PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
 
J Womens Health (Larchmt). Dec 2010; 19(12): 2203–2210.
PMCID: PMC2990281
Studying the Use of Oral Contraception: A Review of Measurement Approaches
Kelli Stidham Hall, M.S.N., Ph.D.,corresponding author1 Katharine O'Connell White, M.D., M.P.H.,2 Nancy Reame, M.S.N., Ph.D.,1 and Carolyn Westhoff, M.D., M.Sc.3
1Columbia University School of Nursing, New York, New York.
2Tufts University School of Medicine/Baystate Medical Center, Boston, Massachusetts.
3Columbia University College of Physicians and Surgeons, New York, New York.
corresponding authorCorresponding author.
Address correspondence to: Kelli Stidham Hall, M.S.N., Ph.D., Princeton University Office of Population Research, Center for Health and Wellbeing, 228 Wallace Hall, Princeton University, Princeton, NJ 08544. E-mail:kshall/at/princeton.edu
Background
Although oral contraception (OC) misuse is presumed to play an important role in unwanted pregnancy, research findings have often been equivocal, perhaps reflecting unaddressed inconsistencies in methodological approaches.
Methods
Using established databases, we performed a systematic review of measurement methods for OC use using primary research reports published from January 1965 to December 2009.
Results
Terminology used to describe OC use, which included “continuation,” “compliance,” and “adherence,” differed across studies and was rarely defined. The majority of studies (n = 27 of 38, 71%) relied solely on self-report measures of OC use. Only two reports described survey or interview questions, and reliability and validity data were seldom described. More rigorous measurement methods, such as pill counts (electronic or manual), serum and urinary biomarkers, and pharmacy records, were infrequently employed. Nineteen studies simultaneously used more than one method, but only three studies compared direct and indirect methods.
Conclusions
The lack of a consistent, well-defined measurement of OC use limits our understanding of contraceptive misuse and related negative outcomes. Future research should clarify terminology, develop standardized measures, incorporate multimethod approaches with innovative methods, and publish details of measurement methods.
The oral contraceptive pill (OC) is the most popular form of hormonal contraception in the United States13 and is highly effective when used perfectly.4,5 Perfect use, however, is seldom achieved.6 As many as 30% of women report missing one or more pills per month,7 and approximately half of new OC users will discontinue use within the first year.8 Recent data from the National Survey of Family Growth indicate that typical users report a 9% failure rate,5 which may be due in part to pill-taking mistakes. Women who misuse or discontinue the pill are three times as likely to have an unintended pregnancy as those who continue the method.7 Over 1 million unintended pregnancies in the United States are believed to result from OC method failure, misuse, or discontinuation, with more than half due to discontinuation alone.7
Although a considerable body of work on OC use patterns exists, researchers rarely use consistent terminology. Terms such as “compliance,” “adherence,” and “continuation” have been used interchangeably,9 and terms such as “misuse”, “nonuse,” and “correct use” are not well defined. Variable terminology contributes to imprecise measurement of OC use and impedes the ability to interpret and apply existing research findings to clinical practice. Additionally, there are no methods for measuring OC use that are accepted as standard.917 The majority of OC investigations have relied on interviews and questionnaires, although self-report is the least rigorous way to assess contraceptive behavior, given the strong potential for reporting bias.18,19
We conducted a review to summarize and evaluate the literature on measurement of OC use with the following questions in mind: What terminology has been used to describe OC use? What methods have been used to measure OC use? To what extent have the reliability and validity of these approaches been tested? Finally, is there evidence to support a particular method for evaluating OC use?
We performed a computerized search for articles published from January 1966 through December 2009 using databases of MEDLINE, Cumulative Index of Nursing and Allied Health Literature (CINAHL), PubMed, Google Scholar, and PsychInfo. The following key words were searched: oral contraception or contraceptives, combined contraceptive pills, birth control pills, use, misuse, compliance, noncompliance, adherence, nonadherence, continuation, discontinuation, behavior. Reference lists of key articles obtained from the database search were also examined for relevant citations; unpublished articles, dissertation reports, or conference abstracts were not searched.
