0022-3999192 $5 CO+ a, @ 1992 Pergamon Press plc

PSYCHOTHERAPY

OF BULIMIA

EFFECTIVE?

NERVOSA:

A META-ANALY

WHAT

IS

SIS

A. HARTMANN,* T. HERZOG*~ and A. DRINKMANN~ (Received

15 January

1991; accepted

in revised form

6 June 1991)

Abstract-The present paper assesses the state of the art of psychotherapy of bulimia nervosa. Five hundred and fifty publications available up to April 1990 were systematically screened. Included in subsequent analysis were all studies with samples of five or more bulimic patients which used operational diagnostic criteria, and reported results of binging and vomiting or other means of purging quantitatively. Only 18 independent studies with a total of 433 patients in 24 treatments and 61 patients in 6 control groups fulfilled these criteria. Therapy outcome across studies was assessed meta-analytically. Therapy process across studies was assessed through ratings of interventions used (behavioural, cognitive, educational, humanistic, psychodynamic techniques and symptom-, conflict-, and relationship-orientation), setting and dose parameters. Settings were out-patients only, mostly group or individual. Most studies were on short-term therapies and follow-ups. Stepwise regression analysis revealed no definite advantage of one setting or therapeutic approach over another. Thirty-six per cent of variance was explained by the number of treatment sessions in combination with relationship orientation.

INTRODUCTION IN OUR search for optimal psychotherapeutic treatments for bulimia nervosa we have used psychoanalytically oriented in-patient and out-patient treatments [ I] and combinations of cognitive behavioural and psychodynamic techniques in various settings adapted from Lacey [ 2-51. In preparation for a large scale prospective study we searched the literature for what is empirically established in the psychotherapy of bulimia nervosa as concerns outcome and its relation to therapy process. The generic model of psychotherapy [6] can provide a conceptual framework for such an assessment. It specifies five ‘elements’ of therapy process: contract (including setting and dose parameters); interventions (including specific techniques and more general focus of therapeutic activity); therapeutic bond (including ‘therapeutic alliance’); patient self-relatedness and therapeutic realization. The two most important methods for the assessment of psychotherapy research literature are qualitative reviews based on operational criteria [ 6, 71 and pooling of results by means of meta-analysis using effect-size (ES) as standardized outcome measure [ 81. While the overall effectiveness of psychotherapy is established [7,8] , there is controversy about what is therapeutically effective [6, 9, lo] The only meta-analysis of treatment studies for bulimia up to now was based on 15 publications with rather wide inclusion criteria up to December 1985 [ 1 l] . It found psychological treatments (mean effect-size: M = 1.14) superior to pharmacological ones (M = 0.60). A recent qualitative review [ 121 covered 32 individual and group psychotherapy studies published between 1976 and 1986 which met somewhat stricter inclusion criteria. No type of treatment showed clear superiority; *Department of Psychotherapy and Psychosomatic Medicine, University of Freiburg, Germany. l-Author to whom correspondence should be addressed at: Dept of Psychotherapy and Psychosomatic Medicine, University of Freiburg Hauptstr. 8, 7800 Freiburg, Germany. IDepartment of Internal Medicine-Psychosomatics, University of Heidelberg, Germany. 159

160

A. HARTMANN

etul

about 40% of patients in both group and individual treatment were reported to be totally abstinent from binging and purging* at follow-up. Neither here nor in other publications are questions of therapy dose addressed nor is an attempt made to operationally describe treatments and to relate process and outcome across studies. However, these overviews support our distinct impression that most practitioners in their actual work favour some combination of different approaches and techniques. Therefore, in order to increase ecological validity, our analysis of available studies relates operational measures of therapy process (contract and interventions) to outcomes characterized through a modified meta-analytic procedure. The following issues concerning psychotherapy of bulimia nervosa are examined: (1) what kind of interventions are helpful (psychodynamic, cognitive-behavioural. combined etc.); (2) which setting (group, family, individual, in-patient, out-patient) is most appropriate; (3) for how many sessions; and (4) for how long should psychotherapy of bulimia nervosa take place? METHOD

