The DHS wealth index is calculated separately for each survey (with a couple of exceptions, not being Nepal) so that the value of the wealth score in one survey may not (usually the case) correspond to the same level of wealth in another survey even in the same country. For that, the Comparative Wealth Index was created. To create the Comparative Wealth Index for those surveys use the following:

CWI score=Alpha + Beta*v191
Country Year Constant (Alpha) Coefficient (Beta)

Nepal, 2001 -1.0876444 0.6696379
Nepal, 2006 -0.8041832 0.8550128
Nepal, 2011 -0.3603931 1.0388343

To create comparable quintiles, use these values as cutpoints:

Cut points for CWI quintiles:
1-2 -0.90802
2-3 -0.38583
3-4 -0.01189
4-5 0.74156

And yes, you can use the values of the CWI (and individual wealth index scores) instead of quintiles.

Shea Rutstein