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pain: A multivariate analysis
Clinical Article Factors Associated with Copper T IUD Removal for Bleeding/Pain:
A Multivariate
Analysis
Jun Zhang, MB Family Health International, 27709, USA
P.O. Box 13950, Research Triangle Park, NC
To examine the factors associated with copper T IUD removal due to bleeding/pain, a nested case-control analysis using data from an international multicenter randomized clinical trial of the copper T-380A IUD was performed. One-hundred-forty-three cases with removal due to bleeding/pain within one year postinsertion and 2,023 controls with the IUD in place at last follow-up visit are included. Proportional hazards regression analysis indicated that uterine length greater than 70 mm and better IUD provider’s skill were associated with a decreased risk of removal due to bleeding/ pain. Amenorrhea and breastfeeding at insertion have shortterm beneficial effects but less long-term effects. These findings may help family planning providers in counseling and practice.
Key words:Bleeding; intrauterine device; pain, removal
Introduction Copper T intrauterine devices (IUD), including TCu-200, TCu-220C and TCu-380A, are widely used throughout the world. They have a T-shaped plastic frame 36 mm long and 32 mm wide. The copper surface is 200, 220 and 380 mm<<, respectively. TCu-380A, one of the latest generation of IUDs, is one of the most effective methods of contraception ever developed, and will be the major IUD available in most countries.’ However, as with most other IUDs, menorrhagia and intermenstrual bleeding and/ or pain are the most common complications of copper T IUD use, which usually leads to medical removal. In developing countries where abnormal
Submitted 1993.
for publication
0 1993 Butterworth-Heinemann
February 4, 1993; Accepted
for publication
May 19,
Contraception 1993:48, July
13
Clinical Article bleeding is religiously unacceptable, this side effect becomes more salient. However, few studies have been done which exclusively examined factors associated with this complication. The present study examines a variety of women’s characteristics prior to insertion and the association of those factors with IUD removal for bleeding/pain.
Materials and Methods Data used in this study are from an international multicenter randomized clinical trial of the copper T-380A compared with other IUDs. Detailed information on the study design has been provided elsewhere.2,3 Briefly, thirteen collaborating centers in Latin America, Asia and Africa used identical case record forms and protocols to collect information on IUD insertion and use from 1985 to 1986. All participants were 18-40 years old, were sexually active, and had no contraindications for IUD use. IUDs were randomly assigned to participants according to sealed random-allocation envelopes, preprinted before study initiation, and opened at the time of IUD insertion. The devices were inserted at least 42 days after last pregnancy termination. Information on selected demographic characteristics, reproductive and contraceptive histories, and pre-existing medical conditions were obtained at the time of admission to the study. Followup examinations were scheduled at one, three, six and 12 months after IUD insertion. There were 3,479 subjects overall in the data set. The current analysis only includes women who received a copper T device: TCu-200 (27%), TCu-220C (6%), and TCu-380A (67%), excluding 598 subjects with other types of IUDs. We also excluded women with an accidental pregnancy (N = 24); IUD expulsion (N = 9.5); IUD removal due to medical reasons other than bleeding/pain (N = 53), planned pregnancy (N = 47), personal reasons (N = loo), or investigators’ choice (N = 8); and women lost to follow-up immediately after insertion (N = 43). Based on the protocol, the multicenter study followed the subjects for one year. Since about half of the women had their last visit somewhat later than exactly 365 days postinsertion, we truncated our data at 430 days postinsertion (excluding 214 women). Also eliminated were those who had missing information on duration of follow-up (N = 131). These exclusions left 2,166 women for analysis. The women were classified as cases with IUD removal due to bleeding/ pain (N = 143) or controls with an IUD in place at last visit (N = 2,023)(Table 1). A variety of traits in the women in association with removal for bleeding by calculating odds ratios and 95% confidence intervals were examined. To fit a multivariable model while accounting for time to removal, Cox proportional hazards regression was used. This regression model predicts the ratio of removal incidence rates, in which
14
Contraception
1993:48, July
IUD removal for bleeding/pain:
Zhang
TABLE1. Number of cases and controls by center location
TCu 200
East & Southeast Asia West Asia & North Africa Sub-Sahara Africa Latin America
TCu 220C
TCu 380A
case
control
case
control
case
control
24
136 4 17
60 181
14 2
255 32 144
17 387 2 31
249 66 545
the likelihood is evaluated conditionally on the set of subjects who remain under observation after each removal occurrence.4 The time interval for the removal events was the duration between IUD insertion and removal; for women without removal, the observation interval was the duration between insertion and the last follow-up visit. Hazards ratios and confidence intervals were computed from beta coefficients and standard errors.
