Results
The results of the three studies are summarized in Table 1. All three
studies demonstrated:
- An overall significantly increased relative risk of outcomes with use
of HC (study 3 only with never-users as reference or young age group)
- Higher relative risk (or odds ratio) of outcomes with non-oral
combined products than with use of combined oral contraceptives.
- Higher relative risk of outcomes in adolescents than in older young
women.
- Higher relative risk of outcomes with levonorgestrel intrauterine
system (LNG-IUS) than with use of oral contraceptives.
- Higher relative risk of outcomes when using never-users as reference,
than when using non-users as reference group (study 1 and 3).
Important differences in results between the three studies were also
demonstrated:
- Study 1 and 2 had generally substantially higher relative risk
estimates for all product groups than study 3.
- Study 1 and 2 demonstrated significantly increased relative risks of
outcomes for all product groups, whereas study 3 demonstrated
significantly increased risks with all products groups except use of
oral contraceptives, which in the main analysis demonstrated a
significant protection against depression.
- With increasing age, oral contraceptive use implied in study 1 a
decrease in relative risk of depression from 1.8 to 1.2, in study 2
from 3.3 to 1.1 and in study 3 from 1.0 to 0.8.