It is correct to use p. (page) and pp. (pages) BEFORE the page range of a cited reference text. However, they should not be used in an index.
The correct abbreviations which should be substituted are f. (and the following page); and ff. (and the following pages). These are placed after the first page number, and separated from it by a thin space (according to "New Hart's Rules").
There are so many different rules for (scientific) writing that I can't assess, if f. and ff. covers them all. So I think the best solutin would be to add f. and ff. option in Index dialog (Tab "Type").
This is a duplicate of Bug 94411.
*** This bug has been marked as a duplicate of bug 94411 ***