Unit Nonresponse in a Population-Based Study of Prostate Cancer

Abstract

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.

Modelling attrition and nonparticipation in a longitudinal study of prostate cancer

“…This study phase is referred to as the pre-Katrina (Pre-K) sample, which enrolled 119 African-Americans (AAs) and 94 EAs. The post-Katrina (Post-K) enrollment resumed in September 2006 and completed in August 2009 with 506 AA and 508 EA participants [ 28 , 34 ].…”

“…Note that an approach with a specific subgroup in a specific study may not work with a similar group under different circumstances. A combination of strategies should be used while monitoring the survey process in real time and modifying them as needed to decrease nonresponse and minimize racial/ethnic differences between respondents and non-respondents [ 28 ].…”

“…Multiple imputation techniques can be used to replace missing data due to attrition by modeling the missingness; however, specifying the correct model from available data is difficult [ 31 ]. Optimal recruitment strategies should be implemented before and during data collection because post-survey adjustments are merely estimated remedies to the problems caused by nonresponse and attrition [ 28 ].…”

“…In order to compare the differences between the two waves of the same study group, we defined “nonparticipation” as “attrition through refusals”. We compared these findings with our previous nonparticipation analyses of the same Louisiana (LA) cohort [ 28 ] and evaluated if the factors affecting refusals were the same in each wave. Specifically, we assessed if racial differences regarding refusals were consistent over time.…”

Surveying Sensitive Topics with Indirect Questioning

“…However, if these strategies are more effective for some particular subpopulations compared to others, a reduction in nonresponse can in reality increase nonresponse bias. Statistical techniques can also be used to minimize the effects of unit nonresponse after the data is collected [7]; yet, none of these approaches can prevent SDB.…”