Concern has been raised that the occurrence of cancer may be increased in neighbourhoods around a former manufactured gas plant in Champaign, Illinois, USA. Thus, we compared historical rates of cancer in this area to comparison communities as well as with nationally standardised rates.
Retrospective population-based community cancer assessment during 1990-2010. Champaign County, Illinois, USA, and zip codes encompassing the location of the former manufactured gas plant to counties that were similar demographically. Residents of the counties and zip codes studied between 1990 and 2010. The relative risk (RR) and 95% CI were used to compare cancer incidence and mortality in the areas near the gas compression site to the comparison counties. Standardised incidence ratios (SIRs) were calculated to compare rates in the areas near the gas compression site to expected rates based on overall US cancer rates.
Total cancer mortality (RR=0.91, 95% CI 0.88 to 0.94) and incidence (RR=0.95, 95% CI 0.94 to 0.97) were reduced significantly in Champaign County versus the comparison counties. Similarly, a reduced rate of total cancer was observed in analyses by zip code (proximal to the former gas plant) when compared with either similar counties (RR=0.89, 95% CI 0.86 to 0.93) or national standardised rates of […]
Objectives Concern has been raised that the occurrence of cancer may be increased in neighbourhoods around a former manufactured gas plant in Champaign, Illinois, USA. Thus, we compared historical rates of cancer in this area to comparison communities as well as with nationally standardised rates.
Design Retrospective population-based community cancer assessment during 1990–2010.
Setting Champaign County, Illinois, USA, and zip codes encompassing the location of the former manufactured gas plant to counties that were similar demographically.
Participants Residents of the counties and zip codes studied between 1990 and 2010.
Main outcome measures The relative risk (RR) and 95% CI were used to compare cancer incidence and mortality in the areas near the gas compression site to the comparison counties. Standardised incidence ratios (SIRs) were calculated to compare rates in the areas near the gas compression site to expected rates based on overall US cancer rates.
Results Total cancer mortality (RR=0.91, 95% CI 0.88 to 0.94) and incidence (RR=0.95, 95% CI 0.94 to 0.97) were reduced significantly in Champaign County versus the comparison counties. Similarly, a reduced rate of total cancer was observed in analyses by zip code (proximal to the former gas plant) when compared with either similar counties […]
Interpreting epidemiologic studies of diet and health is often complex because it involves many methodological issues and sources of uncertainty. Pertinent examples are false-positive and false-negative results, that is, findings that erroneously indicate the presence or absence, respectively, of association. Our objective in this commentary is to help nutrition and other health professionals interpret epidemiological studies when faced with this task. Our aim is not to provide an exhaustive discussion of all the methodological nuances of nutritional epidemiology; rather, we focus on some of the salient factors when interpreting findings from dietary studies, and the role that uncertainty (namely, from false-positives) plays, using relevant examples from the past few decades.
Nutrition Today: May/June 2014 – Volume 49 – Issue 3 – p 147-152
Nearly five percent of Americans suffer from functional constipation, many of whom may benefit from increasing dietary fiber consumption. The annual constipation-related healthcare cost savings associated with increasing intakes may be considerable but have not been examined previously. The objective of the present study was to estimate the economic impact of increased dietary fiber consumption on direct medical costs associated with constipation.
Literature searches were conducted to identify nationally representative input parameters for the U.S. population, which included prevalence of functional constipation; current dietary fiber intakes; proportion of the population meeting recommended intakes; and the percentage that would be expected to respond, in terms of alleviation of constipation, to a change in dietary fiber consumption. A dose-response analysis of published data was conducted to estimate the percent reduction in constipation prevalence per 1 g/day increase in dietary fiber intake. Annual direct medical costs for constipation were derived from the literature and updated to U.S. $ 2012. Sensitivity analyses explored the impact on adult vs. pediatric populations and the robustness of the model to each input parameter.
The base case direct medical cost-savings was $12.7 billion annually among adults. The base case assumed that 3% of men and 6% of women currently met recommended […]
The objective of the present meta-analysis was to examine the effect of whey protein (WP), with or without resistance exercise, onbody weight and body composition in randomized controlled trials (RCTs) conducted in generally healthy adult study populations.
A comprehensive literature search was conducted to identify RCTs that investigated WP (concentrate, isolate, or hydrolystate) and bodyweight, body mass index (BMI), body fat, lean body mass (LBM), fat-free mass (FFM), and waist circumference. Random effects meta-analyses were conducted to generate weighted group mean differences (WGMD) for between-group comparisons (WP vs other protein sources or carbohydrates) and within-WP group comparisons (i.e., differences from baseline to trial end). Studies were classified into 2 distinct groups-WP as a supplement without dietary modification (WPS) and WP as a replacement for other sources of calories (WPR)-and were meta-analyzed separately. Subgroup analyses included examining the effect of resistance exercise and type of WP on the relationship between WP and body composition.
Fourteen RCTs were included, with a total of 626 adult study completers. Five studies examined the effects of WPR and the remaining 9 studies examined the effects of WPS. Body weight (WGMD: -4.20 kg, 95% confidence interval [CI], -7.67, -0.73) and body fat (WGMD: -3.74 kg, 95% CI, -5.98, -1.50) were significantly decreased from baseline in the WPR within-group analyses. In the between-group analyses, the effects of WP were more favorable when compared with carbohydrates than protein sources other than whey, although findings did not reach […]
The objective was to conduct a meta-analysis of studies of benzene exposure and non-Hodgkin lymphoma (NHL). A total of 8 cohort and 14 case-control studies were analyzed. Meta-analysis of any benzene exposure resulted in a summary relative risk estimate (SRRE) of 1.02 (95% CI: 0.94 to 1.12). The SRRE changed minimally when only data representing the highest level of benzene exposure were analyzed after an a priori data extraction protocol, using cumulative exposure as the optimum metric (SRRE = 1.08, 95% CI: 0.93 to 1.24). Meta-analysis of five studies that reported results for 60 or more ppm-years of cumulative exposure yielded an SRRE of 1.08 (95% CI: 0.36 to 3.24). Similarly, an SRRE of 1.04 (95% CI: 0.96 to 1.12) for each 25 ppm-year increment of benzene exposure was observed. The results from this meta-analysis are not supportive of an independent association between benzene exposure and NHL.
