Prenatal cystic fibrosis carrier testing: designing an information leaflet to meet the specific needs of the target population

Population-based carrier screening for cystic fibrosis: a systematic review of 23 years of research

Cystic fibrosis is the most common severe autosomal recessive disease, with a prevalence of 1 in 2,500-3,500 live births and a carrier frequency of 1 in 25 among Northern Europeans. Population-based carrier screening for cystic fibrosis has been possible since CFTR, the disease-causing gene, was identified in 1989. This review provides a systematic evaluation of the literature from the past 23 years on population-based carrier screening for cystic fibrosis, focusing on the following: uptake of testing; how to offer screening; attitudes, opinions, and knowledge; factors influencing decision making; and follow-up after screening. Recommendations are given for the implementation and evaluation of future carrier-screening programs.

Factors affecting decisions to accept or decline cystic fibrosis carrier testing/screening: A theory-guided systematic review

PURPOSE

To assess factors affecting individuals' decision to accept or decline cystic fibrosis carrier testing/screening, as reported in studies published until December 2006. The Health Belief Model guided classification of each factor, and the studies' methodological quality was assessed.

METHODS

A three-stage search and retrieval process, alongside application of specific inclusion/exclusion criteria, yielded 40 studies (in 35 articles). For each reviewed study, authors abstracted and organized selected data into a matrix and assigned a methodological quality score.

RESULTS

The four most frequently identified acceptance factors included three Health Belief Model factors and one non-Health Belief Model factor: perceived benefits of undergoing cystic fibrosis carrier testing/screening, weaker perception of barriers to cystic fibrosis carrier testing/screening, fewer/no children or desiring children, and research-related factors (non-Health Belief Model factor construct). All four most frequent factors associated with declining testing were Health Belief Model factor constructs: perceived barriers to obtaining cystic fibrosis carrier testing/screening, parity, lack of knowledge, and weaker perception of benefits of undergoing cystic fibrosis carrier testing/screening. The average methodological quality of the studies was 10.2 (SD=3.2; range, 5-18 points).

CONCLUSIONS

The methodological and theoretical quality of this body of literature could be substantially improved if researchers employed theory-based approaches, tested (and reported) the validity/reliability of their own data, and employed multivariate statistical analyses and/or better controlled research designs. Improving the quality of future studies may allow better inferences regarding the relative contribution of each factor identified in this review to individuals' decision-making process.

Perceived personal control (PPC): a new concept in measuring outcome of genetic counseling

Many researchers have tried to establish criteria for the evaluation of genetic counseling and the assessment of its success. Most studies focused on counseling outcomes mainly educational and reproductive variables. In the present study we introduced the concept of "perceived personal control" (PPC), which captures a wider and more meaningful range of effects of genetic counseling. It was found to be central to coping with health threats and to adapting to a broad spectrum of health problems. This study investigated 154 counseling cases. Counselees were requested to complete pre- and post-counseling questionnaires consisting of a knowledge test, measures of PPC, expectations/evaluations of counseling, and satisfaction with the procedure. Comparisons of mean PPC scores before and after counseling showed significant increases. Higher post-counseling PPC was found among counselees who had been given a definite diagnosis, a specific recurrence risk, and been offered prenatal diagnosis. Post-counseling PPC also correlated with knowledge, satisfaction, counseling evaluations, and expectation fulfillment. The findings suggest that PPC is a valid measure for the evaluation of genetic counseling outcomes. The psychometrically reliable scales developed in this study can become helpful tools for assessing genetic counseling both in research and in clinical practice, helping the counselor evaluate the counseling session and focus on the counselees' needs.

