Item nonresponse on the Myeloproliferative Neoplasms Symptom Assessment Form (MPN-SAF): a comparison of missing data strategies.

Administering questionnaires to patients is an efficient and effective method for assessing patients' symptoms. However, item nonresponse (skipped questions) potentially compromises the utility of these questionnaires. Using an international sample of 2,067 patients with myeloproliferative neoplasms, we evaluated the impact of item nonresponse on scoring of the Myeloproliferative Neoplasms Symptom Assessment Form Total Symptom Score (MPN-SAF TSS or MPN-10). We characterized item nonresponse on the MPN-10 and compared strategies for addressing item nonresponse (available-case analysis, proration, and multiple imputation) on the MPN-10 (multi-symptom assessment) and Brief Fatigue Inventory (BFI; single-symptom assessment). Characteristics of multi-symptom assessments would be expected to adversely affect proration, yet proration and multiple imputation provided very similar results for both the MPN-10 and BFI. This is likely because the MPN-10 item missing data rates were low, consistent with prior clinic- and internet-based studies. These results support the published scoring method for the MPN-10 (proration).