Table 1

The years lived with disability (YLDs) and the years of life lost (YLLs)

Dimensions	YLD	YLL
Dimensions	Two-dimensional (time×disability weight)	One-dimensional (time)
Concern about individual burden
Experience: Do we experience it?	Yes	No
Time: Does it harm us through time?	Yes	No
Symmetry: Does it treat the past and future equally?	Yes	No

Based on the three arguments, we may question whether YLLs measure an individual burden, if not, then YLDs and YLLs will be incommensurable.