JrMed Genet 1997;34:459-464

The uptake and acceptability to patients of cysticfibrosis carrier testing offered in pregnancy by theGP

N E Hartley, D Scotcher, H Harris, P Williamson, A Wallace, D Craufurd, R Harris

Wolfson FoundationGenetic Centre, 6thFloor, St Mary'sHospital, HathersageRoad, ManchesterM13 OJH, UKN E HartleyD ScotcherH HarrisP WilliamsonA WallaceD CraufurdR Harris

Correspondence to:Dr Hartley.

Received 10 April 1996Revised version accepted forpublication 13 January 1997

AbstractObjective-To determine the uptake andacceptability of cystic fibrosis (CF) car-rier testing when offered to women at thefirst antenatal booking appointment bytheir general practitioner.Setting-Eight general practices in thenorth west region with a combined patientlist size of 42 000.Design-Offer of carrier screening at firstantenatal booking appointment to preg-nant women below 14 weeks' gestation;women accepting were alternately allo-cated to either couple testing (with fulldisclosure) or stepwise testing.Subjects-Six hundred and twenty threewomen were offered CF carrier testing.Main outcome measures-(1) Acceptanceof the offer of CF carrier testing. (2)Acceptability of the test to women follow-ing screening, evaluated through (i) postalquestionnaire, (ii) semistructured inter-view.Results-Five hundred and twenty-nine(84.9%) women accepted the test; the levelofuptake varied across the eight practices(range 11-99%). In 26/249 (10%) coupletests no paternal sample was provided.When asked what had influenced theirdecision to be tested, 59/377 (16%) womendid not refer to CF in their answers and six(2%) said that they did not feel they couldrefuse the test. After receiving theirresults, 368/379 (97%) women felt that theyhad made the right decision to be tested,but two carriers and three non-carriershad felt unhappy about testing. Coupletesting with full disclosure was associatedwith lower anxiety levels two weeks afterreceiving the result for the pregnancy thanstepwise testing and 82/278 (29%) non-carriers believed that they had no residualrisk in relation to CF.Conclusions-The response from women

accepting CF carrier testing was largelypositive but a minority of women ex-

pressed concern about the test and theway it was offered and a substantialproportion of women were falsely reas-

sured by their "negative" result. Higherlevels ofacceptance tended to occur in thepractices which offered the test there andthen rather than giving couples more timeto decide about testing. Some women

appeared to have accepted the test be-cause of a belief in the importance of test-

ing in pregnancy rather than because ofthe disease in question.(J Med Genet 1997;34:459-464)

Keywords: cystic fibrosis; screening in pregnancy;general practice

Before the cloning of the cystic fibrosis (CF)gene,`3 CF carrier testing used linkage analysisand was thus restricted to people with a familyhistory of CF. The subsequent development ofPCR technology has made it feasible to offerCF carrier screening to the general population.Extending CF carrier testing beyond familieswith a family history has raised new issues.How do we know who would want such testingand should it be offered before pregnancy orduring pregnancy, in primary care, in theantenatal clinic, or in some other setting? Test-ing in pregnancy has the advantage of ap-proaching women at a time when they arereceptive to the idea of screening.4-6 The iden-tification of carrier couples before the end ofthe first trimester also allows couples theoption of an early termination of an affectedpregnancy. However, as this test is not specificto pregnancy, offering the test outside preg-nancy has the advantage of enabling carriercouples to opt for counselling and considertheir reproductive options without the anxietyof an ongoing pregnancy.79 It would seempreferable to offer testing before pregnancy,'0but it is debatable how relevant this is thoughtto be by people with no previous CF familyhistory. As well as the timing of the offer of thetest, there is also the question of who shouldoffer it: GPs, practice nurses, midwives,antenatal doctors, genetic coworkers, or publichealth workers.

Consideration should also be given to themethod by which the test is offered. Wald"introduced "couple" testing in pregnancywhereby samples are obtained from both part-ners but only those couples where bothpartners were found to be carriers wereinformed of their carrier status. This methodhas the advantage of concentrating counsellingresources on carrier couples and avoids theinevitable time of anxiety when a carrier mustwait for the partner's sample to be tested as isthe case in stepwise testing.' However, coupletesting without full disclosure of the resultsdoes not allow for cascade testing in familieswhere only one member of the couple has beenfound to be a carrier. Resolution of these ques-tions has implications for the large number of

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new genetic screening tests which will probablybecome available.

