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Low unit response rates can increase bias and compromise study validity. Response rates have continued to fall over the past decade despite all efforts to increase participation. Many factors have been linked to reduced response, yet relatively few studies have employed multivariate approaches to identify characteristics that differentiate respondents from nonrespondents since it is hard to collect information on the latter. We aimed to assess factors contributing to enrollment of prostate cancer (PCa) patients. We combined data from the North Carolina-Louisiana (LA) PCa Project’s LA cohort, with additional sources such as US census tract and LA tumor registry data. We included specific analyses focusing on blacks, a group often identified as hard to enroll in health-related research. The ability to study the effect of Hurricane Katrina, which occurred amidst enrollment, as a potential determinant of nonresponse makes our study unique. Older age (≥ 70) for blacks (OR 0.65) and study phase with respect to Hurricane Katrina for both races (OR 0.59 for blacks, OR 0.48 for whites) were significant predictors of participation with lower odds. Neighborhood poverty for whites (OR 1.53) also was a significant predictor of participation, but with higher odds. Among blacks, residence in Orleans parish was associated with lower odds of participation (OR 0.33) before Katrina. The opposite occurred in whites, with lower odds (OR 0.43) after Katrina. Our results overall underscore the importance of tailoring enrollment approaches to specific target population characteristics to confront the challenges posed by nonresponse. Our results also show that recruitment-related factors may change when outside forces bring major alterations to a population's environment and demographics. [ABSTRACT FROM AUTHOR]

Purpose: The study aims to describe the characteristics and etiologic causes of intermediate uveitis (IU) patients seen by a tertiary eye center in Singapore over 8 years. Methods: This was a retrospective analysis of the clinical records of consecutive new cases of IU that presented to the uveitis subspecialty clinic from 2004–2011 at Tan Tock Seng Hospital. Data collected included demographics, clinical and laboratory findings. Diagnoses were based on standardized clinical history, ophthalmological examination and investigations. Results: There were 66 new cases of IU, comprising 5.7% of 1168 new uveitis patients. The median age of diagnosis was 40 years (mean 39.4±15.9), with largest subgroup of the patients in the age group of 41–60 years (36.4%). The majority was Chinese (57.6%), followed by Asian Indians (18.2%) and Malays (16.7%). The ethnicity distribution was dissimilar to our ethnic distribution in Singapore (p<0.001) with an increased incidence of IU in the Asian Indian population. Most were idiopathic (59.1%) in etiology, followed by tuberculosis (TB) (15.2%). Ocular complications developed in 21 patients (31.8%), with cystoid macular edema (CME) being the commonest (28.8%). Severe vitritis occurred in 9.1% of patients, and was significantly associated with TB-associated IU (p<0.001). There was a downward trend for the incidence of the proportion of IU patients over the total uveitis patients (p = 0.021), with Spearman’s rho of −0.786. Conclusions: Despite the downward trend, TB-associated IU was still of higher prevalence compared to less endemic areas, emphasizing the need for increased TB surveillance. A high index of suspicion for TB-associated IU is required in patients with severe vitritis. Comparisons with other countries revealed disparities in the IU etiologies, indicating possible geographical differences. Prevalence of known immune-mediated etiologies of IU is less compared to the western population. Our study also suggests a probable predisposition of the Singapore local Indian population for IU. [ABSTRACT FROM AUTHOR]