HD-ISS Calculator

Based on the paper, A biological classification of Huntington's disease: the Integrated Staging System, by Tabrizi et al.

Directions: insert values for each variable indicated (missing data is not allowed). Then click Calculate Stage for results.

Age in Years

Round to nearest year (18 or older)

CAG Expansion

Must be 40 or longer

Putamen Volume

Must be proportion of
ICV ICV: intra-cranial volume
(range 0 to 1)

Caudate Volume

Must be proportion of
ICV ICV: intra-cranial volume
(range 0 to 1)

UHDRS UHDRS: Unified HD Rating Scale
Total Motor Score (TMS)

Range 0 to 124

UHDRS UHDRS: Unified HD Rating Scale
Symbol Digit Modalities Test (SDMT)
(0 or greater)

Education: Required for SDMT interpretation
0 = HS or less, 1 = more than HS
(0 or 1)
UHDRS UHDRS: Unified HD Rating Scale
Total Functional Capacity (TFC)

Range 0 to 13

UHDRS UHDRS: Unified HD Rating Scale
Independence Scale (IS)

Range 0 to 100 (increments of 10)

Huntington's Disease Integrated Staging System Overview

stage