http://hdl.handle.net/10027/7227 Sun, 26 May 2013 08:56:15 GMT 2013-05-26T08:56:15Z http://hdl.handle.net/10027/8755 Defining Reproducibility Statistics as a Function of the Spatial Covariance Structures in Biomarker Studies Helenowski, Irene B.; Vonesh, Edward F.; Demirtas, Hakan; Rademaker, Alfred W.; Ananthanarayanan, Vijayalakshmi; Gann, Peter H.; Jovanovic, Borko D. The reproducibility of a biomarker plays a paramount role in determining whether it provides an accurate indication of the true underlying disease or risk status of an individual. When biomarker measurement involves obtaining samples of tissue at random from the organ of interest, sampling variability based on spatial effects can affect this reproducibility. This situation arises when a target organ, such as the prostate or esophagus, is evaluated by multiple random needle biopsies or when an excised organ is randomly sampled. We present a general approach toward estimating reproducibility in the presence of different variance-covariance structures needed to account for possible spatial or temporal variation and correlation. Specifically, we extend the work of previous authors involving applications of the concordance correlation coefficient (CCC) by allowing for different variance-covariance structures of the data. A general concordance correlation matrix representing pairwise concordance correlation coefficients is presented along with an overall concordance correlation coefficient both of which may be obtained from models assuming different variance-covariance structures. The overall concordance correlation coefficient provides a measure of the overall reproducibility and its validity relative to various assumed covariance structures can be assessed by examining commonly employed goodness-of-fit measures. We illustrate these methods to minichromosome maintenance protein 2 (MCM2) data coming from the prostate glands of seven subjects having prostate biopsies between 2002 and 2003. The final publication is available at www.degruyter.com The International Journal of Biostatistics at DOI: 10.2202/1557-4679.1128 Sat, 01 Jan 2011 06:00:00 GMT http://hdl.handle.net/10027/8755 2011-01-01T06:00:00Z http://hdl.handle.net/10027/8581 Factors Associated with Repeat Visits among Clients Attending a Clinic for Sexually Transmitted Infections in Kisumu, Kenya Pultorak, Elizabeth; Odoyo-June, Elijah; Hayombe, Juma; Opiyo, Felix; Odongo, Winnie; Ogollah, James Aggrey; Moses, Stephen; Bailey, Robert C.; Mehta, Supriya D. Purpose: To identify factors associated with repeat visits among patients attending a clinic for sexually transmitted infections (STIs) in Kisumu, Kenya. Methods: Records of clinic visits were examined from March 2009 through May 2010. Multivariable logistic regression identified factors associated with repeat visits occurring > 30 days after the initial visit. Results: Among 1,473 clients (1,296 single-visit individuals vs. 177 individuals with repeat visits), the median age was 24 years, 67% were male, and 8.6% self-reported being HIV positive. In adjusted analyses, men with repeat visits were more likely to report > 2 recent sex partners (adjusted odds ratio (AOR) =1.60) and being HIV-positive (AOR=2.35). They were less likely to have been referred from other health facilities (AOR=0.14) and more likely to have urethral discharge at initial visit (AOR=2.46). Among women, repeat visits were associated with vaginal discharge (AOR=2.22), but attending the clinic with a partner was protective (AOR=0.38). Conclusions: The association between sexual risk, HIV positivity and repeat visits among male clients highlights the need to focus intervention efforts on this group. For women, attending with a partner may reflect a decreased risk of re-infection if both partners are treated and counseled together. This is the final draft, after peer-review, of a manuscript published in RSM journals: www.rsmpress.com. © 2011 Royal Society of Medicine Press Limited. DOI: 10.1258/ijsa.2011.010483. Tue, 01 Nov 2011 05:00:00 GMT http://hdl.handle.net/10027/8581 2011-11-01T05:00:00Z http://hdl.handle.net/10027/8514 Supplemental Materials: Risks and Benefits of Consumption of Great Lakes Fish Turyk, M. E.; Bhavsar, S. P.; Bowerman, W.; Boysen, E.; Clark, M.; Diamond, M.; Mergler, D.; Pantazopoulos, P.; Schantz, S.; Carpenter, D.O. Background: Beneficial effects of fish consumption on early cognitive development and cardiovascular health have been attributed to the omega-3 fatty acids in fish and fish oils, but toxic chemicals in fish may adversely affect these health