Anesth Analg 2000;91:369-373
© 2000 International Anesthesia Research Society
OBSTETRIC ANESTHESIA
Informed Consent for Obstetric Anesthesia Research: Factors that Influence Parturients’ Decisions to Participate
Deanna M. Dorantes, MD,
Alan R. Tait, PhD, and
Norah N. Naughton, MD
Department of Anesthesiology, The University of Michigan Medical Center, Ann Arbor, Michigan
Address correspondence and reprint requests to Deanna M. Dorantes, M.D., Department of Anesthesiology, 1500 E. Medical Center Dr., Ann Arbor, MI 48109. Address e-mail to ddorantes{at}umich.edu
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Abstract
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Patients who are approached to participate in clinical studies just before delivery may have insufficient time to make an informed decision and/or may feel pressured into participation. This study was designed to examine factors that influence parturients to consent or decline participation in an anesthesia study related to their delivery. Parturients who had been approached to participate in a continuing clinical obstetric anesthesia study were subsequently given a questionnaire that documented their reasons for consenting or declining participation. There were no demographic differ-ences among the consenters (n = 166) and nonconsenters (n = 109). The most important factors in the patient’s decision to consent were related to their understanding and perceived importance of the study and the potential benefit to other women. Forty-one (40.6%) nonconsenters strongly considered their pain/discomfort a factor in declining participation. Only one patient felt some pressure to consent, suggesting that the overall environment was noncoercive. Logistic regression analysis demonstrated that patients who read the consent form completely, those who had participated in a previous research study, and those who were less anxious about participating were more likely to consent.
Implications: Obtaining informed consent for obstetric anesthesia studies presents a challenge to the anesthesiologist. Results from this study suggest that the environment in which consent for obstetric studies is sought is not coercive. However, it is important that the anesthesiologist ensures that the patient fully understands the study and develops a rapport with the patient to allay any anxiety associated with her participation as a potential research subject.
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Introduction
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Obtaining informed consent for obstetric anesthesia studies presents a unique challenge for the anesthesiologist (1). First, unlike most specialties, anesthesiologists must rely on a patient population that is not primarily their own. Surgical or obstetric patients for example, may be reluctant to participate in a study for a physician with whom they are unfamiliar. Second, the decision to consent requires consideration of another party, i.e., the fetus. Third, obtaining consent for pregnant women to participate in studies during their labor presents an important ethical dilemma because these women may be particularly anxious and/or in pain at the time that consent is sought. For these reasons, many believe that seeking consent just before surgery or delivery is potentially coercive (2). This study, therefore, was performed to determine the factors that influence parturients to consent to participate in clinical obstetric anesthesia studies.
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Methods
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After institutional review board approval, 294 healthy parturients who had requested epidural analgesia and had been approached to participate in an anesthesia study examining the effect of epidural analgesia by using the minimum local analgesic concentration model (MLAC) were enrolled in this study (3). Regardless of whether they consented to participate in the MLAC study, patients were subsequently asked to complete a questionnaire detailing the reasons for their decision. Two questionnaires were used: one for parturients who had consented to participate (consenters) and one for those who had declined (nonconsenters). Although most of the questions were common to both, we used two separate questionnaires to allow patients to focus on specific factors that influenced their decision to consent or decline participation. The questionnaires were based on a previously published study from our department and modified for use in adult patients (4). Parturients were asked whether they "strongly considered," "considered somewhat," or "did not consider" certain factors when deciding to participate or not. The questionnaires were designed to be completed anonymously to avoid the potential for self-report bias. Eligible parturients were given the questionnaire to complete in-house at their leisure. Completed questionnaires were collected before the patient’s discharge from the hospital.
Parametric data were analyzed by using t-tests. Nonparametric data were analyzed by using 
2 and Fisher’s exact test, where appropriate. A principal components factor analysis was performed to identify factors that summarized the relationships among the items in the questionnaire and that helped explain their variance. Criteria used to determine the number of factors to rotate included eigenvalues greater than 1, a scree test, proportionate variance greater than 10%, and the interpretability of the factor solution. Items were said to load on a factor if the factor loading was 0.5 or greater for that factor, and was <0.5 for the others. Internal consistency estimates of reliability of the questionnaire were computed by using measurements of coefficient (Cronbach’s) 
. Items that demonstrated Cronbach values of 0.7 and higher were considered reliable. Finally, predictors of consent and nonconsent were analyzed by using a forward stepwise logistic regression model. Data were expressed as mean and SD. Statistical significance was accepted at the 5% level (P < 0.05).