We considered articles for inclusion if they were written in English, published in peer-reviewed journals, and focused on human females. Article titles and then abstracts were screened to identify primary research reports in which OC use was characterized in some identifiable way. Editorials and studies that did not specifically address combined OC or measurement were excluded.
Information on the following study characteristics was collected: study purpose, design, level of evidence,20 population, sample size, intervention, primary and secondary outcomes, and outcome variable terminology. We examined each report for descriptions of the measurement method(s) used to assess OC use, including features of reliability and validity. Methods were classified according to the categories described by Osterberg and Blaschke11 for assessing patient adherence to oral medication. This classification system includes both direct methods, such as serum or urinary measures of medication or hormone metabolite levels, and indirect methods, such as electronic monitoring devices. Descriptions of each category, along with their advantages and disadvantages are given in Table 1.
Table 1.
Table 1.
Advantages and Disadvantages for Direct and Indirect Evaluation of Oral Medication Use
General study characteristics
Thirty-eight articles14,15,2156 met inclusion criteria. Selected study characteristics from the articles reviewed are presented in Table 2. Six studies were level I randomized controlled trials with OC use as a primary outcome,29,36,38,43,44,49 and the remaining 32 studies met criteria for level II quality of evidence. Few interventions in these studies were interventions of OC use measures.
Table 2.
Table 2.
Selected Characteristics of Studies Measuring Oral Contraceptive Use
Purposes for measuring OC use varied among studies reviewed (Table 3). Seventeen reports described OC use in defined populations,15,21,2527,29,31,33,35,37,39,42,47,5356 15 reports identified predictors of OC use,14,23,24,30,32,40,41,45,46,48,50,51,5456 7 were randomized trials that evaluated some aspect of OC use,29,34,36,38,43,44,49 and 2 were validation studies that evaluated approaches to measuring OC use.22,52
Table 3.
Table 3.
Method of Measurement for Studies Assessing Oral Contraceptive Misuse, by Purpose of Measurement
All studies except 2 were conducted in clinic-based settings; the remaining 2 used population-based samples.48,56 The most common setting was reproductive health practices.2124,2629,4952 All but 5 studies were carried out in the United States.25,34,39,44,14 The reported race/ethnicity of samples was mixed14,32,33,36,37,3942,43,44,5356 or Caucasian.2124,26,35,48 Sample sizes ranged from 1152 to 237,242.54
Terminology used to describe OC use differed among studies. Continuation/discontinuation14,24,2932,36,37,39,33,40,45,5456 and compliance/noncompliance14,3338,43,44,5053 were the most commonly used terms, followed by use/misuse,14,15,23,2528,41,4648 behavior,15,21,26,46,47 and adherence/nonadherence.27,42 No study clearly defined the outcome term used.
Indirect measures of OC use
Self-report
The most common measurement method for OC use was self-report. Interviewer-administered questionnaires were used by 26 research teams.14,15,26,27,2931,3437,3941,4352,55,56 Self-administered surveys were used by 11 research groups25,26,28,3539,42,44,45 and daily diaries by 6 teams.2124,38,42 Nine studies used a combination of two or more self-report methods;26,3538,4245 only 6 studies combined a self-report method with a direct method or more rigorous indirect measure.2123,49,50,52
Few researchers provided information on reliability and validity of measures from studies using self-report methods. Only 2 reports described survey or interview questions or diary formats.55,56 Moreau et al.56 used data from the 2002 cycle of the National Survey of Family Growth to investigate discontinuation due to method dissatisfaction and described the standardized procedures used for the interview-collected data in this population-based survey. Oakley et al.26 used computer-assisted interviews, provided training for interviewers, and performed repeat interviews 1 month after initial assessments in order to improve reliability of the self-report by family planning patients and reported a Cohen's kappa of 0.8 for most items as well as a coefficient of 0.6 or higher for test-retest reliability. Other studies used pilot-tested or previously used questionnaires27,3537,15,47,55 and training for interviewers26,27,29,40,55 to improve reliability and validity.
