Studies on pediatric norms to be used for upper extremity post thrombotic syndrome (PTS) assessment have been conducted in North America, but these norms have never been evaluated in non-North American children. A validation study to assess the validity and reliability of the two currently available pediatric PTS assessment instruments, i.e. the Modified Villalta Score (MVS) and the Manco-Johnson Instrument (MJI), on a non-North American convenience sample of healthy children is necessary in order to account for differences that may exist across cultural boundaries.
To determine pediatric norms for upper extremity PTS assessment in a non-North American cohort and to determine normal discrepancies in arm circumference, which in American children have been found to be ≤1 cm in the MJI (1) and <3% in the MVS (2). In addition we aimed to evaluate the specificity of the upper extremity PTS assessment instruments by testing the hypothesis that healthy children receive a score of 0 (indicating absence of PTS) when using the pediatric PTS tools.
The study design was a community-based observational cross-sectional study using a cohort of 28 healthy children with no history of thrombosis, central venous catheter use and/or family history of thrombosis. Inter-rater reliability of the measurement instruments was assessed using two trained PTS examiners.
Among the 28 healthy children, the median age was 6.6 years (range 1.5-12.8 years). The median (interquartile range, (IQR)) contra-lateral difference for mid-forearm circumference was 0.4 cm (0.3 cm); and for the mid-upper arm circumference was 0.3 cm (0.5 cm). The upper limit of normal for contra-lateral differences in upper limb circumference was 0.8 cm for mid-forearm and 1.0 cm for mid-upper arm. None of the children had greater than a 1 cm difference in mid-forearm or mid-upper arm circumference. Differences of greater than 3% were present in 4 children (14.3%) in the mid-upper arm circumference. In a simple linear regression model, the absolute difference in upper-arm circumference was positively associated with age (= -0.006 + 0.38 * age; R2=0.18, p=0.025). Agreement between two trained examiners for the healthy child cohort varied depending on the criteria used for determination of normal differences. Using a 1.0 cm cut-off for determination of normal differences resulted in 96% agreement between two trained examiners for both mid-upper arm and mid-forearm measurements. Use of a 3% difference as the cut-off resulted in a 93% agreement between the two examiners. There was 100% agreement for the remaining items of the PTS score. In addition to differences in arm circumference, three healthy children had signs and symptoms associated with PTS; one child (3.6%) presented with bilateral venous collaterals on the chest and shoulders and two children (7.1%) reported pain in the upper extremities, although the pain did not interfere with functioning.
In a sample of Israeli children, the use of an absolute cut-off measure for contra-lateral differences in upper limb circumference of >1.0 cm is a more applicable and reliable measurement than a 3% cut-off. The presence of signs and symptoms of PTS in the upper extremity of healthy children questions the specificity of the current available PTS assessment tools for upper extremity in children.
1. Goldenberg NA, Pounder E, Knapp-Clevenger R, Manco-Johnson MJ. Validation of Upper Extremity Post-Thrombotic Syndrome Outcome Measurement in Children. J Pediatr. 2010 Nov; 157(5):852–5.
2. Boulden BM, Crary SE, Buchanan GR, Journeycake JM. Determination of pediatric norms for assessment of upper venous system post-thrombotic syndrome. J Thromb Haemost. 2007 May; 5(5): 1077–9.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.