Normally Long-term drift are available on product specifications but there are another datasheet that it was not mentioned. To determine, check similarities with digipot that has the long-term drift specification. For example, both are using the same fab process and model (resistance, leakage current, max current rating, etc.).
Example: AD5141 does have LTD specification, but AD5290 has no LTD, but both products use the same resistors. This way, the LTD of AD5141 can be used as reference for AD5290.