Mixed messages: presentation of information in cystic fibrosis-screening pamphlets

Written pamphlets are an important source of information for individuals deciding whether to undergo carrier testing for cystic fibrosis (CF). Adequate understanding of the condition and reproductive options following the diagnosis of a fetus with CF are critical to informed decision making. The information given about CF and reproductive options in 28 pamphlets about carrier testing, from commercial and noncommercial organizations in the United States and the United Kingdom, aimed at prenatal and other populations, was assessed. The amount of information provided about CF showed a range of 1-37 sentences (median 6.5), with most being relatively neutral and with a minority conveying a positive or a negative image. Positive sentences were less common in British, U.S. commercial, and prenatal pamphlets. Statements about life expectancy also varied considerably, both in the ages provided and in the degree of optimism conveyed. In addition, the pamphlets varied in the amount of information they provided about reproductive options following the diagnosis of a fetus with CF. Abortion was mentioned in just 15 pamphlets, more often in the United Kingdom than in the United States and more frequently in pamphlets from noncommercial than in those from commercial organizations. Wide variation in the descriptions of CF and the reproductive options presented raises concerns about the extent to which any one pamphlet may present balanced information. The choices about what information to include in educational materials need to be explicitly considered on the basis of the message intended to be sent.

Prenatal screening for cystic fibrosis carriers: does the method of testing affect the longer-term understanding and reproductive behaviour of women?

A comparative study of women who underwent prenatal cystic fibrosis (CF) carrier screening by either the 'two-step method' or the 'couple method' was carried out 2-4 years after testing. Recall of the screening test and test result, understanding of the implications of the test result, and reproductive intentions and behaviour were compared. Women screened by the two-step method were significantly better informed on the genetic implications of the test result and the significance of being a single gene carrier than their couple screen counterparts. Regardless of the method of screening, a majority of those who had received a negative test result erroneously believed that they were definitely not a carrier. However, women who intended having further children were significantly more likely to understand correctly that a negative test result meant that they were unlikely to be a CF carrier. The method of testing had no influence on reproductive intentions or behaviour. Differences in emphasis, content and presentation of pre-screening information and counselling between the two methods of screening are identified. Reasons for variation in the long-term understanding between women screened by the two methods are discussed.

Cystic fibrosis carrier population screening in the primary care setting

To determine the receptivity of prenatal care providers and their patients to carrier testing for cystic fibrosis (CF), we offered free carrier screening, followed by genetic counseling of carriers, to all prenatal care providers in Rochester, NY, for all their female patients of reproductive age, pregnant or not. Of 124 prenatal care providers, only 37 elected to participate, but many of these offered screening only to pregnant women. The acceptance rate among pregnant women was approximately 57%. The most common reasons for accepting screening were to obtain reassurance (50.7%) and to avoid having a child with CF (27.8 %). The most common reasons for declining screening were not intending to terminate a pregnancy for CF (32.4%) and believing that the chance of having a CF child was very low (32.2%). Compared with decliners, acceptors were more likely to have no children, regarded having a child with CF as more serious, believed themselves more susceptible to having such a child, knew more about CF, would be more likely to terminate a pregnancy if the fetus were shown to have CF, and more strongly supported offering CF screening to women of reproductive age. Of 4,879 women on whom results were obtained, 124 were found to be carriers. Of these 124 carriers, the partners of 106 were tested. Of the five at-risk couples, four requested prenatal diagnosis and one requested neonatal diagnosis. No woman found to be a carrier whose partner tested negative requested prenatal diagnosis. Except for the imperfect knowledge of those testing negative, none of the adverse outcomes predicted for CF carrier testing in the general population were observed in this study.

Carrier screening for cystic fibrosis

A number of different models of CF carrier screening have now been tested in pilot trials. Apart from opportunistic and cascade testing (which are strictly speaking not true forms of screening), the major programmes have been directed either to young adults in primary care or to pregnant women in antenatal clinics. Only in the latter form of screening has sufficient data been collected to allow conclusions to be reached on the optimum mode of delivery. It seems very probable that when CF carrier screening passes into routine service, it will be the antenatal couple model that is used.

