Predictive genetic testing: Mediators and moderators of anxiety

Predictive Genetic Testing:Mediators and Moderators

of Anxiety

Susan Michie, David P. French,and Theresa M. Marteau

Mediators and moderators of anxiety following predictive genetic testing were inves-tigated in a cross-sectional study of 208 individuals at risk for familial adenomatouspolyposis (FAP). Receiving a positive test result was associated with increased anxi-ety. The relationship between test result and anxiety was mediated by how threatenedindividuals felt by their test results. The impact of a positive test result was greater forthose who felt distressed about FAP in their families, perceived FAP to be more seri-ous, and perceived the genetic test to be more accurate. The results suggest that as-sessing, and possibly modifying, people’s appraisals of the condition and of its impacton the family and of the threat of the genetic test may help to reduce subsequent anxi-ety. This has implications for the practice of genetic counseling.

Keywords: genetic testing, predictive testing, psychological impact, emotional re-sponse, anxiety

Predictive genetic tests for late-onset diseases are becoming increasingly availablefor asymptomatic people from high-risk families. Although the majority of the earlystudies of psychological impact were of the untreatable neurological condition,

INTERNATIONAL JOURNAL OF BEHAVIORAL MEDICINE, 9(4), 309–321Copyright © 2002, Lawrence Erlbaum Associates, Inc.

Susan Michie, University College, London, UK; David P. French, King’s College, London UK;Theresa M. Marteau, King’s College, London, UK.

This study was funded as part of a program grant from The Wellcome Trust. Susan Michie andTheresa Marteau are funded by The Wellcome Trust. David French is a Wellcome Trust Training Fel-low in Health Services Research.

Correspondence concerning this article should be addressed to T. M. Marteau, Psychology and Ge-netics Research Group, King’s College London, Thomas Guy House, Guy’s Campus, London SE1 9RT,UK. E-mail: [email protected]

Huntington’sdisease,morerecent studieshavebeenofpreventableand treatablehe-reditary cancers. A recent systematic review demonstrated that, for treatable and un-treatable conditions, pretest emotional state was a more powerful predictor of emo-tional outcome than test result (Broadstock, Michie, & Marteau, 2000). Althoughthese studies have assessed predictors of psychological outcome, they have not ex-plored what mediates or moderates that outcome. A recent study of predictive ge-netic testing for familial adenomatouspolyposis (aprecursor tobowelcancer) foundtest results predicted anxiety, but not depression (Michie, Bobrow, & Marteau,2001). Adults receiving positive (i.e., high-risk) results were highly anxious. Thisarticle investigates possible mediators and moderators of that association in the totalstudy sample.

Receiving a positive result may be perceived as a threat to a person’s identityand to his or her functioning. According to Lazarus and Folkman’s (1984)transactional model, there are two key appraisals that determine coping and con-sequent stress and anxiety. These are the cognitive representation of the threat-ening situation (primary appraisal) and the appraisal of the availability ofresources to manage the situation (secondary appraisal).

This study investigated three aspects of primary appraisal: appraisal of the seri-ousness of the condition, the accuracy of the test, and distress about FAP in the fam-ily. These aspects of appraisal are treated as potential moderators of the threatexperienced following receipt of a genetic test result for the following reasons. Theperceived seriousness of illness has been found to be important in adjusting to thethreat that illnessposes (Petrie, Weinman,Sharpe, & Buckley,1996), providing evi-dence for Leventhal’s self-regulation model of how people interpret and cope withhealth threats (Leventhal et al., 1997). Perceptions of test accuracy were also foundto be associated with reassurance provided by genetic test results: perceiving the testto be less accurate was associated with hoping for future surveillance despite it beingclinicallyunnecessary (Michieetal., 2002).Finally, it ishypothesized that receivinga positive test result in a family in which there is background worry about FAP in thefamily will be associated with greater perceived threat and anxiety.

Test representations were found to influence the extent to which the test re-sult is perceived as a threat in both clinical and analogue studies. Respondentswho were informed that their cholesterol levels were in the borderline–high-riskrange rated the test results as less accurate than those who were informed thattheir cholesterol levels were in the desirable range (Croyle, Sun, & Louis, 1993).In experimental studies, students given a positive result for a fictitious enzymedeficiency rated the test result as less accurate and the condition as less seriousthan those receiving a negative result (Croyle & Sande, 1988; Ditto & Lopez,1992). It appears that perceiving the test as inaccurate and the condition as lessserious is moderating and minimizing the associated threat.

