EMPIRICAL ARTICLE
Eating Disorder Symptoms and Quality of Life: Where Should Clinicians Place their Focus in Severe and Enduring Anorexia Nervosa? Bryony Bamford, DclinPsy1* Christina Barras, MBBS1 Richard Sly, PhD2 Colleen Stiles-Shields, MA3,4 Stephen Touyz, PhD5 Daniel Le Grange, PhD4 Phillipa Hay, MD6,7 Ross Crosby, PhD8,9 Hubert Lacey, MD1
ABSTRACT Objective: The aim of this study was to examine the relationship between quality of life (QoL), weight, and eating disorder symptoms across treatment in individuals with severe and enduring anorexia nervosa (SE-AN). Method: Participants were 63 adult females with SE-AN presenting to an outpatient, multisite randomized clinical trial. QoL was assessed using three wellvalidated QoL questionnaire measures, the EDQOL, SF-12, and WSAS. Participants’ weight and severity of symptoms was assessed by Eating Disorder Examination (EDE) and weekly BMI change. Results: Predictors of QoL were evaluated in the context of concurrent, prospective,1 and lagged mixed-effects
Introduction Anorexia nervosa (AN) continues to prove a difficult condition to treat, with a significant number of patients remaining ill for many years. Individuals with a longer duration of illness are less likely to
This article was published online on 22 July 2014. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected 22 December 2014. Accepted 14 June 2014 *Correspondence to: Bryony Bamford; Eating Disorders Team, 6th Floor Hunter Wing, St. Georges University, Cranmer Terrace, Tooting, London, SW170RE. E-mail: [email protected] 1 St George’s, University of London, Eating Disorders Research Team, London, United Kingdom 2 School of Nursing Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, United Kingdom 3 Northwestern University Feinberg School of Medicine, Department of Preventive Medicine, Chicago, Illinois 4 The University of Chicago, Department of Psychiatry and Behavioral Neuroscience, Chicago, Illinois 5 University of Sydney, School of Psychology, Sydney, Australia 6 University of Western Sydney, Centre for Health Research, School of Medicine, Sydney, Australia 7 Add also School of Medicine, James Cook University, Townsville, Australia 8 Neuropsychiatric Research Institute, Fargo, North Dakota 9 University of North Dakota School of Medicine, Grand Forks, North Dakota Published online 22 July 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/eat.22327 C 2014 Wiley Periodicals, Inc. V
International Journal of Eating Disorders 48:1 133–138 2015
models. Changes in both BMI and EDE were found to significantly affect current and future QoL ratings. Discussion: Findings suggest that improvements in QoL may be dependent on symptom change and weight gain. Treatments seeking solely to improve QoL may be unlikely to produce lasting change and clinicians should maintain a focus on weight and behavioral symptoms as much as on improvements in C 2014 Wiley Periodicals, Inc. QoL. V Keywords: anorexia nervosa; severe and enduring; quality of life; treatment outcome (Int J Eat Disord 2015; 48:133–138)
recover,1–4 and suffer significant physical, social, and psychological sequalae as a result of their illness.5–8 Whilst no universally accepted definition of severe and enduring anorexia nervosa (SE-AN) exists, the term is increasingly prevalent in the field. For the purposes of this study, SE-AN refers to individuals with a self-reported illness duration in excess of 7 years. Existing treatments for AN place emphasis on primary medical symptoms, most notably weight gain. This can be seen as indicated for the majority of individuals with AN where the traditional definition of recovery that includes full symptom remission is the ultimate goal. Offering treatment where the clinician is focused on weight restoration and recovery could be seen as ill matched to a patient who has been struggling with their disorder for many years and does not share these goals. This mismatch likely contributes to the low retention rates that have typically characterized treatment studies of this group.9–11 There is increasing thought that the focus of treatment in individuals with severe and enduring anorexia (SE-AN) may need to change.3,12,13 The recovery model, along with more recent clinical papers, have suggested that the impact of a disorder should be the primary target of interventions, rather than the symptoms.9,12,14–16 This shift in treatment focus has been met with some resistance 133
BAMFORD ET AL.