This study concentrates on the acceptabilityof CF carrier testing to participating womenand its immediate effect on individual subjectsand couples.'2

MethodsSUBJECTSBetween July 1992 and February 1993, eightnorth west general practices with a combinedlist size of 42 000 began offering cystic fibrosiscarrier screening to pregnant women at the firstantenatal booking appointment. GPs wereasked to participate for two years. Women wereexcluded from the study if they booked after 14weeks' gestation or requested a termination ofpregnancy at the booking appointment. As CFgene carrier frequency is highest in the whitepopulation (1 in 20 in the north west region ofEngland), all but one of the practices selectedhad a low ethnic minority. However, as it wasdesirable for GPs to incorporate the offer of thetest into their routine antenatal bookingappointment, GPs were asked to offer the testto all eligible pregnant women, irrespective oftheir ethnic background. Appropriate correc-tions were made to carrier risks using theinformation provided by GPs about a person'sethnicity.Women were provided with a leaflet describ-

ing cystic fibrosis, its genetic inheritance, andthe implications of a positive carrier screeningtest. Having accepted the offer of the test,women were alternately allocated by the GPeither to stepwise or couple testing and weregiven a second more general leaflet which wasspecific to the method of testing. Stepwise test-ing involved the woman providing a mouth-wash sample in the surgery. Her partner wasonly tested if she tested positive. For coupletesting the woman provided a sample in thesurgery and included in their second leafletwere instructions on how her partner shouldprovide and return a mouthwash sample alongwith the necessary equipment. Both sampleswere tested simultaneously.

In order to investigate the possibility thatwomen may not be given enough time to makean informed decision about accepting the offerof the test, practice 7 was asked to offer the testin an alternative way. The intention was toexamine whether the uptake was altered by thismethod. The GP discussed the test with thepregnant woman, who took the informationleaflet and test equipment home to explain thetest to her partner. The couple then returnedboth samples to the practice if they wanted thetest. In reporting the results of the project, thispractice will not be included in any comparisonof stepwise and couple testing methods.

Couples with a known family history of CFwho had not previously been CF carrier testedwere offered the test, but because of theincreased prior risk, GPs were asked to obtainsamples from both partners. This avoidedunnecessary delay if either sample tested posi-tive. When appropriate one of the genetic asso-ciates (DS, NH) visited these couples to clarify

their family history and to establish whether amutation analysis had been carried out in theaffected family member.

All samples were sent to the RegionalMolecular Genetics Laboratory at St Mary'sHospital, Manchester, where they were testedfor the four most common cystic fibrosis muta-tions in the north west region of England (AWallace, personal communication). The risk ofthe person being a carrier and the risk to thepregnancy of CF were reported in writing to allpatients tested and to their respective GPs.

EvaluationTwo weeks after the test result was posted,women were sent a questionnaire containing27 questions covering women's feelings aboutthe way the test was offered, their anxiety whilewaiting for the results, and their knowledgeabout cystic fibrosis, its inheritance, and theirpersonal carrier risk. Women were also asked tocomplete a Spielberger State Trait AnxietyIndex questionnaire'4 and during the latter 18months of the project an additional question-naire was introduced exploring womens' feel-ings towards their pregnancy.'5Women willing to complete a questionnaire

were also asked to agree to be interviewed athome by a genetic associate (DS, NEH). Thesemistructured interview covered similar areasto the questionnaire but in more detail, as wellas more sensitive questions about reproductiveintentions that were thought to be inappropri-ate for inclusion in a postal questionnaire.

ResultsOf the 623 women offered the test, 529(84.9%) women accepted. Two hundred andsixty two were allocated to couple testing and267 were allocated to stepwise testing. Fortytwo women declined the test and a further 52women, having taken information and equip-ment away, then failed to return samples. In thestepwise group, 10 maternal carriers werefound and all their partners were found to be atlow risk. In the couple group, seven maternalcarriers were found and nine paternal carriers,including the only carrier couple detected.4

All except practice 7 were asked to offer thetest in the same way. Fig 1 indicates how someGPs modified the original method during thestudy. The reasons for these modificationsranged from practical issues, such as the timetaken to offer the test, to GPs' concerns aboutpopulation screening and whether informedconsent was being given by women before test-ing and also the direct experience of identifyingCF carriers.

