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Biomedical subjects

R K Peters

Publications and source records attributed to R K Peters.

At least 37 records · Page 2Linked to original sources
PubMed1995

Predicting future diabetes in Latino women with gestational diabetes. Utility of early postpartum glucose tolerance testing.

We tested 32 routine clinical parameters for their ability to discriminate between a high risk and a low risk of non-insulin-dependent diabetes mellitus (NIDDM) within 5-7 years after pregnancies complicated by gestational diabetes mellitus (GDM). Latino women (n = 671) with GDM who did not have diabetes 4-16 weeks after delivery returned for at least one 75-g oral glucose tolerance test (OGTT) within 7.5 years. Multivariate analysis was used to identify parameters ascertained during or immediately after the index pregnancy that were independently associated with the development of diabetes during follow-up. Life table analysis revealed a 47% cumulative incidence rate of NIDDM 5 years after delivery for this cohort of patients who did not have diabetes at the initial postpartum examination. Four variables were identified as independent predictors of NIDDM: the area under the OGTT glucose curve at 4-16 weeks postpartum, the gestational age at the time of diagnosis of GDM, the area under the OGTT glucose curve during pregnancy, and the highest fasting serum glucose concentration during pregnancy. Examination of relative risks (RRs) of NIDDM between the highest and lowest quartiles of the cohort for each variable, adjusted for the other three variables, revealed that the postpartum OGTT provided the best discrimination between high-risk and low-risk individuals (adjusted RR = 11.5 [95% confidence interval 4.5-29.1] compared with adjusted RRs of only 0.5-2.5 for the other three variables).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMed1994

Oral contraceptive use and adenocarcinoma of cervix.

The incidence of adenocarcinoma of the cervix in the USA more than doubled between the early 1970s and the mid 1980s among women under 35 years of age. It was suggested that this increase was due to the introduction of oral contraceptives in the early 1960s. Adenocarcinoma of the cervix diagnosed in women born after 1935 was identified between 1977 and 1991 from the Los Angeles County Cancer Surveillance Program. Data from personal interviews of 195 cases and 386 controls (matched on age, race, and neighbourhood) were analysed. Information on medical, sexual, contraceptive, and reproductive history, previous cervical smears, and sexually transmitted diseases was collected. Compared with never use, ever use of oral contraceptives was associated with twice as great a risk of adenocarcinoma of the cervix (adjusted odds ratio 2.1, 95% CI 1.1-3.8). The highest risk was observed for oral contraceptive use for more than 12 years (4.4, 1.8-10.8). No additional increased risk was found for early age at start of oral contraceptive use, use before age 20 or before first pregnancy, time since first use, time since last use, or particular formulations, once total duration of use had been accounted for.

Adenocarcinoma↗
PubMed1993

Cost of non-insulin-dependent diabetes in women with a history of gestational diabetes: implications for prevention.

Women with gestational diabetes have a 50% risk of developing non-insulin-dependent diabetes mellitus within 10 years of delivery and thus constitute a well-defined target population for primary prevention. Current obstetric standards advocate universal screening of all pregnant women for gestational diabetes. Therefore, approximately half the reproductive-age United States population is screened for carbohydrate intolerance before the onset of overt disease. Continuation of dietary and behavioral changes initiated during pregnancy theoretically could delay or prevent progression to overt diabetes. We present an economic model of the health care dollars that could be saved by promoting postpartum life-style changes in women diagnosed with gestational diabetes. Assuming the incidence of diabetes could be reduced by 10, 25, or 50% in a national cohort of women with gestational diabetes, then 32, 140, or 331 million health care dollars could be saved over 10 years.

Diabetes Mellitus, Type 2↗
PubMed1992

Asbestos and colon cancer: lack of association in a large case-control study.

Previous studies linking exposure to asbestos with human colon cancer have used mortality rather than incidence as their endpoint and have neither assessed nor controlled for confounding by diet, genetic factors, or other risk factors for colon cancer. A case-control study of 746 histologically confirmed cases of colon cancer and 746 matched neighborhood controls was conducted in Los Angeles County, California. In univariate analyses of the 419 male pairs, a weak association was found between asbestos exposure and colon cancer (odds ratio (OR) = 1.16, 95% confidence interval (CI) 0.80-1.69). When confounding by family history of large bowel cancer, diet, body weight, and physical activity was controlled, there was no association between colon cancer and exposure to asbestos among males (OR = 0.99, 95% CI 0.66-1.50). When asbestos exposure was restricted to occurrences preceding diagnosis by more than 15 years, there was no clear association between such exposure and colon cancer, either before (OR = 1.14, 95% CI 0.76-1.70) or after confounding was controlled (OR = 0.93, 95% CI 0.60-1.44). Further analyses by frequency and duration of exposure failed to show any association between asbestos and risk of colon cancer, but did show a consistent pattern of confounding by nonoccupational factors that, when controlled, invariably produced a weak protective effect of asbestos exposure. Among the 327 female pairs, only 6 cases and 11 controls reported asbestos exposure (OR = 0.55, 95% CI 0.20-1.48), and there was no evidence of risk increasing as the frequency or duration of exposure increased. This study suggests not only that occupational exposure to asbestos is not a risk factor for colon cancer in the general population of Los Angeles, but also that observed associations between asbestos and colon cancer should not be interpreted as causal unless confounding by nonoccupational factors has been evaluated and controlled.

