The Sit-Up Test to Assess Orthostatic Hypotension in Individuals with Spinal Cord Injury: Validity and Reliability

Abstract Due to decentralized autonomic nervous system function, individuals with spinal cord injury (SCI) are reported to have an increased prevalence of orthostatic hypotension (OH). Diagnosis of OH is made with active standing or tilt table testing, with limited the use in individuals with SCI. An alternative approach to assess OH is the sit-up test which involves passive repositioning from the supine to the seated position. The purpose of this study was to determine the reliability and validity of the sit-up test in a large, diverse group of individuals with SCI. A total of 166 participants completed two sit-up tests, 119 individuals with SCI and 47 uninjured controls and 36 individuals who completed the sit-up tests also underwent a head-up tilt test. The mean difference in change in BP from sit-up test 1 to sit-up test 2 was not significant for either SBP or DBP, and neither level nor severity of injury contributed significantly to the reliability assessments. However, the reliability assessments showed disappointing results with generally low interclass correlation coefficients (ICC) values and large standard error of measurement (SEM). Comparison of the BP responses between the sit-up test and the head up tilt showed good sensitivity and specificity, with positive predictive values of 75% for both SBP and DBP. Prevalent BP instability likely contributed to the poor reliability of the sit-up test, but the test is easy to perform with good sensitivity and specificity and a high likelihood ratio for the valid assessment of OH in individuals with SCI.