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ORIGINAL RESEARCH |
From the Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco; Division of Health Services and Policy Analysis, University of California, Berkeley, School of Public Health; and Medical Effectiveness Research Center, University of California, San Francisco.
Address reprint requests to: Dr. Aaron Caughey, Department of Obstetrics, Gynecology, and Reproductive Sciences, 505 Parnasssus Avenue, Box 0132, San Francisco, CA 94143; e-mail: abcmd{at}uclink.berkeley.edu.
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ABSTRACT |
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METHODS: We surveyed 447 women of varying ages, ethnicity, and socioeconomic levels to assess their desire to undergo and willingness to pay for invasive prenatal testing for chromosomal disorders. Each woman was asked what she would be willing to pay for invasive diagnostic testing up to the full cost of the procedure. We also asked several demographic and attitudinal questions.
RESULTS: Overall, 49% of the women indicated an interest in undergoing invasive prenatal diagnostic testing. Women aged 35 years and older were more likely to desire testing as compared with women aged less than 35 years (72% versus 36%, P < .001). Of the women aged less than 35 years who desired testing, 31% indicated that they would be willing to pay the full price of $1,300, whereas 73% were willing to pay a portion of the cost. Maternal age of 35 years or greater (odds ratio [OR] 3.3; 95% confidence interval [CI] 2.0, 5.6) and willingness to have an elective abortion (OR 2.8; 95% CI 1.6, 4.9) were significant predictors of desire to undergo prenatal diagnostic testing after controlling for income, race/ethnicity, and education. Maternal age of 35 years or greater (OR 3.5; 95% CI 1.59, 7.88) and having an income greater than $35,000 (OR 2.3; 95% CI 1.02, 5.26) were significant predictors of willingness to pay the full price of testing.
CONCLUSION: A substantial proportion of women of all ages indicate a desire to undergo and a willingness to pay for prenatal diagnostic testing. Variations in willingness to pay are correlated with both socioeconomic and attitudinal differences in addition to age. Guidelines regarding use of prenatal genetic diagnosis should be expanded to offer testing to all women, not just those deemed at increased risk.
LEVEL OF EVIDENCE: II-2
One of the original rationales for limiting the use of diagnostic testing to women aged 35 years and older6 was the determination that at this age the risk of a procedure-related miscarriage was approximately equal to the likelihood of giving birth to an infant affected by a chromosomal disorder.7–9 (The estimated procedure-related miscarriage risk ranges from 0.5% to 1%,10 and the overall risk of a chromosomal abnormality is approximately 0.5% at age 35.4) From a societal standpoint, it seems reasonable that a diagnostic procedure should have greater benefits than risks for patients and that the economic benefits from testing outweigh the economic costs.11,12 Therefore, determining the benefits and risks of prenatal diagnostic testing is an important goal for setting rational guidelines. The primary risk from an invasive prenatal diagnostic procedure such as amniocentesis is of a procedure-related miscarriage. The biggest risk of a pregnancy complicated by an undiagnosed chromosomal abnormality is delivering and raising a child with Down syndrome. If these 2 outcomes have the same value to women, then comparing the risk of these outcomes is reasonable. If they are of different value, then a comparison weighting both risk and the valuation of these outcomes may be preferable. Our previous work in this area shows that these 2 outcomes are not valued the same.13
There are a variety of ways in which values for medical outcomes can be measured. The most direct approach is to simply ask patients whether they would like to undergo a diagnostic test. In a study of pregnant women in New York City aged less than 35 years, almost a quarter chose to undergo invasive prenatal testing when it was offered.14 A more explicit approach to understanding how women weigh the risks and benefits of testing is to have the patient assign values to each of the possible outcomes of testing. In our previous work we used utility analysis, a quantitative measure of preference for an outcome, to assess the relative value of Down syndrome–affected birth and miscarriage.13 Another method of measuring a patient’s valuation of a procedure or outcome is by assessing her willingness to pay15–17 to undergo the procedure or to achieve or avoid a particular outcome. To estimate willingness to pay, patients are described different medical outcomes or interventions and are asked what they would be willing to pay to avoid or achieve the stated outcome or to undergo the stated intervention. Advantages of the willingness to pay method as compared with estimating patient utilities include the simplicity of the assessment, the likely comfort patients will have with the units being used (monetary versus life or life years), and the immediate translatability of results to cost–benefit analyses where both the costs and outcomes are measured in monetary units.16,17
The goal of our study was to investigate whether the current standards that reserve invasive prenatal testing for high-risk women are supported by evidence of lack of desire for such testing as demonstrated by decreased willingness to pay among low-risk women (eg, women under the age of 35 years). We also sought to assess the value of such testing to pregnant women and to investigate predictors of interest in and willingness to pay for prenatal diagnosis.