however and is often poorly conceived or misconstrued. Recent reviews have concluded that a history of any eating disorder (ED) including DSM-IV Eating Disorder Not Otherwise Specified (EDNOS), subclinical EDs, and recovered ED sufferers, is associated with poorer quality of life (QoL).17–19 As such QoL, rather than weight or ED symptomology, has been proposed as a primary target for some psychological treatments for SE-AN.20 It is argued that individuals may be more motivated to improve these areas of their life even if they do not want to focus on weight restoration or recovery.15 A recent randomized clinical trial (RCT)21 sought to deliver modified versions of Specialist Supportive Clinical Management (SSCM) and Cognitive Behavioral Therapy for anorexia nervosa (CBT-AN) to 63 patients with SE-AN. In this RCT the primary outcome measures were QoL, mood disorder symptoms, and social adjustment. Secondary outcomes included weight (body mass index; BMI) and eating disorder symptomatology. The outcomes reflected the focus of therapy, where goals were set collaboratively and weight gain was encouraged, but not mandated or seen as the primary focus of treatment. The RCT demonstrated a high retention rate (85%), which is unusual in this population.9 Both SSCM and CBT-AN showed improvements in the majority of outcome measures, including QoL, weight, and eating disorder symptoms. The authors arrived at two conclusions: (1) by shifting the focus from weight gain to QoL, patients were potentially more willing to engage in therapy, therefore addressing symptom change in the longer term; (2) offering psychological treatment with a QoL focus might help chronic patients make changes to their overall life satisfaction, even with very modest weight gain. However, it is unclear if and how improved QoL, weight, and ED symptoms were related in this group. To our knowledge, whether improvement in QoL can occur without weight gain or reduced ED symptoms remains unknown. The aim of the current study is to examine the strength of the relationship between QoL, BMI, and ED symptoms in patients with SE-AN undergoing treatment. Previous studies have shown that BMI is a predictor of QoL,22 but the relationship between the two variables is still not fully understood. We hypothesized that there would be a significant correlation between BMI, ED symptomatology, and QoL across treatment. Additionally, we aim to explore whether changes in BMI and ED symptomatology were associated with future changes in QoL.
134
Method Participants and Procedure This study is a secondary analysis of data acquired during an RCT conducted between July 2007 and November 2010. A detailed description of the study and its primary outcomes is provided elsewhere21 but is briefly described here. Participants were 63 females with a diagnosis of SE-AN either restricting subtype (n 5 47; 75%) or binge-purge subtype (n 5 16, 25%). For the purposes of this study, SEAN was defined as “having had a duration of illness for at least seven consecutive years”. Participants were randomly assigned to receive either CBT-AN23 or SSCM24 as an outpatient. Exclusion criteria were as follows: any concurrent treatment for eating, weight or psychiatric problems, medical conditions that influence eating or weight, alcohol or drug dependence and factors that would interfere with the likelihood of treatment completion (e.g. plans to move beyond commuting distance). The study was approved by the relevant ethical review boards and all participants gave written informed consent. Treatments Both treatment arms involved 30 3 50-minute individual treatment sessions provided over a period of eight months in an outpatient setting. Both treatments were adapted in order that the primary focus was taken off symptom and weight change and placed onto improving QoL (see Touyz et al. 2013 for a more detailed description of the modifications). Measures All measures were administered at pre-randomization assessment, 15 weeks, end of treatment, 6 and 12 months follow-up. Physical Assessment. to calculate body mass index (BMI 5 kg/m2), participants’ weight and height were measured by a trained research assistant using a calibrated digital or balance-beam scale and stadiometer. All patients were weighed in light indoor clothing, without shoes. Eating Disorder Examination.25 The Eating Disorder Examination (EDE) is a semistructured investigatorbased interview measuring cognitive and behavioral symptoms related to ED. The EDE global scale was used to assess the severity of ED behavioral symptoms. The EDE has previously demonstrated good reliability and validity.26,27 Eating Disorders QoL Questionnaire.28 The Eating Disorders QoL Questionnaire (EDQOL) is a diseasespecific self report measure designed to assess QoL in eating disorder populations. It has 25 items comprising International Journal of Eating Disorders 48:1 133–138 2015
QUALITY OF LIFE AND BMI
