Background: The COU-AA-301 phase 3 trial showed that AA + prednisone (P) improved overall survival in mCRPC patients (pts) post-docetaxel. Compared with P alone, AA + P also had significant benefits on patient-reported pain. Here we describe post hoc sensitivity analyses of pain data from that trial, using different methods to compensate for the potential impact of missing data. Methods: Pts with mCRPC progressing after docetaxel-based chemotherapy were randomized 2:1 to AA + P or placebo + P. Pain intensity and interference of pain with daily activities were assessed with the Brief Pain Inventory-Short Form (BPI-SF) questionnaire at baseline, Day 15 of Cycle 1, and Day 1 of each 28-day treatment cycle thereafter until treatment discontinuation. The effect of treatment on BPI-SF scores was analyzed using repeated measure mixed-effects (RMM) models, piecewise linear mixed-effects (PWLME) models, and joint mixed-effects and log time-to-dropout (JMEL) models. RMM and PWMLE models assumed missing data (due to death, study dropout, or administrative issues) to be missing at random, the JMEL model to be missing not at random. Model results were compared between treatment arms. Results: 797 pts were randomized to AA + P, and 398 to P only. RMM model estimates suggested statistically significant (p < 0.05) differences in change from baseline for pain intensity and pain interference scores in favor of AA + P at the majority of study visits through cycle 11. PWLME models yielded significantly smaller areas under the curve (AUCs) for AA + P vs P for pain intensity (p = 0.0031) and pain interference (p = 0.0006); smaller AUCs reflect better pain outcomes. Results using JMEL models were nearly identical to those with PWLME models, with AUCs for AA + P significantly smaller than for P alone for pain intensity (p = 0.0031) and pain interference (p = 0.0007). Conclusions: Using various modeling methods that assess the impact of missing data, AA + P showed superior patterns of pain outcomes over time compared with P only in mCRPC pts refractory to docetaxel. These results support the previously reported pain benefits of AA + P over P alone from the same trial. Clinical trial information: NCT00638690.