We screened all the published literature on bulimia, bulimia nervosa, bulimarexia, bulnnic eating disorders available in books, articles and abstracting services (Medline, Psyndex, Psycinfo) up to April 1990. Only 243 of about 550 located articles on psychotherapy of bulimic patients reported on therapy studies. Studies were classified in six categories, which were: controlled studies with and without followup; uncontrolled studies with and without follow-up; case-studies with and without follow-up. We obtamed all controlled and all follow-up studies and most simple case-studies as well. Included in the meta-analysis were all treatments which fulfilled the following criteria: five or more patients per treatment, use of diagnostic criteria according to DSM-III 131 , DSM-III-R 1141 or Russell [ 151,clear identification of bulimic (vs anorectic) patients, quantitative presentation of results. Studies which merely reported percentages of improvement in certain categories had to be excluded due to the exigencies of the meta-analysis. Only 18 studies reporting on 24 treatment groups (433 patients) and 6 control groups (61 patients) met those criteria (Table I). All available published information about these studies was used for subsequent analysis. These studies were assigned a rating of methodological quality adapted from the psychotherapy outcome research criteria used by Gurman and Kniskern, and Luborsky er al. as described by Cox and Merkel [ 121 Outcome

(e@ct-sizr

ES)

Measures of binging and/or purging were the only outcome variables given by all studies. Therefore, the calculation of ES could only be based on these very narrow measures of outcome. Effect-size was computed on the basis of the mean value of binging and purging or on the value of either binging or purging depending on availability of data. This procedure seemed justified because of the high correlation of binging and purging. Calculations could only be based on pre-post treatment changes, not on results of follow-ups because of lacking or largely varying duration of follow-ups (mean: M = 27 wk, range: 6-52 wk) and the type of data presented. EfTect-size is generally conceived as a measure of the strength of an experimental effect. Classically, it is based on the comparison of one or more experimental groups with a control group. The calculation of ES can be a powerful tool in summarizing results from several studies that use classical experimental designs. However, the meta-analytic evaluation of psychotherapy studies meets with considerable difficulties. To the authors’ knowledge there are no strategies which make allowance for repeated measurements, especially in multifactorial designs without control groups. Furthermore, many psychotherapy studies are methodologically less than sound. Often. there are no controls and if there are randomization remains doubtful. Therefore, the calculation of efIecective-sire is a complex problem. Laessle et cd. 11I I used a simple solution. They decided to calculate the eff&ct-size as the difference between the mean pre-treatment score and the mean post-treatment score divided by the SD of the pre-treatment

*As most of the studies vomiting.

were American

the term ‘purging’

follows

the American

usage and includes

et al. (1989)

[ 181

Treatment-label (given by study author)

I.-STUDIES

.

..-

_

Treatment components: B: Behavioural; R: Relationship-Oriented. Ratings of the components: 0 = none; 1 = slight;

--

-

33010302 13010302 13310202 12100300 32100300 H: Humanistic;

3 = very strong

E: Educational;

2 = marked:

Cg: Cognitive;

f

G G

G

G G

I I G G G I I G G IG G G G G G IF G G

I

S: Symptom-Oriented;

16 16 7 6 6

16 16

14 14 14 4 15 10 15 15 15 12 20 24 12 10 12 12 -

1440 1440 630 540 540

1440 1440

840 840 840 960 1350 900 900 900 900 1080 1800 2160 720 900 360 1440 -

Total time (min)

1.519 0.977 0.665 0.260 0.493

1.051 1.349 0.684 0.914 1.503 1.529 1.213 0.929 1.301 0.201 2.890 1.041 0.645 1.220 0.483 0.804 0.996 1.234 1.061

Effect - size

Cf: Conflict-Oriented;

