Progression index and disability status in multiple sclerosis: a resurvey of 207 patients in central Poland.
The progression index (disability grade divided by the duration of the disease) and disability status are presented in multiple sclerosis (MS) patients from two hospital series in central Poland. The natural course of 207 patients showed continuously decreasing progression index (PI) from 4.15 after the first year to 0.72 and 0.23 after 10 yr. or 26 yr. respectively. Within the duration of the disease from 1 to 40 years mean PI was 1.12. Among 207 hospitalized patients 156 (75.6%) showed moderately speedy progression with PI 0.21-1.33. Mean neurologic impairment evaluated on Disability Status Scale (DSS) was 6.27 (range 4.40-8.25). Overall neurologic disability slowly increased from 5.82, 6.50, 7.04 at 5 years intervals up to 7.17 after 26 years. Out of 207 patients 127 (71.1%) demonstrated either moderate or severe impairment (4-9 grades at DSS). These figures represent rather biased hospital over-representation of grave cases than more malignant natural course of MS in Poland. It was also considered that very slow PI (0.20 or less) has at least approximately as good prognostic value as Kurtzke's "rule of 5 yr. at DSS". In the present hospital series none of MS patients with low PI - less than or equal to 0.20 - had deteriorated after 26 yr. of the disease beyond 6th grade of DSS.