Calendar-defined missed-workday gaps in radiotherapy: a site- and phase-stratified audit with linkage sensitivity...

Missed treatment workdays can prolong overall treatment time and may reduce tumor control, yet routine audits often conflate weekends, statutory holidays, and departmentally accepted rest schedules with untreated institutional workdays.

We quantified calendar-defined missed-workday gaps-inter-fraction intervals containing ≥1 untreated institutional workday after excluding routine rest days-among patients with first treatment between June 2021 and December 2025 who were linkable between the MOSAIQ radiotherapy information system and the institutional oncology database (1,319 patients; 1,342 episodes). A locked stratified sample of 100 algorithm-positive gaps underwent documentation-based chart review as unplanned relevant (UR) or planned/appropriate (PA). We analyzed linkage sensitivity, opportunity-adjusted site rates with patient-clustered confidence intervals (CIs), opportunity-offset Poisson generalized estimating equations (GEE) including calendar year, and episode-clustered phase GEE.

Under the documentation-based chart-review rule, 92 of 100 algorithm-positive gaps were labeled UR (17 department/equipment; 75 patient-factor) and 8 PA. Gaps occurred in 638/1,342 episodes (47.5%; patient-level 48.0%). Linked versus unlinked prevalence was 48.2% versus 51.7% (absolute difference -3.4 percentage points, 95% CI -11.2 to 4.4; P = 0.435). Among subgroups with ≥50 episodes, head and neck had the highest prevalence (75.3%) and breast the lowest (41.3%); opportunity-adjusted rates were 5.63 (cluster-bootstrap 95% CI 4.76-6.52) versus 2.63 (2.36-2.92) per 100 opportunities. Opportunity-offset Poisson GEE with calendar year gave a head-and-neck versus breast incidence rate ratio (IRR) of 2.99 (95% CI 2.18-4.11). An exploratory phase GEE (29,763 intervals; 1,323 clusters) showed a late versus early odds ratio (OR) of 1.31 (95% CI 1.12-1.54; P = 0.0009; absolute rates 2.8% vs 3.6%); after site, year, and intent adjustment, the OR was 1.32 (95% CI 1.12-1.57).

This operational audit of institutional workdays without recorded treatment-rather than clinically confirmed unplanned interruptions-shows frequent gaps after excluding routine rest. Most reviewed positives received patient-factor labels under a documentation rule. Calendar-aware auditing may support departmental monitoring; priority-based compensation remains a proposed application.