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Biomedical subjects

L L Perkins

Publications and source records attributed to L L Perkins.

At least 19 recordsLinked to original sources
PubMed2001

Breast implants and cancer: causation, delayed detection, and survival.

Concern for many women with breast implants has been focused on three topics: cancer (both breast and other cancers), delayed detection of breast cancer, and increased breast cancer recurrence or decreased length of survival. In this study, a qualitative review of the literature on these subjects was conducted, coupled with a meta-analysis of the risk for breast cancer or other cancers (excluding that of the breast). Researchers have consistently found no persuasive evidence of a causal association between breast implants and any type of cancer. The meta-analysis results obtained by combining the epidemiology studies support the overall conclusion that breast implants do not pose any additional risk for breast cancer (relative risk, 0.72; 95% confidence interval, 0.61 to 0.85) or for other cancers (relative risk, 1.03; 95% confidence interval, 0.87 to 1.24). This analysis suggests that breast implants may confer a protective effect against breast cancer. Women with implants should be reassured by the consistency of scientific studies which have uniformly determined that, compared with women without implants, they are not at increased risk for cancer, are not diagnosed with later-stage breast malignancies, are not at increased risk for breast cancer recurrence, and do not have a decreased length of survival.

Animals↗
PubMed1998

Quality of measurement of smoking status by self-report and saliva cotinine among pregnant women.

OBJECTIVE: The objectives of this paper were to determine the rate of misclassification of smoking and nonsmoking status by self-reports and saliva continine of pregnant women participating in a smoking cessation trial, determine the relationship of the number of cigarettes smoked per day and saliva continine, and examine whether misclassification was due to an inappropriate saliva continine cutoff point. METHODS: End of pregnancy self-reports of smoking status and saliva continine were used to calculate misclassification rates. RESULTS: The findings revealed that 61 of 441 self-reported smokers had biochemical values inconsistent with smoking status for a smoking misclassification rate of 13.8%. The results also revealed that 28 of 107 self-reported quitters had continine values consistent with smoking status for a nonsmoking misclassification rate of 26.2%. Receiver Operating Characteristic (ROC) curves were then plotted to determine whether misclassification resulted from an inappropriate cutoff point. The continine cutoff point that maximized sensitivity and specificity for all women was 24 ng/ml. Racial ROC comparisons indicated a higher cutoff point for blacks than whites. Use of any of the ROC indicated cutoff points would not change the misclassification rates. CONCLUSIONS: These findings suggest that underreporting of smoking status during pregnancy is high and that social desirability of nonsmoking status may have contributed to the lack of precision in saliva continine to distinguish smoking status in this study.

Adult↗
PubMed1997

Estimating a relative risk across sparse case-control and follow-up studies: a method for meta-analysis.

Meta-analysis is the quantitative technique of combining results from different studies. There is a variety of procedures available for combining effect measures across epidemiologic studies. None of these methods provides an overall effect estimate when the data are sparse within studies and come from different study designs. In this paper we discuss the statistical relations between case-control studies and two types of follow-up studies. We use these relations to develop an exact methodology for combining results across study designs. We also use these relations to derive Mantel-Haenszel type formulae for summarizing results across studies. We illustrate these techniques with data pertaining to breast implants and connective tissue disease.

Breast Implants↗
PubMed1996

The prevalence of breast implants among women in the United States.

Estimates of the number of women with breast implants have varied from less than one million to over three million. Most of these appear to be extrapolations from either industry production figures or reports of surgical procedures. In late 1989 under contract to the Dow Corning Corporation, Market Facts, Inc. conducted a mail survey of 40,000 households selected to be representative of the population of the United States. They received responses from 70.7%. Based upon the data collected, 8.08 per 1,000 women in the United States reported ever having had some type of breast implant. Approximately 60% of the procedures had been done for cosmetic reasons. Most of the women were White (94.6%) and rates were highest in the South or West. Although younger women were more likely to have had implants for augmentation and older women for reconstruction presumptively following breast cancer surgery, the largest prevalences for either of the two procedures were in the 45 to 54 year old age group. Breast implant prevalence also increased in direct proportion to household income with the largest increases being related to cosmetic augmentation. Based upon the data collected in this survey, the total number of women in the United States in late 1989 who had ever had breast implants was estimated to be 815,700 (95% confidence interval: 715,757-924,729).