Record reviews
Two reports examined patient charts but did not describe the specific chart information extracted or how outcomes, such as pregnancy, were determined. Blumenthal et al.39 used chart reviews and the physiological outcome of pregnancy to inform a clinical judgment of OC use. Lara Torre and Schoeder33 compared chart records of women who initiated OC by a Quick Start intervention vs. traditional Sunday start to determine compliance over time. Westhoff et al.29 collected chart information as a secondary measure of misuse and resulting pregnancy only if they were unable to contact women for telephone follow-up interviews.
Zink et al.53 used Medicaid-paid claims to determine the number of pill packs claimed during the 12-month study period as a measure of months of contraceptive coverage. Foster et al.32 used pharmacy-paid claims, examining the number of packs dispensed, timing of dispensation, gaps in dispensation, and pack dispensation or method change before finishing previous packs to identify pill cost as a correlate of OC use. Similarly, Murphy and Brixner54 used a large claims database to examine number of filled contraceptive prescriptions over 3 months. None of these studies were able to determine if patients actually ingested prescribed pills or obtained pill packs from other sources.
Pill counts
Gilliam et al.43 used manual pill counts and pregnancy outcome after written surveys and interviews. To increase reliability, researchers trained pill counters and concealed treatment assignments. The method of pregnancy confirmation was not described, and comparisons of data by measurement method were not compared. Oakley et al.21,23 tested a daily diary card method against a pill-counting electronic monitoring device in which a microchip recorded the time and date when a pill was pushed out of the pill pack. Reliability and validity were not addressed. The authors reported a decline in missed pill self-reporting over time and poor record taking during the third month, resulting in an overestimation of appropriate pill use with diaries compared with the electronic monitors.
In a separate report, Potter et al.22 compared the validity of the same electronic device with that of a self-report diary. The investigators found diaries significantly overestimated daily pill use rates when compared with rates obtained from the device. By the third month of monitoring, measurement agreement between methods was 38%, and the rate of women missing pills as determined by the device was triple the rate reported by diaries. The authors concluded that the electronic device was more accurate in measuring OC pill use, although reliability and validity features were not provided.
DuRant et al.50 used the four-factor Guttman scale to identify factors related to OC compliance in participants in a randomized clinical trial (RCT). Participants received a low-dose combined OC, with 28 mg riboflavin added as a urinary metabolite marker for pill ingestion. The Guttman scale, which was evaluated in pilot work, assessed avoidance of pregnancy (not described), appointment adherence (three visits), interview-assessed self-reported missed OCs (three or more during a month), and fluorescence intensity of urinary concentrations of riboflavin.50,51 At follow-up, the presence of urinary riboflavin was assessed by ultraviolet light and was determined in a double-blind fashion by three independent observers. The Guttman scale yielded strong coefficients of reproducibility (0.96) and scalability (0.84). Additionally, self-report had good agreement with the urinary metabolite assessment and other indirect measures, although tests for statistical agreement were not given.
In another report from this study, Jay et al.52 compared results from their clinical trial with findings from a pilot study of urinary florescence of 31 urine samples from 11 subjects. Urinary fluorescence determinations and self-reports from both study samples were significantly associated, and when agreement was achieved between measures, compliance was confirmed by evaluation of serum norethindrone (a synthetic progestin) concentrations in 90% of the cases. Jay et al.49 also conducted an analysis on 26 randomly selected participants in a clinical trial who underwent random serum testing for hormone metabolites as a confirmatory measure of the Guttman scale. Serum norethindrone samples were measured using a radioimmunoassay method. A high degree of association between the serum and urinary tests was found (p < 0.02).52
Summary of findings
This literature review highlights several important weaknesses in measurement approaches for OC use. Language to describe OC use varies and moreover is not always defined. As the outcomes of OC use studies are dependent on the definition of the main outcome, it is difficult to compare results across studies or to use results to create interventions to improve OC use. Of the 38 reports reviewed, > 70% relied exclusively on self-reports from written survey, interview, or diary. Studies provided no information on specific survey or interview questions or diary formats, making it difficult to assess how outcomes might differ depending on type and number of questions asked. Self-report remains the most common OC use measure, likely for its convenience, ease of administration, and noninvasiveness.11 The likelihood of social desirability bias in OC-using populations,18 however, diminishes the accuracy of such studies.
