Women are less likely to experience irregular bleeding when
switching to NuvaRing compared with combined oral contraceptives-data from a
pooled analysis
I Milsom1, E Ng2, J in ‘t Hout3
1Sahlgrenska Academy at
Göteborg University, Department of Obstetrics and Gynaecology, Göteborg,
Sweden, 2Organon International, Medical Services, Roseland, NJ, United States,
3NV Organon, Biometrics Department, Oss, Netherlands
Background In a previous
large comparative clinical trial, the incidence of breakthrough bleeding and
spotting was lower per cycle in women using NuvaRing compared with those using a
combined oral contraceptive (COC) containing 30 mcg ethinylestradiol (EE) and
150 mcg levonorgestrel [Oddsson et al, Hum Reprod 2005; 20: 557-62]. Data
looking at cycle control from the women’s perspective (the percentage of women
experiencing breakthrough bleeding) however, have never been reported.
Objective
To further characterise the likelihood of breakthrough bleeding and spotting in
women using NuvaRing vs 30 mcg EE COCs by performing a pooled data analysis of
two large randomised trials.
Design and methods Data were pooled from two
randomised controlled trials comparing NuvaRing to Microgynon (30 mcg EE/150 mcg
levonorgestrel) and Yasmin (30 mcg EE/3 mg drosperinone), both over 13 (28-day)
cycles. The analysis comprised women from the intent-to-treat cohort (NuvaRing =
978; Microgynon = 488; Yasmin = 474). Inclusion and exclusion criteria and
clinical report forms used for data collection were similar for the two studies.
In addition, a subgroup analysis was performed on starters and switchers in all
groups to look at the effect of prior exposure to hormonal contraception on
cycle control.
Results The percentage of women without breakthrough bleeding
was consistently higher in the NuvaRing group (92%) vs the COC groups (81%
Microgynon and 85% Yasmin; 83% combined) after 13 cycles of treatment. The
difference was statistically significant (p<0.0001 log-rank test NuvaRing vs the COC groups). In the subgroup analysis, the percentage of subjects without breakthrough bleeding was consistently highest among those who switched to NuvaRing (95%) followed by the NuvaRing group consisting of new starters (90%) after 13 cycles. Starters in the COC groups were most likely to have irregular bleeding. When data from the first two cycles were omitted, the difference between the starters and switchers diminished amongst the COC groups.
Conclusions The likelihood of experiencing breakthrough bleeding and spotting
was lower in women using NuvaRing vs COCs within 1 year of treatment. In
particular, superior cycle control was observed in women switching to NuvaRing
from other hormonal contraceptives.