Informed choice in antenatal Down syndrome screening: A cluster-randomised trial of combined versus separate visit testing

https://doi.org/10.1016/j.pec.2005.02.006Get rights and content

Abstract

Objective

Building upon the results of an observational study, this clinical trial aimed to test the hypothesis that conducting antenatal Down syndrome screening (DSS) at the same time as other tests result in higher rates of informed choice to accept DSS, than when it is conducted separately from other tests.

Methods

The trial used a cluster-randomised controlled design, with informed choice as the outcome measure. The post of midwife was randomised to offer DSS at the same time as other tests (combined visit) or separately from other tests (separate visit).

Results

Overall 43.5% of women made an informed choice about DSS. There was no difference in rates of informed choice for women accepting DSS according to the method of conducting testing (23.7% at combined visit versus 22.5% at separate visit, OR = 1.1, 95% CI: 0.70–1.7, p = 0.67).

Conclusion

Rates of informed choice about DSS were low, but there was no evidence to support that hypothesis that conducting testing at that same time as other tests increased rates of informed choice. This may reflect the limitations of conducting the trial in one centre.

Introduction

There is a consensus that undergoing screening should be the result of an informed choice [1], [2], [3]. This is particularly the case for antenatal Down syndrome screening (DSS) where termination of pregnancy is a possible outcome of the screening process. There are currently two common methods of conducting DSS in the UK: at the same time as other antenatal tests are provided (combined visit); or, separately from other antenatal tests at a test-specific visit (separate visit) [4]. The policy regarding the method of conducting DSS is determined by local practice rather than by national guidelines. Some hospitals offer DSS at a separate visit on the basis that women are more likely to be aware of the tests they are undergoing, whereas others offer DSS at a combined visit on the basis that this is more convenient for women who want to undergo DSS. There is an absence of evidence to inform policy in this area.

Four descriptive and two experimental studies have shown that the uptake of screening tests is higher when they are conducted at the same time as other procedures than when conducted in isolation from other procedures at test-specific visits [4], [5], [6], [7], [8], [9]. It is unclear, however, how the method of conducting screening tests might facilitate or impede the making of informed choices. It may be that conducting screening tests at separate visits leads to more informed choices because it facilitates greater awareness of the screening test to be undergone and allows people to evaluate more carefully whether or not they want to undergo screening. An alternative view is that when screening tests are conducted as part of a combined visit, it leads to greater levels of informed choice by removing practical barriers to test uptake, such as the need to make an extra visit.

We have compared rates of informed choice, using a validated classification, in two hospitals, one where DSS was conducted at a combined visit, and one where it was conducted at a test-specific separate visit [10]. The results of this descriptive study showed that rates of informed choice made by women about DSS were low (52%, 95% CI: 49–55). The results also indicated that the hospital conducting DSS at a combined visit had higher rates of informed choice compared to the hospital conducting it at a separate visit (64% versus 44%, 95% CI: 16, 26%). The difference occurred in the proportion of women making an informed choice to have DSS (41% at the hospital where DSS was conducted at a combined visit versus 21% at the hospital where it was conducted at a separate visit). There was no difference in the proportion of women making an informed choice not to have DSS (23% at both hospitals). These results held when controlling for demographic differences between the women attending the two hospitals. Conducting DSS at a combined visit appeared to facilitate informed choices in those accepting DSS without impairing informed choices in those declining DSS. That is, the removal of practical barriers in the combined visit hospital appeared to increase rates of informed choice to accept DSS without compromising rates of informed choice to decline DSS. The current trial was designed to experimentally test the hypothesis that conducting DSS at a combined visit results in more women making an informed choice to accept DSS, than when it is conducted at a separate visit and thus provide evidence to inform policy in this area.

Section snippets

Design

The trial comprised a cluster-randomised design in which the post of midwife was the unit of randomisation. Allocation was to two groups: the Combined Visit group where midwives offered DSS at the same time as other investigations; and the Separate Visit group where midwives offered DSS at a test-specific separate visit. Randomisation was stratified by four midwife teams.

Setting

The trial took place in a UK district general hospital that was part of a Health Action Zone, indicating a high level of

Midwives

Forty-one midwives providing antenatal care at the trial hospital were invited to participate in the trial, of whom 37 agreed (90%). The 37 midwives who participated in the trial worked in 29 midwife posts. Eight midwives resigned from their posts during the course of the study and were replaced by eight midwives who agreed to participate in the trial, and were trained to conduct testing according to the randomisation of the post.

Women

One thousand two hundred and ninety-two women were invited to

Discussion

There was no evidence to support the study hypothesis that conducting DSS at a combined visit results in more women making an informed choice to accept DSS than when it is conducted at a separate visit: similar proportions of women made an informed choice to accept DSS when it was offered at a combined or separate visit.

The strengths of this trial are two-fold. First the methods used were robust: the design comprised a randomised, controlled trial and, the end point was measured using a

Acknowledgements

We thank the women who participated in this trial. We are also grateful to the community midwives at Luton and Dunstable NHS Trust. This trial was funded by NHS Executive London Regional Office (grant number RDC02020).

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