The Face, Legs, Activity, Cry, and Consolability (FLACC) scale is one of the most commonly and widely used behavioral observation pain scales. The aim of this study was to test the psychometric and practical properties of the FLACC scale to quantify procedural pain in infants and young children. Twenty-six clinicians independently applied the FLACC scale to segments of video collected from 100 children aged 6 to 42 months undergoing a procedure. Video segments were scored by 4 reviewers. Inter- and intrarater reliability coefficients were high (.92 and .87, respectively). Linear mixed modeling confirmed scale responsiveness (differences in difference between FLACC scores across phases for painful versus nonpainful procedures was 4.2, 95% confidence interval = 3.67-4.81). Sensitivity and specificity were 94.9% and 73.5%, respectively, at a cutoff of 2. However, the mean difference across phases for children with baseline scores >3 was much lower than for children with scores <3, P = .0001. Correlations between FLACC and Visual Analog Scale observer pain and distress were good (r = .74 and r = .89, respectively). This study supports the reliability and sensitivity of the FLACC scale for procedural pain assessment. However, the circumstances of procedures interfered with application of the scale and the findings question the capacity of the scale to differentiate between pain- and nonpain-related distress.
Perspective: This article provides evidence that the FLACC scale is reliable and sensitive to pain for procedural pain assessment. Concerns remain about specificity and scale design. Identification of a scale valid for this purpose is needed to provide a platform for improved procedural pain management in infants and young children.
Keywords: FLACC scale; Face, Legs, Activity, Cry, and Consolability scale; pain assessment; psychometric evaluation; reliability; validation.
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