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Results
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Two hundred seventy-five patients completed questionnaires were returned, 166 (60.4%) from those who consented to participation in the MLAC study and 109 (39.6%) from those who declined. The overall response rate was 93.5% (275 of 294).
Items from each of the questionnaires were analyzed by principal components factor analysis with varimax rotation. Analysis of items on the consent questionnaire indicated that the rotated solution yielded two meaningful factors. The first factor was labeled the "comfort " factor. Five items loaded on this factor. These included: "you understood the study," "the researcher put you at ease," "sufficient privacy to decide," "the study was explained well," and "sufficient time to make a decision." The second factor was labeled the "altruism" factor. Three items loaded on this factor. These included: "contributing to medical science," "others might benefit," and "importance of the study." Analysis of the nonconsent questionnaire yielded one interpretable factor which was labeled the "anxiety" factor. Four items loaded on this factor. These included: "fear for the baby’s safety," "fear of the unknown," "fear of the outcome of the study," "increased risk to the baby."
Internal consistency estimates of reliability were computed for the items underlying each of the factors of interest. Coefficient for items composing the comfort and altruism factors were 0.76 and 0.77, respectively. Items underlying the anxiety factor yielded a coefficient of 0.84. These values demonstrate satisfactory reliability.
A principal components factor analysis was also computed that excluded those parturients who strongly considered their labor pain as a factor in their decision not to participate. Although this analysis yielded the same two factors, i.e., comfort and anxiety, the amount of variance explained by these factors differed. For example, when patients who strongly considered their pain were included, the anxiety factor explained most of the variance, whereas when these patients were excluded, the comfort factor became the principal factor.
Although the factor analysis identifies items that help to explain the variance in the data, other items were nevertheless important in the patients’ decision-making process. The principal factors used in the patients’ decision-making are outlined in Tables 1 and 2. One hundred twenty-eight (79.5%) consenters strongly considered a perceived low risk to the baby as a contributing factor in their decision to participate. In addition, there appears to be little evidence of coercion to consent, because only 19 (11.8%) felt uncomfortable saying "no," 1 (0.7%) felt pressured, and 1 (0.7%) felt obligated to consent. Similarly, among nonconsenters, there was little evidence that the environment in which consent was sought was coercive. For example only 12 (11.9%) strongly considered a lack of time as a deciding factor, 3 (2.9%) felt pressured, and 10 (10%) strongly considered a lack of privacy. In addition, only 15.8% strongly considered a perceived increased risk to their baby. The decision to consent did not appear to be influenced by family members or caregivers. For example, only 13 (12.9%) consenters and 1 (1.0%) of nonconsenters strongly considered input from the baby’s father or caregivers, respectively. Of consenters, 16 (9.9%) and 3 (2.0%) nonconsenters strongly considered input from the father and caregivers.
There is concern that parturients may be in discomfort or pain when approached for informed consent. In this study, 40.6% of nonconsenters strongly considered their labor pain as a factor in their decision not to participate.
Variables that were significantly associated with consent by univariate analysis were further analyzed by logistic regression. Results showed that the greater degree to which the patients read the informed consent document and the more intently they listened to the researcher who explained the study were both independent predictors of consent. Patients were also less likely to consent if the thought of participating had made them more anxious, but were more likely to consent if they had participated in a previous research study. The results of the logistic regression are shown in Table 3. Logistic regression also showed that if subjects who had previous experience with participation in research were excluded from the analysis, the extent to which subjects read the consent document (P = 0.004) and their level of anxiety (P = 0.01) remained independent risk factors for consent. The degree to which they listened to the researcher was moderately predictive (P = 0.07).
Consenters were significantly more likely to consent to future studies than nonconsenters (80.5% vs 19.5% respectively, P < 0.05). Factors that might cause consenters to reach a different decision and decline participation in a future study included: if the study were poorly explained (n = 109, 65.7%), if the study interfered with care (n = 105, 63.3%), and if there were increased risk to the baby (112, 67.5%) or to themselves (n = 108, 65.1%). Forty-two (38.5%) consenters and 43 (39.5%) of nonconsenters stated that they might consent to a future study if there were less perceived risk to the baby or themselves, respectively.