Results Table 2 shows characteristics of cases and controls prior to IUD insertion. Compared with Latin American women, West Asian and North African women were more likely to have IUD removal due to bleeding/pain. The length of external OS to fundus was inversely associated with risk of removal. Women with cervical laceration had twice the risk of removal compared to those without. An IUD inserted by a person other than an obstetrician/gynecologist was 1.8 times more likely to be removed within a year. Women who were breastfeeding at insertion appeared to have decreased risk of removal. Women still in amenorrhea at insertion had a significantly lower risk of removal than those whose menses had resumed. Other factors listed in Table 2 seem not strongly related to removal for bleeding/pain. A series of other variables such as intermenstrual pelvic pain and cervical dilation for insertion. Since the number of subjects in these categories was very small, these factors should not have practical meaning and are therefore not presented here. A proportional hazards model that initially included the factors in Table 2 and was then reduced in a backward elimination approach (but centers, additional children wanted, age and parity were included in each step) was created. Table 3 presents the results of the final model. Maternal age and parity did not have an effect on removal. Length of external OS to fundus was inversely associated with the risk of removal. Basically, a length less than 70 mm increased the risk of removal due to bleeding/pain in comparison with that over 70 mm. IUDs inserted by a non-obstetrician/ gynecologist were twice as likely to be removed. Lactation at insertion
Contraception
1993:48, July
15
Clinical Article TABLE 2.
Characteristics
of cases and controls prior to IUD insertion
Center location East & Southeast Asia West Asia & North Africa Sub-Sahara Africa Latin America Women’s age (years) <20 20-29 30-34 35+ Additional children wanted no yes Parity 0, 1 2, 3 4, 5 6+ History of induced abortion no yes History of spontaneous no
Control N = 2,023
(%)
F%)
22 39 4 35
25 26 6 43
1 .l 1.9 0.8 1.0
(0.7-l .7) (1.2-2.8) (0.3-2.1)
5 59 22 14
6 60 21 13
0.7 0.9 0.9 1.0
(0.3-l (0.5-l (0.5-l
.8) .6) .7)
49 51
48 52
1.0 1 .o
(0.7-l
.4)
27 43 15 15
25 51 16 8
1.0 0.8 1 .o 1.7
(0.5-l .3) (0.5-l .7) (0.9-3.1)
93 7
94 6
1.0 1 .l
(0.5-2.2)
86 14
82 18
1.0 0.8
(0.5-l
.3)
94 6
90 10
1.0 0.6
(0.2-l
.2)
66 19 15
57 25 18
1.0 0.7 0.7
(0.4-l (0.4-l
.O) .l)
66 34
69 31
1.0 1 .l
(0.8-l
.7)
52 8 29 11
51 10 23 16
1.0 0.7 1.3 0.7
(0.4-l (0.8-l (0.4-l
.5) .9) .3)
9 40 25 26
33 27 33
1.6 1.5 1.2 1.0
Crude odds ratio (95% confidence interval)
abortion
yes History of cesarean section no yes Uterine position anterior mid-position posterior Pelvic pain at insertion no yes Contraceptive method used in past month none IUD hormonal methods other Length of external OS to fundus (mm) 50-59 60-69 70-79 80+
16
Case N = 143
(0.8-3.2) (1 .O-2.4) (0.7-l .9)
Contraception 1993:48, July
IUD removal for bleeding/pain: TABLE 2.
