Collaborative cancer epidemiology in the 21st century: the model of cancer consortia.

During the last two decades, epidemiology has undergone a rapid evolution toward collaborative research. The proliferation of multi-institutional, interdisciplinary consortia has acquired particular prominence in cancer research. Herein, we describe the characteristics of a network of 49 established cancer epidemiology consortia (CEC) currently supported by the Epidemiology and Genomics Research Program (EGRP) at the National Cancer Institute (NCI). This collection represents the largest disease-based research network for collaborative cancer research established in population sciences. We describe the funding trends, geographic distribution, and areas of research focus. The CEC have been partially supported by 201 grants and yielded 3,876 publications between 1995 and 2011. We describe this output in terms of interdisciplinary collaboration and translational evolution. We discuss challenges and future opportunities in the establishment and conduct of large-scale team science within the framework of CEC, review future prospects for this approach to large-scale, interdisciplinary cancer research, and describe a model for the evolution of an integrated Network of Cancer Consortia optimally suited to address and support 21st-century epidemiology.

Body mass index at the time of diagnosis of autoimmune type 1 diabetes in children.

OBJECTIVES: To describe the body mass index (BMI) distribution of children developing autoimmune type 1 diabetes (T1D) compared with the general population and to assess factors associated with BMI at T1D onset. STUDY DESIGN: Children age 2-<19 years enrolled in the Pediatric Diabetes Consortium at 7 US pediatric diabetes centers at T1D onset were included. Eligibility for analysis required a diagnosis of T1D, ≥1 positive diabetes autoantibody, and availability of BMI within 14 days of diagnosis. BMI at diagnosis was compared with the general population as described by the 2000 Centers for Disease Control. Regression analysis was used to assess the association between BMI and various participant characteristics. RESULTS: BMI scores for the 490 participants were slightly lower than the 2000 Centers for Disease Control population (P = .04). The median BMI percentile for age and sex was 48(th), 11% of the children were overweight (BMI ≥85(th) and <95(th) percentile), 8% obese (BMI ≥95(th) and <99(th) percentile), and 2% severely obese (≥99(th) percentile), percentages that were comparable across age and sex groups. Higher BMI Z-scores were associated with African American and Hispanic race/ethnicity (P = .001) and lower hemoglobin A1c (P < .001), and diabetic ketoacidosis, age, and Tanner stage were not associated. CONCLUSIONS: Although the BMI distribution in children developing autoimmune T1D was lower than that of the general population, 21% of children were obese or overweight. Youth who are overweight, obese, racial/ethnic minority, and/or present without diabetic ketoacidosis should not be presumed to have type 2 diabetes because many patients with autoantibody-positive T1D present with the same clinical characteristics.

Accuracy and precision of the Axis-Shield Afinion hemoglobin A1c measurement device.

BACKGROUND: The Afinion HbA1c (Axis-Shield) is a newer point-of-care device for measurement of hemoglobin A1c (A1C) using a boronate affinity method unlike the more commonly used DCA immunoassay method (Siemens Medical Solutions Diagnostics). The Afinion's accuracy and precision, when compared with high-performance liquid chromatography (HPLC) and DCA methods, have not been established in pediatric practice settings. METHODS: Capillary blood was collected from 700 subjects with diabetes mellitus at seven Pediatric Diabetes Consortium sites. Each subject's A1C was measured locally using Afinion and DCA devices, and by a central laboratory (University of Minnesota) using a Tosoh HPLC method. In addition, repeated measurements on six whole blood samples provided by the National Glycohemoglobin Standardization Program (NGSP) were taken at three clinical centers using the Afinion and DCA methods and centrally using the Tosoh HPLC method to assess the precision of each device. RESULTS: The coefficient of variation for measurements of whole blood samples for precision analysis was 2% for Afinion, 3% for DCA, and 1% for HPLC. In the patient samples measured at the seven clinic sites, the Afinion generated higher A1C results than the HPLC (mean difference = +0.15; p < 0.001), while the DCA produced lower values (mean difference = -0.19; p < 0.001). The absolute differences with HPLC were similar for the Afinion and DCA (median 0.2%) with a slight advantage for the Afinion when compared with DCA (p < 0.001 by rank test). The DCA tended to read lower than HPLC, particularly at high A1C levels (p < 0.001), while the Afinion's accuracy did not vary by A1C. CONCLUSIONS: When compared to the central laboratory HPLC method, the differences between the results of the Afinion and DCA devices are clinically insignificant, and the Afinion and DCA have similar accuracy and precision when used in pediatric practice settings.

