Abstract / Summary
Importance Time toxicity, defined as the time patients spend receiving cancer treatment and interacting with health care systems, is an emerging treatment-related burden. Existing studies typically quantify time toxicity using health care contact days, which may inadequately capture patient burden because encounters of different durations are weighted equally. Objective To develop and internally validate the Multinational Association of Supportive Care in Cancer (MASCC) Time Intensity and Measurement of Encounters (TIME) tool, a standardized medical record abstraction instrument for measuring documented health care encounter time. Design, Setting, and Participants This multiphase mixed-methods prognostic study, including tool development, was conducted from March to May 2026, through a 3-round international consensus process involving 16 oncology trialists from 9 countries and internal validation using electronic medical records from a cohort of patients with prostate cancer treated at a tertiary cancer center in Toronto, Ontario, Canada. Validation compared standardized abstraction using the MASCC TIME tool with prior unstructured medical record abstraction across 367 health care encounters. Main Outcomes and Measures Content validity, extraction accuracy compared with investigator consensus review, interrater reliability assessed using the Gwet agreement coefficient 1 (AC1) and percentage agreement, and abstraction feasibility. Results Sixteen oncology trialists participated in tool development. The final tool included 8 variables: encounter start date, start time, end date, end time, purpose, planned or unplanned status, mode of contact, and primary clinician. All variables achieved a content validity ratio of 1.0. Accuracy of medical record extraction increased from 31% (95% CI, 28%-35%) to 90% (95% CI, 87%-93%) without the tool to 66% (95% CI, 62%-69%) to 99% (95% CI, 99%-100%) with the tool, with absolute differences of 2 percentage points (95% CI, −1 to 5 percentage points) to 35 percentage points (95% CI, 30 to 40 percentage points); 7 of 8 variables demonstrated statistically significant increases with the tool. Percentage agreement between abstractors increased from 31% to 82% without the tool to 42% to 99% with the tool, while the Gwet AC1 increased from −0.24 to 0.87 without the tool to 0.14 to 0.99 with the tool. Mean abstraction time decreased from 10 to 5 minutes per encounter. Conclusions and Relevance In this prognostic study of the MASCC TIME tool, it was found to be associated with excellent content validity, improved accuracy, high interrater reliability, and acceptable feasibility for standardized measurement of documented health care encounter time. Standardized assessment of time toxicity may improve comparability across oncology studies and support more rigorous evaluation of health care–related burden in cancer research.