Based on 3 studies by the same authors that used designs that have not been recently replicated, serum and urinary biomarkers appear to be a reliable measure for OC use.49,50,52 However, these investigators did not address the potential errors in direct methods resulting from white-coat adherence, that is, improved compliance immediately preceding clinic visits.57,58 Scheduled appointments remind patients to take their medications in the days just before the visit, resulting in compliance overestimates from temporarily elevated serum concentrations of the medication that are not reflective of actual drug use during the time between appointments.57,58
Studies of other types of pill use have shown electronic monitoring devices to be superior to self-report for their ability to characterize pill-taking patterns between appointments, particularly the timing between successive doses.5860 Timing of OC doses is critical, given the relatively short half-life of low-dose combined estrogen-progestin steroids in blocking ovulation.6065 Missed pills with “typical use” can cause a 50-fold less effectiveness rate than with “perfect use.”66 Although electronic monitoring has been evaluated as a successful approach for detecting patterns of medication misuse,5860 only 3 studies by the same authors have evaluated a single electronic monitoring commercial product for OC use, which is no longer available.2123
Recommendations
Based on a paucity of rigorous contraceptive studies, we were unable to identify a single superior measure of OC use. The World Health Organization has recommended standardizing terminology and the measurement approach used for describing and evaluating menstrual bleeding patterns67; OC use measurement studies could benefit from such standardization. Inconsistent use of the terms compliance, adherence, continuation, and pill-taking behavior has contributed to conflicting and equivocal findings in contraceptive research. Clarification of terminology used to describe optimal and suboptimal pill use will improve measurement quality. Consensus on a single term and standardized applications of it will increase reliability and validity across studies and improve our ability to synthesize findings and evaluate approaches for measurement.12,13 Such terms as misuse and noncompliance place blame on the research participant and fail to account for those who may have every intention of complying, but may not understand how to use it correctly or may not have continuous access.
Given these shortcomings in research methodologies, we recommend the following terms, which may attribute less intent to the pill user and more objectively describe OC-taking behavior:
  • Continuation to describe pill use that is, on average, maintained daily for subsequent menstrual cycles in research subjects using OC as the primary method of birth control
  • Discontinuation to describe pill use that is stopped for a period of ≥ 7 days and never resumed within a menstrual cycle or at onset of the following cycle
  • Interrupted use to describe a gap of pill nonuse for ≥ 7 days during the menstrual cycle or in-between packs in OC users but that is resumed within a cycle or at onset of the following cycle
  • Missed pills to describe pill use that is stopped within a menstrual cycle for less than a 7-day period
Self-report measures will likely remain the mainstay of contraceptive research. We recommend the development of standardized measures for OC use, as has been developed for general medication use6870 and sexual risk behavior, particularly with sexually transmitted infection acquisition.18 To strengthen self-reports, techniques that have been used in other health behavior research fields, such as anonymity in self-administration of questionnaires, audiocomputer-assisted self-interviews, and telephone administered methods, can reduce threats of socially desirable answers.18
Multidimensional measurement permits reliability and validity checks to verify findings and provides more robust assessment.11,4952 The value of self-reports is enhanced when complemented with more objective methods.18 Direct methods provide quantitative data but are most reliable when used in conjunction with electronic monitoring devices.58,59 We recommend reevaluation of the accuracy of electronic monitoring devices and serum/urine tests in current populations and settings, specifically to confirm time intervals between successive pill doses. Electronic monitoring devices are especially useful in contraceptive intervention studies because they provide information that can be used for both analysis of pill use and creation of strategies for cognitive behavioral modification.6
We also recommend the evaluation of alternative approaches, such as visual analog scales (VAS),71 and pharmacoeconomic estimates of pill use patterns, such as medication adherence rate (MRA),72,73 that have been tested in studies of other health-related conditions and offer additional quality assessments for measuring medication use.