Zhang
Continued
Cervical laceration no yes Person performing insertion obstetrician/gynecologist other’ Current breastfeeding status no yes Menstrual status at insertion still amenorrheic resumed menses
Case N = 143 (%)
Control N = 2,023 WJ)
91 9
95
5
1.0 2.1 (1.1-4.0)
65 35
77 23
1.0 1.8 (1.2-2.6)
73 27
64 36
1.0 0.7 (0.4-l .O)
6
13
0.4 (0.2-0.9) 1.0
(N z4135) Length of cycle before insertion** <2a days 28,29 days 30 days 31+ days Duration of flow before insertion** l-5 days 6+ days Amount of flow before insertion** usual more than usual Dysmenorrhea before insertion** no yes Intermenstrual bleeding before insertion*’ no yes
Crude odds ratio (95% confidence interval)
(N =‘:.747)
21 25 32 22
11 25 44 20
1.7 (0.9-3.0) 0.9 (0.5-l .5) 0.6 (0.4-l .l) 1.0
88 12
91 9
1.5 (0.8-2.6)
92 a
93
1.0
7
1.l
(0.5-2.2)
66 34
65 35
1.0 1.o
(0.7-l .5)
92 a
93
1.0 1.3 (0.6-2.5)
7
1.0
*including general physician, medical student, nurse, qualified midwife, student nurse/midwife, and paramedic, **only including those who had resumed menses at insertion.
decreased the risk of removal in the first year. The interaction between breastfeeding and menstrual status was examined; no significant interaction was identified.
Discussion IUD removal due to bleeding and/or pain is influenced by psychosocial and biomedical factors. The kind of counseling and support women receive, their attitudes toward using IUDs, and accessibility to postinsertion
Contraception
1993:48, July
17
Clinical Article TABLE 3.
Proportional
hazards regression analysis of predictors for IUD removal for bleeding/
pain
Variables
Additional no
Hazards ratio’
95% confidence
interval
children wanted 1 .o 0.99
yes Women’s age (years) <20 20-29 30-34 35-t
1 .Ol 1.11 1.05 1 .o
0.661.50 0.38-2.68 0.62-l .97 0.59-l .87
Parity 1.0 0.71 0.78 1.23
0, 1 2, 3 4, 5 6+
Length of external OS to fundus (mm)“* 50-59 1.80 1.77 60-69 1.22 70-79 1.0 80+ Person performing insertion obstetrician/gynecologist other Current breastfeeding no
0.45-l .12 0.41-l .49 0.58-2.59 0.89-3.64 1.08-2.89 0.75-2.01
1 .o 1.91
l.lS2.93
1.0 0.75
0.59-0.97
status
yes Menstrual status at insertion still amenorrheic resumed menses
0.56 1.0
0.27-l
.18
“adjusted for the centers and other variables in the table, *‘trend test p < 0.05.
care all affect rates of discontinuation due to bleeding and pain.’ Religion and physician’s attitudes toward acceptable bleeding levels may also influence the removal rates reflected by the variations between regions and centers. Women who want no more children might be more tolerant of heavy bleeding and less likely to discontinue than women who plan to have more children. However, this is not confirmed by the current study. Further, this study did not find any association between medical removal and marital status, women’s residency (rural or urban) and education (results not shown). Several biomedical factors have also been reported to be related to bleeding/pain removal in addition to IUD size and type
18
Contraception
1993:48,
July
IUD removal for bleeding/pain:
Zhang
of medication. For instance, younger and nulliparous women have a higher removal rate than older multiparous women5 However, since age and parity are often correlated with each other, one factor may be indicative of the other. The multivariate analysis in this study indicated that neither age nor parity is a strong predictor for IUD removal for bleeding after controlling for other factors. In the current study, uterine length is a strong predictor for IUD removal. Unfortunately, complete information on endometrial length was not available. A study by Hasson et a1.6 showed that the total cervical and endometrial length is a less refined predictor of IUD performance than endometrial cavity length alone. Therefore, to use uterine length to approximate endometrial length may have introduced misclassification because the cervix-to-corpus ratio varies. Such misclassification is likely to be non-differential, which would bias the results toward the null, i.e., the odds ratios were underestimated in this study. Nevertheless, Hasson et al.6 found that the relationship between endometrial length and total uterine length tends to be linear and may be described by the following linear regression equation: Endometrial cavity length (mm) = - 23.6 + 0.81 x (total uterine length [mm]). Based on this equation and the length of the copper T IUD of 36 mm, the ideal total uterine length should be 74 mm, where an IUD could completely reside in the endometrial cavity. This ure agrees with the present findings and generally endorses the empirical guideline of a minimal 65 mm of total uterine length for copper T IUD use.’ A smaller IUD may be recommended for women with a shorter uterine length. On the other hand, since the uterine length may not reflect endometrial length, a smaller IUD may not be necessary for some women. Further studies are needed to more precisely address this issue. The service provider’s skill and experience are also indicated as a predictor for IUD removal. This is consistent with a Belgian study, in which the rate of removal for bleeding/pain was lower when IUDs were inserted by more experienced practitioners.’ The present study also found that the number of IUD removals occur almost evenly within the first year (not shown). This observation is different from the belief that IUD removals are concentrated within the first three months after insertion. This notion probably arises from the rate of removals, where the denominator is accumulated women-months. The rate of removal seems to decrease with duration of IUD use because of the increasing denominator, but the number of removals (numerator) within the first year is actually constant. Therefore, in practice, post-insertion care should be available for copper T IUD users for at least one year. The present study also suggests that lactation at IUD insertion may decrease the risk of IUD removal. This finding was adjusted for menstrual status as well as other factors. It has been proposed that an increased
Contraception
1993:48, July
19
Clinical
Article secretion of p-endorphin resulting from suckling and a decreased level of estrogens in lactating women may decrease the uterine sensitivity, which in turn reduces the risk of removal for pain during the breastfeeding period.“,8 However, this finding needs cautious interpretation. It is obvious that women with amenorrhea are less likely to have IUD removal for bleeding. But when their menses resume, those who have the potential risk of bleeding may have similar likelihood of removal as those with menses at insertion. Therefore, amenorrhea at IUD insertion may just postpone the risk of removal. Similarly, the protective effect of lactation on uterine sensitivity to pain may just postpone the risk of removal, i.e., breastfeeding has less long-term beneficial effects on removal due to bleeding/pain. This is supported by a previous study which showed that the differences in removal rates between breastfeeding and non-breastfeeding women were beginning to converge by the end of 12 months after insertion.” On the other hand, since the amount of elevated menstrual bleeding after IUD insertion decreases after several cycles, amenorrhea at insertion may avoid the risk of increased bleeding in the first several months. If this is true, amenorrhea, and, perhaps, lactation at insertion, may be able to decrease the risk of removal due to bleeding and pain. Further studies are warranted. Family planning providers need to understand the short-term effects of lactation on IUD insertion, e.g., more likely to have a smooth, pain-free insertionH and less long-term effects. In summary, copper T IUDs, especially TCu-380A, are becoming the most widely used devices in many countries. The current study indicates that uterine length and health care provider’s skill are associated with IUD removal due to bleeding/pain. Amenorrhea and breastfeeding at insertion have short-term beneficial effects but perhaps less long-term effects.
Acknowledgement Investigators in several countries contributed data used in this analysis. The author gratefully acknowledges that without the efforts of these investigators, this work would not have been possible. The author would also like to give special appreciation to Dr. I-cheng Chi for his careful review, Ms. Amy Burdan for data set assistance, and Mr. Tom Grey for editorial assistance. Partial support for this study was provided by Family Health International (FHI) with funds from the US Agency for International Development (USAID), although the views expressed in this article do not necessarily reflect those of FHI or USAID.
References 1.
Treiman K, L&kin L. IUDs-A new look. Popul Rep, Series B, number B-5, 1988. 2. Chi I-c, Potts M, Wilkens LR, Champion CB. Performance of the copper T-
20
Contraception
1993:48,
July
IUD removal for bleeding/pain:
3.
4. 5.
6. 7. 8.
Contraception
Zhang
380A intrauterine device in breastfeeding women. Contraception 1989;39:603-18. Farr G, Rivera R. Interactions between intrauterine contraceptive device use and breastfeeding status and breastfeeding status at time of intrauterine device insertion: Analysis of TCu-380A acceptors in developing countries. Am J Obstet Gynecol 1992; 167: 144-51. Kalbfleisch JD, Prentice RL. The Statistical Analysis of Failure-Time Data. New York: Wiley, 1980. Aref I, El-Sheikha Z, Badraoui MHH, Hafez ESE. Factors affecting IUD-induced menstrual bleeding. In: Hafez ESE & van OS WAA, eds. IUD Pathology and Management. Boston, MA: G.K. Hall Medical Publishers, 1980:109-20. Hasson HM, Berger GS, Edelman DA. Factors affecting intrauterine contraceptive device performance. Am J Obstet Gynecol 1976;126:973-81. Thiery M, Van Kets H, Van Der Pas H. Immediate postplacental IUD insertion: the expulsion problem. Contraception 1985 ;3 1:33 l-49. Chi I-c, Wilkens LR, Champion CB, Machemer RE, Rivera R. Insertional pain and other IUD insertion-related rare events for breastfeeding and nonbreastfeeding women-a decade’s experience in developing countries. Adv Contraception 1989;5:101-19.
