Catherine M. Crespi

Pooled analysis of recent studies on magnetic fields and childhood leukaemia

Background:Previous pooled analyses have reported an association between magnetic fields and childhood leukaemia. We present a pooled analysis based on primary data from studies on residential magnetic fields and childhood leukaemia published after 2000.Methods:Seven studies with a total of 10 865 cases and 12 853 controls were included. The main analysis focused on 24-h magnetic field measurements or calculated fields in residences.Results:In the combined results, risk increased with increase in exposure, but the estimates were imprecise. The odds ratios for exposure categories of 0.1–0.2 μT, 0.2–0.3 μT and ⩾0.3 μT, compared with <0.1 μT, were 1.07 (95% CI 0.81–1.41), 1.16 (0.69–1.93) and 1.44 (0.88–2.36), respectively. Without the most influential study from Brazil, the odds ratios increased somewhat. An increasing trend was also suggested by a nonparametric analysis conducted using a generalised additive model.Conclusions:Our results are in line with previous pooled analyses showing an association between magnetic fields and childhood leukaemia. Overall, the association is weaker in the most recently conducted studies, but these studies are small and lack methodological improvements needed to resolve the apparent association. We conclude that recent studies on magnetic fields and childhood leukaemia do not alter the previous assessment that magnetic fields are possibly carcinogenic.

Comparison of methods for estimating the intraclass correlation coefficient for binary responses in cancer prevention cluster randomized trials.

The intraclass correlation coefficient (ICC) is a fundamental parameter of interest in cluster randomized trials as it can greatly affect statistical power. We compare common methods of estimating the ICC in cluster randomized trials with binary outcomes, with a specific focus on their application to community-based cancer prevention trials with primary outcome of self-reported cancer screening. Using three real data sets from cancer screening intervention trials with different numbers and types of clusters and cluster sizes, we obtained point estimates and 95% confidence intervals for the ICC using five methods: the analysis of variance estimator, the Fleiss-Cuzick estimator, the Pearson estimator, an estimator based on generalized estimating equations and an estimator from a random intercept logistic regression model. We compared estimates of the ICC for the overall sample and by study condition. Our results show that ICC estimates from different methods can be quite different, although confidence intervals generally overlap. The ICC varied substantially by study condition in two studies, suggesting that the common practice of assuming a common ICC across all clusters in the trial is questionable. A simulation study confirmed pitfalls of erroneously assuming a common ICC. Investigators should consider using sample size and analysis methods that allow the ICC to vary by study condition.

Mindfulness meditation for younger breast cancer survivors: A randomized controlled trial

Premenopausal women diagnosed with breast cancer are at risk for psychological and behavioral disturbances after cancer treatment. Targeted interventions are needed to address the needs of this vulnerable group.

Refinement and Psychometric Evaluation of the Impact of Cancer Scale

BACKGROUND Instruments are needed to measure the influence of cancer on quality of life in the expanding population of long-term cancer survivors. We conducted refinement and psychometric evaluation of the Impact of Cancer (IOC) scale by use of data from a large sample of long-term breast cancer survivors and developed an instrument, the Impact of Cancer version 2 (IOCv2), to measure quality of life outcomes. METHODS Questionnaires including 81 potential IOC scale items, the Center for Epidemiologic Studies-Depression (CES-D) scale, and the Breast Cancer Prevention Trial (BCPT) symptom scales, as well as demographic, treatment, and medical information, were completed by 1188 disease-free breast cancer survivors 5-10 years after diagnosis. We used exploratory factor analysis to identify scales and assessed reproducibility by split-sample cross-validation. Higher-order scales were extracted and all scales were evaluated for internal consistency and construct and concurrent validity. RESULTS The analysis yielded a factor structure relating IOC items to psychosocial impact domains that exhibited high factor loadings (factor-item correlations of 0.59-0.94), high internal consistency (Cronbachs alpha statistics of 0.76-0.89), and a total congruence of 0.98 across the split samples. The Impact of Cancer version 2 (IOCv2) scales consist of a Positive Impact Summary scale with four subscales (Altruism and Empathy, Health Awareness, Meaning of Cancer, and Positive Self-Evaluation), a Negative Impact Summary scale with four subscales (Appearance Concerns, Body Change Concerns, Life Interferences, and Worry), and subscales for Employment and Relationship Concerns. Patterns of association between IOCv2 scale scores and CES-D and BCPT scores indicated good concurrent validity. Patterns of associations between IOCv2 scale scores and demographic, medical, and treatment characteristics indicated good construct validity. CONCLUSION The IOCv2 scales provide a validated tool for measuring the impact of cancer on quality of life in long-term cancer survivors.

