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Low-Dose Oral Contraceptive Use and the Risk of Myocardial Infarction
Lynn Rosenberg, ScD;
Julie R. Palmer, ScD;
R. Sowmya Rao, MS;
Samuel Shapiro, MB, FRCP(Edin)
Arch Intern Med. 2001;161:1065-1070.
ABSTRACT
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Background Studies of oral contraceptives (OCs) containing 50 µg or more
of estrogen suggest an increased risk of myocardial infarction (MI) among
current users, particularly if they smoke heavily.
Objective To assess whether use of the newer lower-dose OCs increases the risk
of MI.
Methods A case-control study was conducted from January 1985 through March 1999
in 75 hospitals in the greater-Boston and greater-Philadelphia areas. Data
on OC use and MI risk factors were obtained by interview from 627 women with
a nonfatal first MI (cases) and 2947 female hospital controls younger than
45 years.
Results The overall odds ratio (OR) for current OC use relative to never used
was 1.3 (95% confidence interval [CI], 0.8-2. 2). The OR was elevated, 2.5
(95% CI, 0.9-7.5), among heavy smokers ( 25 cigarettes per day) but close
to 1.0 among lighter smokers (OR = 0.8) and nonsmokers (OR = 1.3). For current
OC use together with heavy smoking relative to nonuse and nonsmoking, the
OR was 32 (95 % CI, 12-81), considerably greater than that for heavy smoking
alone, 12 (95% CI, 8.6-16). The ORs did not vary according to the type of
formulation or the dose of estrogen; there were too few users to assess the
new 20-µg preparations. Past OC use was unrelated to risk.
Conclusion Current use of low-dose OCs in the United States is unrelated to an
increased risk of MI among nonsmokers and light smokers, but users who smoke
heavily may be at greatly increased risk.
INTRODUCTION
SOON AFTER oral contraceptives (OCs) were first marketed in the 1960s,
case reports linked their use to the occurrence of myocardial infarction (MI).1 By the late 1970s epidemiological studies had established
that the risk of MI was increased among women using OCs, particularly if they
smoked heavily.2-3 The preparations
assessed in these studies contained 50 µg or more of estrogen combined
with a fixed dose of progestin. The relative risk estimates ranged from about
2 to 5 for the overall comparison of current OC users to nonusers, and the
increase was much greater, about 20- to 30-fold, for OC users who smoked heavily
relative to women who did not use OCs and were nonsmokers.4-6
Over the years, OC manufacturers have progressively lowered the doses,
developed new progestins, and devised new types of formulations, such as triphasic
preparations that release different doses of estrogen and progestin over the
course of the menstrual cycle.7-10
To assess whether the newer preparations are safer than earlier formulations,
we carried out a large case-control study of OC use and the occurrence of
first MI in young women.
PARTICIPANTS AND METHODS
From January 1985 through December 1998 our central office telephoned
collaborating hospitals every week to identify women younger than 45 years
who had been admitted with a definite or possible first MI; 50 hospitals in
Massachusetts and Rhode Island (the greater Boston area) and 25 in Pennsylvania,
New Jersey, and Delaware (the greater Philadelphia area) participated. The
physicians of potential cases were telephoned for details of the diagnosis
and for permission to contact the patients for an interview. Potential control
subjects, female patients younger than 45 years who had never had an MI, were
drawn from the medical and surgical wards of the collaborating hospitals;
they were identified from admission lists or from patient files on the wards.
Interviews were conducted between January 1985 and March 1999. Among the potential
cases, the participation rate was 79.4% (5.2% physician refusals, 8.5% patient
refusals, and 6.9% died, too ill for interview, or could not be located).
Among the potential controls, the participation rate was 83.9% (2.0% physician
refusals, 10.7% patient refusals, and 3.4% died, too ill for interview, or
could not be located).
Our nurse-interviewers interviewed patients in person in the hospital
or by telephone at home after discharge. They administered standard questionnaires
to obtain information on demographic factors, OC use, and MI risk factors
that included cigarette smoking, hypertension, diabetes mellitus, elevated
serum cholesterol level, height and weight, and family history of MI. We found
previously that information obtained in our case-control studies by in-person
and telephone interviews was relatively similar, as were the results.11-12 In this study patients interviewed
in the hospital were shown pictures of OC pills and packets to aid recall;
patients interviewed at home by telephone were not. For 104 women who reported
current OC use (ie, in the month before admission), who were willing for us
to contact the prescribing physician, and whose physician responded, we compared
self-report of current OC use and the product used with the report of the
physician. In all but one instance the physician's report indicated that the
patient was a current OC user. There was concordance on the product name for
84% of the comparisons; concordance was 86% for hospital interviews (52 women)
and 81% for the telephone interviews (42 women).