Comparison of Tono-Pen and Goldmann applanation tonometers for measurement of intraocular pressure in healthy children.

PURPOSE: To assess the agreement of intraocular pressure (IOP) measured with the Tono-Pen and the Goldmann applanation tonometer (GAT) in normal children and adolescents. METHODS: A total of 439 subjects from birth to <18 years of age without anterior segment anomalies or glaucoma had their IOP measured with the two instruments by separate, masked examiners in the office or under general anesthesia. RESULTS: On average, the Tono-Pen measured values slightly lower than the GAT for IOP <11 mm Hg and slightly higher than the GAT for IOP >11 mm Hg in the office setting. Using the average of GAT and Tono-Pen IOPs to estimate the true IOP, the average difference (GAT - Tono-Pen) was 0.4 mm Hg at IOP of 10 mm Hg and -3.0 mm Hg at IOP of 20 mm Hg. The 95% limits of agreement on the average difference between instruments were ± 6.4 mm Hg in the office setting and ± 6.8 mm Hg under general anesthesia. Larger differences between instruments were found with younger age. Standard error of measurement with the Tono-Pen was 1.44 mm Hg and 1.82 mm Hg for the office and anesthesia settings, respectively. Thicker corneas were associated with higher IOP with both the GAT and the Tono-Pen. CONCLUSIONS: In normal children, average differences between IOP measured by Tono-Pen and GAT were small, although there was substantial test-retest variability. Younger age was associated with larger average differences, as was higher IOP in the office setting.

Central corneal thickness in children.

OBJECTIVES: To determine the central corneal thickness (CCT) in healthy white, African American, and Hispanic children from birth to 17 years of age and to determine whether CCT varies by age, race, or ethnicity. DESIGN: Prospective observational multicenter study. Central corneal thickness was measured with a handheld contact pachymeter. RESULTS: A total of 2079 children were included in the study, with ages ranging from birth to 17 years. Included were 807 whites, 494 Hispanics, and 474 African Americans, in addition to Asian, unknown race, and mixed-race individuals. African American children had thinner corneas on average than that of both white and Hispanic children (P < .001 for both) by approximately 20 µm. Thicker median CCT was observed with each successive year of age from age 1 to 11 years, with year-to-year differences steadily decreasing and reaching a plateau after age 11 at 573 µm in white and Hispanic children and 551 µm in African American children. For every 100 µm of thicker CCT measured, the intraocular pressure was 1.5 mm Hg higher on average (P < .001). For every diopter of increased myopic refractive error, CCT was 1 µm thinner on average (P < .001). CONCLUSIONS: Median CCT increases with age from 1 to 11 years, with the greatest increase present in the youngest age groups. African American children on average have thinner central corneas than white and Hispanic children, whereas white and Hispanic children demonstrate similar CCT.

Distance versus near visual acuity in amblyopia.

PURPOSE: There are conflicting reports about whether distance and near visual acuity are similar in eyes with amblyopia. The purpose of this study is to compare monocular distance visual acuity with near visual acuity in amblyopic eyes of children. METHODS: Subjects 2 to 6 years of age were evaluated in a randomized trial of amblyopia therapy for moderate amblyopia (20/40 to 20/80) due to anisometropia, strabismus, or both. Prior to initiating the protocol-prescribed therapy, subjects had best-corrected visual acuity measured with standardized protocols at 3 meters and 0.4 meters using single-surrounded HOTV optotypes. RESULTS: A total of 129 subjects were included. The mean amblyopic eye visual acuity was similar at distance and near (mean, 0.45 logMAR at distance versus 0.45 logMAR at near; mean difference, +0.00, 95% CI, -0.03 to 0.03). Of the 129 subjects, 86 (67%) tested within 1 line at distance and near; 19 (15%) tested more than 1 logMAR line better at distance, and 24 (19%) tested more than 1 logMAR line better at near. The mean visual acuity difference between distance and near did not differ by cause of amblyopia, age, or spherical equivalent refractive error. CONCLUSIONS: We found no systematic difference between distance and near visual acuity in 2- to 6-year-old children with moderate amblyopia associated with strabismus and/or anisometropia. Individual differences between distance and near visual acuity are likely due to test-retest variability.