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MATERIALS AND METHODS |
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Eligible subjects were sent letters informing them of the study and that a recruiter would call unless they returned an enclosed postcard indicating that they declined participation. Those who did not return cards were called within 2 weeks. Of the 1,099 women contacted, 401 were ineligible, typically because they were no longer pregnant or their gestational age was more than 20 weeks. Among the remaining 698 women, 447 (64%) participated. The most commonly cited reasons for nonparticipation were disinterest (54%) and lack of time (10%). Further details of this study are described elsewhere.13,18 Patients who participated were reimbursed $20.
The questionnaires began with a series of questions addressing demographics, obstetric history, the risks of the procedure and Down syndrome, and attitudes about pregnancy and abortion. Subjects were then asked whether they would want to have an amniocentesis if it were offered to them, and if so, how much they would be willing to pay for the procedure. The willingness to pay question had a 2-part structure that first asked whether the patient would be willing to pay the full cost of testing ($1,300) and, if not, whether they would be willing to pay partial amounts ranging from $50 to $1,000.
The data were entered into a database and analyzed with STATA software (StataCorp LP, College Station, TX). We used univariate analysis to estimate the percentage of women who stated they would undergo invasive prenatal testing if it was offered. We then used multivariable logistic regression analysis to analyze 3 outcome variables of interest: 1) a stated desire to undergo invasive prenatal testing, and among these women 2) willingness to pay the entire cost of the procedure, and 3) willingness to pay at least a portion of the cost.
For these outcome variables an initial explanatory model composed of predictor variables, including age, income, education, occupation, ethnicity, religion, national origin, obstetric history, and attitudes about abortion and the pregnancy, were analyzed. One by one, variables that did not have a significant P 
.05 were removed from the full model, and the restricted versus full models were compared by using the likelihood ratio 
2 test. Provided they did not distort the results of the remaining variables, several variables were left in the model for their clinical relevance despite lack of statistical significance, including ethnicity, religiosity, educational level, and income. To examine effect modification within different strata of predictor variables, a series of cross-product variables was created using the predictor variables left in the model. Groups of cross products were removed from the overall model and significance tested with likelihood ratio 2 test.
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RESULTS |
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). Of these women, 49% (95% confidence interval [CI] 45%, 54%) were interested in having prenatal diagnosis. Not surprisingly, the demand for invasive prenatal testing was higher in women aged 35 years and older as compared with women aged less than 35 years (72% versus 36%, P < .001, 2 test). Among women aged less than 35 years, 39% (95% CI 35%, 42%) stated they would want invasive prenatal testing (Table 2). Again, although the proportion of women aged 35 years and older willing to pay for the procedure was higher than the women aged less than 35 years (61% versus 31%, P < .001, 2 test), almost a third (31%) of the younger women indicated that they would be willing to pay the full price of $1,300 (Table 2). Moreover, 73% were willing to pay a portion of the cost. These proportions are of the women who stated they would undergo prenatal testing if offered. When considering the entire cohort of women under the age of 35, this would be 11% willing to pay full price and 26% willing to pay a portion of the cost. We also observed significant differences in the willingness to both undergo and pay for invasive prenatal diagnosis by income and education (Table 3).
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We next explored whether individuals would be willing to pay full price ($1,300) for an amniocentesis (Table 4) using logistic regression. This was investigated among women who had a stated desire to undergo invasive prenatal testing. After controlling for race, income, religion, and willingness to terminate a pregnancy, women aged 35 years or greater were 3.5 times as likely as women aged less than 35 years to be willing to pay full price for their amniocentesis (95% CI 1.59, 7.88; P = .002). As might be expected, those women who came from households with an annual income greater than or equal to $35,000 were also more likely to be willing to pay the full price for an amniocentesis (OR 2.31; 95% CI 1.02, 5.26, P = .046) when compared with women who came from households whose total income was less than $35,000.
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Different predictors emerged when we examined willingness to pay for at least some portion of the cost of prenatal diagnosis. Household income greater than or equal to $35,000 remained a significant predictor (OR 6.66; 95% CI 2.11, 21.09; P = .001) when compared with women from households with less than $35,000 annual income. Controlling for income, Asian Americans were now found to be 5 times less likely than white women to be willing to pay at least a portion of the cost of the test (Table 5). Age, level of education, religion, and being willing to consider abortion were not found to be statistically significant predictors of being willing to pay a portion of the costs of amniocentesis.
