0	Completely asymptomatic.
1	Symptoms present, but no significant functional disability; can carry out all daily activities and live independently.
2	Minor disability; unable to carry out all activities prior to illness but can look after personal affairs without assistance.
3	Moderate disability; requires some assistance but can walk independently.
4	Moderate disability; requires some assistance but can walk independently.
5	Severe disability; bedridden, incontinent, and completely dependent on others for daily living.
6	Death.