Reliability of the sit-up test in individuals with spinal cord injury

OBJECTIVE: To determine the day-to-day reliability of blood pressure responses during a sit-up test in individuals with a traumatic spinal cord injury (SCI). DESIGN: Within-subject, repeated measures design. SETTING: Community outpatient assessments at a research laboratory at the University of British Columbia. PARTICIPANTS: Five men and three women with traumatic SCI (age: 31 ± 6 years; C4-T11; American Spinal Injury Association Impairment Scale A-B; 1-17 years post-injury). OUTCOME MEASURE: Maximum change in systolic (ΔSBP) and diastolic (ΔDBP) blood pressure upon passively moving from a supine to seated position. RESULTS: The average values for ΔSBP were -11 ± 13 mmHg (range -38 to 3 mmHg) for visit 1, and -12 ± 8 mmHg (range -26 to -1 mmHg) for visit 2. The average values for ΔDBP were -9 ± 8 mmHg (range -21 to 0 mmHg) for visit 1, and -13 ± 8 mmHg (range -29 to -3 mmHg) for visit 2. The ΔSBP demonstrated substantial reliability with an intraclass correlation coefficient of 0.79 (P = 0.006; 95% CI 0.250-0.953), while the ΔDBP demonstrated almost perfect reliability with an intraclass correlation coefficient of 0.92 (P < 0.001; 95% CI 0.645-0.983). The smallest detectable differences in ΔSBP and ΔDBP were 7 mmHg and 6 mmHg, respectively. CONCLUSION: Blood pressure responses to the sit-up test are reliable in individuals with SCI, which supports its implementation as a practical bedside assessment for orthostatic hypotension in this at risk population.