Examining the measurement equivalence of the Maslach Burnout Inventory across age, gender, and specialty groups in US physicians.

BACKGROUND: Disparities in US physician burnout rates across age, gender, and specialty groups as measured by the Maslach Burnout Inventory-Human Services Survey for Medical Personnel (MBI) are well documented. We evaluated whether disparities in US physician burnout are explained by differences in the MBI's functioning across physician age, gender, and specialty groups.
METHODS: We assessed the measurement equivalence of the MBI across age, gender, and specialty groups in multi-group item response theory- (IRT-) based differential item functioning (DIF) analyses using secondary, cross-sectional survey data from US physicians (n = 6577). We detected DIF using two IRT-based methods and assessed its impact by estimating the overall average difference in groups' subscale scores attributable to DIF. We assessed DIF's practical significance by comparing differences in individuals' subscale scores and burnout prevalence estimates from models unadjusted and adjusted for DIF.
RESULTS: We detected statistically significant age-, gender-, and specialty- DIF in all but one MBI item. However, in all cases, average differences in expected subscale-level scores due to DIF were < 0.10 SD on each subscale. Differences in physicians' individual-level subscale scores and burnout symptom prevalence estimates across DIF- adjusted and unadjusted IRT models were also small (in all cases, mean absolute differences in individual subscale scores were < 0.04 z-score units; prevalence estimates differed by < 0.70%).
CONCLUSIONS: Age-, gender-, and specialty-related disparities in US physician burnout are not explained by differences in the MBI's functioning across these demographic groups. Our findings support the use of the MBI as a valid tool to assess age-, gender-, and specialty-related disparities in US physician burnout.