RELIABILITY AND VALIDITY OF SEMMES-WEINSTEIN MONOFILAMENT TESTING IN OLDER COMMUNITY-DWELLING ADULTS.

Abstract

Purpose/Hypothesis: Semmes-Weinstein monofilament (SWM) testing is commonly used to identify the loss of protective sensation. Debate continues as to the most efficient, accurate, and reliable protocol for sensory screening. Therefore, the purpose of this study was to assess the reliability and validity of SWM testing in older adults in a health fair setting. Number of Subjects: Twenty-three (17 females and 6 males) community dwelling elders, ranging in age from 50-89 years volunteered and completed sensory testing. Materials/Methods: Semmes-Weinstein testing was conducted with a 5.07/10g monofilament. The monofilament was applied to dorsum of the big toe and held for approximately one second. Subjects eyes were closed and they verbally responded if they perceived the monofilament. Testing was completed four times on each foot for a total of 8 trials. Inability to perceive the monofilament on 5 or more trials was defined as a positive test for sensory impairment. The Biothesiometer, a reliable and valid instrument for quantitative vibration perception threshold (QVPT) testing, acted as the reference standard. The instrument rested on the pulp of the great toe and the intensity was increased until the subject perceived the vibration. This was repeated three times on each foot. A value exceeding 25 volts served as the criterion for the loss of protective sensation. The protocol was repeated by a second examiner who was blinded to the prior test results. Data analysis included descriptive statistics, intraclass correlation coefficients (ICC), standard error of measurement (SEM), kappa statistic, and Spearman rank correlation coefficients. Contingency tables (2X2) were used to calculate sensitivity and specificity for SWM testing. Results: Monofilament (kappa=.74; rs= .89-.93) and QVPT (ICC=.77-.94; SEM=3.4-6.0 V; kappa= .74) testing demonstrated good to excellent interrater reliability. A significant relationship (rs .49, p<.05) also existed between SWM and QVPT scores. Sensitivity, specificity, positive and negative predictive values were 36%, 92%, 80%, and 61% respectively. Conclusions: Semmes-Weinstein and QVPT testing were reliable measures in this sample of older community dwelling adults. Monofilament testing demonstrated a high degree of specificity, but lacked adequate sensitivity as a sole screening procedure. Finally, the modest correlation between QVPT and monofilament testing suggests that these tests are predominately examining different domains of sensation. Clinical Relevance: Findings imply that the described SWM testing protocol was a reliable and specific instrument for identifying older adults with a loss of protective sensation. This study supports previous research that suggests clinicians should consider a combination of examination items when screening older adults for sensory impairment.