Secondary appraisal is investigated by measuring two dispositional factors thatwere found to be associated with coping with threatening situations, dispositional

310 MICHIE, FRENCH, MARTEAU

optimism, and self-esteem (Schwarzer, 1994). These may be seen as personal re-sources moderating the association between test result and the extent to which it isperceived as threatening and experienced as anxiety provoking. Higher optimismhas been found to be associated with lower anxiety, better mood, and better immunesystem functioning (Segerstrom, Taylor, Kemeny, & Fahey, 1998).

This article tests the following hypotheses:

• The association between test result and anxiety is mediated by the degree ofthreat perceived in the test result.

• The association between test result and threat, and between threat and anxiety,is moderated by the appraisals of the seriousness of the condition, the accuracy ofthe test, and distress about FAP in the family, such that appraisal of low seriousness of the condition, low distress about FAP in the family, and low test accu-racy act as buffers against emotional distress.

• The association between test result and threat, and between threat and anxiety,is moderated by optimism and self-esteem, such that high optimism and self- es-teem act as buffers against emotional distress.

METHOD

Design

This is a cross-sectional multicentered study, involving seven United Kingdom ge-netics centers and one Australian center.

Sample

The sample consisted of unaffected individuals at risk of FAP who had under-gone genetic testing since 1990 and who knew their results: 154 receiving nega-tive results and 54, positive results. The sample size is sufficient to detect amedium effect size (r = 0.5) on anxiety at a power of 80% and significance levelof 0.05 for a one-tailed test (Cohen, 1992). A one-tailed test is used as the basisof the power calculation as the hypotheses tested are directional. Table 1 showsthe demographic and test characteristics of the sample.

Procedure

Health professionals at the collaborating centers invited eligible patients to partici-pateeitherduringaclinicconsultationorby letter andgave themastudy information

PREDICTIVE GENETIC TESTING 311

sheet. Patients willing to take part were asked to complete a consent form. Parentalconsentwasrequiredforparticipantsagedunder16years.Onreceiptof theconsent

form, the research team sent a questionnaire to the participant, followed by up to tworeminders, if necessary. Recruiting clinicians were contacted regularly about thestudy, by telephone calls, collaborators’ meetings, and visits from the studyco-ordinator, to monitor recruitment and ensure adherence to the study protocol.

Measures

The study measures were selected following an interview-based pilot study(Michie, McDonald, & Marteau, 1996), with the aim of including well-validatedmeasures used in other studies of genetic testing.


TABLE 1Demographic Characteristics of Those With Positive and Negative Test Results

Test Results Positivea Negativeb

Time since tested (weeks) 80.2 (86.8) 71.1 (80.3)(range 1–342) (range 1–321)

Age 17.6 (8.1) 30.0 (13.7)***Adults (>16) 23 (42%) 125 (81%)Children (< = 16) 31 (57%) 29 (19%)***

GenderMale 26 (48%) 60 (39%)Female 28 (52%) 94 (61%)

Ethnic groupWhite 43 (80%) 141 (92%)Non-white 1 (2%) 3(2%)Missing 10 (18%) 10 (6%)

Highest educational qualification(adults only)Higher 7 (30%) 36 (29%)School/other 9 (39%) 42 (34%)None 1 (4%) 14 (11%)Missing 6 (26%) 33 (26%)

Marital status (adults only)Cohabiting 7 (13%) 81 (65%)**Single/seperated 15 (28%) 34 (27%)Missing 1 (2%) 10 (8%)

an = 54. bn = 154.**p < 0.01. ***p < 0.001.

Dispositional optimism. A two-item short-form (Johnston, Wright, &Weinman, 1995) of the Life Orientation Test (Scheier & Carver, 1985) was used,with acceptable reliability (α = 0.76).

Self-esteem. Rosenberg’s (1989) 10-item scale (α = 0.77).

Perception of Illness

Perceived seriousness. Respondents answered “how serious would youconsider the condition if YOU developed it” from (0) not at all serious to (6) ex-tremely serious.

