Validity and reproducibility of the Jamar dynamometer in children aged 4-11 years

Area of Science:

• Pediatric neurology
• Musculoskeletal disorders
• Diagnostic tools

Background:

• Hand grip strength is a key indicator of neuromuscular function.
• Accurate assessment tools are crucial for diagnosing conditions like myopathy in children.
• The Jamar dynamometer's utility in pediatric populations requires validation.

Purpose of the Study:

• To evaluate the validity and reproducibility of the Jamar dynamometer for hand grip strength measurement in children aged 4-11 years.
• To assess the device's ability to differentiate between children with and without myopathy.

Main Methods:

• Hand grip strength was measured in 67 children with suspected myopathy using the Jamar dynamometer.
• Validity was assessed using logistic regression and Receiver Operating Characteristic (ROC) analysis.
• Reproducibility was determined through test-retest reliability using the intraclass correlation coefficient (ICC).

Main Results:

• The Jamar dynamometer demonstrated discriminative power, with Area Under the Curve (AUC) values ranging from 0.78 to 0.82.
• Sensitivity was 81%, with specificity ranging from 67% to 73%.
• Intraclass correlation coefficients (ICCs) for reproducibility were high, ranging from 0.91 to 0.93.

Conclusions:

• The Jamar dynamometer is a valid and reproducible tool for assessing hand grip strength in children.
• It possesses good discriminative power for identifying suspected myopathy in this age group.
• While effective, the Jamar dynamometer is not a completely accurate diagnostic test for myopathy.