Subjective and objective workload of critical care nurses in a tertiary hospital in Switzerland: a retrospective analysis

BACKGROUND: Nursing workload in intensive care units affects outcomes and staff well-being. Objective measures such as Nine Equivalents of Nursing Manpower Score (NEMS) capture task demands, whereas subjective ratings reflect nurses' workload; how these relate is unclear (1-4). METHODS: All shifts over 6 months in an adult ICU of a tertiary hospital were analyzed. For each shift, staffing (number of nurses, patients, patient-to-nurse ratio PNR), number of interventions, admissions and discharges, cumulative Richmond agitation sedation scale RASS score and intensivist identity were recorded. Shift workload was measured as cumulative NEMS and subjective rating on a 1-7 scale (LEP). Analyses used Pearson correlations, linear regression, one-way ANOVA, and multiple regression. RESULTS: 531 shifts showed a mean NEMS of 347.7 and subjective rating of 4.6 with a mean PNR of 1.42. Early shifts had the highest NEMS; the highest subjective ratings occurred in late shifts (4.8 late, 4.6 early, 4.4 night; p < 0.0001). Subjective workload correlated weakly with NEMS overall (r = 0.254, p < 0.0001), but moderately in early (r = 0.31) and late (r = 0.43) shifts with no association at night. PNR correlated with subjective workload in early (r = 0.37) and late (r = 0.24) but not night shifts. Multiple regression including NEMS, PNR, RASS, admissions and discharges and consultant identity explained 12.4% of variance in subjective workload (p < 0.001). NEMS (B = 0.0030, p < 0.0001), admissions (B = 0.0687, p = 0.048) and interventions (B = 0.0603, p < 0.008) were independent predictors. PNR, cumulative RASS, discharges and consultant identity were not independently associated. CONCLUSION: NEMS, admissions and interventions were related to perceived workload but explained little of what makes a shift demanding. The NEMS-subjective workload association was confined to early and late shifts, suggesting night-time workload is driven by other factors. ICU workload is multidimensional and cannot be adequately captured by objective task counts alone. Routinely recorded key performance indicators from intensive care units can only partially reflect the fluctuations in the subjective workload perceived by nurses. TRIAL REGISTRATION: Not applicable.