Alexander DD, Wagner ME. Benzene exposure and non-Hodgkin lymphoma: a meta-analysis of epidemiologic studies. J Occup Environ Med. 2010 Feb;52(2):169-89.
The relationship between red meat consumption and colorectal cancer (CRC) has been the subject of scientific debate. To estimate the summary association between red meat intake and CRC and to examine sources of heterogeneity, a meta-analysis of prospective studies was conducted. Thirty-four prospective studies of red meat and CRC were identified, of which 25 represented independent nonoverlapping study populations. Summary relative risk estimates (SRREs) for high versus low intake and dose-response relationships were calculated. In the high versus low intake meta-analysis, the SRRE was 1.12 (95% CI: 1.04-1.21) with significant heterogeneity (P=0.014). Summary associations were modified by tumor site and sex. The SRREs for colon cancer and rectal cancer were 1.11 (95% CI: 1.03-1.19) and 1.19 (95% CI: 0.97-1.46), respectively. The SRREs among men and women were 1.21 (95% CI: 1.04-1.42) and 1.01 (95% CI: 0.87-1.17), respectively. The available epidemiologic data are not sufficient to support an independent and unequivocal positive association between red meat intake and CRC. This conclusion is based on summary associations that are weak in magnitude, heterogeneity across studies, inconsistent patterns of associations across the subgroup analyses, and the likely influence of confounding by other dietary and lifestyle factors.
Alexander DD, Weed DL, Cushing CA, Lowe KA. […]
The objective was to systematically evaluate epidemiologic studies on pesticides and colon cancer and rectal cancer in agricultural pesticide applicator populations using a transparent “weight-of-evidence” (WOE) methodological approach. Twenty-nine publications from the Agricultural Health Study (AHS) and 13 additional epidemiologic studies were identified that reported data for pesticide applicators and/or specific pesticide compounds and colorectal, colon, or rectal cancer. The AHS evaluated pesticide applicators as well as dose-response associations for specific pesticide compounds, whereas the large majority of non-AHS evaluated applicators but did not analyze specific compounds or dose-response trends. This WOE assessment of 153 different pesticide-outcome pairs emphasized several key evidentiary features: existence of statistically significant relative risks, magnitude of observed associations, results from the most reliable exposure assessments, and evidence of convincing dose-response relationships (i.e., those monotonically increasing, with statistically significant trend tests). Occupation as a pesticide applicator or pesticide application as a farming-related function was not associated with increasing the risk of colon or rectal cancer. Deficits of colon or rectal cancer were observed across most studies of pesticide applicators. After applying the WOE methodology to the epidemiologic studies of specific pesticide compounds and colon or rectal cancer, a number of pesticide-outcome pairs were identified and evaluated […]
The non-Hodgkin lymphomas (NHL) are a heterogeneous group of B-cell and T-cell neoplasms that arise primarily in the lymph nodes. NHL incidence rates in the US doubled between about 1970 and 1990, and stabilized during the 1990s. NHL accounts for approximately 3.4% of cancer deaths in the US. Although some of the observed patterns in NHL have been related to HIV/AIDS, these conditions cannot fully explain the magnitude of the changes; neither do changes in classification systems nor improved diagnostic capabilities. Studies of occupational and environmental exposures (e.g., pesticides, solvents) have produced no consistent pattern of significant positive associations. Inverse associations with ultraviolet radiation exposure and alcohol and fish intake, and positive associations with meat and saturated fat intake have been reported in several studies; additional studies are needed to confirm or refute these associations. Family history of NHL or other hematolympho-proliferative cancers and personal history of several autoimmune disorders are associated with increased risk of NHL, but are not likely to account for a large proportion of cases. HIV and other infectious agents, such as human herpesvirus 8 and Epstein-Barr, appear to be associated with differing types of NHL, such as some B-cell lymphomas. Future epidemiologic studies should evaluate […]
Although a large body of literature has been devoted to examining the relationship between eicosapentaenoic and docosahexaenoic acids (EPA+DHA) and blood pressure, past systematic reviews have been hampered by narrow inclusion criteria and a limited scope of analytical subgroups. In addition, no meta-analysis to date has captured the substantial volume of randomized controlled trials (RCTs) published in the past 2 years. The objective of this meta-analysis was to examine the effect of EPA+DHA, without upper dose limits and including food sources, on blood pressure in RCTs. Random-effects meta-analyses were used to generate weighted group mean differences and 95% confidence intervals (CIs) between the EPA+DHA group and the placebo group. Analyses were conducted for subgroups defined by key subject or study characteristics. Seventy RCTs were included. Compared with placebo, EPA+DHA provision reduced systolic blood pressure (-1.52mm Hg; 95% confidence interval (CI) = -2.25 to -0.79) and diastolic blood pressure (- 0.99mmHg; 95% CI = – 1.54 to – 0.44) in the meta-analyses of all studies combined. The strongest effects of EPA+DHA were observed among untreated hypertensive subjects (systolic blood pressure = – 4.51mm Hg, 95% CI = – 6.12 to – 2.83; diastolic blood pressure = – 3.05mm Hg, 95% CI […]