Mortality in a Swedish rubber tire manufacturing plant: Occupational risks or an “unhealthy worker” effect?

BACKGROUND: In this cohort study a classification of 12 work categories, with specified common exposures, is used to evaluate the mortality among workers in a Swedish rubber tire plant. METHODS: Mortality among the cohort members is compared with expected values from national rates. Standardized mortality ratios (SMR) were calculated for the total cohort, for sub-cohorts and with the inclusion of a latency requirement. RESULTS: Male workers had increased risks for total mortality, circulatory death, respiratory death, mental disorders, epilepsy, injuries/poisoning, and for alcohol-related death. Many risks were noted among workers exposed to dust, fumes, or vapor. No trend in risk with increasing duration of employment was seen. DISCUSSION: Some established risks for rubber workers could be related to some specified work categories. The highest risks were noted among workers having a very short duration of employment indicating a possible "unhealthy worker effect" associated with life-style factors or to tasks offered to unskilled workers.     

Estimation of future mortality from pleural malignant mesothelioma in Japan based on an age-cohort model

BACKGROUND: Japanese consumption of asbestos increased rapidly after the 1950s and lingered at a high level while the world's consumption decreased substantially after the 1980s. Mesothelioma is due primarily to asbestos, and the number of deaths in Japan is expected to increase in the future. METHOD: We estimated the future number of pleural mesothelioma deaths among males in Japan using an age-cohort model. RESULTS: Analyses showed that there would be about 100,000 deaths in Japan due to pleural mesothelioma in the next 40 years. Compared with the statistics in European countries, the ratio of expected death numbers to the population size is remarkably close to linear. The data-point for Japan was slightly lower than that which could be expected from the linear relationship. CONCLUSIONS: The limited availability of data may result in underestimation. Taking into consideration the consumption pattern of asbestos in recent decades, the incorporation of later cohorts will improve the estimation.     

Approaches to fitting age-period-cohort models with unequal intervals

Age-period-cohort models have provided useful insights into the analysis of time trends for disease rates, in spite of the well known identifiability problem. Unique parameter estimates that avoid arbitrary constraints are provided by estimable functions of the parameter estimates. For data that are generated using equal interval widths for age and period, the identifiability issue may be expressed in terms of the age, period and cohort slopes. However, when the interval widths are not the same for age and period, additional identifiability problems arise. These may be represented in terms of macro-trends, which have the identical identifiability problem seen in the equal interval case, and micro-trends, which are the source of the additional problems. A framework for testing estimability is presented, and a variety of potentially interesting functions of the parameters considered. Unlike the equal interval case, drift is not estimable for unequal intervals, but local drift may be. In addition, the available functions for forecasting are much more restrictive in the latter case. This estimability problem induces cyclical patterns in the estimates of trend as is demonstrated using data on leukaemia in Connecticut males, but this can be avoided through the use of smoothing splines. These methods of are illustrated for three-year period and five-year age intervals using data on lung cancer mortality in Californian women.     

Anorexia nervosa in young men: A cohort study

OBJECTIVE: The current study investigates the background and outcome of anorexia nervosa (AN) in young men. METHOD: All (N = 61) men, born in 1968-1977 with hospital care in Sweden between 1987 and 1992 due to AN, were compared with the general population. Information about socioeconomic background, health-related outcome (hospital care for AN, other psychiatric diagnoses, abuse of alcohol/drugs and/or suicide attempt), and social outcome (major income from sick leave/sick pension or > or = 6 months social welfare, living with birth parents, and living with child and partner; education level) was taken from national registers. RESULTS: On a group level, the findings suggest some differences between male patients with AN and the male population without AN concerning social background, capacity to support oneself, and living with partner and child. Mental ill-health outcome was almost the same for men with AN as for the general population. CONCLUSION: Male gender in AN--on a group level--suggests a good psychiatric prognosis.     

