Vol. 10: e33-e37, June 2005

BRIEF REPORT

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Key words: Bulimia, character,pharmacotherapy,temperament.Correspondence to:Filip Rybakowski, MDDepartment of Child andAdolescent Psychiatry University of MedicalSciencesUl. Szpitalna 27/3360-572 Poznan, PolandE-mail: filrybak@polbox.comReceived: May 24, 2004Accepted: September 9, 2004

Temperament and character inventoryand pharmacotherapeutic outcome inbulimia nervosa

F. Rybakowski, A. Slopien, R. Komorowska, R. Antkowiak, R. Ciesielski, and A. Rajewski Department of Child and Adolescent Psychiatry, University of Medical Sciences, Poznan, Poland

ABSTRACT. Objective: To assess the relationship between the personality dimensions mea-sured by the temperament and character inventory (TCI) and pharmacotherapeutic outcome inbulimia nervosa (BN). Methods: Thirty female BN patients aged 19.5±2.9 years were enrolledto receive 12 weeks’ treatment with fluoxetine or buspirone and assessed using the Polish ver-sion of the TCI. The personality dimensions of the patients with good and poor treatmentresponses were compared. Results: The subjects with a good outcome had a higher self-directedness and lower harm avoidance score; this difference was more pronounced in thefluoxetine-treated subjects. At multiple regression analysis, only self-directedness predicted agood outcome. Discussion: The results indicate that self-directedness is associated with agood pharmacotherapeutic outcome in BN. This seems to confirm the results of previousstudies of the pharmacotherapy of depression and cognitive-behavioural therapy (CBT) in BN.(Eating Weight Disord. 10: e33-e37, 2005). ©2005, Editrice Kurtis

INTRODUCTION

Various forms of treatment have beenfound to be effective in bulimia nervosa(BN), particularly cognitive-behaviouraltherapy (CBT) (1) and pharmacotherapywith selective serotonin reuptakeinhibitors (2). However, remission ratesafter such treatments are still only 50%.Identifying the predictors of a good out-come would reduce the cost of currenttreatment modalities by administeringthem only to patients with a probablygood response, and introducing moresophisticated and innovative treatmentsfor patients with a supposedly poor out-come.

Personality disorders may influence theresponse to treatment of patients withdepression and anxiety disorders, and anumber of studies have indicated that theymay predict a poor treatment outcome inpatients treated with tricyclic antidepres-sants (3). The results of studies of theeffects of comorbid personality disorderson bulimia are conflicting, but there issome evidence that cluster B personalitydisorders (especially borderline personalitydisorder) may predict a poor outcome (4-6);moreover, features associated with person-ality disorders such as impulsiveness and

substance abuse have also been repated aspredictors of a poor outcome (7, 8).

The categorical approach to the diagnosisof personality disorders of both the DSM-IVand ICD-10 diagnostic systems is still debat-ed because of its poor validity and question-able inter-rater and time reliability, and thishas recently led to more emphasis beingplaced on the dimensional approach.

Cloninger et al. proposed the 7-dimen-sional, psychobiological model of personali-ty (9), initially suggesting that the dimen-sions of temperament are novelty seeking(NS), harm avoidance (HA) and rewarddependence (RD), which can be measuredusing the Tridimensional PersonalityQuestionnaire (TPQ) (10); subsequent workindicated that the RD dimension should beseparated into persistence (P) and threeother RD subscales.

A number of studies have found that theTPQ/TCI dimensions predict treatment out-come in patients with major depression (11)and indicated that a better response is asso-ciated with a low HA score, and it has alsobeen found that a high self-directedness(SD) score in the character dimension isassociated with a better outcome indepressed patients (12); both of these traitsmay be influenced by the severity of thedepression. Some studies have also found

that psychobiological personality dimensionsmay also have predictive value in eating disor-ders (13, 14): for example, Bulik et al. reportedthat a high SD score is associated with both theshort-term and 1-year outcomes of CBT inpatients with BN.

