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Psychiatric disorders in bariatric surgery candidates: a review of the literature and results of a German prebariatric surgery sample
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General Hospital Psychiatry 31 (2009) 414 – 421
Psychiatric disorders in bariatric surgery candidates: a review of the literature and results of a German prebariatric surgery sample Barbara Mühlhans, Psy.D.a,⁎, Thomas Horbach, M.D.b , Martina de Zwaan, M.D.a a
Department of Psychosomatic Medicine and Psychotherapy, University Hospital of Erlangen, 91054 Erlangen, Germany b Department of Surgery, Obesity Control Center, Municipal Hospital Schwabach, 91126 Schwabach, Germany Received 21 January 2009; accepted 6 May 2009
Abstract Objective: To investigate the prevalence of Axis I psychopathology in bariatric surgery candidates and to compare our results with the findings of the few studies published thus far. Method: Structured clinical interviews (SCID) were conducted in 146 consecutive bariatric surgery candidates [71.9% women; mean age: 38.7 years (S.D.=10.0); mean BMI: 49.3 kg/m2 (S.D.=7.8)] between September 2004 and January 2007 at the University Hospital of Erlangen. Assessments were administered independently of the preoperative screening and approval process. Results: The overall prevalence of current Axis I disorders was 55.5%; 72.6% had a lifetime history of at least one Axis I disorder. Axis I psychopathology was related to gender (with women reporting higher prevalence rates) and was positively associated with a lifetime history of any eating disorder. We compared our results with the findings of the three published studies having used structured clinical interviews to assess psychiatric comorbidity in bariatric surgery candidates. The authors provide an overview of evidence so far and highlight some details in the assessment and comparisons of different samples in different countries. Conclusion: About one half of the bariatric surgery candidates in Germany presented with a current Axis I disorder. Prevalence rates reported in the literature so far are based on different premises. Details for example about the evaluation should be taken into account when interpreting the results. © 2009 Published by Elsevier Inc. Keywords: Bariatric surgery candidates; Psychiatric disorders; Psychiatric comorbidity; SCID interview; Axis I disorders
1. Introduction Obesity is an increasingly prevalent chronic condition in Europe as well as in the United States [1,2]. It is a wellestablished risk factor for a myriad of medical conditions, among them diabetes mellitus, certain forms of cancer, cardiovascular disease and degenerative joint disease, and is associated with an overall increased mortality [3–7]. Bariatric surgery is the most effective — if not the only effective treatment in patients with extreme obesity (BMI ≥40 kg/m2) [8]. Weight loss results are superior to those of conservative weight loss treatments. Two years postoperatively, patients typically lose 62% of excess body weight with gastric bypass, 48% with gastric banding, 70% with ⁎ Corresponding author. E-mail address: [email protected] (M. de Zwaan). 0163-8343/$ – see front matter © 2009 Published by Elsevier Inc. doi:10.1016/j.genhosppsych.2009.05.004
biliopancreatic diversion or duodenal switch and about 68% with gastroplasty [9]. Postoperative weight loss is associated with significant improvements in obesity-related comorbidities [10,11] and mortality rates [12]. The 1991 NIH Consensus Development Conference Panel [13] advised careful selection of candidates for bariatric surgery after evaluation by a multidisciplinary team with medical, surgical, psychiatric and nutritional expertise. The National Obesity Society in Germany in their guidelines recommended special care in making decisions regarding patients with severe depression, psychosis and severe eating disorders such as bulimia nervosa or binge eating disorder (BED). In such cases, a mental health care professional should be part of the decision-making team [14]. Whether obesity is associated with psychiatric disorders in the general population is an ongoing debate. Results are mixed, with some results indicating that obesity is related to
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increased psychopathology and some studies finding no relationship or even a negative association [15]. It became obvious that heterogeneity of associations between obesity and psychiatric states exists. Several moderators of the association between depression and obesity have been found, such as gender or socioeconomic status (SES) [16]. Onyike et al. [17] reported that increasing severity of obesity is associated with an increasing risk of depression. Friedman and Brownell [18] in their comprehensive metaanalysis described three generations of studies. The first generation merely described the association between obesity and psychosocial functioning in general — and failed to find differences between nonobese and obese persons. The second generation uses a risk factor model to identify individuals who are likely to suffer from psychosocial consequences of obesity. The third generation is going to establish causal pathways between body weight and psychosocial functioning. Today, the quality of population-based research has improved considerably. In the last few years, several studies have assessed the relationship between obesity and psychiatric disorders in large representative samples using structured clinical interviews and DSM-IV diagnostic criteria. In nearly all of these studies, obese persons show elevated rates of mood and anxiety disorders in comparison to members of the general population. This is especially true for women [19,20], and prevalence rates of mental disorders seem to increase with increasing severity of obesity [17,19]. These studies really represent the “second generation of studies” as stated by Friedman and Brownell [18], which identify risk factors such as gender and severity of obesity and linking them to psychopathology. Obese patients presenting for bariatric surgery are about 70–80 % female, some with Grade II obesity but most with Grade III obesity. So these patients present with several wellestablished risk factors linked to psychosocial impairment in obesity. The first studies assessing psychiatric comorbidity in bariatric surgery candidates were published about 30 years ago. Hopkins and Bland [21] found elevated rates of depressive disorders as well as carbohydrate craving in 73 females presenting for gastric bypass surgery. Stunkard et al. [22] described in their review assessing psychological aspects of surgical treatment of obesity two types of emotional disturbances not measured by standard tests: adverse responses to dieting and disparagement of the body image. Black et al. [23] reported in 88 gastric banding candidates an elevated rate of lifetime mood disorders, anxiety disorders, bulimia and tobacco dependence. As in population-based studies, the quality of research in the field of psychiatric comorbidity in bariatric surgery candidates has improved considerably in the last few years. Three studies assessing Axis I disorders in large consecutive bariatric surgery samples with structured interviews have been published (Table 1). The studies so far present valuable data from different countries and different methodological approaches. The
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Table 1 Comparison across studies Erlangen Kalarchian Rosenberger Mauri et al. current study et al. (2007) et al. (2006) (2008) [26] (N=146) [24] (N=288) [25] (N=174) (N=255) % Women Mean BMI (S.D.) Mean age, years (S.D.) % Married
71.9 49.3 (7.8)
83.3 52.2 (9.7)
75.3 50.2 (8.5)
79.8a N40a
38.7 (10.0)
46.6 (9.4)
42.9 (11.1)
42.1 (11.4)a
51.4
57.3
59.8
69.5a
a Mauri et al. also included patients with BMI 35–40 kg/m2. To allow a comparison to the other studies, we excluded this group and recalculated the rates of psychiatric disorders. Sample characteristics could not be recalculated, so the data given in the table is for the whole sample of Mauri et al.
