A Cluster Analysis of Purging Disorder

Krug, I., Granero, R., Giles, S., Riesco, N., Agüera, Z., Sánchez, I., Jiménez-Murcia, S.,Fernández-Aranda, F.

I, Isabel Krug, have no commercial relationships

to disclose.

BulimiaNervosa(BN)

BingeEatingDisorder(BED)

AnorexiaNervosa(AN)

Bingeeating

Self-induced vomiting

DSM-5 Eating Disorder Diagnoses

AtypicalANSubBN&BEDNESUFED

50-60%

Purging Disorder (PD) – Key Points• Treatment settings: PD ≈ 3% at an inpatient facility (Dalle

Grave, Calugi 2007).• Vomiting associated with PD can cause tears in the

oesophagus & life-threatening haemorrhages.• 5 year follow up study (Koch et al.2014):• Mortality rate 2 x higher than BN and OSFED• Chronicity: PD > AN-BP• PD persists in 31% of patients & full remission observed in

21%.• Meta-Analysis of PD (Smith et al., 2017): AN --- PD ---BN

Keel 2019

Is PD distinctive ? Taxometric studies Taxometric studies• BN spectrum disorder = distinct PD group, characterized by frequent purging behaviour and minor bingeing (e.g. Striegel-Moore et al., 2005; Mitchell et al., 2007).

BUT• Failed to distinguish women who purged & binged from women who purged without objectively large binge episodes (e.g. Wade et al., 2006).

STUDY 1

Objectives • Characterize a large PD sample using a new

taxometric approach (cluster analyses).• 1.) Cluster analysis: indicators (vomits, laxative

use, diuretic use)• 2.) Validation analyses: ED symptomatology,

general psychopathology & personality• 3.) Compare clusters to DSM-5 severity index

for BN

• PD sample: n=223 ED Unit/Bellvitge University Hospital (Barcelona, Spain).

• Diagnosed through DSM IV-RT/5 (APA, 2004 & 2013)• Controls: n=822 from the community• No history of an ED or mental health disorder • Age: ED sample: M = 27.3 yrs (SD=9.7); HC: M= 22.52 yrs (SD-

5.65); p

Definition of PD !• Purging episodes (e.g., self-induced vomiting, laxative

and/or diuretic misuse) in the ABSENCE of objectively large binge-eating episodes to control their weight or shape

• Frequency: ONCE per week; past THREE months• BMI: >18.5

• Keel et al., 2007; Keel 2019

EDI-2: ED symptomatology

SCL-90-R: GeneralPsychopathology

TCI-R: Personality

ValidatorsMethod

Vomits

LaxativeUse

DiureticUse

Indicators

STUDY 1

Clustering of PD behaviours

n=223

Validation analyses: Clinical ED variablesMeans Pairwise

comparisons (p)Mean Pairwise

comparisons (p)C1 C2 C3 C1 C1 C2 HC C1 C2 C3

n=121 n=55 n=47 vs C2

vs C3

vs C3

n=822 vs HC vs HC vs HC

Age of onset (yrs-old)

18.84 19.58 22.94 .546 .002* .025*

Duration (yrs) 6.89 7.53 6.90 .580 .992 .657BMI (current, kg/m2)

22.30 22.04 23.26 .681 .140 .107 22.29 .988 .564 .037*

BMI (max., kg/m2) 27.66 26.48 28.43 .238 .463 .110 23.60

Means Pairwise comparisons (p)

Mean Pairwise comparisons (p)

C1 C2 C3 C1 C1 C2 HC C1 C2 C3n=121 n=55 n=47 vs C2 vs C3 vs C3 n=822 vs HC vs HC vs HC

Eating (EDI-2)Drive for thinness 14.60 16.25 16.19 .021* .036* .942 4.18

Validation analyses: SCL-90-RC1 C2 C3 C1 C1 C2 HC C1 C2 C3

n=121 n=55 n=47 vs C2 vs C3 vs C3 n=822 vs HC vs HC vs HCPsycho. (SCL-90R)Somatization 1.91 2.08 2.00 .157 .485 .578 0.68

Validation analyses: TCI-RMeans Pairwise

comparisons (p)Mean Pairwise

comparisons (p)C1 C2 C3 C1 C1 C2 HC C1 C2 C3

n=121 n=55 n=47 vs C2 vs C3 vs C3 n=822 vs HC vs HC vs HCPersonality (TCI-R)Novelty seeking 102.3 101.6 99.5 .749 .232 .439 99.6 .017* .219 .949Harm avoidance 118.4 119.6 120.4 .665 .479 .796 100.1

Distribution of PD clusters based on DSM-5 severity index for BN

42.1%

1.8%

34.7%

36.4%

10.6%

5.0%

20.0%

12.8%

18.2%

41.8%

76.6%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Cluster1 Cluster2 Cluster3

Extreme(more 13 episodes)

Severe(8-13 episodes)

Moderate(4-7 episodes)

Mild(1-3 episodes)

Summary of findings1.) A 3-cluster profile was the best fitting solution for our PD data• Cluster 1 (only vomiting), Cluster 2 (vomiting & laxative use) and

Cluster 3 (vomiting, laxative & diuretic use).2.) Only a few significant differences in the measures used (EDI-2, SCL-90-R and TCI-R) between Cluster 1 & Cluster 3• à Cluster 1 < Cluster 33.) Three PD clusters differed from the HC group, on ED and general psychopathology, but less so for personality.4.) Only some correspondence of the 3 clusters with the DSM-5 (APA, 2013) severity index for purging behaviour for BN

Clinical Implications• PD is a clinically significant disorder, for which patients seek

treatment. • Not clear what forms of treatment may be most beneficial for PD

patients.• CBT program reduces purging behaviours & improves ED related

symptomatology (Riesco et al., 2018 ).• Other treatments such as DBT and interpersonal treatment found to

be effective in BN, need to be tested in PD.• Clinicians should record useful interventions in changing symptoms

with a specific focus on the main symptoms that seem to differentiate across the 3 PD classes (e.g. BMI, drive for thinness, perfectionism & persistence).

Limitations !!!!

•Subjective Binge Eating ????•Loss of Control over Eating ???•à EDE can assess for this•Treatment response/cross-over ???

Acknowledgements

• Roser Granero, • Sarah Giles,• Nadine Riesco, • Zaida Agüera, • Isabel Sánchez,• Susana Jiménez-Murcia,• Fernando Fernández-Aranda

Thank you !

Isabel.krug@unimelb.edu.au