Qualitative research is done by experienced academics and researchers who have been trained in qualitative methodologies. These things go through ethics review panels. The methodologies are examined and are closely followed.
Anecdote is different. Anecdote is asking one person what happened and not putting that under any kind of critical appraisal. It's not going through any kind of ethics review to see the impact of the information you're seeking on the community of a person. It doesn't go through any kind of peer review, which all qualitative research does.
Anecdote just stands alone as someone's statement. Qualitative research has a long-standing history of quality and describing people's experiences in health care.