16 16 I 6 6

16 16 16 1 15 10 15 15 15 12 10 16 6 10 14 12 52 16 16

Duration (wk)

Individual Group Family N of sessions

Dose parameters

Setting

P:Psychodynamic;

13020310 2 3 0 0 0 3 0 0 33000300 11220222 12110301 2301 1222 31000300 23000300 10220200 11222122 12112222 32000300 22100300 22000300 12030300 23000300 11111223 22220300 22112220

g

BCEHPSCR

rating

IN META-ANALYSIS

Interventions

INCLUDED

Self-monitoring Cognitive behavioural therapy (CBT) CBT + response prevention Bohanske and Lemberg (1987) [ 191 Intensive weekend Dedman et al. (1988) [20] CBT Dixon and Kiecolt-Glaser (1984) [ 211 Combined treatment Freeman et al. (1988) [22] Behaviour therapy (BT) Cognitive therapy ‘Group therapy’ Frommer et a[. (1987) [23] CBT and psychodynamics Lacey (1985) [2] CBT and psychodynamics Laessle et al. (1988) [24] BT and education Lee and Rush (1986) [ 251 CBT Ortega er al. (1987) [26] CBT Rogerian Counselling Paul et al. (1986) [27] Paul and Jacobi (1986) [28] CBT Russell et al. (1987) [29] Family and individual therapy Schneider and Agras (1985) [30] CBT Stevens and Salisbury (1984) [31 CBT and psychodynamics Wilson et al. (1986) [32] Cognitive restructuring (CR) + vomiting prevention CR only Wolchik er (II. (1986) [33] Education CBT Yates and Sambrailo (1984) [34] CBT + behaviour therapy

Agras

Study

TABLE

162

A. HARI‘MANN et al

scores and multiplied by a correction calculation of effect-size [ 161 :

factor

dependent

on sample

size

[ 111 We useda variant of the

This formula uses the means (M) and via pooled variance also takes into consideration the variances (SD = standard deviation) and sample sizes (N) at both pre- and post-treatment (tl, t2) measurements. However, like the formula used by Laessle et al. it does not control for dependency of values in repeated measurements.

Orlinsky and Howard [6] identified five elements of process, however, of these only ‘contract’ and ‘interventions’ are frequently described in psychotherapy studies. We operationalized contract through setting and the dose parameters ‘total number of sessions’, ‘duration of treatment’ and ‘total time’ spent in therapy sessions. Two of us (T.H.. A.H.) independently rated the studies selected on four-point rating scales in order to assess the degree to which various interventions (techniques and focus of therapy) were used. * Our operational categories are similar to those used by Schmalstieg-Maurer in the Bern project [ 171 We used rather strict criteria for the presence of ‘psychodynamic (P) techniques (e.g. fairly explicit reference to unconscious processes and conflicts) and for the presence of ‘humanistic’ (H) techniques (e.g. explicitly Rogerian, actively encouraging the expression of feelings). We distinguished between cognitive (including self-monitoring) (Cg), behavioural (B) and explicitly educational (E) techniques. To assess the focus of therapy, we rated the extent to which the symptom (the eating disorder) is connected by the therapIst with relationships between the patient and her self, inner objects, therapist, friends and family (R), the degree of symptom-orientation (S) and the degree of conflict-orientation (Co.

RESULTS

Analysable

studies

Of the total of 32 studies previously reviewed by Cox and Merkel [ 121 only nine group studies met our inclusion criteria. Our quality ratings completely agreed with theirs on the class level (low. medium, high). The quality of the more recent studies had clearly improved and these better studies also had more treatment conditions. Quality of the study and outcome (effect-size) were not related (r = 0.047, p > 0.5).

