Combined Oral
Contraceptive Pills
(COCs)
Advanced Slide Set
Advanced Slide Set, Slide #1
Combined Oral Contraceptives
Effectiveness
Spermicides
Female condom
Standard Days Method
Male condom
Oral contraceptives
DMPA
IUD (TCu-380A)
Pregnancy rate when used
correctly and consistently
Female sterilization
Male sterilization
Pregnancy rate as commonly used
Implants
0
Source: Trussell, 2011.
5
10
15
20
25
30
Percentage of women pregnant in first year of use
Advanced Slide Set, # 2
Protective Effect of COC Use on
Ovarian and Endometrial Cancer
Lifetime risk of acquiring ovarian or endometrial cancer after 8+ years of COC use
Number per 100 women
100
10
Ovarian Cancer
Non COC users
COC users
8
Endometrial Cancer
Non COC users
COC users
Protection
develops
after 12
months of
use and is
present for at
least 15 years
6
4
2
3.1
1.7
1.2
0.7
0.6
0.7
0.2
Reduces
risk by more
than 50%
0.3
0.6
0.2
0.4
0.1
0
United States
Costa Rica
Source: Petitti and Porterfield, 1992; CASH Study 1987.
China
Advanced Slide Set, # 3
Understanding Relative Risk
Definition
Relative Risk =
Probability of developing condition X
in exposed population
Probability of developing condition X
in unexposed population
Advanced Slide Set, # 4
Understanding Relative Risk
Risk Versus Protection
Relative Risk Log Scale
10
5
Increased
Risk
1
No Effect
0.5
Protective
Effect
Exposure
increases risk of
disease
No association
Exposure
decreases risk of
disease
0.1
Advanced Slide Set, # 5
Understanding Relative Risk
Confidence Interval
Relative Risk Log Scale
10
5
A
B
Increased
Risk
C
No Effect
1
D
0.5
Statistical interpretation:
0.1
A – Significant risk
Protective
Effect
B – Nonsignificant risk
C – Nonsignificant protection
D – Significant protection
Advanced Slide Set, # 6
Relative Risk for Breast Cancer
among COC users and Non-users
Relative Risk Log Scale
10
Increased
Risk
1.0
1.24
1.16
1.07
1.01
[1.15–1.33]
[1.08–1.23]
[1.02–1.13]
[0.96–1.05]
No Effect
1
0.1
Protective
Effect
[95% Confidence Interval]
Nonusers
Current
COC
users
1–4 yrs
after
stopping
5–9 yrs
after
stopping
10+ yrs
after
stopping
Source: Collaborative Group on Hormonal Factors in Breast Cancer, 1996; Milne, 2005; Silvera, 2005 .
Advanced Slide Set, # 7
COC Users and Risk of Blood Clots
Estimates of venous thromboembolism per 100,000 woman-years
Incidence
Relative Risk
4–5
1
Low-dose COCs
12–20
3–4
High-dose COCs
24–50
6–10
Pregnant women
48–60
12
Young women in the general
population
Pregnancy presents a higher risk of blood clots
than do COCs.
Source: WHO, 1998; Speroff, 2005.
Advanced Slide Set, # 8
COC Users and Risk of Heart Attack
Estimated number of heart attacks per million woman-years
Characteristic
Age 20-24
Age 30-34
Age 40-44
Healthy non-COC user
0.14
1.7
21.3
Healthy COC user
0.34
4.2
53.2
COC user who smokes
1.6
20.4
255
COC user with  BP
2.0
25.5
319
Screening for existing risk factors is important.
Source: Farley, 1998.
Advanced Slide Set, # 9