1993:48, July
21
A Multivariate
Analysis
Jun Zhang, MB Family Health International, 27709, USA
P.O. Box 13950, Research Triangle Park, NC
To examine the factors associated with copper T IUD removal due to bleeding/pain, a nested case-control analysis using data from an international multicenter randomized clinical trial of the copper T-380A IUD was performed. One-hundred-forty-three cases with removal due to bleeding/pain within one year postinsertion and 2,023 controls with the IUD in place at last follow-up visit are included. Proportional hazards regression analysis indicated that uterine length greater than 70 mm and better IUD provider’s skill were associated with a decreased risk of removal due to bleeding/ pain. Amenorrhea and breastfeeding at insertion have shortterm beneficial effects but less long-term effects. These findings may help family planning providers in counseling and practice.
Key words:Bleeding; intrauterine device; pain, removal
Introduction Copper T intrauterine devices (IUD), including TCu-200, TCu-220C and TCu-380A, are widely used throughout the world. They have a T-shaped plastic frame 36 mm long and 32 mm wide. The copper surface is 200, 220 and 380 mm<<, respectively. TCu-380A, one of the latest generation of IUDs, is one of the most effective methods of contraception ever developed, and will be the major IUD available in most countries.’ However, as with most other IUDs, menorrhagia and intermenstrual bleeding and/ or pain are the most common complications of copper T IUD use, which usually leads to medical removal. In developing countries where abnormal
Submitted 1993.
for publication
0 1993 Butterworth-Heinemann
February 4, 1993; Accepted
for publication
May 19,
Contraception 1993:48, July
13
Clinical Article bleeding is religiously unacceptable, this side effect becomes more salient. However, few studies have been done which exclusively examined factors associated with this complication. The present study examines a variety of women’s characteristics prior to insertion and the association of those factors with IUD removal for bleeding/pain.
Materials and Methods Data used in this study are from an international multicenter randomized clinical trial of the copper T-380A compared with other IUDs. Detailed information on the study design has been provided elsewhere.2,3 Briefly, thirteen collaborating centers in Latin America, Asia and Africa used identical case record forms and protocols to collect information on IUD insertion and use from 1985 to 1986. All participants were 18-40 years old, were sexually active, and had no contraindications for IUD use. IUDs were randomly assigned to participants according to sealed random-allocation envelopes, preprinted before study initiation, and opened at the time of IUD insertion. The devices were inserted at least 42 days after last pregnancy termination. Information on selected demographic characteristics, reproductive and contraceptive histories, and pre-existing medical conditions were obtained at the time of admission to the study. Followup examinations were scheduled at one, three, six and 12 months after IUD insertion. There were 3,479 subjects overall in the data set. The current analysis only includes women who received a copper T device: TCu-200 (27%), TCu-220C (6%), and TCu-380A (67%), excluding 598 subjects with other types of IUDs. We also excluded women with an accidental pregnancy (N = 24); IUD expulsion (N = 9.5); IUD removal due to medical reasons other than bleeding/pain (N = 53), planned pregnancy (N = 47), personal reasons (N = loo), or investigators’ choice (N = 8); and women lost to follow-up immediately after insertion (N = 43). Based on the protocol, the multicenter study followed the subjects for one year. Since about half of the women had their last visit somewhat later than exactly 365 days postinsertion, we truncated our data at 430 days postinsertion (excluding 214 women). Also eliminated were those who had missing information on duration of follow-up (N = 131). These exclusions left 2,166 women for analysis. The women were classified as cases with IUD removal due to bleeding/ pain (N = 143) or controls with an IUD in place at last visit (N = 2,023)(Table 1). A variety of traits in the women in association with removal for bleeding by calculating odds ratios and 95% confidence intervals were examined. To fit a multivariable model while accounting for time to removal, Cox proportional hazards regression was used. This regression model predicts the ratio of removal incidence rates, in which
14
Contraception
1993:48, July
IUD removal for bleeding/pain:
Zhang
TABLE1. Number of cases and controls by center location
TCu 200
East & Southeast Asia West Asia & North Africa Sub-Sahara Africa Latin America
TCu 220C
TCu 380A
case
control
case
control
case
control
24
136 4 17
60 181
14 2
255 32 144
17 387 2 31
249 66 545
the likelihood is evaluated conditionally on the set of subjects who remain under observation after each removal occurrence.4 The time interval for the removal events was the duration between IUD insertion and removal; for women without removal, the observation interval was the duration between insertion and the last follow-up visit. Hazards ratios and confidence intervals were computed from beta coefficients and standard errors.