Aged↗
PubMed1992

Diet and colon cancer in Los Angeles County, California.

The diets of 746 colon cancer cases in Los Angeles County, California (USA) were compared with those of 746 controls matched on age, sex, race, and neighborhood. In both genders, total energy intake was associated with significantly increased risk, and calcium intake was associated with significantly decreased risk. These effects were reduced only slightly after adjustment for the nondietary risk factors (weight, physical activity, family history, and, if female, pregnancy history). In men, total fat and alcohol intakes were responsible for the calorie effect; in women, no individual source of calories was associated independently with risk. Neither saturated fat nor fat from animal sources was responsible for the fat effect. There were no additional independent significant effects for sucrose, fiber, cruciferous vegetables, beta-carotene, other vitamins, or any other nutrient or micronutrient. In univariate analyses, meats, poultry, breads, and sweets were associated with excess risk, and yogurt was protective. After adjustment for sources of calories, no individual food was associated with excess risk, but yogurt remained significantly protective. Total calories were associated with excess risk throughout the colon while the effects of calcium, fat, and alcohol appeared somewhat stronger in the distal colon. After adjustment, crude fiber was significantly protective in the ascending colon but not even weakly protective in the distal colon.

Adenocarcinoma↗
PubMed1991

Meat, cooking methods and colorectal cancer: a case-referent study in Stockholm.

The associations between methods of cooking meats and colorectal cancer were examined in a population-based case-referent study performed in Stockholm in 1986-1988. The study included 559 cases and 505 referents. Total meat intake, frequent consumption of brown gravy, and a preference for a heavily browned meat surface each independently increased the risk for colorectal cancer. The relative risks (RR) were higher for rectal than for colon cancer, and for boiled meat (RR colon = 1.7, RR rectum = 2.7) than for meat fried with a medium or lightly browned surface (RR colon = 0.8, RR rectum = 1.1), but the highest risks were for meat fried with a heavily browned surface (RR colon = 2.8, RR rectum = 6.0). The analyses were adjusted for year of birth, gender and fat intake. Further adjustments for total energy, dietary fiber intake, body mass and physical activity had little or no influence on the results. The findings suggest that, in addition to frequent meat intake, a heavily browned meat surface formed when frying meat at high temperatures is important in the etiology of colorectal cancer.

Animals↗
PubMed1990

Type A behavior and exercise: a follow-up study of coronary patients.

Several previous studies have reported decreased Type A behavior pattern (TABP) after initiation of an exercise program. To determine if changes in TABP could be linked to exercise patterns in a cardiac rehabilitation program, both physical activity and TABP were measured in 81 male cardiac patients over a period of one year after hospitalization for an initial cardiac event. Changes in TABP scores were not associated with differences in activity patterns as measured by kilocalories per week of exercise, self-ratings of both job and leisure-time physical activity levels, or participation in a cardiac rehabilitation program. However, in Type A subjects there was a discrepancy between simple self-ratings of activity and more objective measures of exercise: subjects who had high TABP scores perceived themselves to be significantly more physically active than did subjects with lower TABP scores, even though the more objective estimates of physical activity were not associated with TABP scores.

Coronary Artery Bypass↗
PubMed1990

Reproductive factors and colon cancers.

In Los Angeles County, the age-adjusted incidence rate of colon cancer in men is almost 30% higher than that in women; however, in the descending and sigmoid colon, age-specific incidence rates for women are higher than those for men before age 55. Since menstrual and/or reproductive factors may be involved in producing this crossover in age-specific rates, they were examined in a population-based case-control study involving 327 white women with adenocarcinoma of the colon and age-, race- and neighbourhood-matched controls. After adjustment for other factors associated with colon cancer in this study (family history of large bowel cancer, total fat intake, calcium, weight and activity level), ever having been pregnant was protective (RR = 0.56, 95% CI = 0.33-0.97). For one to two pregnancies, the RR was 0.76 (CI = 0.42-1.37); for three or more pregnancies, the RR was 0.45 (CI = 0.25-0.81). However, the relationship between the number of pregnancies and colon cancer risk was actually U-shaped, with risk decreasing with successive pregnancies up to four and then increasing with additional pregnancies. The U-shaped relationship was present for incomplete as well as for full-term pregnancies and was more striking for cancers occurring in the distal (descending and sigmoid) than proximal (caecum to splenic flexure) colon. Risk was not related to age at menarche or use of exogenous oestrogens, but delayed natural menopause was weakly protective in the proximal but not distal colon. The crossover in incidence rates in the distal colon can be completely accounted for by the pregnancy effect. The U-shape of the pregnancy curve suggests the possibility of competing factors, some protective, especially after one or several pregnancies, and others conferring increasing risk with successive pregnancies, regardless of the pregnancy outcome.