However, as little is known about the predic-tive value of personality dimensions in relationto the drug treatment of BN, the aim of thisstudy was to investigate whether the pretreat-ment personality characteristics of BN patientspredicted treatment outcome in patients partic-ipating in a drug trial comparing the short-term efficacy of buspirone and fluoxetine.

MATERIAL AND METHODS

PatientsThe data were taken from an open-label

study comparing the efficacy of buspiron andfluoxetine in treating BN. Fifty-eight femalepatients aged 16-29 years (mean 20.7±3.1 years)were consecutevely assigned to treatment withfluoxetine or buspirone in a ratio of 2:1because of the known efficacy of the former.The inclusion criteria were female gender, anage of 15-30 years, and the presence of currentDSM-IV (15) and ICD-10 (16) criteria for BN.The diagnosis was made on the basis of thestructured SCID-P interview. The exclusion cri-teria were a current diagnosis of anorexia ner-vosa, schizophrenia or other psychotic disor-ders, current obesity (BMI >30 kg/m2), severemedical illnesses or any other medical illnesspossibly affecting appetite. Recruitment wasmainly based on referrals from general practi-tioners and community care centres. Thirty ofthese patients agreed to undergo a personalityassessment based on the Temperament andCharacter Inventory (TCI). All of the subjectsgave their informed consent; in the case ofsubjects aged less than 18 years, the consent oftheir legal guardians was also obtained. Thestudy protocol was approved by the EthicsCommittee of the University of MedicalSciences, Poznan, Poland.

TreatmentThe patients were assigned to two treatment

groups: every third patient received buspirone15-35 mg/day (28.8±8.9 mg/day); the othersreceived fluoxetine 40-60 mg/day (56.4±7.8mg/day) because of its known efficacy. Thetreatment consisted of a 1-4 week period of in-patient stay care, depending on the level ofpatient functionig, followed by a period ofoutpatient treatment with control visits every3-4 weeks. During their hospitalisation, the

patients participated in two group psy-chotherapy sessions per week. The trial lasted12 weeks, and found no statistical differencesin basic outcome measures between the twogroups (the detailed results will be reportedelsewhere).

Measures All of the subjects were thoroughly evaluat-

ed before starting the study treatment, andwere diagnosed as being affected by BN onthe basis of ICD-10 and DSM-IV criteria. Theirpersonality dimensions were assessed usingthe previously validated Polish version of theTCI (17), a self-report instrument of yes/noanswers assessing novelty seeking (40 items),harm avoidance (35 items), reward depen-dence (24 items), persistence (8 items), and thethree character dimensions of self-directed-ness (SD: 44 items), cooperativeness (C: 42items) and self-transcendence (ST: 33 items)(9). Novelty seeking is defined as a tendency torespond actively to novel stimuli; harm avoid-ance reflects a tendency towards an inhibitoryresponse to signals of aversive stimuli; rewarddependence measures a tendency towards apositive response to signals of reward, andpersistence assesses the ability to perpetuatethe activity without the reward. The threecharacter dimensions respectively refer to theability to adapt to different situations accord-ing to ones goal, the ability to interact withother people, and the ability to identify withthe whole world.

The main outcome measures were theBulimia Severity Scale (BSS) and Beck’sDepression Inventory (BDI) (18). The BSS is a10-item self-report instrument assessing theseverity of bulimic symptoms (i.e. the frequencyof binge eating and compensatory behaviours,and preoccupations with weight and shape).The BDI is a self-report instrument assessingdepressive symptoms. All of the patients wereassessed at baseline, and after four and 12weeks of treatment.

Statistical analysisA good treatment response was defined as a

reduction of ≥50% in the severity of bulimicsymptoms and the severity of depressivesymptoms after 12 weeks of treatment. Thedifferences in baseline characteristics (age,age at symptom onset, the duration of symp-toms, BDI and BSS scores, and the TCI per-sonality dimensions) were analysed using one-way analysis of variance (ANOVA). We firstcompared the patients who dropped-out withthose completing the study and, then, amongthe latter, we used good treatment outcome as

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the independent variable and clinical charac-teristics and personality dimensions as depen-dent variables. The predictive pretreatmentvariables showing statistically significant dif-ferences between the treatment outcomegroups were analysed to check whether theypredicted outcome in both treatment arms,and then underwent stepwise multiple logisticregression analysis together with treatmentmodality (fluoxetine vs buspirone) and thelength of in-patient stay. All of the statisticalanalyses were made using SPSS 10.0 softwarefor Windows (19).