Results Table 2 shows characteristics of cases and controls prior to IUD insertion. Compared with Latin American women, West Asian and North African women were more likely to have IUD removal due to bleeding/pain. The length of external OS to fundus was inversely associated with risk of removal. Women with cervical laceration had twice the risk of removal compared to those without. An IUD inserted by a person other than an obstetrician/gynecologist was 1.8 times more likely to be removed within a year. Women who were breastfeeding at insertion appeared to have decreased risk of removal. Women still in amenorrhea at insertion had a significantly lower risk of removal than those whose menses had resumed. Other factors listed in Table 2 seem not strongly related to removal for bleeding/pain. A series of other variables such as intermenstrual pelvic pain and cervical dilation for insertion. Since the number of subjects in these categories was very small, these factors should not have practical meaning and are therefore not presented here. A proportional hazards model that initially included the factors in Table 2 and was then reduced in a backward elimination approach (but centers, additional children wanted, age and parity were included in each step) was created. Table 3 presents the results of the final model. Maternal age and parity did not have an effect on removal. Length of external OS to fundus was inversely associated with the risk of removal. Basically, a length less than 70 mm increased the risk of removal due to bleeding/pain in comparison with that over 70 mm. IUDs inserted by a non-obstetrician/ gynecologist were twice as likely to be removed. Lactation at insertion
Contraception
1993:48, July
15
Clinical Article TABLE 2.
Characteristics
of cases and controls prior to IUD insertion
Center location East & Southeast Asia West Asia & North Africa Sub-Sahara Africa Latin America Women’s age (years) <20 20-29 30-34 35+ Additional children wanted no yes Parity 0, 1 2, 3 4, 5 6+ History of induced abortion no yes History of spontaneous no
Control N = 2,023
(%)
F%)
22 39 4 35
25 26 6 43
1 .l 1.9 0.8 1.0
(0.7-l .7) (1.2-2.8) (0.3-2.1)
5 59 22 14
6 60 21 13
0.7 0.9 0.9 1.0
(0.3-l (0.5-l (0.5-l
.8) .6) .7)
49 51
48 52
1.0 1 .o
(0.7-l
.4)
27 43 15 15
25 51 16 8
1.0 0.8 1 .o 1.7
(0.5-l .3) (0.5-l .7) (0.9-3.1)
93 7
94 6
1.0 1 .l
(0.5-2.2)
86 14
82 18
1.0 0.8
(0.5-l
.3)
94 6
90 10
1.0 0.6
(0.2-l
.2)
66 19 15
57 25 18
1.0 0.7 0.7
(0.4-l (0.4-l
.O) .l)
66 34
69 31
1.0 1 .l
(0.8-l
.7)
52 8 29 11
51 10 23 16
1.0 0.7 1.3 0.7
(0.4-l (0.8-l (0.4-l
.5) .9) .3)
9 40 25 26
33 27 33
1.6 1.5 1.2 1.0
Crude odds ratio (95% confidence interval)
abortion
yes History of cesarean section no yes Uterine position anterior mid-position posterior Pelvic pain at insertion no yes Contraceptive method used in past month none IUD hormonal methods other Length of external OS to fundus (mm) 50-59 60-69 70-79 80+
16
Case N = 143
(0.8-3.2) (1 .O-2.4) (0.7-l .9)
Contraception 1993:48, July
IUD removal for bleeding/pain: TABLE 2.