The need for a reassessment of the safe upper limit of selenium in drinking water

Results of recent epidemiologic studies suggest the need to reassess the safe upper limit in drinking water of selenium, a metalloid with both toxicological and nutritional properties. Observational and experimental human studies on health effects of organic selenium compounds consumed through diet or supplements, and of inorganic selenium consumed through drinking water, have shown that human toxicity may occur at much lower levels than previously surmised. Evidence indicates that the chemical form of selenium strongly influences its toxicity, and that its biological activity may differ in different species, emphasizing the importance of the few human studies on health effects of the specific selenium compounds found in drinking water. Epidemiologic studies that investigated the effects of selenate, an inorganic selenium species commonly found in drinking water, together with evidence of toxicity of inorganic selenium at low levels in from in vitro and animal studies, indicate that health risks may occur at exposures below the current European Union and World Health Organization upper limit and guideline of 10 and 40 μg/l, respectively, and suggest reduction to 1 μg/l in order to adequately protect human health. Although few drinking waters are currently known to have selenium concentrations exceeding this level, the public health importance of this issue should not be overlooked, and further epidemiologic research is critically needed in this area.

Trends in Colorectal Cancer Screening Utilization among Ethnic Groups in California: Are We Closing the Gap?

Background: Given the low prevalence of and racial/ethnic disparities in colorectal cancer screening, it is important to monitor whether prevalence and disparities are increasing or decreasing over time. Methods: We estimated the prevalence of colorectal cancer screening by year (2001, 2003, and 2005), modality (endoscopy, fecal occult blood test, either), and recency (ever had, up-to-date) for the California population as a whole, major racial/ethnic groups (White, Black, Latino, Asian), and selected Asian subgroups (Chinese, Filipino, Japanese, Korean, Vietnamese) using data from the California Health Interview Survey. All prevalence estimates were age- and gender-standardized. Results: From 2001 to 2005, prevalence of up-to-date screening increased significantly among Whites and Latinos but not among Blacks and Asian Americans. Screening prevalence varied substantially among Asian subgroups, with Korean, Filipino, and Vietnamese Americans having the lowest prevalence. Korean Americans were the only group in the analysis with a significant decline in screening prevalence from 2001 to 2005. The gap between the highest and the lowest up-to-date screening prevalence using any screening modality, exhibited by Japanese and Korean Americans, increased from 18% in 2001 to 30% in 2005. Conclusions: Findings suggest that we need to intensify efforts to increase colorectal cancer screening, especially among Korean Americans but also among Filipinos, Vietnamese, and Latinos. (Cancer Epidemiol Biomarkers Prev 2009;18(3):752–9)

Cerebrospinal fluid of newly diagnosed amyotrophic lateral sclerosis patients exhibits abnormal levels of selenium species including elevated selenite

Exposure to selenium, and particularly to its inorganic forms, has been hypothesized as a risk factor for amyotrophic lateral sclerosis (ALS), a fast progressing motor neuron disease with poorly understood etiology. However, no information is known about levels of inorganic and some organic selenium species in the central nervous system of ALS patients, and recent observations suggest that peripheral biomarkers of exposure are unable to predict these levels for several Se species including the inorganic forms. Using a hospital-referred case-control series and advanced selenium speciation methods, we compared the chemical species of selenium in cerebrospinal fluid from 38 ALS patients to those of 38 reference neurological patients matched on age and gender. We found that higher concentrations of inorganic selenium in the form of selenite and of human serum albumin-bound selenium were associated with increased ALS risk (relative risks 3.9 (95% confidence interval 1.2-11.0) and 1.7 (1.0-2.9) for 0.1μg/L increase). Conversely, lower concentrations of selenoprotein P-bound selenium were associated with increased risk (relative risk 0.2 for 1μg/L increase, 95% confidence interval 0.04-0.8). The associations were stronger among cases age 50 years or older, who are postulated to have lower rates of genetic disease origin. These results suggest that excess selenite and human serum albumin bound-selenium and low levels of selenoprotein P-bound selenium in the central nervous system, which may be related, may play a role in ALS etiology.