CASES
We obtained the discharge summaries of 90% of the potential cases, of
which 98% met the criteria for inclusion after review by the study's physician-investigator
(S.S.): pathologic Q waves with evolution, or any 2 of the following: other
electrocardiographic changes with evolution, typical history of chest pain,
elevated cardiac enzyme levels, or angiographic evidence of coronary occlusion.
After exclusion of 25 cases that did not meet the enrollment criteria, there
were 627 cases; 88% were white.
CONTROLS
From the pool of 3668 potential controls, we selected 2947 patients
whose hospital admission was for a nonmalignant condition that we judged was
unrelated to OC use. Thus, for example, patients admitted for cardiovascular
disease or deep vein thrombosis were ineligible. The diagnoses were documented
by review of discharge summaries. The selected controls were admitted for
trauma or orthopedic disorders (1100 patients), acute infection (913 patients),
or a wide range of other conditions (934 patients), most of which affected
fewer than 50 controls; 90% were white. The rates of current OC use (use within
the month before admission) in the 3 diagnostic categories among the controls,
adjusted to the overall age-distribution of the controls, were 8.3%, 7.1%,
and 9.0%, respectively; the rates of past OC use (use that ended at least
a month before admission) were 63.6%, 66.6%, and 65.3%, respectively.
STATISTICAL ANALYSIS
The relative risk for MI among OC users was estimated by the odds ratio
(OR) obtained by multiple logistic regression.13
Terms were included for age, region, interview year, type of interview (telephone
or hospital), cigarette smoking, drug-treated hypertension, drug-treated diabetes
mellitus, history of an elevated serum cholesterol level, body mass index
(measured in kilograms per meters, squared), menopausal status, and history
of MI before the age of 60 years in a parent or sibling. Reduced models with
terms for only age, region, and interview year were used when there were fewer
than 5 current OC users among either the cases or controls.
RESULTS
Table 1 gives the distributions
of age, region of the hospital, interview year, and potential MI risk factors
among the cases and controls. Cigarette smoking, hypertension, diabetes mellitus,
elevated serum cholesterol level, high body mass index, and positive family
history of MI occurred more commonly among the cases.
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Table 1. Selected Factors Among 627 Cases of First Myocardial Infarction
(MI) and 2947 Control Subjects*
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As given in Table 2, the
overall OR for current OC use relative to never used (hereafter, never-use)
was 1.3 (95% confidence interval [CI], 0.8-2.2). The ORs for current OC use
among women younger than 30 years and women aged between 30 and 34 years were
3.0 and 2.1, respectively. However, in those age groups and in all other age
categories, the ORs for current OC use were compatible with 1.0. Eighty percent
of current users had used OCs for 10 years or longer: the OR was 1.9 (95%
CI, 0.7-5.0) for less than 10 years of use and 1.3 (95% CI 0.7-2.3) for 10
or longer.
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Table 2. Current and Past Oral Contraceptive (OC) Use Overall and According
to Age Among 627 Cases of First Myocardial Infarction and 2947 Controls Subjects*
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For past OC use (Table 2),
the overall and age-specific ORs were close to 1.0 and not statistically significant.
The OR did not vary according to the duration of use: for less than 5, 5 to
9, 10 to 14, and 15 years or longer of OC use, the ORs were 1.0, 0.9, 1.0,
and 1.0, respectively.
Hypertension is a contraindication to OC use. Among 140 cases and 238
controls with drug-treated hypertension, only 1 case (0.7%) and 5 controls
(2.1%) were current OC users. The numbers were too small for informative estimation
of the OR.
Table 3 gives current OC
use according to levels of cigarette smoking. The OR for current OC use among
heavy smokers (25 cigarettes per day) was elevated, 2.5, but not statistically
significant (95% CI, 0.9-7.5). Among nonsmokers and smokers of 1 to 24 cigarettes
per day, the ORs were close to 1.0 and not statistically significant.
