Health care decisions should be perceived by patients and research participants as voluntary. Until now, there have been no adequate tools for measuring perception of voluntariness. Here we describe a new instrument to measure the perceived voluntariness of parental decisions about a research protocol or non-research treatment protocol for their seriously ill child. Factor analysis yielded three correlated factors of Self-Control, Absence of Control, and Others’ Control. Confirmatory factor analysis on the same data set supported a 3-factor covariance structure model as most consistent with the data. The three factors and the composite score have internal consistency values ranging from moderate to high. We tested the preliminary validity of the DMCI by examining associations with affect, self-efficacy, and trust. Parents who perceived greater control reported being more confident and clearheaded at the time of the decision, having greater decision self-efficacy, and having greater trust in the physician most involved in the target decision. The correlations were similar for the three subscales of the DMCI. This finding is not surprising, given that each subscale is part of the construct of voluntariness, with higher scores on each indicative of greater perceived control. At this early stage of development, our understanding of the joint contributions of the three subscales of the DMCI is still evolving. However, these associations support the initial construct validity of the DMCI, by demonstrating that it operates in relation to theoretically-related variables in the expected manner. When attempting to validate new measures, it must be kept in mind that virtually all efforts toward validation are preliminary. An instrument is only considered to be truly “valid” after years of documented evidence across multiple groups, settings, and forms. Evidence provided here is only a first step, though admittedly a very positive first step, toward creating a generalizable measure of decision making control for use in biomedical research.
The DMCI is easy to administer and score, and parents were willing and able to complete the DMCI despite being in a highly stressful medical environment and caring for a seriously ill child. The DMCI can be used to inform our understanding of how parents experience the decision-making process and factors that may influence their perceived voluntariness over specific decisions. This assessment is important, because perceptions of voluntariness may be related to health-related outcomes, such as health status and personal adjustment (see 30
), and to aspects of the clinician-patient relationship. The DMCI can also be used to identify individuals who are struggling with medical decisions and in need of additional support and guidance during the consent process.
Although voluntariness of action cannot be measured directly, a person’s perception of whether his or her action is voluntary can be measured by testing for perception of intentionality and noncontrol. For measure development, we operationalized voluntariness as the individual’s perception of the degrees of noncontrol and self-control over the target decision (12
). This approach recognizes that the decision maker’s subjective perspective is critical, because whether an influence is “undue” may vary by individual (31
). However, the perception
of voluntariness is different from being in fact
voluntary. There may be controlling influences that the individual is not aware of, such as when someone intentionally deceives the decision-maker. From a regulatory and ethical standpoint, such a decision in a research or medical setting should be considered non-voluntary, even if the decision-maker’s DMCI score reflects a high degree of perceived voluntariness. Although the DMCI does not assess aspects of the situation
that may render a decision non-voluntary, it provides insight into the individual’s perception of the degree to which the decision was self-controlled versus controlled by others. When used alongside an assessment of situational factors, the DMCI may be useful in identifying external conditions that lead to decreased perceived voluntariness.
Appelbaum and colleagues also suggest such a joint approach (31
). However, their approach is based on the “legal doctrine of informed consent” and thus presumes that voluntariness is an inherently value-laden concept. In our account, whether an external influence is morally legitimate is conceptually and morally distinct from whether the action taken in response to that influence is voluntary or involuntary (12
). In addition, their qualitative empirical approach may be unwieldy and difficult to implement widely in real-world situations (3
). An alternative would be to use the DMCI, which is short and easy to administer, on a regular basis and to reserve a more thorough assessment of situational factors for when scores on the DMCI indicate diminished perceived control. This use of the DMCI as a screening measure would require additional research to establish statistically and clinically relevant threshold scores.
This study has several limitations. First, target decisions included those about both research protocols and non-research treatment protocols and the sample size did not permit us to compare measurement models for these two different types of decisions. Our assumption was that the measurement of voluntariness would be similar, because both decisions involve medical interventions for a child’s serious illness and occur under conditions of uncertainty. However, the factors related to perceptions of voluntariness may differ for the two types of decisions. Second, our sample had a skewed distribution of DMCI scores, with most participants indicating high perceived voluntariness. This ceiling effect means that the measure may not distinguish between individuals at the high end of the scale, resulting in a lack of sensitivity when testing associations of the DMCI with potential predictors and outcomes. A third limitation is that we used a convenience sample, and those who participated in our research may be different in important ways than those who did not participate. In particular, parents who agreed to participate may have been more likely to perceive that their decisions were voluntary, thus contributing to the ceiling effect. Subgroups that may be susceptible to undue influence, such as those with a lower socioeconomic status or who use publicly-funded insurance, may not have been adequately sampled.
Fourth, our sample was heterogeneous in terms of illness, prognosis, and duration of diagnosis. While this diversity may increase the generalizability of our findings, there may be important differences between subgroups that we could not test. Fifth, we did not collect data on the test-retest reliability of the DMCI; future research using the DMCI should determine the extent to which scores are stable across time. The interpretation of such findings will be complicated by the likelihood that perceptions of voluntariness may change over time, especially if the respondent’s emotions and cognitions regarding the decision or the child’s health status change over time. Thus, a short retest period (e.g., 1-week) is recommended. For the same reason, the DMCI should be administered as close to the actual decision as possible. Sixth, while the present findings regarding the DMCI are promising, additional research is needed to determine if the factor structure remains stable in other samples, especially when the nine items are presented separately from the original 28-item pool. Seventh, findings from the present study do not address the discriminant and incremental validity of the DMCI. Future research is needed to test the validity of the measure in more depth, including the way in which the DMCI operates in relation to measures of locus of control. Finally, we acknowledge that the DMCI contains one item that co-loads on another factor in the 0.30 to 0.40 range (item 16), and a second item that co-loads just beneath our threshold (item 3). Given that our simple structure is well supported for 7 of the 9 items, and that this is the first of many planned studies in this new area, we are optimistic about these early findings and expect the DMCI to perform well in future studies. As with all validity studies, and in particular with very new instruments such as the DMCI, additional studies will be needed to verify the factor structure of the DMCI and the generalizability of these findings to other populations and settings, including studies that lead toward a refinement of the existing scale.
The DMCI can be used in future research to address several important questions. First, the DMCI can explore the potential causes of decreased perceived voluntariness for treatment and research decisions. Factors such as disease state (32
), prognosis (34
), clinical setting (35
), and substance abuse (37
) can influence decisions, but whether these factors create an undue influence is unclear. Similarly, we know little about the impact of inducements on perceived voluntariness, or whether patients are unduly influenced when their own physicians request their participation in research. Second, future research should employ cross-sectional and longitudinal methodologies to assess the influence of perceptions of voluntariness on outcomes, including satisfaction with the decision, clinician-parent communication, health status, and adjustment. Finally, the DMCI should be tested with populations that may be particularly vulnerable to undue influence, such as children and adolescents, those who are economically disadvantaged and/or lack access to health care, and individuals with mental illness. It is our hope that research utilizing the DMCI will provide the empirical foundation for the development of guidelines to enhance the voluntariness of decisions in a variety of medical settings and for different subgroups of patients.