LEVEL OF UPTAKE BY PRACTICEThe uptake figures shown in fig 2 relate to thewoman's acceptance of cystic fibrosis carriertesting as distinct from accepting a particularmethod of testing. GPs were not asked todiscuss and record the details of why womendeclined to be carrier tested.

For women accepting the test and allocatedto couple testing, the paternal sample wasreturned by over 90% of partners in five prac-tices but by only 52% and 72% in practices 2

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The uptake and acceptability to patients ofCF carrier testing in pregnancy

Woman thinks/knows she is pregnant

Variation:Leaflets taken home todiscuss with partner, furtherappointment made ifnecessary [prac 1:1/3,prac 3:1/3, prac 4:1/4,prac 6:2/3*, prac 7:3/3]

Antenatal booking appointment:test offered there and then by GP

[prac 1:2/3, prac 2:1/1,prac 3:2/3, prac 4:3/4,prac 5:2/2, prac 6:1/3,prac 8:1/1]

Test accepted

See GP (or practice nursein prac 1:3/3)

Allocation:leaflets given

Stepwise Couple

Maternal sample givenon day in surgery

Paternal sample provided at homeand handed to surgery next day

*One of these GPs provided women with tubes and saline and asked them topost their sample (and their partner's where appropriate) directly to thelaboratoryFigure 1 Protocol variations in the method of offering cystic fibrosis carrier screening by 20 GPs in eight practices. Thepractice (prac) number is followed by the proportion of GPs in that practice who offered the test in a particular way. OneGP not wishing to participate has been excludedfrom this figure.

and 3, respectively. In 12 of the 26 cases wherea paternal sample was not returned the womeneither declined or did not respond to follow upso no information about the partner's samplewas available. In the remaining couples thematernal interview and questionnaire datashowed that four of the 14 partners "didn't getround to it" and in 2/14 the sample was notreceived by the laboratory. In eight cases thepartner either declined or was reluctant to givea sample.

CHARACTERISTICS OF WOMEN TAKING THE TESTThe median age at the time of testing was 27years (range 15-42) with 96% giving their eth-nicity as white. Comparable data were not col-lected from women declining the test. Themedian gestation at the time of testing wasseven completed weeks.

RESPONSE BIASQuestionnaires were not sent to seven womenwho had miscarried, one woman who had hada termination of pregnancy since providing thesample, one woman who had a family history ofCF, one woman in the stepwise group whosesample failed to give a result and who did not

provide a repeat sample, and one woman foundto be in a carrier couple. A total of 382completed questionnaires were returned. Thedifference between questionnaire completionrates in the stepwise (79%) and couple (85%)groups was of borderline statistical significance(p=0.06). A total of 305 women also agreed tobe interviewed of whom 13 failed to completethe questionnaire.There were 123 women from whom no

questionnaire or interview data were obtained;for 35 it was not appropriate either because thewoman had subsequently miscarried, had atermination of pregnancy, or was unwell, a fur-ther 60 declined follow up, and for 28 the rea-son was unknown. All but one of the 14 mater-nal carriers whom it was appropriate toapproach provided either questionnaire orinterview data or both (93%) compared to82% of maternal non-carriers.

REASONS FOR UPTAKE OF TESTWomen were asked to indicate which, if any, ofthe factors suggested had influenced theirdecision to take the test (table 1). All sixwomen who only ticked the option "I did notfeel I could refuse the test" were asked to do the

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77

98

96

95

99

64

45

11

0 25 50 75Percentage providing sample

100

Figure 2 Uptake of cystic fibrosis carrier testing by practice. Vertical line indicatesestimate ofpercentage accepting, horizontal line indicates 95% confidence intervalestimate. *In this practice, percentage accepting is where both maternal and paternsamples were provided.

Table I Factors influencing the decision to have the test

Factors listed in questionnaire

(a) You feel that all tests offered in pregnancy are important(b) You wanted to know if you were a carrier of the cystic fibrosis gene

(c) You were sure that you didn't want to have a child with cystic fibrosis(d) You didn't feel that you could refuse the test

(e) Your partner was keen for you to have the test(f) It's difficult to remember now(g) None of the reasons given

Categorised response No ofwomenAnswer included a reference to CF (b or c) 304 (81%)Answer did not include a reference to CF but indicated

that woman felt all tests in pregnancy were important(a but not b or c) 59 (16%)

Answered only that they did not feel they could refusethe test (d only) 6 (2%)