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Table 3. Current and Past Oral Contraceptive (OC) Use According to
Cigarette Smoking Among 627 Cases of First Myocardial Infarction and 2947
Control Subjects*
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Table 4 gives data on the
joint effect of current OC use and heavy cigarette smoking relative to nonuse
of OCs (the combined category of never and past use) and nonsmoking. Past
OC users were combined with never-users because past use was unrelated to
the risk of MI. The OR for current OC use among nonsmokers, 1.6, was compatible
with 1.0. The ORs for current OC use together with smoking 1 to 24 cigarettes
per day, 3.4 (95% CI, 1.4-8.0), did not differ materially from that for smoking
1 to 24 cigarettes per day in the absence of OC use, 4.7 (95%CI, 3.6-6.1).
By contrast, the estimate for current OC use and heavy smoking together, 32
(95% CI, 12-81), was considerably larger than the estimate, 12 (95% CI, 8.6-16),
for heavy smoking in the absence of OC use; the difference between the 2 estimates
was of borderline statistical significance (z = 1.94, P = .05).
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Table 4. Joint Effects of Current Oral Contraceptive (OC) Use and Cigarette
Smoking Among 627 Cases of First Myocardial Infarction and 2947 Control Subjects*
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Table 5 gives data on the
type of OC formulation used, the dose of estrogen, and the type of progestogen
in formulations containing less than 50 µg of estrogen. The most commonly
used formulations were fixed-dose combination products (an estrogen with a
progestogen); the most common estrogen dose was 30 or 35 µg; and the
most commonly used progestogen was norethindrone. For the overall comparison
of current OC use to never-use, all ORs for the various categories considered
were compatible with 1.0 except that for OCs containing norethindrone, for
which the OR was 2.5 (95% CI, 1.1-5.8). For the joint effect of current OC
use with cigarette smoking relative to nonuse and nonsmoking, the ORs ranged
from 17 to 110, all were statistically significant, and all were compatible
with a uniform value. The numbers of current OC users were small in some categories,
particularly for the type of progestogen in the OC and for the joint effect
of OC use with heavy smoking, and 95% CIs were wide. There were too few users
of the lowest-dose preparations, 20 µg (1 case and 12 controls) for
separate analysis.
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Table 5. Current Oral Contraceptive (OC) Use Overall and by Smoking
of 25 Cigarettes or More per Day According to OC Formulation Among 627 Cases
of First Myocardial Infarction and 2947 Control Subjects*
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The ORs for current OC use relative to never-use were consistent across
interview year and study center. The results were similar regardless of the
method of interview: for current OC use relative to never-use, the OR was
1.4 (95% CI, 0.5-3.6) based on hospital interviews and 1.1 (95% CI, 0.6-2.1)
based on telephone interviews; the corresponding estimates for current OC
use and heavy smoking together relative to nonuse and nonsmoking were 31 (95%
CI, 8.0-117) and 21 (95% CI 5.9-77), respectively.
COMMENT
This study suggests that current OC use has little or no influence on
the risk of a nonfatal first MI among women who do not smoke or who smoke
fewer than 25 cigarettes a day. However, current use seems to increase the
risk among smokers of 25 or more cigarettes per day, and we estimate that
current OC use together with heavy smoking increases the risk of MI to a level
about 30 times that of nonsmokers who do not use OCs. As in previous studies,2-3,14 past OC use was not
associated with an increase in the risk of MI and there was little, if any,
influence of the duration of OC use. There was little variation in risk according
to the type of formulation (fixed-dose combined or triphasic) or the estrogen
dose (<35 µg, 35-49 µg, or 50 µg). However, only
one case used a preparation containing 20 µg of estrogen and we were
unable to assess the effect of these low-dose preparations.
The results of a recent case-control study of British and European women
suggested that use of OCs containing the so-called third-generation progestogens,
notably gestodene and desogestrel, was not associated with an overall increase
in the risk of MI, whereas second-generation progestogens were.15
However, another British study16 found no overall
increase for either second- or third-generation pills. In the present study
third-generation pills were not commonly used. The overall effect of OCs,
and of OC use together with heavy smoking, did not vary by the type of second-generation
progestogen used. However, the numbers of current OC users of any particular
type tended to be small and CIs were wide.
Four recent reports have provided information on OCs containing less
than 50 µg of estrogen. Sidney et al17
assessed 271 cases and 993 controls from 2 population-based case-control studies
of US women. The overall relative risk estimate for current OC use was 0.94.
