Healthy user bias in this study is used to describe the behavior that those who have negative outcomes on OC cease using OC.
Other uses of the term healthy user bias within this study:
Research on the effect of oral contraceptive (OC) use on the risk of depression shows inconsistent findings, especially in adult OC users. One possible reason for this inconsistency is the omission of women who discontinue OCs due to adverse mood effects, leading to healthy user bias.
Similar underestimation of effects can be seen in observational studies not considering previous OC use, as exemplified in the Netherlands Study of Depression and Anxiety cohort, which found that current OC use in a between-person analysis was associated with lower risk of depression, while the within-analysis showed that the time during OC use was associated with an increased risk of depression. This discrepancy is likely explained by a healthy user bias as those negatively affected by OC use had discontinued and thus represented nonusers in the between-person analysis (Morssinkhof et al., Reference Morssinkhof, Lamers, Hoogendoorn, de Wit, Riese, Giltay, van den Heuvel, Penninx and Broekman2021).
This sentence you're quoting indicates the exact opposite of what you've attributed it to.
Self strangulation with vines?