Answered only that none of the reasons given applied to

them (g) 8 (2%)Total 377 (100%)

Table 2 Decision making

What wouldyou do ifyou andyour partner both were found Maternal Maternalto be carriers? non-carrier (%4) (%o)

Not thought about situation at all 34 (12) 4 (25)Did not know 6 (2) 0 (0)Wait for results before making decision 113 (40) 4 (25)Would consider further testing 84 (30) 6 (38)Would not consider termination 46 (16) 2 (13)Total 283 (100) 16 (100)

Table 3 Anxiety while awaiting test result for pregnancy (measured two weeks aftknown): comparison between couple and stepwise groups

We would like to know how you felt while waitingfor theresults of the test, compared to how you usually feel, Stepwise Couple ca

were you non-carriers (Yo) nzon-carri

Much more worried than usual 3 (2) 6 (3)A bit more worried than usual 54 (31) 65 (35)No more worried than usual 109 (63) 115 (61)Less worried than usual 6 (4) 2 (1)Total 172 (100) 188 (100

Number test there and then in the GP's surgery andoffered there is no indication that they had been given

66 the option of more time to decide about havingthe test. At interview, three of these women,

58 including one maternal carrier found in thestepwise group, reported having felt unsureabout doing the test, while the remaining three

50 had no regrets about being tested.

202 DECISION MAKINGFrom the questionnaire completed two weeksafter receiving their result, 368/379 (97%)women replied that they did feel they had madethe right decision to have the test, six did not

92 know, and five said they felt they had not madethe right decision by having the test. In this last

29 group, two of the women were found to be car-

riers and felt generally unhappy about thewhole testing procedure, two found to be non-

18 carriers had expressed uncertainty and con-cern about the test and neither couple wouldhave opted for further testing in pregnancy,while at interview the remaining one womanappeared to be happy with all aspects of the

s test. Of the six women who had expressedfor doubt about their decision to be tested, threeal

felt that they had needed more time to discussthe test and to make up their mind about beingtested, one woman had agreed to be testedmostly on the grounds of helping research andhad reservations about tests in pregnancy, andtwo had reported feeling more anxious thannormal while waiting for the results.The responses at interview given by carriers

and non-carriers to the question "What wouldyou have done if you and your partner wereboth found to be carriers?" are shown in table2.

ANXIETY

Waitingfor the resultThe median time between the maternal samplebeing provided and the result for the pregnancybeing communicated to the couple was ninedays for stepwise non-carriers and 11 days forboth stepwise carriers and all couple tests. If amaternal carrier was found in the stepwisegroup, the communication was by telephonewhenever possible, in order to obtain a paternalsample quickly. The 10 women found to be

carrier carriers in the stepwise group then had to waitfor a median of two days (range 1-8 days) forthe respective paternal sample result.The level of anxiety experienced while wait-

ing for the test result (table 3) did not differsignificantly for women allocated to stepwisetesting subsequently found to be non-carrierscompared with women allocated to coupletesting (chi-square trend test statistic=2.0,p>0. 1). Maternal carriers found in the stepwise

ter result group are excluded from this analysis becauseof ambiguity about whether they recalled theiranxiety while waiting for their own result or for

rriers and that of their partners. Nine other cases areers (9/o) excluded from this analysis since no answer was

given.

Two weeks after receiving resultTable 4 shows results for state anxiety levelapproximately two weeks after receiving a final

Practice 1

Practice 2

Practice 3

Practice 4

Practice 5

Practice 6

Practice 7*

Practice 8

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The uptake and acceptability to patients ofCF carrier testing in pregnancy

Table 4 Spielberger state anxiety scores and attitudes to pregnancy, measured two weeksafter result known

Method ofscreeningDifference between methods

Measure Stepwise Couple (95% confidence interval)

"State" anxietyMean (SD) 36.9 (11.3) 33.3 (8.7) 3.6 (1.3-5.9)No of women (% responding) 144 (60) 168 (73)

"How you feel about being pregnant"Positive attitudeMean (SD) 16.0 (4.2) 15.9 (3.8) 0.1 (-1.0-1.3)

Negative attitudeMean (SD) 7.6 (6.4) 6.7 (5.1) 0.9 (-0.7-2.5)

No ofwomen (% responding) 93 (39) 109 (48)

Table 5 Perception of test results by non-carriers:comparison between couple and stepwise groups

What were the results ofyourscreening test?