Educational supervisors evaluate the preparedness of graduates from a reformed UK curriculum to work as pre-registration house officers (PRHOs): a qualitative study

INTRODUCTION: In 1996 the University of Liverpool introduced an integrated problem-based learning (PBL) medical curriculum incorporating the recommendations of Tomorrow's Doctors. This paper investigates whether the PRHO (pre-registration house officer) educational supervisors who supervise Liverpool graduates believe that the reformed curriculum is producing house officers who have the competencies outlined by the General Medical Council. METHODS: Forty-one interviews were arranged with a sample of educational supervisors in the Mersey Deanery area to ascertain their views on the competencies of Liverpool PRHOs. The interviews were tape-recorded, transcribed and analysed. RESULTS: The supervisors felt that the PRHOs had been well prepared to work as PRHOs, and compared with traditional graduates they were actually better prepared for the job of PRHO. They saw the PRHOs as competent communicators with improved clinical skills, who had good attitudes, were aware of limitations, were team workers, good at history-taking and examination and had different approaches to finding information. There was a very confusing picture regarding basic knowledge, with some consultants expressing concerns, despite saying they had adequate knowledge to work as PRHOs. It emerged that there was little consensus about the knowledge base of the traditional or PBL graduates or what knowledge level was needed at this stage. DISCUSSION: Educational supervisors believe that the reformed curriculum in Liverpool is producing competent PRHOs who have been better prepared for the role of PRHO than previous graduates. It could be that uncertainty over knowledge base may be the price paid for reducing the factual burden and improving preparedness for professional practice.     

Comparative academic performance of medical students in rural and urban clinical settings

OBJECTIVE: To determine whether the academic performance of medical students learning in rural settings differs from those learning in urban settings. DESIGN: Comparison of results of assessment for 2 full cohorts and 1 part cohort of medical students learning in rural and urban settings in 2002 (209 students), 2003 (226 students) and 2004 (220 students), including results for each specialist rotation in the 3rd year and end-of-year examinations in the 2nd and 4th years. SETTING: University of Queensland School of Medicine, Brisbane. Students spent the whole 3rd year (of a 4-year graduate entry programme) conducting 5 specialist 8-week rotations in either the rural clinical division (rural students) or in Brisbane (urban students), all following the same curriculum and taking the same examinations. RESULTS: For the 2002 cohort there were no statistically significant differences in academic performance between rural and urban students. For the 2003 cohort the only significant difference was a higher score for rural students in the end of the 4th-year clinical skills examination (65.7 versus 62.3%, P = 0.025). For the 2004 cohort, rural students scored higher in the 3rd-year mental health rotation (79.3 versus 76.2%, P = 0.038) and lower in the medicine rotation (65.5 versus 68.6%, P = 0.037). CONCLUSION: Academic performance among students studying in rural and urban settings is comparable.     

Intake of the major carotenoids and the risk of epithelial ovarian cancer in a pooled analysis of 10 cohort studies

Carotenoids, found in fruits and vegetables, have the potential to protect against cancer because of their properties, including their functions as precursors to vitamin A and as antioxidants. We examined the associations between intakes of alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin and lycopene and the risk of invasive epithelial ovarian cancer. The primary data from 10 prospective cohort studies in North America and Europe were analyzed and then pooled. Carotenoid intakes were estimated from a validated food frequency questionnaire administered at baseline in each study. Study-specific relative risks (RR) were estimated using the Cox proportional hazards model and then combined using a random-effects model. Among 521,911 women, 2,012 cases of ovarian cancer occurred during a follow-up of 7-22 years across studies. The major carotenoids were not significantly associated with the risk of ovarian cancer. The pooled multivariate RRs (95% confidence intervals) were 1.00 (0.95-1.05) for a 600 microg/day increase in alpha-carotene intake, 0.96 (0.93-1.03) for a 2,500 microg/day increase in beta-carotene intake, 0.99 (0.97-1.02) for a 100 microg/day increase in beta-cryptoxanthin intake, 0.98 (0.94-1.03) for a 2,500 microg/day increase in lutein/zeaxanthin intake and 1.01 (0.97-1.05) for a 4,000 microg/day increase in lycopene intake. These associations did not appreciably differ by study (p-values, tests for between-studies heterogeneity >0.17). Also, the observed associations did not vary substantially by subgroups of the population or by histological type of ovarian cancer. These results suggest that consumption of the major carotenoids during adulthood does not play a major role in the incidence of ovarian cancer.     