Conclusions
In order to gain a more accurate assessment of pill misuse and its negative sequelae, researchers need to speak the same language. Using consistent terminology across studies will allow for better comparison of results. Additional research using standardized psychometric evaluations of indirect and direct methods and improved measurement reporting are also needed to provide more reliable findings and facilitate improved understanding of OC use patterns. With a more accurate and comprehensive assessment, researchers can better develop and evaluate strategies to promote successful contraception and improved family planning outcomes.
Acknowledgments
This work was supported in part by NRSA individual training grant 1F31NR011119-01A1(K.S.H.) and HRSA grant D09HP14667 (N.E.R.) and the NIH Center for Evidence-Based Practice P30NR010677 (N.E.R., co-investigator; S. Bakken, PI).
Disclosure Statement
The authors have no conflicts of interest to report.
1. Mosher WD. Martinez GM. Chandra A. Abma JC. Willson SJ. Use of contraception and use of family planning services in the United States: 1982–2002. Advance Data from Vital Health Stat. 2004:350. [PubMed]
2. Centers for Disease Control and Prevention. Teenagers in the United States: Sexual activity, contraceptive use and childbearing, 2002. Vital Health Stat. 2004;23(24)
3. Hatcher RA. Trussell J. Stewart F, et al. Contraceptive technology 1994–1996. 18th. New York: Irving Publishers; 1994.
5. Kost K. Singh S. Vaughan B. Trussell J. Bankole A. Estimates of contraceptive failure from the 2002 National Survey of Family Growth. Contraception. 2008;77:10–21. [PMC free article] [PubMed]
6. Cramer JA. Compliance with contraceptives and other treatments. Obstet Gynecol. 1996;88:4s–12s. [PubMed]
7. Rosenberg MJ. Burnhill MS. Waugh MS. Grimes DA. Hillard PJA. Compliance and oral contraceptives: A review. Contraception. 1995;52:137–141. [PubMed]
8. Hatcher RA, editor; Trussell J, editor; Stewart F, et al., editors. Contraceptive technology 1990–1992. New York: Irving Publishers; 1988.
9. Coons SJ. Medication compliance: The search for answers continues. Clin Ther. 2001;23:1294–1295. [PubMed]
10. American Pharmacists Association. Medication compliance-adherence-persistence (CAP) digest. Washington, DC: American Pharmacists Association and Pfizer Pharmaceuticals; 2003.
11. Osterberg L. Blaschke T. Adherence to medication. N Engl J Med. 2005;353:487–97. [PubMed]
12. Marinker M. Blenkinsopp A. Bond C, et al. From compliance to concordance: Achieving shared goals in medicine taking. London, UK: Royal Pharmaceutical Society of Great Britain; 1994.