Interventions. Inter rater reliabilities for assessment of interventions were satisfactory (between 0.86 and 0.98 [ 351). The values reported in Table I were reached by consensus. Cognitive and behavioural techniques were described in practically all studies. Twenty three treatments had a marked or very strong symptom orientation, regardless of theoretical orientation. Explicit connections between the symptoms and the experience of relationships were made in six more treatments than just in those three that we considered more than slightly ‘psychodynamic’. Cmtruct. The majority of the treatments (IV = 16) took place in a group setting only. There were six individual treatment settings. One setting combined group and individual therapy [2] and one study did not allow for a differentiation of the individual and family settings that were used as alternatives nor did it give the number

*T. H. is a psychiatrist, psychoanalyst modes of treatment: A. H. is a research and cognitive theories.

and clinical psychologist with experience in cognitive behavioural psychologist with a clinical background based on systems theory

Psychotherapy of bulimia nervosa

163

of treatment sessions [29] . None of the studies which reported an in-patient treatment qualified for inclusion. Dose parameters. All treatments were economical, none exceeded 24 sessions (number of sessions: A4 = 13.0, SD = 4.6), and they usually took place within 4 months or less with one notable exception [29] (M = 13.9 wk, SD = 9.2 wk). The drop-out rate for active treatments was slightly over 20 % Outcome Conventionally, effect-sizes are being categorized as ‘no effect’ (ES < 0.2), low (0.2 < ES < = 0.5), medium (0.5 < ES < = 0.8) and high (ES > 0.8) [ 161. In our sample there were nine control groups six of which could be assessed for effectsize [ 2, 18, 2 1, 22, 24, 251 Their means (for binging and purging combined (M = 0.123, SD = 0.183) do not reach the conventional category of ‘low’ effect-size. By separate analysis of two studies not included in our sample because they report only on therapy ‘responders’ [36, 371 we determined effect-size for ‘excellent’ therapy success (M = 1.97). The average effect-size found across all studies was M = 1.042, the average effect-size for the 10 treatments with at least 15 sessions was M = 1.367, the average effect-size for the 13 treatments with less than 15 sessions was M = 0.792 (t = 2.81, df = 21, p < 0.02). Statistical

analysis

Setting and treatment variables were dichotomized and the resulting groups were compared by t-test. No significant differences between the ‘absence’ or ‘presence’ of group setting, cognitive, behavioural, educational, humanistic or psychodynamic techniques or relationship-, symptom- or conflict-orientation, was found. Effect-size however, were significantly correlated and the number of treatment sessions, (r = 0.52, p < 0.01). There was no such relationship between total duration of therapy (time pre-post) and effect-size. As a linear relationship between therapy dose and effect seems most unlikely [ 381 the natural logarithms of the dose variables were computed. The correlation obtained was r = 0.48, 0, < 0.02) for (In [ number of sessions] X Es) and r = 0.56 (p < 0.005) for (In [ total therapy time] x ES) (Fig. l).* 30

-

*

25 r

’

*

4

6

*

00 8

10

number

12

16

14

18

20

22

24

of sessions FIG. 1.

*Total therapy time (number X duration of sessions) probably is a more apt measure than mere number of sessions, particularly for week-end intensives etc. The reporting of duration of sessions often was unclear. Our estimates are given in Table I. Because not entered into the final computation.

of this unreliable

reporting

total therapy

time was

164

A. HARTMANNet al.

A stepwise multiple regression analysis was performed with intervention-, settingand dose-variables as source-variables and ES as dependent variable. Only the addition of the factor ‘relationship-orientation’ significantly improved the amount of variance explained by the logarithm of number of treatment sessions alone. The number of treatment sessions (In [ sess 1) and relationship-orientation (R) together explained 36% of the variance (df model = 2120, F(mode1) = 5.7, p < 0.01; F(ln[sess]) = 8.85, p < 0.007; F(R) = 4.32, p < 0.05). DISCUSSION

