Sensitivity of the EQ-5D-5L for fatigue and cognitive problems and their added value in Q-fever patients

PURPOSE: Measuring health-related quality of life (HRQoL) with the EQ-5D-5L might lack sensitivity for disease-specific health complaints. This cross-sectional study analyzed whether fatigue and cognitive problems are captured by the EQ-5D-5L in a Q-fever patient population with persistent fatigue/cognitive problems, and whether addition of fatigue/cognition improved the explained variance for HRQoL. METHODS: A Dutch sample of Q-fever patients filled out the EQ-5D-5L and EQ VAS, the fatigue subscale of the Checklist Individual Strength, and a cognition dimension in the EQ-5D-5L format. The extent to which fatigue and cognition were captured by the EQ-5D-5L was determined based on distributional effects, head-to-head comparisons, Spearman rank correlation coefficients, and regression analyses. Explanatory power was determined of the EQ-5D-5L for the EQ VAS with and without a fatigue and cognition dimension. RESULTS: Out of 432 respondents, 373(86%) reported severe fatigue, 387(90%) cognitive problems. EQ-5D-5L utility and EQ VAS scores of respondents reporting severe fatigue/cognitive problems were significantly lower. Fatigue was strongly correlated with EQ-5D-5L dimensions usual activities and pain/discomfort (r = 0.602 and r = 0.510) and moderately with other EQ-5D-5L dimensions (r = 0.305–0.476). Cognition was strongly correlated with usual activities (r = 0.554) and moderately with other dimensions (r = 0.291–0.451). Adding fatigue to the EQ-5D-5L increased explanatory power for the EQ VAS with 6%. CONCLUSION: Fatigue and cognitive problems in Q-fever patients were partially captured by the EQ-5D-5L dimensions. The addition of fatigue to the EQ-5D-5L slightly improved explained variance for the EQ VAS. This potentially also accounts for patients who experience sequelae of other infectious diseases, such as COVID-19. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11136-021-03069-9.