RESULTS

Overall, 47 of the 58 enrolled patients (81%)completed the study, including 24 of the 30patients assessed using the TCI (80%). Therewere no statistically significant differences inthe baseline characteristics (age, age at symp-tom onset, the duration of symptoms, and BDIand BSS scores) between the completers andnon-completers, nor any significant differencesin the personality dimensions; however, therewas a statistical trend towards greater harmavoidance (HA) in the patients who droppedout (26.8±6.2 vs 21.4±7.4; df 28; p=0.1).

A reduction of ≥50% in bulimic symptomswas observed in 12 cases (50%), and a reduc-tion of ≥50% in depressive symptoms in 16(66.7%): 10 (41.7%) showed a good outcome onboth measures. There were no statistically sig-nificant differences in baseline demographicand clinical characteristics between the sub-jects showing a good and poor response (Table1); the differences in their personality areshown in Table 2. The good responders topharmacological treatment had a significantly

higher score for the character dimension ofself-directedness (26.4±6.6 vs 16.6±9.4; F=7.846;p=0.01) and a lower score for the temperamen-tal trait of harm avoidance (18.1±5.4 vs24.6±7.5; F=5.439; p=0.03). In the subgroup offluoxetine-treated subjects (n=15), the self-directedness score was significantly higher ingood than poor responders (27.8±6.6 vs15.2±7.9; p=0.01) and there was a trendtowards a lower harm avoidance score(19.6±5.4 vs 25.1±5.2; p=0.09). In the subgroupof buspirone-treated subjects (n=9) the differ-ences between the good and poor responderswere not significant (SD: 24.7±7.2 vs 20.2±11.9;p=0.5; HA: 16.2±5.6) vs 21.2±11.5; p=0.4).

Multiple logistic regression analysis with theforward selection of variables (treatmentmodality, duration of hospitalisation, harmavoidance and self-directedness) showed thatonly self-directedness significantly predicted

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TABLE 1Comparison of baseline demographic and clinical variables in individuals with a good (n=10) and poor outcome (n=14) after

pharmacological treatment. Mean values and standard deviations,with analysis of variance for the group factor.

Subjects with Subjects with Statisticsgood outcome poor outcome

Variable Mean S.D. Mean S.D. ANOVA F Pdf (1,23)

Age (years) 18,9 3,0 20,6 2,8 2,173 0,152

Age at onset (years) 16,6 3,1 17,7 2,6 0,922 0,347

Duration of illness (years) 2,8 1,2 2,8 1,2 0,004 0,952

BDI score 18,4 11,5 22,8 11,3 0,981 0,331

Bulimia symptoms score 18,5 4,8 20,9 4,2 1,983 0,170

TABLE 3Multiple logistic regression with the forward selection of variables.Initial set of variables: treatment modality, duration of in-patienttreatment, harm avoidance score and self-directedness score.

Variable included in the model:

Variable Beta Df p OR 95% CI

Self-directedness 0.215 1 0.025 1.24 1.03-1.50

Variables not included in the model:

Variable Value Df p

Treatment modality (Fluoxetine/ Buspirone) 0.146 1 0.702

Duration of inpatient treatment 1.289 1 0.256

Harm avoidance 2.712 1 0.100

TABLE 2Comparison of personality dimensions in individuals with

a good (n=10) and poor outcome (n=14) after pharmacologicaltreatment. Mean values and standard deviations, with

analysis of variance for the group factor.

