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Sensitivity analysis for nonignorable missingness and outcome misclassification from proxy reports.

ABSTRACT: Researchers often recruit proxy respondents, such as relatives or caregivers, for epidemiologic studies of older adults when study participants are unable to provide self-reports (eg, because of illness or cognitive impairment). In most studies involving proxy-reported outcomes, proxies are recruited only to report on behalf of participants who have missing self-reported outcomes; thus, either a proxy report or participant self-report, but not both, is available for each participant. When outcomes are binary and investigators conceptualize participant self-reports as gold standard measures, substituting proxy reports in place of missing participant self-reports in statistical analysis can introduce misclassification error and lead to biased parameter estimates. However, excluding observations from participants with missing self-reported outcomes may also lead to bias. We propose a pattern-mixture model that uses error-prone proxy reports to reduce selection bias from missing outcomes, and we describe a sensitivity analysis to address bias from differential outcome misclassification. We perform model estimation with high-dimensional (eg, continuous) covariates using propensity-score stratification and multiple imputation. We apply the methods to the Second Cohort of the Baltimore Hip Studies, a study of elderly hip fracture patients, to assess the relation between type of surgical treatment and perceived physical recovery. Simulation studies show that the proposed methods perform well. We provide SAS programs in the eAppendix (http://links.lww.com/EDE/A646) to enhance the methods' accessibility.

SUBMITTER: Shardell M

PROVIDER: S-EPMC3566762 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature

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Sensitivity analysis for nonignorable missingness and outcome misclassification from proxy reports.

Shardell Michelle M Simonsick Eleanor M EM Hicks Gregory E GE Resnick Barbara B Ferrucci Luigi L Magaziner Jay J

Epidemiology (Cambridge, Mass.) 20130301 2

Researchers often recruit proxy respondents, such as relatives or caregivers, for epidemiologic studies of older adults when study participants are unable to provide self-reports (eg, because of illness or cognitive impairment). In most studies involving proxy-reported outcomes, proxies are recruited only to report on behalf of participants who have missing self-reported outcomes; thus, either a proxy report or participant self-report, but not both, is available for each participant. When outcom ...[more]

PMID: 23348065

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Project description:The eight-point extended Glasgow Outcome Scale (GOSE) is commonly used as the primary outcome measure in traumatic brain injury (TBI) clinical trials. The outcome is conventionally collected through a structured interview with the patient alone or together with a caretaker. Despite the fact that using the structured interview questionnaires helps reach agreement in GOSE assessment between raters, significant variation remains among different raters. We introduce an alternate GOSE rating system as an aid in determining GOSE scores, with the objective of reducing inter-rater variation in the primary outcome assessment in TBI trials. Forty-five trauma centers were randomly assigned to three groups to assess GOSE scores on sample cases, using the alternative GOSE rating system coupled with central quality control (Group 1), the alternative system alone (Group 2), or conventional structured interviews (Group 3). The inter-rater variation between an expert and untrained raters was assessed for each group and reported through raw agreement and with weighted kappa (kappa) statistics. Groups 2 and 3 without central review yielded inter-rater agreements of 83% (weighted kappa = 0.81; 95% CI 0.69, 0.92) and 83% (weighted kappa = 0.76, 95% CI 0.63, 0.89), respectively, in GOS scores. In GOSE, the groups had an agreement of 76% (weighted kappa = 0.79; 95% CI 0.69, 0.89), and 63% (weighted kappa = 0.70; 95% CI 0.60, 0.81), respectively. The group using the alternative rating system coupled with central monitoring yielded the highest inter-rater agreement among the three groups in rating GOS (97%; weighted kappa = 0.95; 95% CI 0.89, 1.00), and GOSE (97%; weighted kappa = 0.97; 95% CI 0.91, 1.00). The alternate system is an improved GOSE rating method that reduces inter-rater variations and provides for the first time, source documentation and structured narratives that allow a thorough central review of information. The data suggest that a collective effort can be made to minimize inter-rater variation.

Dataset Information

Sensitivity analysis for nonignorable missingness and outcome misclassification from proxy reports.

Publications

Sensitivity analysis for nonignorable missingness and outcome misclassification from proxy reports.

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