Unlike Smith and Glass [ 81 we could not classify treatments in a satisfactory way by simply putting them into mutually exclusive categories. Clinical work is shaped by local traditions and needs and creates its own reality which may or may not be congruent with theoretical prescriptions of specific schools. Experienced practitioners usually have found their ‘personal formula’ [ 391 The ecological validity and the applicability of findings from experimental psychotherapy studies require much greater attention than in drug treatment trials. Our search for relevant therapy process variables across studies is based on the assumption that there is a close interplay of factors that are common to all or most successful psychotherapies (e.g. ‘therapeutic alliance’) and those that are specific to a certain kind of therapists or a theoretical orientation (e.g. ‘self-monitoring’) and that the common factors are a prerequisite for the effectiveness of the specific factors [ 5 ] . One very simple common factor is the therapy dose [38]. We believe that what we called ‘relationshiporientation’ IS a special way of working with the patient which, however, is not particular to any school of therapy. This leads to a major difficulty of the present work. The extent and way in which the applied interventions are described varies tremendously, depending (among other factors) on the theoretical orientation of the authors and the purpose of the paper. Therefore, the seeming predominance of cognitive and behavioural interventions in our sample might in part be an artefact due to the way these are presented in publications. Our sample is completely biased towards out-patient settings with a strong bias toward group treatment and an almost total neglect of family or couple treatment. There is also a bias towards economical low-dose treatments. The drop-out rate of about 20% in addition to the fact that follow-ups could not be taken into account rather restricts the possible scope of statements on dose-effect relationships. The forcibly narrow measure of effect is unfair to clinical reality characterized by great heterogeneity of patients [2, 41, to some of the studies and to approaches emphasizing other areas of outcome. Measures of outcome should routinely and broadly cover specific symptomatology (including body image), general psychopathology, family and social adjustment and physiological parameters. A core-set of internationally agreed upon instruments for this purpose is urgently needed to allow optimal pooling of knowledge. There is obviously a need for carefully devised controlled long term follow-up studies which are clinically relevant and methodologically sound. The small number of studies fulfilling our not particularly strict inclusion criteria as well as their very limited time-frame show how difficult this is. Therefore, studies about studies, be

Psychotherapy

of bulimia

nervosa

165

they meta-analyses or sophisticated reviews [6, lo] , will retain an important place in assessing current knowledge. This requires a refinement of the application of meta-analytic procedures used to assess psychotherapy studies and a methodological discussion of the problems surrounding the calculation of effect-size in psychotherapy studies [40]. Because our analysis requires means and standard deviations we did some injustice to work like that of Fairburn and his group [ 411, who reported only percentages. Authors should routinely state means, standard deviations and sample sizes of every treatment at every time of repeated measurement and they should carefully and extensively describe what they actually do and how they do it. This would allow inclusion of follow-up studies and better identification of interventions independent of ‘therapy school’ labels and thereby greatly improve the clinical relevance of the findings. CONCLUSIONS

Interventions Explicitly helping to see and (emotionally) understand the connections between symptom behaviours and relationships seems to significantly improve the effect of the therapy, if sufficient therapy dose is provided. Treatment of bulimia nervosa should most likely include careful attention to the symptoms according to the consensus of the studies reviewed, with their usually marked symptom-orientation. Types

ofsetting

The available evidence does not show superiority of group or individual treatments. The outstanding effect of one combined individual and group treatment [ 2 ] could not be replicated [ 41 . Family and in-patient treatments which are probably indicated for specific subgroups, have not yet been sufficiently evaluated. Number

of therapy

sessions

The short-term effect of short-term treatments for bulimia is dependent on the therapy-dose, which should not be less than about 15 sessions for any clinically relevant effect to occur. The available studies do not allow statements about the optimal dose, which probably depends on the degree of disturbance of the patients [41. Duration

of therapy

The studies analysed, almost all on short-term treatments, do not allow a recommendation. New empirical evidence indicates that at least the more severely disturbed patients require treatments of a duration of a year and longer [ 41 . Further comment The low effect-sizes for the control groups support the thesis that (at least in the short run) there is no spontaneous remission of clinically relevant bulimia nervosa. It seems no longer ethical to withhold therapy for scientific reasons (control-groups). AcknowledRr,nents-This study was supported by a grant from the Charles-Hosie-Stiftung, We gratefully acknowledge the helpful and clarifying comments of Lutz Friilich, M.D. Treacher. Ph.D.

