who had not developed AIDS, the mean beta 2M level was 254 nmol/L, and in those who had developed AIDS, the beta 2M level was 347 nmol/L. After 36 months of follow-up, 34% of individuals with beta 2M levels greater than 322 nmol/L at entry developed AIDS, 21% of individuals with levels between 246 and 322 nmol/L developed AIDS, while only 7.3% of those with levels below 246 nmol/L developed AIDS. The beta 2M level predicted the development of AIDS independently of the CD4 lymphocyte count in HIV-seropositive individuals. Thus, 65.5% of HIV-seropositive individuals with beta 2M levels above 322 nmol/L and CD4 lymphocyte counts of below 500/microL developed AIDS in 3 years. This represents an 18.4-fold increased relative hazard at 3 years over individuals with beta 2M and CD4 cell counts within the reference range for uninfected individuals. A nomogram is provided that allows the easy calculation of the probability of an HIV-infected person developing AIDS in 36 months depending on prevalent levels of CD4 lymphocytes and serum beta 2M.

Acquired Immunodeficiency Syndrome↗
PubMed1989

A case-control study of diet and breast cancer in Argentina.

A case-control study of breast cancer was carried out in La Plata, Argentina, where the incidence of the disease is comparable to the highest rates recorded worldwide. One hundred and fifty incident cases were identified through major hospitals. For each case, a hospital control, matched by age and hospital, and a neighbourhood control, matched by residential area and age, were also chosen. Cases and controls were interviewed to obtain information on past diet, as well as demographic and socio-economic characteristics, reproductive and menstrual history and other potential breast-cancer risk factors. The dietary information was obtained from questions on the consumption of specific food items and information on portion sizes from an earlier study was used to estimate intake of calories and selected nutrients. There was a substantial excess energy intake among cases as compared to both control groups, which was present across all 3 major macronutrients which contribute to total calories. Among the food groups, the consumption of eggs was a risk factor for breast cancer, and whole-milk products and green leafy vegetables were protective. After adjusting for the calorie difference in multivariate statistical analyses of nutrients, fibre and beta-carotene consumption were weakly protective. The results are discussed with reference to possible methodological difficulties and previous studies of diet and breast cancer.

Argentina↗
PubMed1988

The San Francisco Men's Health Study: continued decline in HIV seroconversion rates among homosexual/bisexual men.

The incidence of infection by the human immunodeficiency virus (HIV) has been monitored since 1984 in an area probability sample of homosexual/bisexual men drawn from a six-kilometer square area of San Francisco where the epidemic of acquired immunodeficiency syndrome (AIDS) has been most severe. Annualized HIV seroconversion rates in previously uninfected cohort members have declined by 88 per cent from 5.9 per cent during the first six months of 1985 to 0.7 per cent during the last six months of 1987. Concurrent declines of approximately 80 per cent in the prevalence of sexual behaviors associated with HIV transmission were also observed in the sample.

AIDS Serodiagnosis↗
PubMed1986

Epidemiological studies of anticancer drug carcinogenicity.

In recent years, epidemiological methods have been used increasingly to study the carcinogenicity of drugs used in the chemotherapy of cancer. Such studies are useful to clinicians in identifying therapeutic agents with particular long-term risk to patients. They can also provide information on the dose- and time-related risks of cancer in one of the few human populations intentionally exposed to known levels of carcinogens. Aspects of epidemiological studies of second cancer risk are described, including sources of cases, study design, statistical methods, and possible biases. Results from a cohort study of second cancers following ovarian cancer, testicular cancer and Hodgkin's disease and from a case-control study of leukaemia following Hodgkin's disease are also given.

Antineoplastic Agents↗
PubMedDate not supplied

Can preference scores for discrete states be used to derive preference scores for an entire path of events? An application to prenatal diagnosis.

The authors conducted a study exploring whether preferences for sequences of events can be approximated by preferences for component discrete states. Visual-analog-scale (VAS) and standard-gamble (SG) scores for a subset of the possible sequences of events (path states) and component temporary and chronic outcomes (discrete states) that can follow prenatal diagnostic decisions were elicited from 121 pregnant women facing a choice between chorionic villus sampling and amniocentesis. For individuals, preference scores for path states could not be predicted easily from discrete-state scores. Mean path-state VAS scores, however, were predicted reasonably accurately by multiple regression models (R2 = 0.85 and 0.82 for two different anchoring schemes), with most measured scores lying within the 95% confidence intervals of the derived scores. It is concluded that, for individual patient decision making, preferences for path states should be elicited. When mean preference values for a population are sought, however, it may be reasonable to derive regression weights from a subset of respondents and then to apply those weights to preferences for discrete states elicited from a larger group.

Adult↗