Pain and symptom severity outcomes in patients with cancer before and after intrathecal drug delivery: mixed model analysis in 222 cases.

Abstract

Cancer-related pain is common and difficult to manage, and many patients require opioid therapy with dose-limiting toxicity. As pain progresses, opioid escalation may result in adverse effects and suboptimal analgesia. Intrathecal drug delivery (IDD) provides targeted analgesia and may reduce systemic toxicity. This study evaluated temporal trends in pain and symptom burden before and after IDD initiation. Retrospective analysis of longitudinal Brief Pain Inventory (BPI) and Condensed Memorial Symptom Assessment Scale (CMSAS) scores in 435 patients with cancer pain treated with IDD at an academic cancer center between 2013 and 2023. Inclusion required ≥1 symptom assessment within 30 days prior to implantation and survival >10 days postimplant. Primary outcomes were changes in BPI-Severity (BPI-SEV), BPI-Interference (BPI-INT) and CMSAS-Physical (CMSAS-PHYS) after IDD, estimated using joint longitudinal-survival models to account for informative dropout due to death over 1 year. Pre-IDD symptom trajectories were modeled separately. Secondary outcomes included remaining BPI and CMSAS domains assessed at prespecified time points up to 1 year, analyzed descriptively. 222 patients met inclusion criteria. During follow-up, 91% discontinued systemic opioids. In joint models over the first 90 days after implantation, BPI-SEV decreased by 0.014 units/day (n=219; 95% CI -0.020 to -0.009; p<0.001), BPI-INT decreased by 0.020 units/day (n=209; 95% CI -0.029 to -0.011; p<0.001) and CMSAS-PHYS improved by 0.004 units per day (n=195; 95% CI -0.006 to -0.001; p=0.002). Symptom trajectories worsened prior to implantation and improved following IDD initiation. Mean composite scores improved significantly across all time points for BPI-SEV, BPI-INT and CMSAS-PHYS. Among patients with advanced cancer, pain and symptom burden worsened prior to IDD but improved within 90 days after implantation, with sustained benefits observed up to 1 year.