Antenatal screening for cystic fibrosis: a trial of the couple model

OBJECTIVE

To assess the delivery and acceptability of antenatal couple screening for cystic fibrosis. Carrier status was notified only when both members of a partnership had cystic fibrosis alleles and therefore a one in four risk of having an affected child.

DESIGN

Mouthwash samples were tested when both partners participated. Results were returned only to positive couples.

SETTING

Two large maternity hospitals in Edinburgh.

SUBJECTS

Screening was offered to all couples who booked at one of the two hospitals.

MAIN OUTCOME MEASURES

(a) The take up of screening, carriers and carrier couples identified, take up of prenatal diagnosis, and numbers of affected fetuses detected; (b) questionnaire measures of patient satisfaction and stress.

RESULTS

Screening was offered to 8536 couples. 714 (8.4%) were regarded as ineligible, usually because of late booking or absence of a partner. 1900 (24.3%) of the remainder declined screening. Among the 5922 screened couples, four tested positive--that is, both partners were cystic fibrosis heterozygotes. All four elected to have prenatal diagnosis. There were three terminations of pregnancy because of an affected fetus, one couple having two successive pregnancies with affected fetuses. The participation rate was 76% for eligible couples (5922/7822) and 69% for all couples (5922/8536). Only 89 screened couples (1.5%) requested information on individual carrier status. No anxiety was detected among a cohort of the screened population, and 99% of questioned participants expressed satisfaction with the concept of couple screening.

CONCLUSIONS

Antenatal couple screening is a satisfactory and acceptable way of screening for cystic fibrosis and has been adopted as routine in the two trial hospitals.

Cost-benefit analysis of a national screening programme for cystic fibrosis in an Israeli population

The recently acquired ability to identify 97% of CF carriers in an Israeli Ashkenazi population, prompts an evaluation of a nationwide screening programme. In 1993, the programme would first screen and counsel 9,261 parents, then 396 spouses of carrier parents and finally screen 16.5 fetuses where both parents are carriers. Assuming 92% of screened parents choose abortion of fetus screened positive, 2.33 cases of CF will be prevented in 1993 at a direct cost of $781,000. The $326,000 direct costs of preventing a CF case, exceed the lifetime excess direct costs per case of $297,000. However, benefits of screening also accrue to subsequent pregnancies, resulting in a direct benefit ($14.45 million) to cost ($10.39 million) ratio of 1.39/1 for the period 1993-2032. When benefits and costs resulting from mortality changes, work absences and transport costs are included, the benefit ($15.95 million) to cost ($13.88 million) ratio falls to 1.15/1. Benefit-cost ratios are lower for other ethnic groups in Israel, due to lower carrier rates and lower mutation detection abilities. A CF screening programme will increase the freedom of individuals choice, but should be carried out carefully in order to minimize stigmatization and even discrimination against CF carriers.

Prenatal cystic fibrosis carrier screening: factors in a woman's decision to decline testing

Among 2207 women eligible to be screened for cystic fibrosis (CF) carrier status during pregnancy, 325 (15 per cent) declined to be tested. Of these, 260 (80 per cent) answered a questionnaire soliciting their reasons for not participating. The main factor was opposition to termination of pregnancy, with 43 per cent being against termination for any reason and another 11 per cent against termination of a CF fetus. Other reasons given were partner's disapproval or non-participation (10 per cent), perceived risk of a CF child being low (7 per cent), the error rate of the test (6 per cent), and the generation of unacceptable levels of anxiety (5 per cent). Eleven women (4 per cent) said that they did not wish to be tested during pregnancy, but only six of these would have accepted screening at another time.