Adolescent↗
PubMed1996

Seven-year trends in plasma low-density-lipoprotein-cholesterol in young adults: the CARDIA Study.

To identify determinants of recent secular trends in lipids and characterize their influence on age-related increases in LDL-cholesterol, we examined a cohort of black and white men and women aged 18-30 in 1985-1986. Secular trends were determined by comparing participants aged 25-30 at baseline with those aged 25-30 at year 7 (2788 and 1395 participants, respectively). LDL-cholesterol was lower among those 25-30 at year 7 (5.9 to 10.2 mg/dL, depending on race-sex group; P < 0.001); weight was higher (8.3 to 12.5 lb; P < 0.001); Keys score was lower (-4.2 to -7.3 units; P < 0.001); and use of oral contraceptives was greater (white women only, P < 0.01). Among 4086 participants followed for 7 years, LDL-cholesterol changed little or decreased, despite substantial weight increases in all groups (11.6 to 19.0 lb; P < 0.001). Keys scores decreased by 6.1 to 8.0 units, and use of oral contraceptives decreased (P < 0.001). Declining secular trends in LDL-cholesterol occurred despite upward trends in weight; the decline was associated with lower dietary fat and cholesterol and offset expected age-related increases in LDL-cholesterol.

Adult↗
PubMed1995

The prevalence of women with breast implants in the United States--1989.

Most estimates of the number of women with breast implants appear to be extrapolations of industry or clinical data. While both provide valuable information, the former about the total number of devices ever produced or sold and the latter about the cumulative number of surgeries performed, neither can be used to directly estimate the prevalence of women with silicone gel or saline implants. In 1989, Market Facts, Inc., conducted a mail survey of 40,000 households chosen as representative of the population of the United States and received responses from 70.7%. Overall, the prevalence was 8.08 per 1,000 women with about 60% of the devices reportedly implanted for cosmetic reasons. The procedure was more common among Whites of the higher socio-economic classes. Based upon the results of this survey, the total number of US women in 1989 with breast implants was estimated to be 815,700 (95% confidence interval: 715,757-924,729).

Adolescent↗
PubMed1995

A meta-analysis of breast implants and connective tissue disease.

Case reports have raised questions about an increased risk of connective tissue diseases (CTDs) among women with breast implants. From the reviews of more than 2,600 manuscripts, abstracts, and dissertations, this meta-analysis included 13 epidemiology studies that provided a relative risk (RR) estimate for the possible association between breast implants and CTDs. The meta-analysis summary RR was 0.76 for CTD in general (95% confidence interval [CI]: 0.55, 1.04; homogeneity p-value = 0.073) and was 0.98 for scleroderma (95% CI: 0.57, 1.64; homogeneity p = 0.006). Irrespective of which studies were aggregated in this meta-analysis, there was no significant increased risk for scleroderma, rheumatoid arthritis, or CTD in general. Conclusions from this study are consistent with the most recent review by the British Medical Devices Agency that found no scientific evidence to date of an increased risk of CTD associated with silicone gel breast implants.

Arthritis, Rheumatoid↗
PubMed1994

Longitudinal changes in adiposity associated with pregnancy. The CARDIA Study. Coronary Artery Risk Development in Young Adults Study.

OBJECTIVE: To examine the longitudinal associations between a pregnancy and persistent changes in adiposity in young black and white women. DESIGN: Prospective cohort study with 5 years of follow-up. SETTING: Participants recruited by community-based sampling (Birmingham, Ala; Chicago, Ill; and Minneapolis, Minn) and through the membership of a large prepaid health care plan (Oakland, Calif). PARTICIPANTS: A total of 2788 women (53% black) aged 18 through 30 years were assessed at baseline (1985 through 1986) and reassessed at examination 2 (91% retention; 1987 through 1988) and examination 3 (86% retention; 1990 through 1991). Women who remained nulliparous (n = 925) during the 5-year follow-up were compared with women who had a single pregnancy of 28 weeks' duration during that period and who were at least 12 months postpartum at follow-up (primiparas, n = 89; multiparas, n = 114). MAIN OUTCOME MEASURES: Change in body weight and in waist-to-hip ratio during the 5-year period. Analyses were adjusted for demographic factors (age and education), behavioral variables (smoking and physical activity), and baseline level of adiposity. RESULTS: Primiparas within both race groups gained 2 to 3 kg more weight during the 5-year period than did nulliparas in both adjusted and unadjusted analyses. Primiparas also had greater increases in waist-to-hip ratio that were independent of weight gain. Multiparas did not differ from nulliparas in adiposity change in either race group. At each level of parity, black women demonstrated greater adverse changes in adiposity than did white women. CONCLUSIONS: These data suggest that women experience modest but adverse increases in body weight and fat distribution after a first pregnancy and that these changes are persistent.

