I'm not sure what your question is? Are the doctors saying that your sister no longer has Lupus because her ANA is now negative?
Was she taking medication for her Lupus prior to this recent lab result?
If so, what medications was she taking?
Lupus is a chronic disease, meaning that it NEVER goes away. However, we can achieve a state of remission where our lab results are negative and our symptoms are minimal. Remission can last for days or for years, but the underlying disease is still there...it is just dormant and may not need medications.
I hope I've answered your question. Let me know if you need more information.
Peace and Blessings