Construct validity and inter- rater reliability of the Heckmatt scale for assessing muscle quality in critically ill...

Critically ill patients rapidly develop impairments in muscle quality during ICU stay, which are associated with poor recovery. Muscle ultrasound is a bedside tool to assess these changes, but the measurement properties of visual grading scales such as the Heckmatt scale are not well established in this population.

To evaluate construct validity and inter-rater reliability of the Heckmatt scale.

Clinimetric study evaluating the construct validity and inter-rater reliability of the Heckmatt scale using peripheral muscle ultrasound in critically ill patients. Ultrasound images of the quadriceps (rectus femoris and vastus intermedius) and tibialis anterior were obtained on days 1, 3, and 7. Three blinded evaluators scored muscle quality using the Heckmatt scale. Echogenicity was quantified by grayscale analysis (0-255). Construct validity was assessed using Spearman correlations (rho) between Heckmatt scores and echogenicity. Inter-rater reliability was assessed using ICC(1, 2).

On day 1, correlations were strong for rectus femoris (rho = 0.74, p < 0.001) and moderate for vastus intermedius and tibialis anterior (rho = 0.47-0.48, p < 0.001). On day 3, associations were weaker, with no significant correlation for vastus intermedius and tibialis anterior. On day 7, correlations were strong to very strong in the quadriceps (rho = 0.61-0.84, p < 0.001) and moderate in tibialis anterior (rho = 0.36, p = 0.01). Reliability was moderate to good on days 1-3 (ICC range 0.70-0.83) and decreased on day 7 (ICC range 0.48-0.50).

The Heckmatt scale shows acceptable measurement properties for bedside assessment of muscle quality, particularly in larger muscles during early ICU stay.