Prospective study of vegetable consumption and liver cancer in Japan

We examined the relationship between vegetable consumption and the risk of death from liver cancer in a cohort study in Japan. This analysis is based on data from 6,049 subjects aged 40 to 79 years enrolled in a cohort study conducted in Fukuoka Prefecture, Japan. The follow-up period was from 1986 to 1999. All liver cancer deaths were recorded. The vegetable consumption was classified into 3 groups: "once per week or less," "2-4 times per week" and "daily intake." The Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence interval (95% CI). A total of 51 male and 22 female liver cancer deaths were recorded during 62,343 person-years of follow-up. The "once per week or less" group was considered the referent group. In males, the multivariate HRs of liver cancer deaths were 0.61 (95% CI: 0.33-1.14) and 0.25 (95% CI: 0.11-0.59) in the "2-4 times per week" and "daily intake" groups, respectively. In females, the multivariate HRs were 0.44 (95% CI: 0.13-1.51) and 0.51 (95% CI: 0.16-1.69), respectively. The multivariate HRs were also reported by history of hepatitis and cirrhosis. In those without a history of these conditions, the multivariate HRs were 0.54 (95% CI: 0.27-1.09) and 0.36 (95% CI: 0.16-0.83). In those with a history of these conditions, the multivariate HRs were 0.58 (95% CI: 0.22-1.56) and 0.37 (95% CI: 0.13-1.06), respectively. Our study reveals an inverse association between vegetable consumption and the risk of death from liver cancer. These results provide further evidence of the protective effect of vegetables against liver cancer.     

Fruits and vegetables and renal cell carcinoma: findings from the European prospective investigation into cancer and nutrition (EPIC)

We examined the association between fruits and vegetables and risk of renal cell carcinoma (RCC) in the European Prospective Investigation into Cancer and Nutrition (EPIC). Dietary intake data and complete follow-up information on cancer incidence were available for 375,851 participants recruited in EPIC centers of 8 countries. During an average follow-up of 6.2 years, 306 incident cases of RCC were identified. The associations of consumption of total vegetables, total fruits, combined total fruits and vegetables and specific subtypes of vegetables with RCC risk were analyzed using Cox proportional hazards, stratified by centre and adjusted for potential confounders. No significant associations between fruit and vegetable consumption and RCC risk were observed despite a wide range of intake. The estimated relative risks (95% confidence intervals [CI]) in men and women combined were 0.97 (0.85-1.11) per 40 g increase in vegetable intake, 1.03 (0.97-1.08) per 40 g increase in fruit intake and 1.02 (0.93-1.11) per 80 g increase in fruit and vegetable intake combined. Among the vegetable subtypes, an inverse association was observed for root vegetables (RR per 8 g increase: 0.88; 95% CI: 0.78-0.99). These results suggest that total consumption of fruits and vegetables is not related to risk of RCC, although we cannot exclude the possibility that very low consumption is related to higher risk. The relationship of specific fruit and vegetable subgroups with RCC risk warrant further investigation.     

Serum C-peptide levels and breast cancer risk: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)

It has been hypothesized that chronic hyperinsulinemia, a major metabolic consequence of physical inactivity and excess weight, might increase breast cancer risk by direct effects on breast tissue or indirectly by increasing bioavailable levels of testosterone and estradiol. Within the European Prospective Investigation into Cancer and Nutrition (EPIC), we measured serum levels of C-peptide--a marker for pancreatic insulin secretion--in a total of 1,141 incident cases of breast cancer and 2,204 matched control subjects. Additional measurements were made of serum sex hormone binding globulin (SHBG) and sex steroids. Conditional logistic regression models were used to estimate breast cancer risk for different levels of C-peptide. C-peptide was inversely correlated with SHBG and hence directly correlated with free testosterone among both pre and postmenopausal women. C-peptide and free estradiol also correlated positively, but only among postmenopausal women. Elevated serum C-peptide levels were associated with a nonsignificant reduced risk of breast cancer diagnosed up to the age of 50 years [odds ratio (OR)=0.70, (95% confidence interval (CI), 0.39-1.24); ptrend=0.05]. By contrast, higher levels of C-peptide were associated with an increase of breast cancer risk among women above 60 years of age, however only among those women who had provided a blood sample under nonfasting conditions [OR=2.03, (95% CI, 1.20-3.43); ptrend=0.01]. Our results do not support the hypothesis that chronic hyperinsulinemia generally increases breast cancer risk, independently of age. Nevertheless, among older, postmenopausal women, hyperinsulinemia might contribute to increasing breast cancer risk.