Performance of the National Institute of Infectious Diseases disability scale in HTLV-1-associated myelopathy/tropical spastic paraparesis

Abstract

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic disabling disease. However, there is a lack of an adequate and specific health measurement instrument validated and with good performance to assess their degree of physical disability. This led us to carry out this study and to evaluate the performance of Fiocruz's National Institute of Infectious Diseases (IDS) disability scale, a specific instrument for HAM/TSP. Ninety-two HAM/TSP patients participated in the study. One researcher applied the IDS, IPEC scale, Disability Status Scale (DSS), Expanded DSS (EDSS), Osame scale, Beck Depression Inventory, and the WHOQOL-BREF questionnaire. In parallel, blindly, and separately, other researchers applied the IDS. An inter-rater reliability analysis of the IDS, correlation analysis with the other scales, and depression and quality of life questionnaires were performed. The applicability of the IDS was also evaluated. The IDS showed high reliability in all scores. The inter-rater reliability test for the total IDS score was 0.94 (0.82-0.98) on its four dimensions. The scale adequately indicated the different degrees of disability, presenting a distribution similar to normal. There was a high correlation with the other scales (Spearman coefficients > 0.80, p < 0.001). The scale had good acceptance among users and a short application time. IDS for HAM/TSP was reliable, consistent, easy, and fast to use. It can be used for both prospective evaluations and clinical trials. The present study supports the IDS as a valid instrument to measure disability in patients with HAM/TSP compared to previously used scales.

Appendix 1 The INI Disability Scale (IDS)

THE NATIONAL INSTITUTE OF INFECTIOUS DISEASES DISABILITY SCALE (IDS) FOR HAM/TSP
MOTOR SCORE: GAITa     0. Normal     1. Abnormal but walks independently     2. Abnormal and dependent on the eventual use of unilateral support     3. Abnormal and dependent on the permanent use of unilateral support     4. Abnormal and dependent on the eventual use of bilateral support     5. Abnormal and dependent on the permanent use of bilateral support     6. Abnormal and dependent on the permanent use of bilateral support and occasional use of a wheelchair (WC)     7. Permanent use of a WC, stands up and remains upright without support     8. Permanent use of a WC, uses arms to stand up and remains upright without support     9. Permanent use of a WC, needs assistance from others to stand up and remains upright with support     10. Permanent use of a WC, unable to stand up, exhibits voluntary movements of the lower limbs     11. Permanent use of a WC, unable to stand up, and does not have any voluntary movements of the lower limbs
MOTOR SCORE: RUNNINGb     1. Runs     2. Unable to run
MOTOR SCORE: CLIMBING STAIRSc     1. Climbs     2. Climbs with support     3. Unable to climb
MOTOR SCORE: JUMPINGd     1. Jumps on one or two feet     2. Jumps only with both feet     3. Jumps only with both feet with hand support     4. Unable to jump
SPASTICITY SCORE: CLONUSe     1. Absent     2. Only induced by the examiner     3. Spontaneous
SPASTICITY SCORE: FLEXOR/EXTENSOR SPASMSf     1. Absent     2. Present
SENSORY SCORE: PARESTHESIASg     1. Absent     2. Present, eventually     3. Present, permanently
SENSORY SCORE: LUMBAR PAINh     1. Absent     2. Present, eventually     3. Present, permanently
SENSORY SCORE: LOWER LIMB PAINi     1. Absent     2. Present, eventually     3. Present, permanently
SPHINCTER SCORE: BLADDER FUNCTIONj     1. Total control     2. Urgency     3. Eventual incontinence or retention     4. Use of permanent catheter or regular use of relieving catheter
SPHINCTER SCORE: BOWEL FUNCTIONk     1. Normal     2. Constipation     3. Incontinence or total retention; needs manual extraction or enemas
Total: ____ (0-31)

1. ^aAsk the patient to get up from a chair and walk 10 steps. Watch how she/he performs
2. ^bAsk the patient if she/he would be able to run for a bus or a taxi in her/his present condition
3. ^cAsk the patient if she/he can climb a flight of stairs (12 steps)
4. ^d Patients who are unable to stand upright or who are unable to raise the forefoot sole at least 2 cm from the ground during the jump, score 3. For safety reasons, the examiner initially offers the patient the support of both hands. If she/he can jump with bilateral support, the examiner withdraws the hand support and asks the patient to jump with both legs. If she/he succeeds, she/he is asked to try to hop with just one of them. The examiner will always remain at the patient's side
5. ^eThe examiner asks the patient, from a sitting position, to place the feet on the floor. The examiner observes for spontaneous clonus. If there is no clonus, the examiner will conduct the direct examination, using traditional maneuvers for the clonus of the patellae and feet
6. ^fAsk the patient: Are your legs stiff, stretching, or bending involuntarily as if they are spasming?
7. ^gAsk the patient: Do you feel tingling, pins and needles, or cold in your feet or legs?
8. ^hAsk the patient: Does your back hurt?
9. ⁱAsk the patient: Do you feel any pain in your feet or legs?
10. ^jAsk the patient: Do you feel an urge when you have to urinate or have a sudden urge to urinate at inappropriate times? Do you leak urine? Do you have to rush to the toilet and sometimes not make it? Do you have some trouble starting to urinate before urine comes out? Do you use intermittent vesical catheterization or a permanent vesical catheter?
11. ^kAsk the patient: how often do you defecate per week? This frequency has always been like that, or has it changed recently? When did you last open your bowels? Are your stools too dry? Do you need to use your finger, suppository, or enema to help evacuate?