13. Steiner JF. Earnest MA. Lingua Medica: The language of medication-taking. Ann Intern Med. 2000;132:926–930. [PubMed]
14. Rosenberg MJ. Waugh MS. Meehan TE. Use and misuse of oral contraceptives: Risk indicators for poor pill taking and discontinuation. Contraception. 1995;51:283–288. [PubMed]
15. Brown JW. Villarruel AM. Oakley D. Eribes C. Exploring contraceptive pill-taking among Hispanic women in the United States. Health Educ Behav. 2003;30:663–682. [PubMed]
16. Clark LR. Will the pill make me sterile? Addressing reproductive health concerns and strategies to improve adherence to hormonal contraceptive regimens in adolescent girls. J Pediatr Adolesc Gynecol. 2001;14:153–162. [PubMed]
17. Halpern V. Grimes DA. Lopez L. Gallo MF. Strategies to improve adherence and acceptability of hormonal methods for contraception. Cochrane Database of Systematic Reviews. 1 [PubMed]
18. Stuart GS. Grimes DA. Social desirability bias in family planning studies: A neglected problem. Contraception. 2009;80:108–112. [PubMed]
19. Pinter B. Continuation and compliance of contraceptive use. Eur J Contracept Reprod Health Care. 2002;7:178–183. [PubMed]
20. Harris RP. Helfand M. Woolf SH, et al. Current methods of the U.S. Preventive Services Task Force: A review of the process. Am J Prev Med. 2001;20:21–35. [PubMed]
21. Oakley D. Potter L. Leon-Wong E. Visness C. Oral contraceptive use and protective behavior after missed pills. Fam Plann Perspect. 1997;29:277–79. [PubMed]
22. Potter L. Oakley D. Leon-Wong E. Canamar R. Measuring compliance among oral contraceptive users. Fam Plann Perspect. 1996;28:154–158. [PubMed]
23. Smith JD. Oakley D. Why do women miss oral contraceptive pills? An analysis of women's self-described reasons for missed pills. J Midwif Womens Health. 2005;50:380–385. [PubMed]
24. Sanders SA. Graham CA. Bass JL. Bancroft J. A prospective study on the effects of oral contraceptives on sexuality and well-being and their relationship to discontinuation. Contraception. 2001;64:51–58. [PubMed]
25. Fletcher PC. Bryden PJ. Bonin E. Preliminary examination of oral contraceptive use among university-aged females. Contraception. 2001;63:229–233. [PubMed]
26. Oakley D. Sereika S. Bogue EL. Oral contraceptive pill use after an initial visit to a family planning clinic. Fam Plann Perspect. 1991;23:151–154. [PubMed]
27. Davis TC. Fredrickson DD. Potter L, et al. Patient understanding and use of oral contraceptive pills in a southern public health family planning clinic. South Med J. 2006;99:713–718. [PubMed]
28. Sangi-Haghpeykar H. Ali N. Posner S. Poindexter AN. Disparities in contraceptive knowledge, attitudes, and use in Hispanic versus non-Hispanic whites. Contraception. 2006;74:125–132. [PubMed]
29. Westhoff C. Heartwell S. Edwards S, et al. Initation of oral contraceptives using a Quick Start as compared with a conventional start. Obstet Gynecol. 2007;109:1270–1276. [PubMed]
30. Kerns J. Westhoff C. Morroni C. Murphy PA. Partner influence on early discontinuation of the pill in a predominantly Hispanic population. Perspect Sex Reprod Health. 2003;35:256–260. [PubMed]
31. Westhoff C. Kerns J. Morroni C. Cushmand LF. Tiezz L. Murphy PA. Quick Start: A novel oral contraceptive initiation method. Contraception. 2002;66:141–145. [PubMed]
32. Foster DG. Parvataneni R. de Bocanegra HT. Lewis C. Bradsberry M. Darney P. Number of oral contraceptive pill packages dispensed, method continuation, and costs. Obstet Gynecol. 2006;108:1107–1114. [PubMed]
33. Lara-Torre E. Schoeder B. Adolescent compliance and side effects with Quick Start initiation of oral contraceptive pills. Contraception. 2002;66:81–85. [PubMed]