four subscales (Psychological, Physical/Cognitive, Work/ School, and Financial). Each item is coded on a fivepoint scale and assesses the degree to which the participant perceives their ED to impact a specific area of their QoL. Higher scores indicate lower QoL. Items on the Psychological subscale assess how the ED is perceived to impact thoughts and feelings about oneself; items on the Physical/Cognitive subscale assess how the ED is perceived to impact physical sensations or cognitive capacity; items on the Financial subscale assess how the ED is perceived to impact financial status; and items on the Work/School subscale assess how the ED is perceived to impact performance at work or school. The EDQoL has been found to have good psychometric properties.28 Short Form-12 Health Status Questionnaire.29 The Short Form-12 Health Status Questionnaire (SF-12) is a standardized generic measure of impairment associated with physiological or psychological health conditions. It comprises 12 items that contribute to two weighted scales, a Physical Component Summary Scale (PCS) and a Mental Component Summary Scale (MCS). Each scale has a normative mean of 50 and standard deviation of 10 with higher scores indicating higher levels of functioning. Items on the PCS assess how physical health is perceived to limit everyday physical activities, social functioning, and productivity in work and other roles. Items on the MCS assess how emotional health is perceived to limit social functioning and productivity in work and other roles, as well as the extent to which an individual feels anxious, depressed, and lethargic. Good psychometric properties have previously been demonstrated for the SF-12.29 Weissman Social Adjustment Scale.30 The Weissman Social Adjustment Scale (WSAS) assesses social adjustment across a number of different areas of functioning, including marital, family, work, economic, and leisure. WSAS is a five-item self-report measure that assesses the degree to which an individual’s work, social and leisure activities, interpersonal relationships, and home management skills are affected by their physical or psychological impairment. Each item is scored on a 5-point scale with higher scores indicating poorer functioning. The scale has well-established reliability and validity and has been used in a wide variety of populations.30 Beck Depression Inventory.31 The Beck Depression Inventory (BDI) is a 21-item self-report questionnaire designed to assess depressive symptoms. Higher total scores reflect greater depressive symptomatology. The BDI has good psychometric properties.32,33 The BDI was included in order to control for the effects of depression throughout analyses.
Statistical Analyses Predictors of QoL were evaluated in the context of a mixed-effects model conducted using SPSS version 21.0. International Journal of Eating Disorders 48:1 133–138 2015
Outcome variables included four primary dimensional outcomes (EDQOL total score, WSAS total scores, SF-12 mental, and SF-12 physical subscales) and two predictor variables (BMI and EDE global score). The effects of depression (BDI) and treatment group were controlled throughout analyses. Three models were subsequently tested: Concurrent prediction utilizing all five time points, prospective prediction (t 1 1), and prospective incremental prediction (t 1 1 2 t), in which QoL at the previous timepoint was also controlled for.
Results Participant Characteristics and Attrition
Eighty-six percent (N 5 63) of eligible participants agreed to randomization with 30 randomized to CBT treatment and 33 randomized to SSCM. A total of 55 participants (87.3%) completed treatment, with 50 participants (79.4%) completing a 12-month follow-up assessment. All models included all available data after baseline. As in the original data paper, missing data for continuous outcome measures at EOT and follow-ups were imputed using multiple imputation based upon fully conditional Markov chain Monte Carlo modeling. Participants ranged in age from 20 to 62 years (M 5 33.4, SD 5 9.6), had a long duration of AN (M 5 16.6 years, SD 5 8.5), and were underweight (M 5 16.2 body mass index (BMI; kg/m2), SD 5 1.3). Most participants were single (n 5 36; 57%), did not have children (n 5 50; 79%), were in full-time employment (n 5 25; 40%) or study (n 5 10; 16%), and had a graduate or postgraduate degree (n 5 40; 63%). Twenty-six participants (41%) were taking psychotropic medication. In terms of co-morbid SCID-I (DSM-IV-TR) Axis I diagnoses, 22 participants (35%) met criteria for a mood disorder or dysthymia, 20 participants (31.7%) met criteria for generalized anxiety disorder and 16 (25.4%) met criteria for social phobia. Six participants (9.5%) met criteria for obsessive–compulsive disorder and one participant met criteria for current substance dependence. Baseline demographics for EDQoL, SF-13, WSAS, and EDE are provided in Table 1. Concurrent Prediction of QoL
Mixed model analyses (controlling for depression and treatment type) were used to assess the predictive value of BMI and EDE global score with regard to QoL at the same timepoint (Table 2). BMI was significantly associated with QoL as measured by the EDQOL (p < .0005) and SF-12 Physical 135
BAMFORD ET AL. TABLE 1. Baseline characteristics for predictor and outcome variables Variable
Mean
Standard Deviation
Range (Minimum, Maximum)
Age Duration of Illness BMI EDE Global Score EDQoL SF-12 (Physical) SF-12 (Mental) WSAS BDI
33.41 16.57 16.20 3.10 1.81 48.67 36.77 18.43 26.41
9.57 8.45 1.34 1.31 0.60 9.28 11.81 10.08 13.84
42 (20, 62) 42 (7, 49) 6.67 (11.80, 18.47) 5.26 (.41, 5.67) (.52, 2.85) 46.06 (17.85, 63.92) 46.96 (11.88, 58.84) (0, 39) (3,54)
Note. BMI, body mass index; EDE, eating disorders examination; EDQoL, eating disorders quality of life scale, SF-12, short form-12 (physical and mental component scales), WSAS, Weissman social adjustment scale; BDI, Beck depression inventory.
