Comparison of physician's, parent's and patient's global ratings made on linear or 21-circle visual analogue scales (VAS) in juvenile idiopathic arthritis (JIA)

Background

Physician's and parent's global ratings of disease status in JIA are assessed using a 10-cm linear VAS anchored at two ends. However, such measure may lead to clustering of scores at ends of scale. Furthermore, a ruler is required to compute scores. Substitution of linear VAS with 21-circle VAS (each circle = 0.5 cm) has been proposed to increase feasibility and precision.

Objective

To compare construct validity of physician's and parent's ratings made on linear or 21-circle VAS.

Methods

In 723 visits (2007–2008), the physician rated disease activity and a parent rated child's well-being and pain on 21-circle VAS. A historical sample of 1429 visits (1988–2006) including same assessments made on linear VAS was used for comparison. Construct validity of VAS was compared by calculating Spearman's correlations with other JIA outcome measures.

Results

See table 1

Table 1

Conclusion

21-circle VAS yielded better correlations for physician's global assessment, whereas correlations for parent's ratings were greater with linear VAS. This shows that overall construct validity of the two scales is comparable.