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DISCUSSION |
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Our data also showed a strong association between household income greater than $35,000 and willingness to pay for either the full cost or part of the cost of prenatal diagnostic testing. Because the association between how much women are willing to pay for invasive prenatal testing and what the relative benefit of such testing is to these women is markedly confounded by income, subsidizing women who are willing to pay a portion of their testing as well as those unwilling to pay at all may benefit women who cannot reasonably afford such testing. The qualitative benefits to women from testing such as knowledge gained or reassurance should be used in future studies of whether offering invasive prenatal testing to all women is a cost-effective option.20,21
We also observed some racial/ethnic differences in desire and willingness to pay for invasive prenatal testing. We have previously reported that Latinas and African Americans are significantly less likely to undergo prenatal diagnostic testing than are white and Asian women.22 A somewhat-different pattern emerged in this study. Although women of all races and ethnicity were interested in undergoing prenatal diagnosis in this study, we found that Asian women were less willing to pay for testing, even after controlling for age, income, and education. Although African-American women are less likely to present as early in pregnancy for prenatal care as other ethnic groups,23 both of these analyses were only among women who had presented early enough to receive genetic testing. The differences between these studies may be explained in several ways. First, although socioeconomic status was controlled for in both studies, we had less complete information on socioeconomic status in the former study, which was based on chart review. Therefore, biases based on economic circumstances may have been better controlled in this study, revealing differences in attitudes and preferences regarding invasive prenatal testing among the different ethnic groups. Second, the differences seen between the 2 studies may simply reflect the difference between stated desire and actual behavior. In the previous study, the actual behavior of the women was studied, whereas in this study, their stated intent regarding undergoing and paying for invasive prenatal testing were the primary outcomes.
Our study has several limitations. Although our study population was very diverse with respect to race/ethnicity and socioeconomic class, all of the patients lived in the San Francisco Bay area. Preferences of these women may not be representative of the preferences of women who live in other parts of the country. However, each of the different ethnicities—-African American, Asian, White, and Latina—were well represented. The patients also represented a wide variety of socioeconomic status, different languages, and were recruited from both public and private clinics. Another theoretical concern is that the cost of living in the San Francisco Bay area is greater than that of much of the country. Women in our sample may have less disposable income to pay for these tests than women who live elsewhere. Alternatively, because these women are used to paying higher prices, they might have less "sticker shock" about paying the full price of $1,300 for amniocentesis.
We did not formally test patients’ understanding of the risks and benefits of the prenatal diagnostic procedures or their understanding of Down syndrome and other chromosomal disorders. The precision of the estimate of these patients’ demand for invasive prenatal diagnosis is likely associated with their understanding of these procedures and outcomes. That is, the better patients are educated about the risks and benefits of a procedure, the more likely they are able to incorporate these risks and benefits into any decision regarding the procedure. An estimate of the patients in this study making decisions based on known risks and benefits was the increased demand for genetic testing among the older women, who are already known to be at higher risk. In addition, we did not correlate the stated intent of these women with their actual behaviors,24 because women aged less than 35 years who are not at increased risk are not offered testing. Furthermore, because those women that do undergo testing are usually covered by insurance, we did not have any actual data on how much they did pay, if they did indeed undergo testing. Whether the lower-risk women in our population who state that they would undergo testing if offered actually would do so is unknown. However, in a different population,14 22.5% of women aged less than 35 years did choose to undergo invasive prenatal testing (96% amniocentesis and 4% chorionic villus sampling).
When designing the study, we chose $1,300 as the cost of amniocentesis. This was the standard reimbursement from most managed care companies to the genetics unit at the University of California, San Francisco, in 1997. However, for a patient without insurance, the charge might be almost twice that amount. Furthermore, there is likely to be great geographic variation in both the reimbursements and charges depending on managed care penetration into the market and regional economies. Moreover, because the maximum amount women were asked if they would be willing to pay was the cost of the procedure, all of the surplus demand beyond that point was not estimated. There may be women willing to pay more than the $1,300 that managed care companies have contracted to pay. A better estimate of this might have been an open question that simply asked how much the subject would be willing to pay for testing, or an escalating series of questions that began with a low figure such as $50 and went up until the subject would be unwilling to pay the suggested amount.
In conclusion, we found that the 35-year-old (or similar risk) threshold for offering invasive prenatal diagnostic testing for chromosomal disorders is not supported by the preferences of pregnant women, as measured by their stated interest in undergoing and willingness to pay for invasive prenatal testing if these tests were offered to them. These data underscore previous findings that a sizable proportion of "low-risk" women would be interested in prenatal diagnosis if it were offered to them.14 Although current guidelines recommend using an age or risk threshold to determine who should receive invasive prenatal diagnosis, future policy should be informed by individual variation in preferences, including those of women aged less than 35 years or at similar "low" risk.
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Footnotes |
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doi:10.1097/01.AOG.0000116212.89556.42
Received September 28, 2003. Received in revised form November 7, 2003. Accepted December 4, 2003.
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REFERENCES |
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$50) for Invasive Prenatal Genetic Testing