Perception of Test

Perceived accuracy of genetic test. Perceived accuracy of test wasgauged on a 7-point scale from (0) not at all accurate to (6) extremely accurate.

Perceived threat of test result. This measure used the Health Orientationscale (HOS) (Wooldridge & Murray, 1998) plus a single item of perceived likeli-hood of getting FAP, ranging from (0) not at all likely to (6) extremely likely. TheHOS and perceived likelihood were combined because factor analysis showed thatthe HOS loaded highly on a perceived likelihood factor and not on a second, emo-tional factor, made up of anxiety, depression, and distress about FAP in the family(Michie et al., 2001). These two factors were shown to provide a good fit of the data,using maximum likelihood extraction (χ2 = 7.72, df = 9, p = 0.46). The HOS uses thesemantic differential technique, asking people to rate their feelings after beinggiven their genetic test result on 10 items: bad–good, vulnerable–safe, risk–not atrisk, shocked–relieved, sad–happy, afraid–unafraid, abnormal–normal,sick–healthy, ashamed–unashamed, guilty–not guilty. The combined scale, withperceived likelihood, has an of 0.88.

Emotional State

Anxiety. Current levels of anxiety were assessed in adults using the shortform of the state scale of the Spielberger State Trait Anxiety Inventory (α = 0.82)(Marteau & Bekker, 1992), which was prorated to be equivalent to scores obtainedusing the full form of the scale, giving a range of 20–80. For participants under 16


years, the children’s version of the Spielberger State Trait Anxiety Inventory wasused (α = 0.89) (Spielberger, 1973).

Distress about FAP in the family. This was assessed using the Impact ofEvents scale (Horowitz, Wilner, & Alvarez, 1979) comprising items measuring in-trusion of thoughts about FAP in the family and avoidance of those thoughts in thelast seven days (α = 0.86).

Data Analysis

As age (adult vs. 10–16 year old) did not moderate the association between testresult and anxiety, the sample was not subdivided into age group for analysis.Further support for analyzing the group as a whole came from an analysis com-paring anxiety in those with positive test results and an age-matched group withnegative results. The difference in anxiety between those with positive and nega-tive test results was very similar in this age-matched group to that for the groupas a whole (M = 31.1, SD = 9.5 for the age-matched negative group, difference t= 2.99, df = 1,96, p = 0.003). However, age was controlled for in the analyses ofmoderation and mediation, as was the background factor of time since testing.Tests of moderation and mediation were carried out following the guidelines ofBaron and Kenny (1986).

Test of mediation. To establish that perceived threat mediates the effect oftest result on anxiety, it is necessary to show that (a) when anxiety is regressed ontest result, the coefficient for test result is significant, (b) when anxiety is regressedon threat, the coefficient for threat is significant, (c) when threat is regressed on testresult, the coefficient for test result is significant, and, finally, (d) when anxiety isregressed on both threat and test result, the coefficient for anxiety is significantlyreduced, to a nonsignificant level.

Test of moderation. To establish that perceived seriousness and test accu-racy and distress about FAP in the family moderate the effect of test result on threatand on anxiety, it is necessary to (a) create multiplicative composites, which act asinteraction variables of test result and each of the moderators, (b) when these inter-action variables are regressed on test result, the coefficient of the interaction vari-able is significant in a hierarchical regression, partialling out the effects of the pre-dictor and moderator variables (See Jaccard, Turrisi, & Wal, 1990).

Two variables were nonnormally distributed: time since testing, which wastherefore transformed by the square root function, and perceived seriousness,which was transformed by the logarithmic function.


RESULTS

Differences Between Groups

Demographic characteristics. (See Table 1) Those with positive resultswere younger than those with negative results. This was expected, because thosewith the mutation are more likely to become symptomatic as they get older and,hence, to be ineligible for the study. Adults with positive results are less likely to becohabiting than those with negative results, a by-product of the association with age(t = 5.12, df = 1, 135, p < 0.001).

Psychological measures. (See Table 2) Receiving a positive test resultwas associated with raised levels of anxiety and results threat, but not with distressabout FAP in the family. Those with positive results perceived their chance of get-ting FAP to be higher and perceived FAP to be less serious than those with negativeresults. There was no difference in their perception of the accuracy of the genetictest. Self-esteem and dispositional optimism were within the normal range, as werethe levels of anxiety and distress about FAP in the family. Time since testing wasnot associated with emotional outcome.