There was no interaction with cigarette smoking. However, there were only
12 current OC users among the cases, limiting the power of the study to assess
this possibility, and heavy smoking was not considered. Lewis et al15 conducted a hospital-based case-control study of
MI among British and European women. Based on 182 cases and 635 controls,
the OR for current OC use was 0.82 for third-generation OCs and 2.35 for second-generation
OCs. The joint effect of OCs with smoking was not estimated, but the OR for
current smoking among current OC users was 3.9 among users of third-generation
OC products and 9.5 among users of second-generation OC products. The WHO
Collaborative Study of Cardiovascular Disease and Steroid Contraception18 studied 188 cases and 480 controls from European
countries in a hospital-based case-control study. The overall relative risk
estimate for current use of OCs was 5.64 and it did not vary by estrogen dose
(<50 µg or 50 µg). Current OC use together with smoking
10 or more cigarettes daily increased the risk by an estimated 22-fold. Dunn
et al16 studied 448 cases and 1728 controls
in a general practice–based study of British women. The OR was 1.40
for current OC use. The ORs were compatible with 1.0 among smokers of 20 or
fewer cigarettes per day and more than 20 cigarettes per day. Some of the
variation in the relative risks for current OC use among the studies may well
reflect variations in the coexistence of other risk factors among OC users.14
The results of the present study concerning OCs with less than 50 µg
of estrogen are similar to those of earlier studies of higher-dose preparations,4-6 and to the recent results
of the WHO Collaborative Study of Cardiovascular Disease and Steroid Contraception,18 in suggesting that OCs and heavy smoking together
greatly increase the risk. In particular, we conducted an earlier study of
MI (from July 1976 through June 1979) that used the same methods as the present
study.4 Almost all of the OCs used contained
50 µg or more of estrogen. We estimated that the joint effect of current
use of OCs with smoking 25 or more cigarettes per day was to increase the
risk of MI 39-fold.
Differential reporting, such as more complete reporting of OC use by
cases than controls, is unlikely to explain the current findings. There is
strong evidence that women report recent OC use reasonably accurately19-22 and
we found this to be so when we compared self-report with physician report
for a sample of current OC users. In addition, if reporting by the cases had
been more complete than that of the controls, one might expect to have seen
increased ORs for current OC users who were nonsmokers or light smokers, or
for past OC use; no such increases were observed. Major distortion from confounding
is unlikely because the important risk factors for MI were considered. With
regard to potential selection bias, the enrollment rates of cases and controls
were satisfactory. The controls were selected to have diagnoses unrelated
to OC use; that the selection was successful is supported by the observation
of similar rates of current and past OC use across the major diagnostic categories.
While there is little information available on the relation of low-dose OC
use to the risk of MI, there is a large body of evidence on the older higher-dose
pills. Results from our previous hospital-based case-control study of current
OC use and first nonfatal MI, which used methods similar to those of the present
study, were similar to those obtained from population-based case-control studies
and follow-up studies.2-3 Based
on all of these considerations, selection bias seems to be an unlikely explanation
for the present findings.
The newer lower-dose OCs have less adverse effects on serum lipid levels
than earlier preparations.7-8,23
However, the observation in epidemiologic studies that the effect of OCs is
acute,1-5
coupled with clinical evidence of clots in OC users who suffered MIs,24 suggests that a thrombotic rather than an atherogenic
mechanism is involved in OC-related MIs. The newer OCs generally have smaller
effects than earlier pills on clotting factors. The overall effect still tends
to be in the direction of increased clotting,7-8,25
yet within normal ranges. How these changes relate to clinical events is unknown.
The present evidence suggests that OC preparations that contain more than
20 µg of estrogen are safe for nonsmokers and smokers of fewer than
25 cigarettes per day. Whatever the mechanism, for the small subset of OC
users who smoke heavily there is evidence to suggest a greatly increased risk
of MI, just as was the case for older higher-dose preparations. The current
warning on OC package inserts, that users of OCs should not smoke, is still
appropriate.
AUTHOR INFORMATION
Accepted for publication November 7, 2000.
This work was supported by grants HL30225, HL42483, and HL32174 from
the National Heart, Lung, and Blood Institute, Bethesda, Md.
