The impact of intervention-induced symptom awareness on patient reported outcomes in a randomized mobile health intervention for medication adherence in cancer care

Background Mobile health (mHealth) interventions are increasingly used to support medication adherence in cancer care. However, frequent monitoring may inadvertently influence patient-reported outcomes (PROs) responses. This study evaluated PRO data from a trial investigating the impact of text messaging on adherence to aromatase inhibitors (AIs) and explored unintended effects on symptom reporting. Methods A randomized trial was conducted among women with early-stage breast cancer prescribed AIs. Participants were randomized to receive either standard care or unilateral text messages sent twice a week over 36 months. Content themes focused on overcoming barriers to adherence and included statements related to medication efficacy and encouragement about managing side effects. No difference in medication adherence was observed between groups. Patients were assessed every 3 months with PROs representing pain (Brief Pain Inventory) and endocrine symptoms (FACT-Endocrine Symptoms). We evaluated changes in PRO scores over time. Results In total, 724 patients were randomized and baseline scores on PROs were similar between arms. Compared to the control group, participants in the text messaging arm reported lower QoL on the FACT-General (89.8 vs. 87.4,p=0.02), greater average pain (3.3 vs 3.5,p=0.02), and more endocrine symptoms on the FACT-ES (148.8 vs.145.0,p=0.01) in the first 3 months of the trial after controlling for baseline scores. There were no statistically significant differences in scores between arms at later timepoints. Discussion Patients randomized to a text-message intervention focused on improving adherence initially reported worse QoL and symptoms compared to the control group. These findings suggest that text messages may have heightened participants' awareness of AI-related side effects, thereby amplifying symptom reporting in the early phase of the study. This may have implications for the interpretation of PROs in some interventional trials, where frequent symptom checks could inadvertently worsen reported outcomes.