Work Engagement, Burnout, and Self-Care Index Scores in Relation to Self-Reported In-Role and Extra-Role Job Performance Among Nursing Personnel in Six Public Hospitals in Northern Greece: A Secondary Analysis of a Multicentre Cross-Sectional Survey

Background/Objectives: This study examined mutually adjusted associations of work engagement, burnout, and Self-Care Index scores with self-reported in-role and extra-role performance among nursing personnel. Methods: This secondary analysis used pandemic-era cross-sectional data from 586 nurses and nurse assistants recruited by convenience sampling in six public hospitals in Northern Greece (December 2021–April 2022). Measures included the Utrecht Work Engagement Scale–9, Oldenburg Burnout Inventory, a study-developed 35-item Self-Care Index, and a six-item job-performance adaptation. Confirmatory factor analysis (CFA) included 579 participants. Three complete-case regression models (n = 574) simultaneously included the three focal scores, gender, age, and managerial responsibility. Sensitivity analyses used HC3 standard errors and hospital fixed effects; coefficient p-values were nominal. Results: CFA provided only partial support for distinguishing the performance dimensions, with substantial factor overlap (r = 0.833) and residual misfit (root mean square error of approximation = 0.092). Performance scores showed upper-end concentration. Work engagement had the numerically largest standardized coefficients for in-role (β = 0.285) and extra-role performance (β = 0.402; both p < 0.001). Self-Care Index scores showed positive associations (β = 0.193, p < 0.001; β = 0.100, p = 0.018, respectively). Burnout showed no statistically detectable mutually adjusted association. The complementary total-score model showed a similar pattern. Conclusions: Engagement was positively associated with self-reported performance. Self-Care Index findings remain exploratory because construct validity is not established. Shared self-report measurement and the cross-sectional design preclude causal or intervention-effectiveness conclusions. Prospective evaluation using validated measures and independently assessed performance is needed.