Journal of Contraception Reproductive Health Care - The European ...

The 8th Congress of The European Society of Contraception Abstracts of Free Communications
FC1-05
A comparison of Pearl indices and cumulative incidences for use in meta-analysis of contraception
trials
P. O’Brien
Westside Contraceptive Services, London, UK
Objectives: One of the issues encountered when performing meta-analysis of contraceptive trials is the variable way in which
the outcomes are reported, as cumulative rates (Kaplan Meier curves), single or multiple decrement life-tables rates, or Pearl
indices (events per 100 women-years). The latter decrease with time, while the others increase. However, it is usually the ratio
of the rates that we use in meta-analysis. In this analysis we compare the ratio of the Pearl rates to the ratio of the cumulative
incidence and their confidence intervals.
Design and methods: We used data from a large WHO randomised trial of a frameless IUD and TCu380A, to compared the
ratio of Pearl indices to the ratio of cumulative incidences. We used the method described by Kleinbaum to calculate the standard
error of the ratio of cumulative incidences and the method of Hasselblad for the standard error of the ratio of Pearl indices,
to calculate their confidence intervals.
Results: For accidental pregnancies the difference in the ratio of Pearl ratios to ratio of incidence ratios was greatest at year 6 at
13% (Pearl rate ratio 0.95, 95%CI 0.64 to 1.47; incidence rate ratios 0.85, 0.56 to 1.29). In 4 of the 6 years of follow-up, the
difference in ratios was less than 5%. The difference was smaller for removals for bleeding and pain, never exceeding 3% (Pearl
ratio 1.10, 0.90 to 1.33; incidence ratio 1.13, 0.94 to 1.36 at 6 years). For total use-related discontinuations, the difference never
exceeded 4% (Pearl ratio 1.26, 1.10 to 1.45; incidence ratio 1.22, 1.08 to 1.38 at 6 years).
Conclusions: The difference in rate ratios, whether we use the Pearl indices or cumulative incidence rates, is usually small. The difference
in rate ratios from single and multiple decrement life-tables is likely to be smaller. The ability to incorporate trials using different
reporting methods in meta-analyses enhances our capacity to systematically review the literature. Further research is required to understand
the determinants of the magnitude and direction of the differences.
FC1-06
Ease of insertion, contraceptive efficacy and safety of new T-shaped levonorgestrel-releasing
intrauterine systems – First clinical report
D. Wildemeersch (1), D. Janssens (2) , M. Vrijens (3), S. Weyers (4)
Contrel Research, Technology Park Zwijnaarde, Ghent, Belgium (1)
Gynecologische Dienst, Turnhout, Belgium (2)
Gynecologische Dienst, Gent, Belgium (3)
Department of Obstetrics and Gynecology, University Hospital Ghent, Ghent, Belgium (4)
Objective: The objective of the study is to evaluate ease of insertion, contraceptive performance and safety, in parous and nulliparous
women, of two new T-shaped levonorgestrel (LNG)-releasing intrauterine systems (T-LNG-IUS), Femilis TM LNG-IUS
and Femilis TM Slim LNG-IUS, releasing 20 mg of LNG/day. An ancillary objective is to evaluate expulsion and user-continuation.
Design and methods: An open, prospective non-comparative study (interim analysis). Two hundred and fifty-eight insertions
were performed in fertile women for contraception. From these, 143 (55.5%) parous women were fitted with Femilis-LNG IUS
and 115 (44.5%) nulliparous women were fitted with Femilis Slim LNG-IUS. The LNG-IUS is inserted using a simplified
push-in technique (without folding the cross-arms in the insertion tube).
Results: This paper is the first (interim) report with the Femilis LNG-IUS. The push-in technique of insertion was considered
simple and safe. Insertion was reported ‘easy’ in virtually all women (98%). Pain at insertion was absent in 23.6% and ‘mild’ in 64.7%
of women. At the time of study analysis the total number of women-months was 1,867. Seventy-eight women had the T-LNG-
IUS in place for periods in excess of one year. The study was well followed-up with lost-to-follow-up of 3 woman only. No pregnancies
were observed. The following events occurred: there were 3 expulsions in the nulliparous and 1 in the parous group. Fifteen
removals were performed for medical reasons (mainly bleeding and pain). One pelvic infection occurred in a nulliparous women
caused by Chlamydia trachomatis which was cured without removing the IUS. There were no serious adverse events (e.g. perforation)
reported. Both the standard and slim version of T-LNG-IUS were well tolerated which resulted in a high continued use
(91.4%).
Conclusion: The Femilis LNG-IUS insertion procedure is simple and safe. The results of this one-year study are in agreement
with those observed with the Mirena 1 and frameless FibroPlant TM LNG-IUS. However, the simple and safe insertion procedure
could be an advantage for use by non-specialist providers (e.g. nurses, midwives, general practitioners), and for those not using
the LNG-IUS regularly, and contribute to an increased prevalence of use of the method. Femilis Slim could be an attractive
long-term contraceptive option in young, including adolescent women. The study analysis will be updated for the presentation.
32 The European Journal of Contraception and Reproductive Health Care