Subjects with Subjects with Statisticsgood outcome poor outcome

Personality dimension Mean S.D. Mean S.D. ANOVA F Pdf (1,23)

Persistence 3,8 2,3 3,7 2,0 0,034 0,854

Novelty seeking 23,6 5,0 20,8 6,4 1,377 0,251

Harm avoidance 18,1 5,4 24,6 7,5 5,439 0,028

Reward dependence 15,9 2,8 15,0 2,8 0,667 0,421

Cooperativeness 32,9 7,0 32,6 5,7 0,018 0,895

Self-directedness 26,4 6,6 16,6 9,4 7,846 0,010

Self-transcedence 16,7 7,8 14,7 6,4 0,505 0,484

treatment response: a one-point increase in theself-directedness scale increased the odds of agood outcome by 1.24 (1.03-1.50). The resultsare shown in Table 3.

DISCUSSION

The results of this study suggest that the per-sonality dimension of self-directedness maypredict good outcome in the pharmacotherapyof BN; the odds ratio of 1.24 indicates that a 3-point increase in this dimension score wasassociated with doubled likelihood of a goodoutcome. Individuals with high SD dimensionscores are described as being mature, respon-sible, resourceful and capable of achievingtheir goals, a set of traits that may enablepatients to maximise the beneficial effect ofpharmacotherapy and may also be associatedwith better treatment compliance. Bulik et al.(13) have recently reported that a higer SDscore predicts the good outcome of cognitive-behavioural therapy in BN, and Sato et al. (12)observed that SD was associated with a goodresponse to the antidepressant treatment ofmajor depression.

It cannot be excluded that SD may be anunspecific predictor of outcome in differentdisorders regardless of the treatment used. Wefound that SD scores were significantly higherin the good responders in both treatment armsanalyzed together; the difference remained sig-nificant in the subgroup of fluoxetine-treatedsubjects, but not in the subgroup of those treat-ed with buspirone. However, the small numberof subjects does not allow any further conclu-sions to be drawn.

It has been proposed that a low SD score isassociated with different forms of personalitydisorders in bulimia patients (20). We did notexclude patients with axis-II disorders, and soit is possible that the low SD scorers in ouranalysis had personality disorders. This maysomehow confirm the results of earlier reports(5, 6) suggesting that especially borderline per-sonality disorder comorbidity may be associat-ed with a poor outcome in BN.

Some reports have suggested that SD mayincrease in bulimia patients after cognitive-behavioural therapy (21). Additionally, Walsh etal. (22) have reported that the combined treat-ment of bulimia with antidepressants and CBT,but not other forms of psychotherapy, is associ-ated with a better outcome than treatment withantidepressants alone. It can be hypothesisedthat the better outcome obtained by combinedtreatment than antidepressant pharmacotherapyalone is due to the CBT-induced increase in SD.

One of the limitations of our study is thesmall sample size, but the association betweenpersonality and outcome was robust enoughto obtain statistically significant differencesbetween treatment outcomes. Secondly, weonly used self-assessed outcome measures andthe bulimic symptoms were evaluated using aninstrument whose validity is unknown.However, the majority of studies of treatmentefficacy in BN are based on clinical interviewsthat obtain data concerning the frequency ofbingeing, compensatory behaviours, and pre-occupations with weight and shape that can-not be independently verified, and so we sug-gest that this tool may discriminate good andpoor outcomes. Thirdly, despite the exclusionof the patients with psychotic depression andbipolar illness, the severity of depressivesymptoms in some patients was high (BDIscore= 53). In order to eliminate the possibleinfluence of depression on the outcomeassessment we used the composite outcomemeasure of ≥50% reductions in both bulimicand depressive symptoms; moreover, the dif-ference in the baseline BDI between the twooutcomes was far from significant (p=0.33).

In conclusion, our results suggest that thecharacter dimension of self-directedness maybe associated with a good outcome after short-term pharmacotherapy of BN. It may allow theselection of patients with a probably favourableresponse to pharmacotherapy, and its role inthe combined action of CBT and antidepressanttherapy warrants further study.

ACKNOWLEDGEMENTS

This work was sponsored by KBN grants No. 3 PO5B12823 and H01F 03019.

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