Method ofallocation Low risk (%) No risk (%) Total (%)

Couple 99 (69) 45 (31) 144 (100)Stepwise 97 (72) 37 (28) 134 (100)Total 196 (71) 82 (29) 278 (100)

test result. Couple testing with disclosureappears to be associated with lower state anxi-ety levels than stepwise testing (t statistic=3. 1,p=0.002). This difference in state anxiety levelmay reflect a chance difference in the women inthe two groups before they were allocated. Thisassessment was not made at entry to the study.

Feelings about being pregnantResults from the completed questionnaire"How you feel about being pregnant"'5 areshown in table 4. No statistically significantdifference was found between either positive ornegative attitudes towards being pregnant bywomen in the stepwise and couple testinggroups (positive attitude: t statistic = -0.2, 200df, p>0.1; negative attitude: t statistic = -1.1,200 df, p>0.1).

PERCEPTION OF RISKOverall, 82 (29%) of the 278 non-carrierwomen interviewed believed that they had noresidual risk in relation to CF (table 5). Thereis no evidence to suggest that women in eitherthe stepwise or couple group are more falselyreassured (chi-square statistic=0.441, p>0. 1).Of 12 maternal carriers responding, all cor-rectly recalled their carrier status.

FAILED SAMPLESSixteen (2%) of 776 samples tested failed togive a result. Of these, 12 were paternalsamples produced from couple testing. Feed-back from laboratory staff indicated that themajority of these had failed to produce an

adequate amount of DNA, possibly owing tonon-adherence to instructions provided forproduction of a sample.

DiscussionOn the whole the overwhelming response fromwomen who accepted CF carrier screening bytheir GP in early pregnancy has been positive,with the majority of women stating that theywere given enough information, enough timewith their GP, and enough time to decide about

being tested. Using the GP booking appoint-ment to offer CF carrier screening, however, isnot without its difficulties. A handful ofwomencommented that they had felt rushed whenmaking their decision about being carriertested. The study as a whole has provided valu-able information on genetic screening in thegeneral practice setting.The level of uptake of the offer of cystic

fibrosis carrier testing by the GP variedbetween practices in this study. This points to anumber of areas where further studies might beof interest. Although the way in which the testwas offered varied between practices, the studywas not designed to be a randomised trial ofmethods of offering testing and the method isconsequently confounded by other practicevariables. However, it was noted that the higherrates of acceptance were in four practices inwhich the test was offered there and then(practices 2, 3, 4, and 5), compared to thelower rates found in practices 1, 6, and 7 wheremost women/couples were asked to go awayand think about the offer before doing the test.Similar results were found in GP surgerieswhere 453/649 (70%) non-pregnant peoplewho were offered a test there and then usingactive recruitment accepted the offer to betested, while those invited to attend for testingusing a passive recruitment method had a loweracceptance rate of 59/502 (12%).7 Variation inthe return of paternal samples was also notedamong practices in this study, with a lowerreturn rate for two practices (2 and 3). Therewere no obvious reasons for this variation inthis study.

It is not possible in this study to establishhow important a part the method of offeringtesting was in a woman's decision to accept. Itappears that for 16%, agreeing to be tested wasbased on their belief that "all tests in pregnancyare important" rather than because they wererelating the test specifically to cystic fibrosis. Itmay be that these women made a decisionbefore seeing their GP that they would acceptany and all tests offered and CF carrier testingwas not distinguished as being any different. Itcould be argued that those women acceptingthe offer of cystic fibrosis carrier testing arepart of a susceptible population who are com-pliant and amenable to testing in general. Atinterview, over 80% ofwomen in each practicesaid that they would have other screening testsoffered to them in pregnancy. However, acrosspractices, the numbers responding with thequestionnaire did not reflect the pattern inuptake areas.Two weeks after receiving their result, 97%

ofwomen felt they had made the right decisionto have the test. However, when asked at inter-view what they would have done if they hadbeen found to be in a carrier couple, 16% ofwomen said they would not have contemplatedprenatal diagnostic tests or a termination of anaffected pregnancy. This causes concern as towhether these women had appreciated that apositive prenatal diagnosis and offer of termi-nation of pregnancy might be a possibleoutcome. The finding that 113 (40%) non-carriers and four (25%) carriers said that they

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would have waited for the result that they werea carrier couple before making any decisionsimplies that these women may have decided topostpone decision making until the need aroserather than indicating a lack of informedconsent before testing. A similar result wasfound by Sjogen and Uddenberg'6 in a study ofdecision making during the prenatal diagnosisprocedure. Although having received theirresults most women reported the testingprocedure to have been acceptable, in retro-spect 46 of the 305 women interviewed (15%)would have preferred the option of a more lei-surely consideration of the implications of car-rier testing in the absence of an ongoing preg-nancy.