34. Lachowsky M. Levy-Toledano R. Improving compliance in oral contraception: “The reminder card.” Eur J Contraception Reprod Health Care. 2002;7:210–215. [PubMed]
35. Rosenberg MJ. Waugh MS. Burnhill MS. Compliance, counseling, and satisfaction with oral contraceptives: A prospective evaluation. Fam Plann Perspect. 1998;30:89–92. [PubMed]
36. Westhoff C. Osborne LM. Schafer JE. Morroni C. Bleeding patterns after immediate initiation of an oral versus a vaginal hormonal contraceptive. Obstet Gynecol. 2005;106:89–96. [PubMed]
37. Schafer JE. Osborne LM. Davis AR. Westhoff C. Acceptability and satisfaction using Quick Start with the contraceptive vaginal ring versus an oral contraceptive. Contraception. 2006;73:488–492. [PubMed]
38. Urdl W. Apter D. Alperstein A, et al. Contraceptive efficacy, compliance and beyond: Factors related to satisfaction with once-weekly transdermal compared with oral contraception. Eur J Obstet Gynecol Reprod Biol. 2005;121:202–210. [PubMed]
39. Blumenthal PD. Wilson LE. Remsburg RE. Cullins VE. Huggins GR. Contraceptive outcomes among postpartum and post-abortal adolescents. Contraception. 1994;50:451–460. [PubMed]
40. Ramstrom KC. Baron AE. Crane LA. Shlay JC. Predictors of contraceptive discontinuation in a sexually transmitted disease clinic population. Perspect Sex Reprod Health. 2002;34:146–153. [PubMed]
41. Moore PJ. Adler NE. Kegeles SM. Adolescents and the contraceptive pill: Impact of beliefs on intentions and use. Obstet Gynecol. 1996;88:48–56S. [PubMed]
42. Huber LRB. Hogue CJ. Stein AD, et al. Contraceptive use and discontinuation: Findings from the Contraceptive History, Initiation, and Choice study. Am J Obstet Gynecol. 2006;194:1290–1295. [PubMed]
43. Gilliam M. Knight S. McCarthy M., Jr Success with oral contraceptives: A pilot study. Contraception. 2004;69:413–418. [PubMed]
44. Deijen JB. Kornaat H. The influence of type of information, somatization, and locus of control on attitudes, knowledge, and compliance with respect to the triphasic oral contraceptive Tri-Minulet. Contraception. 1997;56:31–41. [PubMed]
45. Rosenberg MJ. Waugh MS. Oral contraceptive discontinuation: A prospective evaluation of frequency and reasons. Am J Obstet Gynecol. 1998;179:577–582. [PubMed]
46. Peterson L. Oakley D. Potter L. Darroch J. Women's efforts to prevent pregnancy: Consistency of oral contraceptive use. Fam Plann Perspect. 1998;30:19–23. [PubMed]
47. Glei D. Measuring contraceptive use patterns among teenage and adult women. Fam Plann Perspect. 1999;31:73–80. [PubMed]
48. Walsemann KM. Perez AD. Anxiety's relationship to inconsistent use of oral contraceptives. Health Educ Behav. 2006;33:197–214. [PubMed]
49. Jay MS. DuRant RH. Shoffitt A. Linder CW. Litt IF. Effect of peer counselors on adolescent compliance in use of oral contraceptives. Pediatrics. 1984;73:126–131. [PubMed]
50. DuRant RH. Jay MS. Linder CW. Shoffitt A. Litt IF. Influence of psychosocial factors on adolescent compliance with oral contraceptives. J Adolesc Health Care. 1984;5:1–6. [PubMed]
51. Litt IF. Know thyself—Adolescents' self-assessment of compliance behavior. Pediatrics. 1985;75:693–696. [PubMed]
52. Jay MS. DuRant RH. Litt IF. Linder CW. Shoffitt T. Riboflavin, self-report, and serum norethindrone: Comparision of their uses as indicators of adolescent compliance with oral contraceptives. Am J Dis Child. 1984;138:70–73. [PubMed]
53. Zink TM. Shireman TL. Ho M. Buchanan T. High risk teen compliance with prescription contraception: An analysis of Ohio Medicaid claims. J Pediatr Adolesc Gynecol. 2002;15:15–21. [PubMed]
54. Murphy PA. Brixner D. Hormonal contraceptive discontinuation patterns according to formulation: Investigation of associations in an administrative claims database. Contraception. 2008;77:257–263. [PubMed]