Mediation

The association between test result and anxiety was mediated by how threatenedindividuals felt by their result, meeting all four criteria of mediation described


TABLE 2Psychological Characteristics of those with Positive and Negative Test Results

Positivea Negativeb

1. Psychological resourcesDispositional optimism (0–32) 21.1 (6.1) 21.9 (5.9)Self-esteem (10–40) 32.5 (5.0) 32.6 (5.4)

2. Perception of illnessSeriousness of FAP (0–6) 4.8 (1.6) 5.4 (0.9) **

3.Perception of testsPerceived accuracy genetic test (0–6) 5.4 (0.8) 5.4 (1.1)Results threat(11–55) 34.0 (7.6) 17.4 (6.1) ***

4. Emotional stateAnxiety (20–80) 37.7 (12.2) 32.7 (10.9) **Distress about FAP in the family

(0-75)17.2 (14.3) 14.2 (15.1)

an = 54. bn = 154.

earlier. (a) when anxiety is regressed on test result (β = –.255, df = 1,193, p <0.001) (b) when anxiety is regressed on threat (β = .714, df = 1,176, p < 0.001)and, finally, (d) when anxiety is regressed on both threat and test result (β =.550, df = 2,167, p < 0.001) and b = .107, df = 2,167, p = .303 respectively). Thecoefficient for anxiety is significantly reduced, test result is no longer a signifi-cant predictor, and the reduction in the regression slope is significant (β change= 0.44)

Moderation

There were several moderating effects of the association between test result andemotional consequence (See Table 3 and Figure 1). The impact of a positive testresult on the perceived threat of the result and on anxiety was greater for thosewho felt distressed about FAP in the family (R2 change = .013, df = 1,159, p =.017 and R2 change = .032, df = 1,169, p = .007 respectively). The impact on theperceived threat of the result was also greater for those who perceived FAP to bemore serious and who perceived the genetic test to be extremely accurate (R2

change = .014, df =1,161, p = .012 and R2 change = .036, df = 1,157, p < .001 re-spectively). Neither optimism nor self-esteem was found to have moderating ef-fects on the association between test result and threat, or on the associationbetween test result and anxiety.


FIGURE 1 Association between test result, and anxiety: mediators, and moderators.

317

TABLE 3Hierarchical Linear Regression Models Showing Moderators of the Association

Between Test Result and Anxiety and Threat

Step VariableRaw

CorrelationPartial

CorrelationStandardized

Final β t R2

IncreaseR2

AdjR2

Dependent variableAnxiety

Step 1Age –.11 –.04 –.04 –.0.50 .01 .01 .01

Time since testing .09 .14 .14 1.96 .03 .02 .02Step 2

Test results –.28*** –.01 –.02 – 0.18 .08 .06*** .07

Distress aboutFAP in the family .31*** .27 1.08 3.76*** .17 .09*** .15

Step 3Results x

Distress aboutFAP in the family

.19** .20 –.82 –.2.80** .20 .03** .18

ThreatStep 1

Age –.21** .11 .08 1.4 .04 .04** .04Time since testing .06 .01 .01 0.08 .06 .01 .06

Step 2Test results- distress

about FAP in thefamily

–.76*** –.54 –.64 –8.17*** .58 .53*** .58

.26*** .24 .64 3.20** .62 .04*** .61Step 3

Results xDistress aboutFAP in the family

.01 –.18 –.47 –2.32* .63 .01* .62

Step 2Test results

seriousness–.75*** –.72 –.93 13.66*** .57 .52*** .57

–.01 –.25 –.58 –3.41*** .60 .03*** .59Step 3

Results xseriousness

–.17* .19 .42 2.54* .62 .02* .60

Step 2.Test results –.75*** –.30 –.42 –4.05*** .57 .51*** .56Test accuracy –.17* .05 .04 0.66 .59 .02** .58

Step 3Results x –.74*** –.30 –.45 –4.00*** .63 .04*** .61Test accuracy

*p < 0.05. **p < 0.01. ***p < 0.001.