Prenatal screening for cystic fibrosis: attitudes and responses of participants

A screening programme to detect cystic fibrosis heterozygotes has been running in the antenatal clinics of a major Edinburgh maternity hospital for more than 2 years. A questionnaire was used to assess participants' knowledge of the genetics of the disorder and their attitudes to being screened. The respondents were 64 female heterozygotes and 63 of their non-heterozygous male partners, 101 female controls and 100 male controls. Although the two groups of controls received far less direct information than the carriers and their partners, all four groups were well informed about the genetics of cystic fibrosis and the significance of being a gene carrier. A majority of each group felt that adequate information had been given in the information leaflet, that they understood the purpose of screening and that they were glad to have participated. There was a consensus that CF carrier testing should be routinely offered to pregnant women, and also that it should be available in family planning clinics and GP health centres, but not in schools.

What young people think and do when the option for cystic fibrosis carrier testing is available

We report findings in phase II of a pilot study of cystic fibrosis (CF) carrier screening/testing by mutation analysis. Phase I has been reported elsewhere. Eligible participants in phase II (n = 815) were students (15 to 17 years of age) in public high schools. An educational component (exchange of information and discussion about common genetic disorders including CF) preceded, by one week or more, voluntary participation in the screening component which required a blood sample. The uptake rate for screening was 42%. Nine carriers (2pq = 0.0260) were identified, all with the delta F508 mutation; students were also tested for G551D, G542X, W1282X, and -549-mutations, but no carriers of these alleles were found. Carriers had positive views of the education and testing experiences. Persons identified as 'non-carriers' were also surveyed (n = 135, response rate 41%). As in phase I, the majority (83%) again understood that a negative DNA test had not excluded them from possible carrier status. Students who participated in the informational component but were not screened served here as controls in the follow up survey (n = 208, response rate 53%). Their views were similar to those of the screened non-carriers, and similar also to those held by students, adults, pregnant women, couples, and CF relatives in other communities.

Prenatal screening for cystic fibrosis: psychological effects on carriers and their partners

This study aimed to assess the psychological impact of screening for cystic fibrosis (CF) carrier status in a population of pregnant women. A cohort of 1798 women, who accepted the offer of testing before 18 weeks of pregnancy, filled in a self administered questionnaire seeking information on their perceived risk of carrier status and their emotional response, as well as a general health questionnaire (GHQ). Sixty-four women identified as CF carriers had partners who received a negative test result. This group and their partners were assessed, together with selected controls, on four further occasions: (1) on receiving the carrier's positive test result; (2) on receiving the partner's negative test result; (3) six weeks later; (4) six weeks after delivery. The instruments used were the GHQ and the Symptom Rating Test (SRT). When compared to control subjects, carriers showed a significant increase in generalised psychological disturbance which could be attributed specifically to symptoms of anxiety and depression during the period (average four days) that they awaited their partner's test result. On receiving a partner's negative test result, the carriers returned to control levels and maintained this equilibrium. Although there was no significant difference in generalised psychological disturbance between partners and their selected controls, partners did become significantly more anxious and manifested feelings of inadequacy while awaiting their own test result. Both male partners and male control subjects were more likely to become anxious if their partner was distressed.

Prenatal screening for cystic fibrosis

Screening for carriers of CF (cystic fibrosis) is now possible but the best way of delivering such a service is unknown. In one model 4348 women attending antenatal clinics in an Edinburgh maternity hospital were invited to participate in a trial of prenatal screening. Mouthwash samples were tested for six CF alleles (85% of mutant genes) and when a woman was found to be a CF carrier her partner was also tested. Heterozygous couples were offered prenatal diagnosis. 609 (14%) women declined to enter the trial and another 574 (13%) were not screened, usually because of late booking. Among the remaining 3165 women there were 111 carriers of a CF gene (1 in 29). 4 of these 111 had carrier partners and these couples opted for prenatal diagnosis, the 1 pregnancy with an affected fetus being terminated. The psychological impact of screening was assessed by the general health questionnaire. There was a significant increase in stress at the time of the test result among women identified as carriers. However, this disappeared when their male partners tested normal and did not reappear later in the pregnancy. By providing time for couples to discuss the possibility of screening and by offering the test at a point (the antenatal booking clinic) at which most pregnant women are seen, this approach has advantages, provided that counselling is readily available.