Table 2. Effect of mobility impairment categorized by Patient Determined Disease Steps and the NARCOMS Mobility Performance Scale on indirect and intangible costs#.
| Mobility Impairment | Indirect Costs ± SD | Change in Indirect Costs (%) * | EQ-5D ± SD | Change In EQ-5D (%) * | Intangible Costs (WTP $50,000, $100,000) |
| PDDS (N = 3,484) | |||||
| None (n = 1,343) | $21,245± $28,808 | Referent | 0.83±0.14 | Referent | Referent |
| Mild-to-Moderate (n = 1,507) | $ 35,611± $31,533 | $14,366 (67.6%)† | 0.70±0.16 | 0.13 (15.7%)† | $6,500, $13,000 |
| Severe-to-Total (n = 634) | $38,510± $30,291 | $17,265 (81.3%)† | 0.62±0.19 | 0.21 (25.3%)† | $10,500, $21,000 |
| Mobility PS/“In the past 4 weeks, compare your current condition to your mobility before you developed MS” (N = 3,503) | |||||
| Normal (n = 628) | $15,611± $26,556 | Referent | 0.89±0.12 | Referent | Referent |
| Minimal Gait Disability (n = 566) | $22,055± $29,113 | $6,444 (41.3%)† | 0.80±0.13 | 0.09 (11.3%)† | $4,500, $9,000 |
| Mild Gait Disability (n = 536) | $33,380± $31,269 | $17,769 (113.8%)† | 0.72±0.16 | 0.17 (23.6%)† | $8,500, $17,000 |
| Occasional use of cane (n = 598) | $37,384± $31,330 | $21,733 (139.5%)† | 0.70±0.16 | 0.19 (27.1%)† | $9,500, $19,000 |
| Frequent use of cane (n = 527) | $39,440± $30,199 | $23,829 (152.6%)† | 0.67±0.17 | 0.22 (32.8%)† | $11,000, $22,000 |
| Severe Gait Disability (n = 543) | $37,012± $30,824 | $21,401 (137.1%)† | 0.63±0.18 | 0.26 (41.3%)† | $13,000, $26,000 |
| Total Gait Disability (n = 105) | $30,576± $31,166 | $14,965 (95.8%)† | 0.53±0.22 | 0.36 (67.9%)† | $18,000, $36,000 |
EQ-5D = EuroQol 5 Dimension, MS = Multiple Sclerosis, PDDS = Patient Determined Disease Steps (scores of 0–2 representing “no walking disability”, 3–5 as “mild-to-moderate” and 6–8 as “severe-to-total”), PS = Performance Scale, Q = question number, SD = standard deviation, WTP = willingness-to-pay.
*
No mobility impairment was used as referent,
†
P<0.001.
#
Sample sizes for each scale varied due to survey completeness.