Adenocarcinoma↗
PubMed1989

A case-control study of occupational and dietary factors in colorectal cancer in young men by subsite.

With the hope that exposures responsible for colorectal cancer might be especially obvious among those in whom it develops early, 147 men with colorectal carcinomas first diagnosed between the ages of 25 and 44 years were compared to neighborhood controls. Physical activity on the job was protective for tumors located in the transverse and descending portions of the colon. Rectal cancer and to a lesser extent sigmoid cancers were associated with jobs in which dusts or fumes were inhaled, especially if those jobs were held for long periods in young adulthood. While risk for rectal cancer did not seem to be limited to any particular type of dust or fume, the excess risk was strongest for wood and metal dusts. Consumption of fruits and vegetables and a preference for whole grain breads were protective for colon but not rectal cancers, while consumption of deep fried foods and barbecued/smoked meats increased risk at specific subsites. Beef intake, alcohol consumption, and cigarette smoking appeared to play little or no role at any subsite.

Adenocarcinoma↗
PubMed1989

Barriers to screening for cancer of the cervix.

Despite the widespread availability and demonstrated efficacy of screening with the Papanicolaou smear, many women are screened irregularly or not at all. This study was designed to identify the barriers that prevent those women at risk for cervical cancer from being screened. Complete cervical cytology screening histories were taken during a population-based case-control study of invasive squamous cell carcinoma of the cervix involving 200 patients and their matched neighborhood controls. Smears taken during the previous 5 years were verified whenever possible. Ordinal logistic regression analysis was used to identify seven factors that significantly (P less than 0.05) and independently predicted regular recent screening among both cases and controls [failure to understand the importance and screening nature of cervical smears (-), expressed fears of embarrassment (-), having had a urogenital infection (+), number of pregnancies during the last 5 years (+), the number of pregnancies for which no prenatal care was sought (-), and knowledge of the recommended screening interval (+)], two variables that predicted screening among cases but not controls [age (-) and number of years of oral contraceptives use (+)], and one that predicted screening only among controls [years of living in the United States (+)]. Education, income, Latin heritage, being married, having a regular physician for one's medical care, and all other methods of birth control were significant predictors of screening in the univariate analyses, but were explained by the other more powerful predictors in the multivariate analysis.

Adult↗
PubMed1988

Invasive squamous cell carcinoma of the cervix after recent negative cytologic test results--a distinct subgroup?

A study was conducted to determine if invasive cervical cancer diagnosed shortly after negative cytologic test results represents a demographically or epidemiologically distinct subgroup of these tumors. A total of 200 patients with invasive squamous cervical cancer and matched, neighborhood control subjects were interviewed. Cytology reports for smears taken 5 years before diagnosis were obtained, and reportedly negative smears were solicited and reevaluated. Thirty-three patients (group 1) had had one or more negative smears within 5 years and no previous abnormal cytologic results. At diagnosis cancers in group 1 had progressed further than those of patients with nondiagnostic positive smears (group 2, n = 43) but not as far as those of patients with no cytologic tests done within 5 years (group 3, n = 96). Age and social class were the same in groups 1 and 2, but both groups were younger and better educated than group 3. Otherwise group 1 did not differ from the other groups and the same risk factors prevailed roughly equally in all three groups. Therefore cervical tumors diagnosed soon after negative cytologic test results do not appear to differ etiologically from other squamous carcinomas at this site, and the failure of screening to detect these tumors is probably due to rapid progression through the preinvasive stages and/or failure to shed cancer cells in quantities sufficient for detection by routine cytologic screening.

Adolescent↗
PubMed1988

Type A behavior and coronary heart disease: an update.

In the 1970s, Type A behavior became a popular topic of discussion after it was identified as a risk factor for coronary heart disease. Although recent articles have left many physicians wondering whether Type A behavior is truly unhealthy, much evidence still supports this association. Recognition of overt Type A behavior in clinical practice is usually possible without formal testing if the physician is alert to the motor behavior, speech behavior, hostile attitude and physiologic markers that characterize Type A individuals.

Adult↗