TABLE 3. Prospective prediction (using QoL data at next time point) Dependent Independent Variable Variable EDQOL WSAS SF-12 Mental SF-12 Physical
F, (df)
95% CI
Pseudo R2 p Value
BMI EDE BMI EDE BMI
6.20 (93) 20.15, 20.02 10.67 (136) 0.06, 0.23 3.91 (105) 21.83, 0.01 5.66 (118) 0.24, 2.61 2.99 (75) 20.15, 2.13
.489 .470 .551 .388 .139
.015* .001* .051 .019* .088
EDE BMI
2.49 (151) 22.91, 20.12 5.71 (115) 0.19, 2.08
.033 .529
.007* .019*
EDE
0.20 (158) 20.25, 1.59
.567
.655
*p < .05. **p < .01. ***p < .001.
TABLE 4. Prospective incremental prediction (using change in scores between timepoints) TABLE 2. Concurrent prediction (using data at same timepoints) Dependent Independent Variable Variable EDQOL WSAS SF-12 Mental SF-12 Physical
F, (df)
95% CI
Pseudo R2 p Value
BMI EDE BMI EDE BMI
12.93 (174) 20.11, 20.03 48.8 (220) 0.13, 0.23 2.38 (154) 0.13, 1.07 12.94 (197) .65, 2.22 0.07 (138) 0.63, 0.81
.563 .586 .491 .362 .215
Eating Disorder Symptoms and Quality of Life: Where Should Clinicians Place their Focus in Severe and Enduring Anorexia Nervosa? Bryony Bamford, DclinPsy1* Christina Barras, MBBS1 Richard Sly, PhD2 Colleen Stiles-Shields, MA3,4 Stephen Touyz, PhD5 Daniel Le Grange, PhD4 Phillipa Hay, MD6,7 Ross Crosby, PhD8,9 Hubert Lacey, MD1
ABSTRACT Objective: The aim of this study was to examine the relationship between quality of life (QoL), weight, and eating disorder symptoms across treatment in individuals with severe and enduring anorexia nervosa (SE-AN). Method: Participants were 63 adult females with SE-AN presenting to an outpatient, multisite randomized clinical trial. QoL was assessed using three wellvalidated QoL questionnaire measures, the EDQOL, SF-12, and WSAS. Participants’ weight and severity of symptoms was assessed by Eating Disorder Examination (EDE) and weekly BMI change. Results: Predictors of QoL were evaluated in the context of concurrent, prospective,1 and lagged mixed-effects
Introduction Anorexia nervosa (AN) continues to prove a difficult condition to treat, with a significant number of patients remaining ill for many years. Individuals with a longer duration of illness are less likely to
This article was published online on 22 July 2014. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected 22 December 2014. Accepted 14 June 2014 *Correspondence to: Bryony Bamford; Eating Disorders Team, 6th Floor Hunter Wing, St. Georges University, Cranmer Terrace, Tooting, London, SW170RE. E-mail: [email protected] 1 St George’s, University of London, Eating Disorders Research Team, London, United Kingdom 2 School of Nursing Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, United Kingdom 3 Northwestern University Feinberg School of Medicine, Department of Preventive Medicine, Chicago, Illinois 4 The University of Chicago, Department of Psychiatry and Behavioral Neuroscience, Chicago, Illinois 5 University of Sydney, School of Psychology, Sydney, Australia 6 University of Western Sydney, Centre for Health Research, School of Medicine, Sydney, Australia 7 Add also School of Medicine, James Cook University, Townsville, Australia 8 Neuropsychiatric Research Institute, Fargo, North Dakota 9 University of North Dakota School of Medicine, Grand Forks, North Dakota Published online 22 July 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/eat.22327 C 2014 Wiley Periodicals, Inc. V
International Journal of Eating Disorders 48:1 133–138 2015
models. Changes in both BMI and EDE were found to significantly affect current and future QoL ratings. Discussion: Findings suggest that improvements in QoL may be dependent on symptom change and weight gain. Treatments seeking solely to improve QoL may be unlikely to produce lasting change and clinicians should maintain a focus on weight and behavioral symptoms as much as on improvements in C 2014 Wiley Periodicals, Inc. QoL. V Keywords: anorexia nervosa; severe and enduring; quality of life; treatment outcome (Int J Eat Disord 2015; 48:133–138)