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Discussion
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There is concern that consent for clinical studies obtained just before surgery or delivery allows insufficient time for the patient or patient’s surrogate to make an informed decision and, as such, represents a potentially coercive environment (2). Furthermore, many believe that consent (for procedures or research) given during labor is invalidated in the presence of stress and pain (5). In an informal survey of Canadian anesthesiologists, 74% felt that their parturient patients were not adequately informed before anesthesia procedures (6). Additionally, although 80% felt it was the anesthesiologists’ responsibility to educate the parturient about the risks of the procedure, it was deemed unrealistic to expect the patient to assimilate the information during labor. Although this study did not specifically address the issue of consent for research, the same ethical and legal requirements apply. In contrast, a survey of obstetric patients showed that the discomfort of labor did not interfere with their ability to understand the informed consent document (7).
Ideally, consent for anesthesia studies should occur before the day of surgery or delivery, but in practice, this is not always possible. As a result, consent for anesthesia studies is often sought in a common area with little privacy and at a time when the patient is most anxious. In one study, patients reported that they would prefer more time and more privacy to make an informed decision (8); however, our study suggested that these factors have minimal influence on their decision to consent and, as such, do not engender a coercive environment. Recently, Breen et al. (9) reported that women in labor felt no more pressure to consent to anesthesia studies than women who were not in labor. In the present study, only 11.9% of nonconsenters strongly considered a lack of time to make a decision, and <3% felt pressured to participate. Similarly, <1% of consenters felt pressured to consent. These findings are very similar to results from a previous study examining factors that influence parents to consent to their child’s participation in anesthesia research (4) and, thus, lend some external validity to our findings.
Analysis of factors that influenced parturients to consent to participate in a research study suggests that they understood the nature of the study, felt comfortable with their role in participating, and had a strong sense of altruism. Unlike our previous study in children, the potential risk of the study was not considered a major factor in the parturients decision to consent or decline. Although this finding was surprising, it may have been more a reflection of the perceived benign nature of the studies presented rather than a lack of concern for the patient’s safety and that of their baby. Indeed, more than 65% of consenters reported that they would decline consent for future studies if they perceived an increased risk to the themselves or the baby, suggesting that risk is indeed a consideration.
The fact that more parturients consented than declined may also be considered evidence of pressure to consent. However, as stated, there was little evidence to suggest that the environment was coercive. In addition to the small perceived risk, the larger numbers of consenters may also be related to the nature of the proposed studies that required placement of an epidural catheter. Because many patients had requested a labor epidural anyway, as part of their pain management, they may have been more likely to consent to the study.
A few points regarding the design of this study deserve mention. Previous studies examining factors associated with consent for research have been based on hypothetical research studies. Although this approach is easier from a logistical point of view, it does not capture the real-life situation. Anxiety is a powerful force in decision-making, and studies show that anxiety is increased when subjects are asked to participate in research. Therefore, if subjects are asked to base their decisions on being in a hypothetical versus an actual study, their anxiety levels may be quite different and so, too, their decisions. For this reason, we believed it important to examine factors that influenced parturients to participate in an actual study. Although participation in more than one study is not generally advocated by our institutional review board, approval was granted based on the above rationale and the fact that the questionnaire posed no more than minimal risk to the subject. A second issue is that, despite the fact that some patients declined the MLAC study (nonconsenters), they were apparently willing to participate in our study. We believe that this apparent incongruity was a result of a difference in the subjects’ perceived risk between the two studies. The MLAC study had the possibility of receiving a larger or smaller dose of analgesic than normal, whereas our study simply required completion of a questionnaire. Previous work suggests that most research subjects have an altruistic approach to participation in research. However, this altruism may be tempered by the subject’s perceived risk of participating. We believe, that in this case, any conflict between altruism and perceived risk would be easier to justify in our study, and this may explain why some subjects chose to participate despite declining the MLAC study.
This study highlights some of the factors that parturients consider in making decisions regarding participation in obstetric anesthesia studies. Obtaining informed consent for obstetric studies represents a unique challenge with special considerations. Not only is consent usually sought on the day of delivery, but the patient may be anxious, emotional, and in considerable pain or discomfort. Although our results suggest that the environment of labor and delivery was not inappropriate, researchers must be sensitive to the inherent uniqueness of the labor experience when obtaining informed consent for anesthesia obstetric studies.
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Footnotes
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Presented in part at the Society for Obstetric Anesthesia and Perinatology annual meeting, Vancouver, BC, Canada, and has appeared as an abstract in Anesthesiology 1998;Suppl:A35.
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References
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Accepted for publication April 27, 2000.
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Abstract
Introduction