We are grateful to J. A. Grisso, MD, for her assistance with the greater
Philadelphia hospital network; Jacquelyn Smith, MPH, for coordinating the
study; the interviewers; and Len Gaetano, MS, for computer services. We are
grateful to the following hospitals and their physicians for allowing their
patients to participate: Massachusetts: Addison Gilbert
Hospital, Atlantic Care Medical Center, Baystate Medical Center, Beth Israel
Deaconess Medical Center, Boston Medical Center, Boston Regional Medical Center,
Brigham & Women's Hospital, Brockton Hospital, Cambridge Hospital, Cape
Cod Hospital, Charlton Memorial Hospital, Deaconess-Glover Hospital, Deaconess-Waltham
Hospital, Emerson Hospital, Faulkner Hospital, Good Samaritan Hospital, Hale
Hospital, Harrington Memorial Hospital, Health Alliance–Burbank Hospital,
Henry Heywood Hospital, Holy Family Hospital and Medical Center, Jordan Hospital,
Lahey Hitchcock Clinic, Lawrence General Hospital, Lawrence Memorial Hospital,
Leominister Hospital, Lowell General Hospital, Malden Hospital, Marlborough
Hospital, Massachusetts General Hospital, Medical Center at Symmes, Medical
Center of Central Mass, Melrose Wakefield Hospital, Metro West Medical Center,
Morton Hospital, Mt Auburn Hospital, New England Medical Center, Newton Wellesley
Hospital, North Shore Medical Center at Salem Hospital, Norwood Hospital,
Quincy City Hospital, St Vincent's Hospital, Saints Memorial Medical Center,
Somerville Hospital, South Shore Hospital, St Elizabeth's Hospital, Sturdy
Memorial Hospital, University of Massachusetts Medical Center, Winchester
Hospital; Rhode Island: Kent County Hospital, Memorial
Hospital, Rhode Island Hospital, St Joseph Hospital/Fatima; Pennsylvania: Abington Memorial Hospital, Albert Einstein Healthcare
Network, Brandywine Hospital & Trauma Center, Chestnut Hill Hospital,
Christiana Care Health Services, City Ave Hospital/Tenet, Doylestown Hospital,
Frankford Hospital, Grand View Hospital, Hahnemann University Hospital, Holy
Redeemer Hospital and Medical Center, Hospital of the Medical College of Pennsylvania,
Jeannes Hospital, Lawndale Community Hospital, Mercy Catholic Medical Center,
Pennsylvania Hospital, Phoenixville Hospital, Pottstown Memorial Medical Center,
Presbyterian Medical Center of Pennsylvania, Quakertown Community Hospital,
Southern Chester County Medical Center, St Agnes Medical Center, Taylor Hospital,
Temple University Hospital, The Chester County Hospital, Thomas Jefferson
University Hospital; New Jersey: Kennedy Memorial
Hospitals, Underwood Memorial Hospital, West Jersey Hospital, Zurbrugg Hospital;
and Delaware: Delaware County Memorial Hospital,
St Francis Hospital.
Corresponding author: Lynn Rosenberg, ScD, Slone Epidemiology Unit,
Boston University School of Medicine, 1371 Beacon St, Brookline, MA 02446
(e-mail: lrosenberg{at}slone.bu.edu).
From the Slone Epidemiology Unit, Boston University School of Public
Health, Brookline, Mass (Drs Rosenberg, Palmer, and Shapiro and Ms Rao); and
Columbia University School of Public Health, New York, NY (Dr Shapiro). The
Slone Epidemiology Unit has received support for other studies from the following
companies: Astra USA Inc, Bayer Corp, Bristol-Myers Squibb Co, Ciba-Geigy
Corp, Glaxo Wellcome Inc, Hoechst AG, Hoffmann-La Roche Inc, Johnson &
Johnson, Knoll Pharmaceutical Co, McNeil Pharmaceutical, Merck & Co Inc,
Marrion Merrell Dow Inc, Novartis Pharmaceuticals Corp, Ortho Biotech Inc,
Pfizer Inc, Procter & Gamble Pharamceuticals Inc, SmithKline Beecham Pharamceuticals,
Sterling Winthrop, Upjohn Co, Wallace Laboratories, and Warner-Lambert Co.
REFERENCES
| |
1. Ad Hoc Committee for the Evaluation of a Possible Etiologic Relation
With Thromboembolic Conditions. The Final Enovid Report. J New Drugs. 1963;3:201-211.
2. Stadel BV. Oral contraceptives and cardiovascular disease (second of 2 parts). N Engl J Med. 1981;305:612-617; 672-677.
ISI
| PUBMED
3. Vessey MP. Female hormones and vascular disease: epidemiologic overview. Br J Fam Plann. 1980;6(suppl):1-12.
4. Shapiro S, Slone D, Rosenberg L, Kaufman DW, Stolley PD, Miettinen OS. Oral-contraceptive use in relation to myocardial infarction. Lancet. 1979;1:743-747.
ISI
| PUBMED
5. Mann JI, Vessey MP, Thorogood M, Doll SR. Myocardial infarction in young women with special reference to oral
contraceptive practice. BMJ. 1975;2:241-245.