recover,1–4 and suffer significant physical, social, and psychological sequalae as a result of their illness.5–8 Whilst no universally accepted definition of severe and enduring anorexia nervosa (SE-AN) exists, the term is increasingly prevalent in the field. For the purposes of this study, SE-AN refers to individuals with a self-reported illness duration in excess of 7 years. Existing treatments for AN place emphasis on primary medical symptoms, most notably weight gain. This can be seen as indicated for the majority of individuals with AN where the traditional definition of recovery that includes full symptom remission is the ultimate goal. Offering treatment where the clinician is focused on weight restoration and recovery could be seen as ill matched to a patient who has been struggling with their disorder for many years and does not share these goals. This mismatch likely contributes to the low retention rates that have typically characterized treatment studies of this group.9–11 There is increasing thought that the focus of treatment in individuals with severe and enduring anorexia (SE-AN) may need to change.3,12,13 The recovery model, along with more recent clinical papers, have suggested that the impact of a disorder should be the primary target of interventions, rather than the symptoms.9,12,14–16 This shift in treatment focus has been met with some resistance 133
BAMFORD ET AL.
however and is often poorly conceived or misconstrued. Recent reviews have concluded that a history of any eating disorder (ED) including DSM-IV Eating Disorder Not Otherwise Specified (EDNOS), subclinical EDs, and recovered ED sufferers, is associated with poorer quality of life (QoL).17–19 As such QoL, rather than weight or ED symptomology, has been proposed as a primary target for some psychological treatments for SE-AN.20 It is argued that individuals may be more motivated to improve these areas of their life even if they do not want to focus on weight restoration or recovery.15 A recent randomized clinical trial (RCT)21 sought to deliver modified versions of Specialist Supportive Clinical Management (SSCM) and Cognitive Behavioral Therapy for anorexia nervosa (CBT-AN) to 63 patients with SE-AN. In this RCT the primary outcome measures were QoL, mood disorder symptoms, and social adjustment. Secondary outcomes included weight (body mass index; BMI) and eating disorder symptomatology. The outcomes reflected the focus of therapy, where goals were set collaboratively and weight gain was encouraged, but not mandated or seen as the primary focus of treatment. The RCT demonstrated a high retention rate (85%), which is unusual in this population.9 Both SSCM and CBT-AN showed improvements in the majority of outcome measures, including QoL, weight, and eating disorder symptoms. The authors arrived at two conclusions: (1) by shifting the focus from weight gain to QoL, patients were potentially more willing to engage in therapy, therefore addressing symptom change in the longer term; (2) offering psychological treatment with a QoL focus might help chronic patients make changes to their overall life satisfaction, even with very modest weight gain. However, it is unclear if and how improved QoL, weight, and ED symptoms were related in this group. To our knowledge, whether improvement in QoL can occur without weight gain or reduced ED symptoms remains unknown. The aim of the current study is to examine the strength of the relationship between QoL, BMI, and ED symptoms in patients with SE-AN undergoing treatment. Previous studies have shown that BMI is a predictor of QoL,22 but the relationship between the two variables is still not fully understood. We hypothesized that there would be a significant correlation between BMI, ED symptomatology, and QoL across treatment. Additionally, we aim to explore whether changes in BMI and ED symptomatology were associated with future changes in QoL.