Adipose Tissue↗
PubMed1994

Concentrations of Lp(a) in black and white young adults: relations to risk factors for cardiovascular disease.

The purpose of this report is to compare the distribution of total lipoprotein(a) [Lp(a)] mass in a population-based sample of blacks and whites, and to investigate the association of Lp(a) with other cardiovascular risk factors. A cross-sectional study design was used. Black and white men and women (n = 4125), aged 23-35 from the Coronary Artery Risk Development in Young Adults Study had the following data collected: Lp(a), lipids and lipoproteins, other metabolic parameters, anthropometry, physical activity, dietary intake, cigarette use, and alcohol use. Blacks had concentrations of Lp(a) approximately three-fold higher than whites. Medians were: black men 21.5 mg/dL, black women 23.9 mg/dL, white men 6.1 mg/dL, and white women 6.4 mg/dL. Lp(a) concentrations were higher in women than in men. Lp(a) was not consistently associated with smoking, alcohol consumption, physical activity, dietary fat, or obesity. In stepwise regression analyses in both blacks and whites, Lp(a) was consistently associated with low-density lipoprotein (LDL) cholesterol, fibrinogen, and apoB; regression models explained about 7% of the variance in Lp(a). In whites, Lp(a) tended to be higher in those with a positive family history of myocardial infarction. The large differences in Lp(a) between blacks and whites, and the absence of association with many other variables are consistent with previous suggestions that Lp(a) concentration is in large part genetically determined. The association of Lp(a) with LDL and fibrinogen, two strong risk factors for cardiovascular disease (CVD), could represent part of the mechanism of the CVD risk associated with Lp(a) in other studies. Longitudinal data are needed to determine the extent to which Lp(a) will independently predict disease, especially in diverse ethnic groups.

Adult↗
PubMed1994

Plasma homocyst(e)ine, folate, and vitamin B-12 concentrations and risk for early-onset coronary artery disease.

High plasma homocyst(e)ine (Hcy) concentrations may be a determinant of coronary artery disease (CAD). Folate and vitamin B-12 are required for the primary metabolic pathway to reduce Hcy concentrations. The interrelationships of Hcy and these two vitamin cofactors were investigated in a case-control study of 101 white males aged 30-50 y with angiographically demonstrated CAD, and 108 white male, similarly aged, control subjects living in the same community as the patients. The odds ratio (OR) of CAD per quartile increase of plasma Hcy concentration based on control values was 1.6 (95% CI: 1.3, 2.1). After age, HDL and LDL cholesterol, body mass index, smoking, hypertension, and diabetes were controlled for, Hcy remained an independent risk factor (OR: 1.4; 95% CI: 1.0, 2.0). The OR change per quartile increase of folate concentration was 0.8 (95% CI: 0.6, 1.0). This difference was reduced (OR: 0.9; 95% CI: 0.7, 1.2) after Hcy adjustment. No difference in the geometric mean of vitamin B-12 concentration was found between patients and control subjects, both 5.8 nmol/L. However, after Hcy and the other CAD risk factors were controlled for, the OR per quartile increase in vitamin B-12 concentration was 1.5 (95% CI: 1.0, 1.8). Reduction in plasma Hcy by interventions to increase plasma folate concentration may decrease CAD risk.

Adult↗
PubMed1993

Lipoprotein[a] concentrations and apolipoprotein[a] phenotypes in Caucasians and African Americans. The CARDIA study.