6. Croft P, Hannaford PC. Risk factors for acute myocardial infarction in women: evidence from
The Royal College of General Practitioners' Oral Contraception Study. BMJ. 1989;298:165-168.
7. Robinson GE. Low-dose combined oral contraceptives. Br J Obstet Gynaecol. 1994;101:1036-1041.
ISI
| PUBMED
8. Newton JR. Classification and comparison of oral contraceptives containing new
generation progestogens. Hum Reprod Update. 1995;1:231-263.
FREE FULL TEXT
9. Gerstman BB, Gross TP, Kennedy DL, Bennett RC, Tomita DK, Stadel BV. Trends in content and use of oral contraceptives in the United States,
1964-88. Am J Public Health. 1991;81:90-96.
FREE FULL TEXT
10. Fotherby K, Caldwell AD. New progestogens in oral contraception. Contraception. 1994;49:1-32.
FULL TEXT
|
ISI
| PUBMED
11. Rosenberg L, Palmer JR, Lesko SM, Shapiro S. Oral contraceptive use and the risk of myocardial infarction. Am J Epidemiol. 1990;131:1009-1016.
FREE FULL TEXT
12. Rosenberg L, Schwingl PJ, Kaufman DW, Helmrich SP, Palmer JR, Shapiro S. The risk of myocardial infarction 10 or more years after vasectomy
in men under 55 years of age. Am J Epidemiol. 1986;123:1049-1056.
FREE FULL TEXT
13. Schlesselman JJ. Case-control Studies: Design, Conduct, Analysis. New York, NY: Oxford University Press; 1982.
14. WHO Scientific Group on Cardiovascular Disease and Steroid Hormone
Contraception. Cardiovascular Disease and Steroid Hormone Contraception:
Report of a WHO Scientific Group. Geneva, Switzerland: WHO [World Health Organization]; 1997. WHO Technical
Report Series 877.
15. Lewis MA, Heinemann LA, Spitzer WO, MacRae KD, Bruppacher R for the Transnational Study of Oral Contraceptives and Health of Young
Women. The use of oral contraceptives and the occurrence of myocardial infarction
in young women: results from the Transnational Study of Oral Contraceptives
and the Health of Young Women. Contraception. 1997;56:129-140.
FULL TEXT
|
ISI
| PUBMED
16. Dunn N, Thorogood M, Faragher B, et al. Oral contraceptives and myocardial infarction: results of the MICA
case-control study. BMJ. 1999;318:1579-1583.
FREE FULL TEXT
17. Sidney S, Siscovick DS, Petitti DB, et al. Myocardial infarction and use of low-dose oral contraceptives: a pooled
analyses of 2 US studies. Circulation. 1998;98:1058-1063.
FREE FULL TEXT
18. WHO Collaborative Study of Cardiovascular Disease and Steroid Contraception. Acute myocardial infarction and combined oral contraceptives: results
of an international multicenter case-control study. Lancet. 1997;349:1202-1209.
FULL TEXT
|
ISI
| PUBMED
19. Stolley PD, Tonascia S, Sartwell PE, et al. Agreement rates between oral contraceptive users and prescribers in
relation to drug use histories. Am J Epidemiol. 1978;107:226-235.
FREE FULL TEXT
20. Rosenberg MJ, Layde PM, Ory HW, Strauss LT, Rooks JB, Rubin GL. Agreement between women's histories of oral contraceptive use and physicians
records. Int J Epidemiol. 1983;12:84-87.
FREE FULL TEXT
21. Glass R, Johnson B, Vessey M. Accuracy of recall of histories of oral contraceptive use. Br J Prev Soc Med. 1974;28:273-275.
ISI
| PUBMED
22. Norell SE, Boethius G, Persson I. Oral contraceptive use: interview data versus pharmacy records. Int J Epidemiol. 1998;27:1033-1037.
FREE FULL TEXT
23. Godsland IF, Crook D, Simpson R, et al. The effect of different formulations of oral contraceptive agents on
lipid and carbohydrate metabolism. N Engl J Med. 1990;323:1375-1381.
ABSTRACT
24. Mann JI, Inman WH. Oral contraceptives and death from myocardial infarction. BMJ. 1975;2:245-248.
25. Speroff L, DeCherney A and the Advisory Board for the New Progestins. Evaluation of a new generation of oral contraceptives. Obstet Gynecol. 1993;81:1034-1047.
FREE FULL TEXT
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