The SAS 9 (introduced) function ANYDIGIT may also work for you - with my test as compared to INDEXC, it was twice as fast over a large DO/END loop on Windows OS.
I believe the use of INDEX function is not equivalent to either INDEXC or ANYDIGIT. Also, if the OP was to use INDEX, the second argument must be character, so it would need to be enclosed in double-quotation marks to work properly.