In this study current (state) levels of anxietyin women two weeks after receiving the finalresults for the pregnancy were found to behigher following stepwise testing than coupletesting. Anxiety scores were obtained for 144(60%) compared to 168 (73%) of women inthe stepwise and couple testing groups, respec-tively. The validity of the comparison of anxietyscores rests on the assumption that whether thewoman responds or not does not depend onher anxiety state. In a study of pregnant womenundergoing prenatal screening for fetalabnormality,'5 no association was found be-tween the initial state measure of anxiety andwhether all subsequent STAIs were returnedfor women who completed an initial question-naire. This observation lends limited supportto the hypothesis that more anxious women, as

measured using the current (state) anxietyscore, were no more or no less likely to havereturned the questionnaire in the current

study.The alternative allocation of women by GPs

to stepwise and couple testing was quasi-random. It is possible that a GP may have allo-cated a woman preferentially, for example, to

stepwise testing if she was in difficult social cir-cumstances. This situation may be associatedwith a higher general level of anxiety. However,after exclusion of patients who were offered thetest by GPs with unequal allocation rates,couple testing with disclosure remained associ-ated with a lower state anxiety level(t statistic = -2.51, 226 df, p=0.01). Thisdifference did not therefore appear to be as a

result of biased allocation, although thepossibility that the groups were unequal at

entry could not be excluded.This result, although similar in magnitude,

contrasts with the findings from a previousrandomised trial5 where pregnant women

receiving a negative result following stepwisescreening were less anxious than those who hadcouple screening. There was a differencebetween the studies, however, in the disclosureof results for the couple testing method. In theprevious study, individual carrier risks were not

given, meaning that negative results were givento everyone except carrier couples. In the cur-

rent study there was full disclosure of all test

results to people as well as a risk to thepregnancy. For women whose partners havenot been tested, uncertainty about theirpartner's carrier status could be reflected in

raised current (state) anxiety. Conversely, cou-

ples where both partners are tested and there isfull disclosure of both results might beexpected to exhibit lower levels of anxiety.However, although statistically significant, theclinical importance of a three point differencemeasured on the anxiety index is open todebate.The majority of women who provided com-

ments four weeks after testing realised thatthere was a residual risk associated with a

"negative" test result, but 29% understoodthere to be "no risk". This false feeling of reas-

surance was not associated with a particularmethod of testing, in contrast to the study byMiedzybrodzka et ar' where "couple" testingdid seem to be associated with more false reas-

surance.It is uncertain whether population cystic

fibrosis carrier screening will ever be advocatedor implemented on a national scale, but theresults from this study will contribute to thedebate. There is no easy way to apportion thefinite resources available for both screening andtreatment of this disease. At some time in thefuture, attitudes to population screening are

liable to be modified further with the prospectof gene therapy or other effective treatments.

We thank the general practitioners, the attached staff, and themany women and their partners who participated in this project.The project was funded by the Wolfson Foundation.

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2 Riorden JR, Rommens JM, Kerem B, et al. Identification ofthe cystic fibrosis gene: cloning and characterisation ofcomplementary DNA. Science 1989;245: 1066-73.

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7 Bekker H, Modell M, Dennis SG, et al. Uptake of cysticfibrosis carrier testing in primary care: supply push or

demand pull ? BMJ 1993;306:1584-6.8 Watson EK, Mayall E, Chapple J, et al. Screening for carri-

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9 Payne Y, Williams M, Cheadle J, et al. Carrier screening forcystic fibrosis in general practice: experience in SouthWales. Report to Cystic Fibrosis Research Trust 1994.

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12 Harris H, Scotcher D, Hartley NE, Wallace A, Craufurd D,Harris R. Pilot study of the acceptability of cystic fibrosiscarrier testing during routine antenatal consultation ingeneral practice. BrJ7 Gen Pract 1996;46:225-7.

13 Axworthy D, Brock JH, Bobrow M, Marteau TM. Psycho-logical impact of population-based carrier testing for cysticfibrosis: three year follow-up. Lancet (in press).

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