outcomes. Risk–benefit assessments of fish consumption have frequently focused on methylmercury and omega-3 fatty acids, not persistent pollutants such as polychlorinated biphenyls, and none have evaluated Great Lakes fish consumption. O b jectives: The risks and benefits of fish consumption have been established primarily for marine fish. Here, we examine whether sufficient data are available to evaluate the risks and benefits of eating freshwater fish from the Great Lakes. Methods: We used a scoping review to integrate information from multiple state, provincial, and federal agency sources regarding the contaminants and omega-3 fatty acids in Great Lakes fish and fish consumers, consumption rates and fish consumption advisories, and health effects of contaminants and omega-3 fatty acids. D ata synthesis: Great Lakes fish contain persistent contaminants—many of which have documented adverse health effects —that accumulate in humans consuming them. In contrast, data are sparse on omega-3 fatty acids in the fish and their consumers. Moreover, few studies have documented the social and cultural benefits of Great Lakes fish consumption, particularly for subsistence fishers and native communities. At this time, federal and state/provincial governments provide fish consumption advisories based solely on risk. C onclusions: Our knowledge of Great Lakes fish has critical gaps, particularly regarding the benefits of consumption. A risk–benefit analysis requires more information than is currently available on the concentration of omega-3 fatty acids in Great Lakes fish and their absorption by fish eaters in addition to more information on the social, cultural, and health consequences of changes in the amount of fish consumed. Reproduced with permission from Environmental Health Perspectives. The original version is available through National Institute of Environmental Health Sciences at DOI: 10.1289/ehp.1003396. Fri, 23 Sep 2011 05:00:00 GMT http://hdl.handle.net/10027/8514 2011-09-23T05:00:00Z http://hdl.handle.net/10027/8466 Health Risks of Limited-Contact Water Recreation Dorevitch, Samuel; Pratap, Preethi; Wroblewski, Meredith; Hryhorczuk, Daniel O.; Li, Hong; Liu, Li C.; Scheff, Peter A. BACKGROUND: Wastewater-impacted waters that do not support swimming are often used for boating, canoeing, fishing, kayaking, and rowing. Little is known about the health risks of these limited-contact water recreation activities. OBJECTIVES: We evaluated the incidence of illness, severity of illness, associations between water exposure and illness, and risk of illness attributable to limited-contact water recreation on waters dominated by wastewater effluent and on waters approved for general use recreation (such as swimming). METHODS: The Chicago Health, Environmental Exposure, and Recreation Study was a prospective cohort study that evaluated five health outcomes among three groups of people: those who engaged in limited-contact water recreation on effluent-dominated waters, those who engaged in limitedcontact recreation on general-use waters, and those who engaged in non–water recreation. Data analysis included survival analysis, logistic regression, and estimates of risk for counterfactual exposure scenarios using G-computation. RESULTS: Telephone follow-up data were available for 11,297 participants. With non–water recreation as the reference group, we found that limited-contact water recreation was associated with the development of acute gastrointestinal illness in the first 3 days after water recreation at both effluentdominated waters [adjusted odds ratio (AOR) 1.46; 95% confidence interval (CI): 1.08, 1.96] and general-use waters (1.50; 95% CI: 1.09, 2.07). For every 1,000 recreators, 13.7 (95% CI: 3.1, 24.9) and 15.1 (95% CI: 2.6, 25.7) cases of gastrointestinal illness were attributable to limited-contact recrea tion at effluent-dominated waters and general-use waters, respectively. Eye symptoms were associated with use of effluent-dominated waters only (AOR 1.50; 95% CI: 1.10, 2.06). Among water recreators, our results indicate that illness was associated with the amount of water exposure. CONCLUSIONS: Limited-contact recreation, both on effluent-dominated waters and on waters designated for general use, was associated with an elevated risk of gastrointestinal illness. © 2012 by National Institute of Environmental Health Sciences , Environmental Health Perspectives Reproduced with permission from Environmental Health Perspectives DOI: 10.1289/ehp.1103934 Wed, 01 Feb 2012 06:00:00 GMT http://hdl.handle.net/10027/8466 2012-02-01T06:00:00Z