Group-Level Analyses Involving Scores Linked From Legacy Scales to PROMIS Scales: A Novel Alternative Using Imputation.

As the implementation of Patient-Reported Outcomes Measurement Information System (PROMIS) scales has increased, so has the number of studies linking legacy scale scores to PROMIS scale scores. Variability in linked scores for a given PROMIS score can be considerable, leading to potential bias. An alternative method is imputation using a bridge study. We sought to compare linking to this alternative novel method in group-level analyses using linked legacy scores. Adult patients who completed PROMIS Depression and Patient Health Questionnaire (PHQ-9) were included. We randomly allocated data samples to be missing either PROMIS Depression or PHQ-9. We estimated PROMIS T scores using six methods: Linking methods by Choi et al. (2014), linking in our internal data, imputation using bridge study data from external data and from our internal data, each with and without patient demographics. Estimated mean PROMIS T scores using the linking and imputation methods were compared to actual PROMIS T scores across varying proportions of missingness and sample size. We also compared regression coefficients for the six estimation methods to a model using actual PROMIS T scores. Mean estimated versus actual PROMIS T scores varied between 1 and 4 points for the linking methods and within 0.4 points for the imputation method using internal data with patient demographics. The imputation methods had estimated regression coefficients closer to that of the model using actual scores as compared to the linking methods. For group-level analyses, imputation using a bridge study may be a feasible alternative to using linked scores or can be used as a sensitivity analysis. Public Significance Statement: Many legacy scales have been linked to associated PROMIS scales using item response theory and other linking strategies. Group-level analyses involving such linked scores sometimes result in biased parameter estimates. We propose an alternative analysis approach: Imputation using a bridge study. The study findings indicate that imputation using a bridge study may be a feasible alternative to analyzing legacy scale data scored on a PROMIS metric. [ABSTRACT FROM AUTHOR]