Triple-marker screening in British Columbia: current practice, future options

Bassett K, Lee P M, Green C J, Mitchell L et al
Record ID 32000000905
Authors' objectives:

The aim of this report is to examine maternal serum triple-marker screening (TMS) for fetuses with Down syndrome, other chromosomal abnormalities, and spina bifida, in the British Columbia context. Evaluation is both qualitative, addressing the personal and social significance of TMS, and quantitative, assessing effectiveness and cost.

The review is organized around the evaluation of four possible options for funding TMS. The first three options are in essence variations on current TMS practice in the province. A fourth option adds co-ordination of TMS, that is, provision, standardization, evaluation, and education throughout the province.

Authors' recommendations: In terms of the four options considered by this review, we draw the following conclusions: Option 1. Current practice of ad hoc funding. The TMS blood test is currently funded for women of all ages. There is no program funding for co-ordination, systematic quality control, or provider or patient education. This form of funding is termed ad hoc by geneticists and proponents of comprehensive program funding because individual clinicians, institutions and regions, as opposed to a centralized authority, are left to determine whether TMS is integrated into diagnostic and counselling services in their area. Local and international experience recognizes that to pay for TMS without adequately funding infrastructure support for quality assurance and education as well as diagnostic and abortion services, risks unnecessary harm to women who lack ready access to adequately informed clinicians or diagnostic facilities. Option 2. TMS funding for women over age 35. Offering TMS on the basis of maternal age would seem to provide a way to integrate TMS into clinical practice without fundamental change to existing social understandings of pregnancy and disability, especially the awareness of an accelerating risk of Down syndrome with advancing maternal age. However, this approach would detect, at most, 30% of affected fetuses. Moreover, women over age 35 may find the false-negative rate associated with TMS unacceptable, and opt for amniocentesis regardless of negative TMS result. It is of significant concern that much of the literature on womens experiences with prenatal screening suggests that the primary determinants of appropriateness of this type of testing are womens perceptions of risk, not actual risk, and womens perceptions of disability, not actual disability. It is therefore difficult to justify assigning an age cut-off level using pre-determined population-based features such as a detection rate or maximum cost per affected fetus detected. Despite the acknowledged age-dependent prevalence of relevant conditions, from the perspective of the individuals concerned, TMS could be appropriate for as many women under an arbitrary screen-eligible age level as over it. Option 3. No public TMS funding. A decision to withhold government funding for TMS would send a positive message to the Down syndrome and disability-rights community. However, although this community would appreciate the broad-level support, they also recognize that TMS would inevitably continue through private funding, and necessarily with much less opportunity for them to influence the educational messages provided to physicians and women. The privatization of TMS and the subsequent difficulty low-income women and couples would be likely to experience in obtaining TMS risk further marginalization of disadvantaged groups. Option 4. Co-ordinated TMS funding. Co-ordinated TMS funding refers to the cost of maintaining TMS standards, independent of the actual utilization level. Informed opinion and focus groups interviewed during the data-gathering phase of the review gave this option the widest degree of support. The consensus was that TMS needs to be provided as part of a co-ordinated prenatal screening service in order to minimize the potential for harm and to provide equitable access. Since TMS is likely to increase in response to a complex combination of factors influencing clinical care, this option is also the most challenging: to provide TMS as part of a co-ordinated prenatal screening service in northern and isolated regions of the province will require an active government role in achieving an unprecedented level of decentralization for those diagnostic and counselling services currently concentrated in Vancouver.
Authors' methods: Systematic review
Project Status: Completed
Year Published: 2000
English language abstract: An English language summary is available
Publication Type: Not Assigned
Country: Canada
MeSH Terms
  • Costs and Cost Analysis
  • Down Syndrome
  • Mass Screening
  • Prenatal Diagnosis
Organisation Name: British Columbia Office of Health Technology Assessment
Contact Address: B. C. Office of Health Technology Assessment, Centre for Health Services and Policy Research, S-184 Koerner Pavilion, 2211 Wesbrook Mall, The University of British Columbia, Vancouver, B. C., V6T 1Z3, Canada.
Copyright: BCOHTA
This is a bibliographic record of a published health technology assessment from a member of INAHTA or other HTA producer. No evaluation of the quality of this assessment has been made for the HTA database.