Little is known about racial differences in lipoprotein[a] (Lp[a]) concentrations and apolipoprotein[a] (apo[a]) phenotypes. Lp[a] protein concentrations were determined by a double monoclonal antibody enzyme-linked immunosorbent assay method in 4165 Caucasian and African American men and women from four US communities. Apo[a] phenotypes were determined by polyacrylamide gel electrophoresis and immunoblotting on a random subset of these participants (n = 690). The distribution of Lp[a] protein levels in Caucasians was highly skewed (mean, 6.9 mg/dL; median, 3.7 mg/dL). In contrast, the distribution in African Americans was less skewed (mean, 13.0 mg/dL; median, 11.6 mg/dL), and Lp[a] protein levels were approximately double those in Caucasians within most apo[a] phenotypes. The previously described inverse relationship between apo[a] size and Lp[a] concentration was generally confirmed in Caucasians, but the B phenotype had lower Lp[a] levels than the S1 or S2 phenotype. In African Americans, both the B and S1 phenotypes had lower Lp[a] levels than the S2 phenotype. The frequencies of the apo[a] phenotypes in African Americans differed from those in Caucasians (P < .001) and also differed from the frequencies reported in a Sudanese population (P < .002). African Americans had a lower frequency of the S2 phenotype than Caucasians (8% vs 18%; P < .01) and a higher frequency of S3 (36% vs 25%; P < .01). As compared with the data reported in Sudanese, African Americans also had a higher frequency of the S3 phenotype (36% vs 14%; P < .001) and a lower frequency of S4 (29% vs 44%; P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

The dissemination of smoking cessation methods for pregnant women: achieving the year 2000 objectives.

The smoking prevalence rate among adult women and pregnant women has decreased only 0.3 to 0.5% per year since 1969. Without a nationwide dissemination of efficacious smoking cessation methods based on these trends, by the year 2000 the smoking prevalence among pregnant women will be approximately 18%. This estimate is well above the US Department of Health and Human Services Year 2000 Objective of 10%. The US dissemination of tested smoking cessation methods could help an additional 12,900 to 155,000 pregnant smokers annually and 600,000 to 1,481,000 cumulatively to quit smoking during the 1990s. Dissemination could help achieve 31 to 78% of the Year 2000 Objectives for pregnancy smoking prevalence. (With dissemination, at best a 15% smoking prevalence during pregnancy, rather than the 10% objective, is likely to be observed.) Our results confirm a well-documented need for a national campaign to disseminate smoking cessation methods.

Adult↗
PubMed1993

Health education for pregnant smokers: its behavioral impact and cost benefit.

OBJECTIVES: A randomized trial (the Birmingham Trial II) was conducted to evaluate the behavioral impact of health education methods among 814 female smokers at four public health maternity clinics. METHODS: Four hundred patients were randomly assigned to an Experimental (E) Group, and 414 were assigned to a Control (C) Group. Self-reports and saliva cotinine tests confirmed smoking status at the first visit, at midpregnancy, and at end of pregnancy. RESULTS: The E Group exhibited a 14.3% quit rate and the C Group an 8.5% quit rate. A Historical Comparison (C) Group exhibited a 3.0% quit rate. Black E and C Group patients had higher quit rates than White E and C Group patients. A cost-benefit analysis found cost-to-benefit ratios of $1:$6.72 (low estimate) and $1:$17.18 (high estimate) and an estimated savings of $247,296 (low estimate) and $699,240 (high estimate). CONCLUSION: Health education methods are efficacious and cost beneficial for pregnant smokers in public health maternity clinics.

Adult↗
PubMed1992

Hostility and health behaviors in young adults: the CARDIA Study. Coronary Artery Risk Development in Young Adults Study.

Hostility has been associated with coronary heart disease mortality. To assess possible mechanisms linking hostility to coronary heart disease risk, the authors conducted analyses in a cross-sectional study from data collected in 1985 and 1986 on 5,115 young adults, aged 18-30 years, black and white, male and female, in four large urban areas of the United States. The results show that higher levels of hostility as determined by the Cook-Medley Hostility Scale were strongly associated with tobacco and marijuana smoking, increased alcohol consumption, and greater caloric intake in both blacks and whites and in both men and women. The increased caloric consumption was evident in the higher waist/hip ratios, particularly in men (p less than 0.05). The associations were particularly strong (p less than 0.001) for tobacco cigarette smoking and marijuana smoking, with roughly a 1.5 times higher prevalence in the top hostility quartile compared with the bottom quartile after adjusting for age and education. Hostility levels were not related to the percentage of calories from fat or from sucrose intake, to plasma cholesterol levels, or to physical fitness (except for a weak association in the latter in white women). The results describe relations between hostility and health behaviors that may be detrimental to health. The findings provide a possible explanation for the association between hostility and coronary heart disease mortality.

Adolescent↗