It is pretty common to just use the word "index". However, this term is obviously trying to differentiate between the index itself and the value/score assigned to one unit in the study. In this case, I would say, for example when speaking of a consumer price index, "The index value for Houston for 1998 was 110." which means that consumer goods in Houston cost 10% more than the baseline value. I also do think that score is just fine. And like I said, index by itself would generally be fine too (see table column headings here: http://www.bls.gov/news.release/cpi.t01.htm).