134
Method Participants and Procedure This study is a secondary analysis of data acquired during an RCT conducted between July 2007 and November 2010. A detailed description of the study and its primary outcomes is provided elsewhere21 but is briefly described here. Participants were 63 females with a diagnosis of SE-AN either restricting subtype (n 5 47; 75%) or binge-purge subtype (n 5 16, 25%). For the purposes of this study, SEAN was defined as “having had a duration of illness for at least seven consecutive years”. Participants were randomly assigned to receive either CBT-AN23 or SSCM24 as an outpatient. Exclusion criteria were as follows: any concurrent treatment for eating, weight or psychiatric problems, medical conditions that influence eating or weight, alcohol or drug dependence and factors that would interfere with the likelihood of treatment completion (e.g. plans to move beyond commuting distance). The study was approved by the relevant ethical review boards and all participants gave written informed consent. Treatments Both treatment arms involved 30 3 50-minute individual treatment sessions provided over a period of eight months in an outpatient setting. Both treatments were adapted in order that the primary focus was taken off symptom and weight change and placed onto improving QoL (see Touyz et al. 2013 for a more detailed description of the modifications). Measures All measures were administered at pre-randomization assessment, 15 weeks, end of treatment, 6 and 12 months follow-up. Physical Assessment. to calculate body mass index (BMI 5 kg/m2), participants’ weight and height were measured by a trained research assistant using a calibrated digital or balance-beam scale and stadiometer. All patients were weighed in light indoor clothing, without shoes. Eating Disorder Examination.25 The Eating Disorder Examination (EDE) is a semistructured investigatorbased interview measuring cognitive and behavioral symptoms related to ED. The EDE global scale was used to assess the severity of ED behavioral symptoms. The EDE has previously demonstrated good reliability and validity.26,27 Eating Disorders QoL Questionnaire.28 The Eating Disorders QoL Questionnaire (EDQOL) is a diseasespecific self report measure designed to assess QoL in eating disorder populations. It has 25 items comprising International Journal of Eating Disorders 48:1 133–138 2015
QUALITY OF LIFE AND BMI
four subscales (Psychological, Physical/Cognitive, Work/ School, and Financial). Each item is coded on a fivepoint scale and assesses the degree to which the participant perceives their ED to impact a specific area of their QoL. Higher scores indicate lower QoL. Items on the Psychological subscale assess how the ED is perceived to impact thoughts and feelings about oneself; items on the Physical/Cognitive subscale assess how the ED is perceived to impact physical sensations or cognitive capacity; items on the Financial subscale assess how the ED is perceived to impact financial status; and items on the Work/School subscale assess how the ED is perceived to impact performance at work or school. The EDQoL has been found to have good psychometric properties.28 Short Form-12 Health Status Questionnaire.29 The Short Form-12 Health Status Questionnaire (SF-12) is a standardized generic measure of impairment associated with physiological or psychological health conditions. It comprises 12 items that contribute to two weighted scales, a Physical Component Summary Scale (PCS) and a Mental Component Summary Scale (MCS). Each scale has a normative mean of 50 and standard deviation of 10 with higher scores indicating higher levels of functioning. Items on the PCS assess how physical health is perceived to limit everyday physical activities, social functioning, and productivity in work and other roles. Items on the MCS assess how emotional health is perceived to limit social functioning and productivity in work and other roles, as well as the extent to which an individual feels anxious, depressed, and lethargic. Good psychometric properties have previously been demonstrated for the SF-12.29 Weissman Social Adjustment Scale.30 The Weissman Social Adjustment Scale (WSAS) assesses social adjustment across a number of different areas of functioning, including marital, family, work, economic, and leisure. WSAS is a five-item self-report measure that assesses the degree to which an individual’s work, social and leisure activities, interpersonal relationships, and home management skills are affected by their physical or psychological impairment. Each item is scored on a 5-point scale with higher scores indicating poorer functioning. The scale has well-established reliability and validity and has been used in a wide variety of populations.30 Beck Depression Inventory.31 The Beck Depression Inventory (BDI) is a 21-item self-report questionnaire designed to assess depressive symptoms. Higher total scores reflect greater depressive symptomatology. The BDI has good psychometric properties.32,33 The BDI was included in order to control for the effects of depression throughout analyses.
Statistical Analyses Predictors of QoL were evaluated in the context of a mixed-effects model conducted using SPSS version 21.0. International Journal of Eating Disorders 48:1 133–138 2015
Outcome variables included four primary dimensional outcomes (EDQOL total score, WSAS total scores, SF-12 mental, and SF-12 physical subscales) and two predictor variables (BMI and EDE global score). The effects of depression (BDI) and treatment group were controlled throughout analyses. Three models were subsequently tested: Concurrent prediction utilizing all five time points, prospective prediction (t 1 1), and prospective incremental prediction (t 1 1 2 t), in which QoL at the previous timepoint was also controlled for.
