Low uptake of prenatal diagnosis after established carrier status of a balanced structural chromosome abnormality in couples with recurrent miscarriage

Evaluation of Chromosomal Structural Anomalies in Fertility Disorders

Background and objectives: Reproductive disorders may occur not only due to environmental factors (air pollution, stressful lifestyle, previous abortions or the use of contraceptives) but also due to genetic factors. Materials and Methods: The aim of the study was to identify the range and frequency of chromosomal aberrations in couples (n = 99) with infertility or recurrent miscarriages in Lithuania. The data were collected from the out-patient medical histories. The couples were divided into three groups based on pregnancy, childbirth and the number of miscarriages. The Chi-square test was used to carry out the statistical analysis, and the statistical significance was (p < 0.05). Results: There were 6.6% (n = 13) structural changes observed in the karyotype tests. Chromosomal aberrations were found in 3% (n = 6) of the subjects, while 3.6% (n = 7) of them had chromosomal length polymorphisms. No difference was found between the aberration frequency in the karyotypes of men and women (p > 0.05). The most common aberrations were balanced translocations (23.1%, n = 3) which accounted for 15.4% of the reciprocal (n = 2) and 7.7% of the Robertsonian type (n = 1) of translocations. The most frequent aberrations were found in couples with the inability to conceive (42.9% (n = 3), p = 0.031). The childless couples and those with recurrent miscarriages showed an aberration rate of 8.2% (n = 5), while in the couples with at least one child it was 16.1% (n = 5). The group of couples unable to conceive had a significantly higher aberration rate of 28.6% (n = 2), p = 0.029. Miscarriages in partners' families accounted for 8.1%. Miscarriages on the female side of the family accounted for 4.5% (n = 9), on the male side it accounted for 2.5% (n = 5) and on both sides it accounted for 1.1% (n = 2). There were no statistically significant differences observed between the female and male sides (p > 0.05). The miscarriages observed in the second group of couples (childless with ≥2 miscarriages) were more frequent at 18.1% (n = 11), in the third group (having children ≥2 miscarriages) they were less frequent at 12.9% (n = 4), while no miscarriages were recorded in the first group of infertile couples. In total, 3% of the identified significant chromosomal aberrations were likely to trigger miscarriages or the inability to conceive. Conclusions: In couples with reproductive disorders, chromosomal mutations and chromosomal length polymorphisms were found at similar rates: 3% vs. 3.6%. The highest aberration rate was found in couples that were unable to conceive, a lower one was found in a group with children and ≥2 miscarriages, and the lowest one was found in a childless group of subjects with ≥2 miscarriages. The miscarriage rate in partner families was 8.1%; however, no difference was found between the male and female sides.

Economic analysis of chromosome testing in couples with recurrent miscarriage to prevent handicapped offspring

STUDY QUESTION

Which strategy is least expensive to prevent the birth of a handicapped child in couples with recurrent miscarriage (RM); parental chromosome analysis followed by amniocentesis in case of carrier status of one of the parents, or amniocentesis in all ongoing pregnancies without the knowledge of parental carrier status?

SUMMARY ANSWER

For virtually all couples with RM amniocentesis in all ongoing pregnancies without the knowledge of parental carrier status is less expensive in preventing the birth of a handicapped child than parental chromosome analysis followed by amniocentesis in case of carrier status of one of the parents.

WHAT IS KNOWN ALREADY

One of the causes of RM is a balanced chromosome abnormality in one of the partners. If one of the partners is carrier of a balanced structural chromosomal abnormality, the risk of offspring with an unbalanced structural chromosome abnormality is increased. Like all couples, couples with RM also have an age-dependent risk for fetal aneuploidy, of which trisomy 21 is most common.

STUDY DESIGN, SIZE, DURATION

Model-based economic analysis to compare costs and effects of two strategies in couples with RM to prevent the birth of a handicapped child in case of ongoing pregnancy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Comparison of two strategies in women with RM: strategy (I) parental chromosome analysis followed by amniocentesis in pregnancy in case of carrier status of one of the parents and strategy (II) amniocentesis in all ongoing pregnancies without the knowledge of carrier status. No testing was the reference strategy. Data on probabilities and costs were derived from the literature. Incremental costs and effects were calculated [incremental cost-effectiveness ratio (ICER)]. Effectiveness was expressed as the number of prevented births of handicapped child equivalents compared with no testing. In these calculations, the birth of a handicapped child was valued 10 times worse than the loss of a viable pregnancy due to amniocentesis.

MAIN RESULTS AND THE ROLE OF CHANCE

Depending on the risk for carrier status, the ICER for Strategy I (parental chromosome analysis followed by amniocentesis in case of carrier status of one of the parents) varied between € 226,000 and € 6,556,000 per prevented handicapped child equivalent. For Strategy II (amniocentesis in all ongoing pregnancies without the knowledge of carrier status), the ICER varied between € 2000 and € 233 000 per prevented handicapped child equivalent. Strategy I was less expensive than Strategy II only for a small subgroup of couples with maternal age <23 years, three or more previous miscarriages and a family history of RM.

LIMITATIONS, REASONS FOR CAUTION

Our analysis is not a plea for amniocentesis in all women with RM. Individual risk assessment with serum markers and nuchal translucency is probably more effective at lower cost.

WIDER IMPLICATIONS OF THE FINDINGS

This analysis can be used by clinicians to explain the chances of adverse pregnancy outcome in couples with RM, as well as by policy makers in health-care economics. Future guidelines on RM might be more restrictive from the perspective of the limited health-care resources that we have available.