1 facing facts (and lack of facts) about effectiveness of ecps elizabeth raymond, md, mph james...
TRANSCRIPT
1
Facing Facts(and Lack of Facts)
about Effectiveness of ECPs
Elizabeth Raymond, MD, MPH
James Trussell, PhD
Chelsea Polis
Obstet Gynecol 109(1):181-188, January 2007
2
The Hope
Widespread use of ECPscould prevent HALF of all
unintended pregnancies and abortionsin the US each year
(Trussell et al., 1992)
3
The Reality
Eleven studies have examined the impact of increased access to ECPs
on pregnancy and abortion rates
4
Fourteen Years Later
Eleven studies have examined the impact of increased access to ECPs
on pregnancy and abortion rates
None have shown any benefit
5
Agenda Today
• Review these studies
• Discuss possible explanations for disappointing findings
6
The Eleven Studies
• Conducted 1998-2006
• 4 countries
• Yuzpe, LNG, mifepristone
7
The Eleven Studies (continued)
• 9 randomized trials, 1 cohort study – Total of 11,830 women enrolled
• 1 demonstration project – >17,831 women given ECPs
• Followed women up to one year• Compared increased access to standard
access
8
Selected Studies
N Regimen1 Yr Preg. Rates
intervention control
Glasier 1083 Yuzpe 5% 6%
Lo 1030 LNG 1% 2%
Hu 2000 mife 4% 3%
Raine 2117 LNG 8% 9%
Raymond 1490 LNG 9% 10%
9
Explanations
1. Flaws in studies
10
Problems with the Studies
• Small size (160-2868 women)• Huge loss to follow-up (1-62%)• Weak intervention• Good access in comparison group• Low baseline risk of pregnancy – little
room for improvement with EC• Not randomized
11
However…
None of the 11 studies had all ofthese problems ―
Indeed, some were very good!
Consistency of findings hard to ignore
12
Explanations
1. Flaws in studies
2. Increased risk taking
13
ECPs and Risk Taking
• Lots of data• None show (almost) any effect of enhanced
ECP access on unprotected sex or use of regular contraception
• Some suggest “improved” behavior• Most data self-reported• 2 studies showed no effect on STIs
14
Explanations
1. Flaws in studies
2. Increased risk taking
3. Low ECP efficacy
15
Current Estimates
• ECP efficacy conveys the reduction in pregnancy risk after a single coital act
• Plan B package (LNG regimen): 89%
• ICEC Service Delivery Guidelines:– LNG regimen 60% - 94%– Yuzpe regimen 56% - 89% (74%)
16
Methodology
In a group of ECP users, compare:
• observed number of pregnancies
• expected number of pregnancies (number that would have occurred without ECPs)
Calculate the amount of reduction due tothe ECPs
17
Example
WHO 1998 trial of LNG vs. Yuzpe regimen
• 1001 women using LNG regimen• Pregnancies observed: 11• Pregnancies expected without EC: 75.3• Pregnancies prevented: 75.3 - 11 = 64.3 • Efficacy: 64.3 = 85%
75.3
18
Example
WHO 1998 trial of LNG vs. Yuzpe regimen
• 1001 women using LNG regimen• Pregnancies observed: 11• Pregnancies expected without EC: 75.3• Pregnancies prevented: 75.3 - 11 = 64.3 • Efficacy: 64.3 = 85%
75.3
19
Expected Pregnancies
• Collect data on:– date of sex act– date of last menstrual period– usual menstrual cycle length
• Determine the day of the menstrual cycle when the coital act occurred
• Use published data to estimate expected pregnancies
20
Pregnancy Risk by Cycle Day
0%
5%
10%
15%
20%
25%
30%
35%
40%
-8 -7 -6 -5 -4 -3 -2 -1 0 1 2
Menstrual cycle day
Pre
gn
an
cy
ris
k Wilcox 1998
21
Pregnancy Risk by Cycle Day
0%
5%
10%
15%
20%
25%
30%
35%
40%
-8 -7 -6 -5 -4 -3 -2 -1 0 1 2
Menstrual cycle day
Pre
gn
an
cy
ris
k
Schw artz 1979Schw artz 1980Bremme 1991
Weinberg 1998Wilcox 1998Colombo 2002
22
Do Any of the Charts Apply?
Women in the charts wanted to be pregnant
ECP users wanted NOT to be pregnant
• Used broken condom, withdrawal
• Different fertility?
• Different amount of unprotected sex?
• Different accuracy in reporting data?
23
Results
Numbers of expected pregnancies reportedby studies are probably too high
Most published efficacy figures are probably overestimates
24
Don’t Give Up…
ECPs do work!
• Physiology studies show effects incompatible with pregnancy
• LNG regimen proven to be more effective than Yuzpe it must be more effective than nothing
25
Efficacy of LNG Regimen
0%
25%
50%
75%
100%
0% 25% 50% 75%
Efficacy of Yuzpe
Eff
ica
cy
of
LN
G
26
Efficacy of LNG Regimen
0%
25%
50%
75%
100%
0% 25% 50% 75%
Efficacy of Yuzpe
Eff
ica
cy
of
LN
G
27
Explanations
1. Flaws in studies
2. Increased risk taking
3. Low ECP efficacy
4. Insufficient use
28
Effects of Increased Access
• In all studies so far (except one), increased access resulted in substantially increased use
• But…
29
But…
• Repeated use was uncommon
• Many unprotected acts remained uncovered by ECPs
• No ECPs were used in most pregnancy cycles
30
Reasons for Non-Use
Reasons given by women:
• Failure to perceive pregnancy risk
• Forgetting• Lack of motivation to use EC (“I’m lazy”)
• Inconvenience
31
Why Didn’t You Take Them?
“Now, my experience is that most of the time, people have no idea why they're doing what they're doing. They have no idea, so they're going to try to make up something that makes sense.”
- Clotaire Rapaille, Chairman, Archetype Discoveries Worldwide
32
Limits on ECP Use
• Expense
• Side effects
• High dose of hormones
• Psychologic stress
33
Ineffective Use
• Many uses are “wasted” – ECPs taken at times when risk is really low
• Does “wasted” use limit “truly needed” use?
34
Eleven Studies, No Benefit
1. Flaws in studies - but consistency compelling
2. Increased risk taking - no evidence
3. Low ECP efficacy - precise efficacy unknown
4. Insufficient use - definitely a problem
35
What To Do Now?
• Be honest: do not oversell by implying Plan B will reduce unintended pregnancy
• Everyone deserves a second chance to prevent an unintended pregnancy