Explaining disparities in colorectal cancer screening among five Asian ethnic groups: A population-based study in California

BackgroundData from the California Health Interview Survey (CHIS) indicate that levels and temporal trends in colorectal cancer (CRC) screening prevalence vary among Asian American groups; however, the reasons for these differences have not been fully investigated.MethodsUsing CHIS 2001, 2003 and 2005 data, we conducted hierarchical regression analyses progressively controlling for demographic characteristics, English proficiency and access to care in an attempt to identify factors explaining differences in screening prevalence and trends among Chinese, Filipino, Vietnamese, Korean and Japanese Americans (N = 4,188).ResultsAfter controlling for differences in gender and age, all Asian subgroups had significantly lower odds of having ever received screening in 2001 than the reference group of Japanese Americans. In addition, Korean Americans were the only subgroup that had a statistically significant decline in screening prevalence from 2001 to 2005 compared to the trend among Japanese Americans. After controlling for differences in education, marital status, employment status and federal poverty level, Korean Americans were the only group that had significantly lower screening prevalence than Japanese Americans in 2001, and their trend to 2005 remained significantly depressed. After controlling for differences in English proficiency and access to care, screening prevalences in 2001 were no longer significantly different among the Asian subgroups, but the trend among Korean Americans from 2001 to 2005 remained significantly depressed. Korean and Vietnamese Americans were less likely than other groups to report a recent doctor recommendation for screening and more likely to cite a lack of health problems as a reason for not obtaining screening.ConclusionsDifferences in CRC screening trends among Asian ethnic groups are not entirely explained by differences in demographic characteristics, English proficiency and access to care. A better understanding of mutable factors such as rates of doctor recommendation and health beliefs will be crucial for designing culturally appropriate interventions to promote CRC screening.

Analysis of recurrence patterns associated with toxoplasmic retinochoroiditis

PURPOSE Toxoplasmic retinochoroiditis is thought to recur randomly. We sought to determine whether there is, instead, a longitudinal pattern of recurrences and to identify risk factors for recurrence. DESIGN Longitudinal cohort study. METHODS We collected the following data for 143 patients with toxoplasmic retinochoroiditis in The Netherlands: gender, first affected eye, age at first episode, mode of Toxoplasma gondii infection (congenital vs postnatal), treatment history, and presence of retinal scars at initial examination. For each episode, we determined age, duration since first episode, and interval since previous episode. We estimated the relationship between disease-free interval after an episode and recurrence risk. The influence of host and disease factors on recurrence risk was analyzed using Cox regression with frailty modeling for correlated intrapatient recurrence times. We performed a Monte Carlo test for occurrence of clusters after prolonged disease-free intervals. RESULTS Follow-up ranged from 0.3 to 41 years (323 episodes in first-affected eyes). Recurrence risk was highest immediately after an episode, then decreased with increasing disease-free intervals, a pattern consistent with clustering. Relative risk (RR) of recurrence declined 72% (RR, 0.28; 95% confidence interval [CI], 0.22 to 0.36; P < .001) with each 10-year interval since first episode, and declined 15% (RR, 0.85; 95% CI, 0.71 to 1.01; P = .06) for each 10-year increase in age at first episode. Patients more than 40 years of age were at higher risk of recurrence than younger patients (RR, 1.74; 95% CI, 1.06 to 2.86; P = .03). Clusters of episodes occurred after prolonged disease-free intervals. CONCLUSIONS Toxoplasmic retinochoroiditis occurs in clusters over time. Recurrence risk is influenced by patient age and duration of infection.

Results of a community-based randomized trial to increase colorectal cancer screening among Filipino Americans.

OBJECTIVES We conducted 1 of the first community-based trials to develop a multicomponent intervention that would increase colorectal cancer screening among an Asian American population. METHODS Filipino Americans (n = 548) nonadherent to colorectal cancer (CRC) screening guidelines were randomized into an intervention group that received an education session on CRC screening and free fecal occult blood test (FOBT) kits; a second intervention group that received an education session but no free FOBT kits; and a control group that received an education session on the health benefits of physical activity. RESULTS Self-reported CRC screening rates during the 6-month follow-up period were 30%, 25%, and 9% for participants assigned to intervention with FOBT kit, intervention without the kit, and control group, respectively. Participants in either of the 2 intervention groups were significantly more likely to report screening at follow-up than were participants in the control group. CONCLUSIONS A multicomponent intervention that includes an educational group session in a community setting can significantly increase CRC screening among Filipino Americans, even when no free FOBT kits are distributed.