Validity and Reliability of Digital WE Algometer in Subjects with Myofascial Trigger Points on Trapezius Muscle

Abstract

Myofascial pain syndrome (MPS) is one of musculoskeletal disorders. Trigger point (TrPs) is the main characteristic of MPS with low pressure pain threshold (PPT) which could be measured by a digital algometer. Although the commercialized digital algometer is accepted as standard instrument because of high validity and reliability, it is relatively expensive as imported from abroad. A local made instrument namely digital WE algometer (WE) has been produced by Assoc. Prof. Dr. Wichai Eungpinichpong for this purpose without a study on its psychometric properties. This study aimed to examine the validity and reliability of WE algometer and tested it against a commercialized digital algometer (DA). Thirty subjects with myofascial pain syndrome who have at least a trigger point on trapezius muscle were recruited. The researchers (one student and one expert) pressed on the palpable trigger point to assess pressure pain threshold by each of the two randomly allocated algometers on 2 sessions (3 consecutive times per session) with 2 minutes rest between the sessions. The rest period between underwent the two devices was set for 15 minutes. We found that the inter rater reliability of the WE were high with ICC 0.94 (95%CI of 0.88 to 0.97, p-value < 0.001). The ICC for Intra rater reliability was 0.96 (95%CI of 0.91 to 0.98). The concurrent validity between WE and DA presented by Pearson’s correlation coefficient was 0.84 (95%CI of 0.68 to 0.92 and p-value < 0.001). In conclusion, WE algometer has very high reliability and high positive concurrent validity. It could be used as a quantitative tool in novice for assessment and follow-up of progression in physical therapy.