Results Participant Characteristics and Attrition
Eighty-six percent (N 5 63) of eligible participants agreed to randomization with 30 randomized to CBT treatment and 33 randomized to SSCM. A total of 55 participants (87.3%) completed treatment, with 50 participants (79.4%) completing a 12-month follow-up assessment. All models included all available data after baseline. As in the original data paper, missing data for continuous outcome measures at EOT and follow-ups were imputed using multiple imputation based upon fully conditional Markov chain Monte Carlo modeling. Participants ranged in age from 20 to 62 years (M 5 33.4, SD 5 9.6), had a long duration of AN (M 5 16.6 years, SD 5 8.5), and were underweight (M 5 16.2 body mass index (BMI; kg/m2), SD 5 1.3). Most participants were single (n 5 36; 57%), did not have children (n 5 50; 79%), were in full-time employment (n 5 25; 40%) or study (n 5 10; 16%), and had a graduate or postgraduate degree (n 5 40; 63%). Twenty-six participants (41%) were taking psychotropic medication. In terms of co-morbid SCID-I (DSM-IV-TR) Axis I diagnoses, 22 participants (35%) met criteria for a mood disorder or dysthymia, 20 participants (31.7%) met criteria for generalized anxiety disorder and 16 (25.4%) met criteria for social phobia. Six participants (9.5%) met criteria for obsessive–compulsive disorder and one participant met criteria for current substance dependence. Baseline demographics for EDQoL, SF-13, WSAS, and EDE are provided in Table 1. Concurrent Prediction of QoL
Mixed model analyses (controlling for depression and treatment type) were used to assess the predictive value of BMI and EDE global score with regard to QoL at the same timepoint (Table 2). BMI was significantly associated with QoL as measured by the EDQOL (p < .0005) and SF-12 Physical 135
BAMFORD ET AL. TABLE 1. Baseline characteristics for predictor and outcome variables Variable
Mean
Standard Deviation
Range (Minimum, Maximum)
Age Duration of Illness BMI EDE Global Score EDQoL SF-12 (Physical) SF-12 (Mental) WSAS BDI
33.41 16.57 16.20 3.10 1.81 48.67 36.77 18.43 26.41
9.57 8.45 1.34 1.31 0.60 9.28 11.81 10.08 13.84
42 (20, 62) 42 (7, 49) 6.67 (11.80, 18.47) 5.26 (.41, 5.67) (.52, 2.85) 46.06 (17.85, 63.92) 46.96 (11.88, 58.84) (0, 39) (3,54)
Note. BMI, body mass index; EDE, eating disorders examination; EDQoL, eating disorders quality of life scale, SF-12, short form-12 (physical and mental component scales), WSAS, Weissman social adjustment scale; BDI, Beck depression inventory.
TABLE 3. Prospective prediction (using QoL data at next time point) Dependent Independent Variable Variable EDQOL WSAS SF-12 Mental SF-12 Physical
F, (df)
95% CI
Pseudo R2 p Value
BMI EDE BMI EDE BMI
6.20 (93) 20.15, 20.02 10.67 (136) 0.06, 0.23 3.91 (105) 21.83, 0.01 5.66 (118) 0.24, 2.61 2.99 (75) 20.15, 2.13
.489 .470 .551 .388 .139
.015* .001* .051 .019* .088
EDE BMI
2.49 (151) 22.91, 20.12 5.71 (115) 0.19, 2.08
.033 .529
.007* .019*
EDE
0.20 (158) 20.25, 1.59
.567
.655
*p < .05. **p < .01. ***p < .001.
TABLE 4. Prospective incremental prediction (using change in scores between timepoints) TABLE 2. Concurrent prediction (using data at same timepoints) Dependent Independent Variable Variable EDQOL WSAS SF-12 Mental SF-12 Physical
F, (df)
95% CI
Pseudo R2 p Value
BMI EDE BMI EDE BMI
12.93 (174) 20.11, 20.03 48.8 (220) 0.13, 0.23 2.38 (154) 0.13, 1.07 12.94 (197) .65, 2.22 0.07 (138) 0.63, 0.81
.563 .586 .491 .362 .215