Hamburg. and Amal

166

A. HAK.IMANN er crl REFERENCES

I. RAD MV, R~~PPEI.L A. Combined inpatient and outpatient group psychotherapy: A therapeutic model of psychosomatics. Psychother Psychosom 1975; 26: 237.-243. 2. LACEY JH. Time-limited individual and group treatment for bulimia. In Handbook forPsyt-hotherapy, Anorexia Nrrvoscc and Bulimia (Edited by GARNER DM, GARFINKEL PE) pp. 43 l-457. New York: Guilford Press. 3. HERZOF T, HORCH U, BINZ-KERN L. SANDHOLL A. Konflikt- und symptomrentrierte Psychotherapie der Bulimic im ambulanten und stationiren Setting einer psychosomatischen Klinik. Pru_r klin Verhaltensmrd Rehab 1988; 1: 175-186. 4. HERZOG T, HARTMANN A, SANDH~LZ Z, STAMMER H. Prognostic factors in outpatient psychotherapy of bulimia. Psychother Psychosom 1991; 54: 48-55. 15. HERZOG T. Wirkfaktoren der Bulimicbehandlung. In Wir&ktoren der Ps)vfrothrrupie (Edited by LANG H) pp. 251-259. Berlin: Springer. 1990. 6. ORI INSK~ DE. HOWARD Kl. Process and outcome in psychotherapy; In Hundbook c$Psychorhrrap~ and Behaviour Change (Edited by GARFIEI.D SL. BERGIN AE). New York: Wiley. 1986. 7. LUR~RSKY LM, SINGER B. LUBORSKY L Comparative studies of psychotherapies: Is it true that ‘everyone has won and all must have prices. 3’ Arch Cm Psychiat 1975: 32: 995%1008. 8. SMITH ML, Gl.&ss GV. Meta-analysis of psychotherapy outcome studies. Am P.rychol 1977; 32: 752-160. 9. GHAWE K. Psychotherapeutische Verfahren im wisvenschaftlichen Vergleich. Prclx Psychother P.rychosom 1988; 33: 153-167. :O. GKAWE K, BERNAUER F. DONA,~I R. Psychotherapien im Vergleich: Haben wirklich alle einen Preis verdient’? Prar Psychorhrr Psychosom 1990; 40: 102-l 14. 11. LAESSLE RG, ZOETTL. C, PIRKE KM. Meta-analysis of treatment studies for bulimia. /NI J Earl Dis 1987; 6: 647-653. 12. Cox GI., MERKEL. WT. A qualitative review of psychosocial treatments for bulimia. J Nero, Ment Dis 1989; 177: 77-84. 13. AMMI-RICANPsvctttA7aIc Assoc~xr ION. Diagnosric und Stufi6/i( ul Manual of Metrial Disorders, Third Edition (DSM-III). Washington D.C.: APA, 1980. 14. AMERICAN PSYCHIAIKIC ASSOCIATION. Diagnostic und Statistical Marwd ofMmtul Disordt~rs, Third Edition (DSM-III-R). Washington D.C.: APA, 1984. 15. RUSSEI 1. G. Bulimia nervosa: an ominous variant of anorexia nervosa. PsychoI Mtvl 1979; 9: 429-428. 16. FKICKE R, TREINIFS G. Einfiihrurzg

in dir MctaanccIyse. Bern: Huber, 1985. 17. SCH~IA~.S?-IEC;-MAUREKR. Die Therapiemethoden in kontrollierten Therapiestudien. Entwicklung eines K~~leRoriens~slcms. Bern: Psychologisches Institut, 1984. 18. A