55. Kalmuss D. Koenemann S. Westhoff C, et al. Prior pill experiences and current continuation among pill restarters. Perspectives on sexual and reproductive health. 2008;40:138–143. [PubMed]
56. Moreau C. Cleland K. Trussell J. Contraceptive discontinuation attributed to method dissatisfaction in the United States. Contraception. 2007;76:267–272. [PubMed]
57. Podsadecki TJ. Vrijens BC. Tousset EP. Rode RA. Hanna GJ. “White coat compliance” limits the reliability of therapeutic drug monitoring in HIV-1-infected patients. HIV Clin Trials. 2008;9:238–246. [PubMed]
58. Feinstein AR. On white-coat effects and the electronic monitoring of compliance. Arch Intern Med. 1990;150:1377–1378. [PubMed]
59. Vrijens B. Tousset E. Rode R. Bertz R. Mayer S. Urqnhart J. Successful projection of the time course of drug concentration in plasma during a 1-year period from electronically compiled dosing-time data used as input to individually parameterized pharmacokinetic models. J Clin Pharmacol. 2005;45:461–470. [PubMed]
60. Potter LS. Oral contraceptive compliance and its role in the effectiveness of the method. In: Cramer JA, editor; Spilker B, editor. Patient compliance in medical practice and clinical trials. New York: Raven Press; 1991.
61. Social and Sexual Issues Committee; Society of Obstetricians and Gynaecologists of Canada. Missed hormonal contraceptives: New recommendations. J Gynaecol Can. 2008;219:1050–1062.
62. Fraser IS. Forty years of combined oral contraception: The evolution of a revolution. Med J Aust. 2000;173:541–544. [PubMed]
63. Crosignani PG. Testa G. Vegetti W. Parazzini F. Ovarian activity during regular oral contraceptive use. Contraception. 1996;54:271–273. [PubMed]
64. Egarter C. Putz M. Strohmer H. Speiser P. Wenzl R. Huber J. Ovarian function during low-dose oral contraceptive use. Contraception. 1995;51:329–333. [PubMed]
65. Van der Vange NBH. Tweel IVD. Coelingh Bening HJT. Haspels AA. Ovarian activity and low dose oral contraceptives. Contraception. 1985;1:249.
66. Centers for Disease Control and Prevention. Achievements in public health, family planning, 1900–1999. MMWR. 1999;48:1073–1080.
67. World Health Organization Special Programme of Research. Development, Research Training in Human Reproduction. The analysis of vaginal bleeding patterns induced by fertility regulating methods. Contraception. 1986;34:253–260. [PubMed]
68. Kyngas HA. Skaar-Chandler CA. Duffy ME. The development of an instrument to measure the compliance of adolescents with a chronic disease. J Adv Nurs. 2000;32:1499–1506. [PubMed]
69. Paterson C. Britten N. A narrative review shows the unvalidated use of self-report questionnaires for individual medication as outcome measures. J Clin Epidemiol. 2005;58:967–973. [PubMed]
70. Krousel-Wood M. Muntner P. Jannu A, et al. Reliability of a medication adherence measure in an outpatient setting. Am J Med Sci. 2005;330:128–133. [PubMed]
71. Nau DP. Steinke DT. Williams LK, et al. Adherence analysis using visual analog scale versus claims-based estimation. Ann Pharmacother. 2007;41:1792–1797. [PubMed]
72. Hughes D. When drugs don't work: Economic assessment of enhancing compliance with interventions supported by electronic monitoring devices. Pharmacoeconomics. 2007;25:621–635. [PubMed]
73. Hess LM. Raebel MA. Conner DA. Malone DC. Measurement of adherence in pharmacy administrative databases: A proposal for standard definitions and preferred measures. Ann of Pharmacother. 2006;40:1280–1288. [PubMed]
Articles from Journal of Women's Health are provided here courtesy of
Mary Ann Liebert, Inc.