DISCUSSION

Receiving a positive test result was associated with increased anxiety. Two ofthe three hypotheses were supported. The association between test result andanxiety was mediated by how threatened individuals felt by their test result. Theimpact of a positive test result on perceived threat and on anxiety was moderatedas predicted: the impact was greater for those who perceived FAP to be more se-rious, for those who felt distressed about FAP in the family, and for those whoperceived the genetic test to be extremely accurate. Optimism and self-esteemwere not found to moderate the associations between test result and threat, testresult and anxiety, or between threat and anxiety.

Psychological Model of Emotional Response

The finding that anxiety is mediated by how threatened people feel by their testresults shows the importance of including specific, as well as global, distress inresearch. Measures of global distress may lack the sensitivity to detect specificconcerns (Croyle & Lerman, 1995). These results support the transactionalmodel of coping whereby the degree of distress experienced reflects the per-ceived threat of the test results that, in turn, reflects how the situation is ap-praised. Although the individuals are themselves asymptomatic, theconsequences of the illness, assessed by perceived severity and distress aboutthe illness in the family, moderate the impact. In addition to illness representa-tion, test representation moderates the impact, with those perceiving the test tobe most accurate experiencing most distress.

The finding that those with positive results perceive FAP to be less seriousand the results to be less bad than those with negative results is consistent withresearch in other areas (Croyle et al., 1993). It is also consistent with theself-regulation model (Leventhal et al., 1997) in which there is parallel and inde-pendent processing of the threat or danger that an illness is perceived to pose,and the fear that this generates. Emotional distress is said to be regulated by a“defensive bias” that allows the condition to be seen as less serious than it wouldotherwise be seen, thus minimizing the threat. This process of threatminimization is not, however, evident in participants’ perception of the genetictest, with no difference in perceived accuracy between those receiving positiveand negative test results.

Although both optimism and self-esteem contribute significantly to the pre-diction of anxiety even when all other variables are entered into the regressionequation before them (Michie et al., 2001), neither were found to moderate theassociations between test result and test threat or anxiety. These results suggestthat it is not general dispositional factors that influence emotional response to


genetic testing, but more specific cognitions related to the illness and the test,and family context.

Study Strengths and Limitations

Most studies of the psychological impact of genetic testing have investigated theoutcomes, but not the mediators or moderators of those outcomes. By examiningthese process variables, this study is attempting to understand the mechanism ofpsychological response within the framework of a psychological model. How-ever, the study is limited in several ways. The study investigates only parts ofthe psychological model described: although measures of primary appraisalwere included in our study, measures of coping were not. A further limitationconcerns the study design. It is a cross-sectional study, so that statistical predic-tion does not imply causality (although, in this case, it is implausible that anxi-ety could cause test result). Larger longitudinal and intervention studies arerequired to investigate the impact of test result, the psychological processes in-volved, and the direction of any causal relationship found. Longitudinal studieswould allow the assessment of pretest emotional state, found to be an importantfactor in other outcome studies (Broadstock et al., 2000). Future studies wouldbenefit from recruiting a more homogeneous population sample, with a narrowerrange of time since testing, than was the case in this study.

Clinical and Research Implications

Mindful of these limitations, the results of this study have several implications forgenetic counseling. Although some anxiety may be appropriate in those undergoinggenetic counselling, the level of anxiety among one group, adults receiving positiveresults, has been found to be in the clinical range (Michie et al., 2001). Moreover, arecent study found that by 7–10 years after predictive testing for Huntington’s dis-ease, distress increased in those having received positive results (Timman,Zoeteweij, Tibben, Breuning, & Passchier, 2000).

The results of the current study suggest that general anxiety following predic-tive genetic testing may be mediated by the specific threat posed by the test re-sults. It is therefore important that genetic counseling address this threat bothbefore and after testing. Moreover, these results suggest specific ways in whichthat threat may be reduced. Modifying threat-inducing appraisals, namely, re-ducing the perceived seriousness of the condition and distress about the condi-tion in the family, is likely to reduce the threat of test results. Assessing theseappraisals, in addition to pretest emotional state, may also help in targetingcounseling at those most likely to experience high anxiety following testing.


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Predictive genetic testing: Mediators and moderators of anxiety