Zhang
Continued
Cervical laceration no yes Person performing insertion obstetrician/gynecologist other’ Current breastfeeding status no yes Menstrual status at insertion still amenorrheic resumed menses
Case N = 143 (%)
Control N = 2,023 WJ)
91 9
95
5
1.0 2.1 (1.1-4.0)
65 35
77 23
1.0 1.8 (1.2-2.6)
73 27
64 36
1.0 0.7 (0.4-l .O)
6
13
0.4 (0.2-0.9) 1.0
(N z4135) Length of cycle before insertion** <2a days 28,29 days 30 days 31+ days Duration of flow before insertion** l-5 days 6+ days Amount of flow before insertion** usual more than usual Dysmenorrhea before insertion** no yes Intermenstrual bleeding before insertion*’ no yes
Crude odds ratio (95% confidence interval)
(N =‘:.747)
21 25 32 22
11 25 44 20
1.7 (0.9-3.0) 0.9 (0.5-l .5) 0.6 (0.4-l .l) 1.0
88 12
91 9
1.5 (0.8-2.6)
92 a
93
1.0
7
1.l
(0.5-2.2)
66 34
65 35
1.0 1.o
(0.7-l .5)
92 a
93
1.0 1.3 (0.6-2.5)
7
1.0
*including general physician, medical student, nurse, qualified midwife, student nurse/midwife, and paramedic, **only including those who had resumed menses at insertion.
decreased the risk of removal in the first year. The interaction between breastfeeding and menstrual status was examined; no significant interaction was identified.
Discussion IUD removal due to bleeding and/or pain is influenced by psychosocial and biomedical factors. The kind of counseling and support women receive, their attitudes toward using IUDs, and accessibility to postinsertion
Contraception
1993:48, July
17
Clinical Article TABLE 3.
Proportional
hazards regression analysis of predictors for IUD removal for bleeding/
pain
Variables
Additional no
Hazards ratio’
95% confidence
interval
children wanted 1 .o 0.99
yes Women’s age (years) <20 20-29 30-34 35-t
1 .Ol 1.11 1.05 1 .o
0.661.50 0.38-2.68 0.62-l .97 0.59-l .87
Parity 1.0 0.71 0.78 1.23
0, 1 2, 3 4, 5 6+
Length of external OS to fundus (mm)“* 50-59 1.80 1.77 60-69 1.22 70-79 1.0 80+ Person performing insertion obstetrician/gynecologist other Current breastfeeding no
0.45-l .12 0.41-l .49 0.58-2.59 0.89-3.64 1.08-2.89 0.75-2.01
1 .o 1.91
l.lS2.93
1.0 0.75
0.59-0.97
status
yes Menstrual status at insertion still amenorrheic resumed menses
0.56 1.0
0.27-l
.18
“adjusted for the centers and other variables in the table, *‘trend test p < 0.05.
care all affect rates of discontinuation due to bleeding and pain.’ Religion and physician’s attitudes toward acceptable bleeding levels may also influence the removal rates reflected by the variations between regions and centers. Women who want no more children might be more tolerant of heavy bleeding and less likely to discontinue than women who plan to have more children. However, this is not confirmed by the current study. Further, this study did not find any association between medical removal and marital status, women’s residency (rural or urban) and education (results not shown). Several biomedical factors have also been reported to be related to bleeding/pain removal in addition to IUD size and type
18
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of medication. For instance, younger and nulliparous women have a higher removal rate than older multiparous women5 However, since age and parity are often correlated with each other, one factor may be indicative of the other. The multivariate analysis in this study indicated that neither age nor parity is a strong predictor for IUD removal for bleeding after controlling for other factors. In the current study, uterine length is a strong predictor for IUD removal. Unfortunately, complete information on endometrial length was not available. A study by Hasson et a1.6 showed that the total cervical and endometrial length is a less refined predictor of IUD performance than endometrial cavity length alone. Therefore, to use uterine length to approximate endometrial length may have introduced misclassification because the cervix-to-corpus ratio varies. Such misclassification is likely to be non-differential, which would bias the results toward the null, i.e., the odds ratios were underestimated in this study. Nevertheless, Hasson et al.6 found that the relationship between endometrial length and total uterine length tends to be linear and may be described by the following linear regression equation: Endometrial cavity length (mm) = - 23.6 + 0.81 x (total uterine length [mm]). Based on this equation and the length of the copper T IUD of 36 mm, the ideal total uterine length should be 74 mm, where an IUD could completely reside in the endometrial cavity. This ure agrees with the present findings and generally endorses the empirical guideline of a minimal 65 mm of total uterine length for copper T IUD use.’ A smaller IUD may be recommended for women with a shorter uterine length. On the other hand, since the uterine length may not reflect endometrial length, a smaller IUD may not be necessary for some women. Further studies are needed to more precisely address this issue. The service provider’s skill and experience are also indicated as a predictor for IUD removal. This is consistent with a Belgian study, in which the rate of removal for bleeding/pain was lower when IUDs were inserted by more experienced practitioners.’ The present study also found that the number of IUD removals occur almost evenly within the first year (not shown). This observation is different from the belief that IUD removals are concentrated within the first three months after insertion. This notion probably arises from the rate of removals, where the denominator is accumulated women-months. The rate of removal seems to decrease with duration of IUD use because of the increasing denominator, but the number of removals (numerator) within the first year is actually constant. Therefore, in practice, post-insertion care should be available for copper T IUD users for at least one year. The present study also suggests that lactation at IUD insertion may decrease the risk of IUD removal. This finding was adjusted for menstrual status as well as other factors. It has been proposed that an increased
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Article secretion of p-endorphin resulting from suckling and a decreased level of estrogens in lactating women may decrease the uterine sensitivity, which in turn reduces the risk of removal for pain during the breastfeeding period.“,8 However, this finding needs cautious interpretation. It is obvious that women with amenorrhea are less likely to have IUD removal for bleeding. But when their menses resume, those who have the potential risk of bleeding may have similar likelihood of removal as those with menses at insertion. Therefore, amenorrhea at IUD insertion may just postpone the risk of removal. Similarly, the protective effect of lactation on uterine sensitivity to pain may just postpone the risk of removal, i.e., breastfeeding has less long-term beneficial effects on removal due to bleeding/pain. This is supported by a previous study which showed that the differences in removal rates between breastfeeding and non-breastfeeding women were beginning to converge by the end of 12 months after insertion.” On the other hand, since the amount of elevated menstrual bleeding after IUD insertion decreases after several cycles, amenorrhea at insertion may avoid the risk of increased bleeding in the first several months. If this is true, amenorrhea, and, perhaps, lactation at insertion, may be able to decrease the risk of removal due to bleeding and pain. Further studies are warranted. Family planning providers need to understand the short-term effects of lactation on IUD insertion, e.g., more likely to have a smooth, pain-free insertionH and less long-term effects. In summary, copper T IUDs, especially TCu-380A, are becoming the most widely used devices in many countries. The current study indicates that uterine length and health care provider’s skill are associated with IUD removal due to bleeding/pain. Amenorrhea and breastfeeding at insertion have short-term beneficial effects but perhaps less long-term effects.
Acknowledgement Investigators in several countries contributed data used in this analysis. The author gratefully acknowledges that without the efforts of these investigators, this work would not have been possible. The author would also like to give special appreciation to Dr. I-cheng Chi for his careful review, Ms. Amy Burdan for data set assistance, and Mr. Tom Grey for editorial assistance. Partial support for this study was provided by Family Health International (FHI) with funds from the US Agency for International Development (USAID), although the views expressed in this article do not necessarily reflect those of FHI or USAID.
References 1.
Treiman K, L&kin L. IUDs-A new look. Popul Rep, Series B, number B-5, 1988. 2. Chi I-c, Potts M, Wilkens LR, Champion CB. Performance of the copper T-
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6. 7. 8.
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380A intrauterine device in breastfeeding women. Contraception 1989;39:603-18. Farr G, Rivera R. Interactions between intrauterine contraceptive device use and breastfeeding status and breastfeeding status at time of intrauterine device insertion: Analysis of TCu-380A acceptors in developing countries. Am J Obstet Gynecol 1992; 167: 144-51. Kalbfleisch JD, Prentice RL. The Statistical Analysis of Failure-Time Data. New York: Wiley, 1980. Aref I, El-Sheikha Z, Badraoui MHH, Hafez ESE. Factors affecting IUD-induced menstrual bleeding. In: Hafez ESE & van OS WAA, eds. IUD Pathology and Management. Boston, MA: G.K. Hall Medical Publishers, 1980:109-20. Hasson HM, Berger GS, Edelman DA. Factors affecting intrauterine contraceptive device performance. Am J Obstet Gynecol 1976;126:973-81. Thiery M, Van Kets H, Van Der Pas H. Immediate postplacental IUD insertion: the expulsion problem. Contraception 1985 ;3 1:33 l-49. Chi I-c, Wilkens LR, Champion CB, Machemer RE, Rivera R. Insertional pain and other IUD insertion-related rare events for breastfeeding and nonbreastfeeding women-a decade’s experience in developing countries. Adv Contraception 1989;5:101-19.
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