samples are similar in several aspects such as mean age, gender distribution or mean BMI. Even though there are no distinct differences in the prevalence rates of severe obesity between men and women, bariatric surgery candidates are predominantly female, a homogenous finding in all samples described so far in the academic literature. In the current study, we will review the data published thus far and present data from a German sample of bariatric surgery candidates, comparing our results with the results of the three published studies. This will be the first study to give a comprehensive overview of the findings so far, highlighting some possible health system effects, geographic differences and effects of differing approaches.
2. Methods 2.1. Patients Between September 2004 and January 2007, 240 consecutive patients considering bariatric surgery presented at the University Hospital of Erlangen. Of those patients, 146 (60.8%) gave written informed consent to participate in our study. Inclusion criteria for the present study were age ≥18 years and a BMI of ≥35 kg/m2, as well as sufficient German language skills. Assessments were typically scheduled immediately after the psychological evaluation required for an application for reimbursement of costs for the surgery by health insurance companies. Consequently, assessments were conducted at a very early stage of the process, up to 6 months prior to the surgery. Participants were assured that information provided for research would not influence their candidacy for surgery. The study was approved by the ethics committee of the medical school of the University of Erlangen-Nuremberg. All participants gave written informed consent. 2.2. Assessment The patients were scheduled for a 2- to 3-h psychological evaluation, which was independent of the evaluation required for the bariatric surgery candidacy process. We wanted to enhance patients' willingness to disclose problems that they
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Table 2 Age and BMI
Age Women Men BMI Women Men
Mean (S.D.)
T (144)
38.6 (9.8) 39.1 (10.6)
−0.31; ns
48.9 (7.8) 50.3 (8.0)
−0.96; ns
might perceive as having an influence on the approval for the surgery. Evaluation included two structured psychiatric diagnostic interviews regarding psychiatric disorders and eating behavior. The interviews were conducted by three psychologists as well as by a graduate student of psychology. All raters were trained and received ongoing supervision by the last author of this article. Current and lifetime Axis I diagnoses were assessed with the German version of the Structured Clinical Interview for DSM-IV (SCID) [27]. The SCID is considered as the “gold standard” for assessing psychiatric comorbidity and has wellestablished validity and reliability [28]. Current eating disorders were assessed in detail using the German version of the Eating Disorder Examination (EDE [29]). The EDE is a structured clinical interview for the assessment of eating patterns and eating-related psychopathology, and allows one to make DSM-IV diagnoses of all eating disorders. Therefore, the diagnostic items are also rated for duration. The EDE is used widely in the assessment of eating disorders [30]. Psychometric studies of the EDE have demonstrated good inter-rater and test–retest reliability for binge eating behaviors [31,32]. The EDE was used for the assessment of current eating disorders, since the EDE allows the assessment of current binge eating and purging behavior in a more thorough manner than the SCID. An eating disorder not otherwise specified (EDNOS) was diagnosed in patients reporting binge eating behavior and other aspects of BED but not meeting the full
Table 3 Demographic characteristics Characteristic Sex Female Male Marital status Single Relationship Married Living apart/divorced/widowed Missing Education No degree 9 years 10 years Finished high school (13 years) College/university degree (N13 years) Missing
n (%) 105 (71.9) 41 (28.1) 26 (17.8) 24 (16.4) 75 (51.4) 12 (8.2) 9 (6.2) 17 (11.6) 77 (52.7) 24 (16.4) 9 (6.2) 10 (6.8) 9 (6.2)
criteria for a BED diagnosis (“subsyndromal BED”). The extent to which the DSM-IV criteria make meaningful distinctions between full and subsyndromal eating disorders has been questioned, and it has been suggested that the diagnostic criteria should be broadened. Individuals with binge eating problems frequently do not meet the frequency criterion of two binge days per week. Other patients meet the frequency criteria but deny “marked distress.” There is evidence that subsyndromal BED subjects do not differ significantly from subjects meeting full criteria and frequently evidence the same level of distress, low self-esteem, impaired social adjustment and overconcern with shape and weight. Overall, there is no sharp demarcation between the full syndrome and the subsyndromal groups, and, consequently, some recent treatment studies have started to include subsyndromal cases [33,34]. We decided to report lifetime prevalence rates of BED and subsyndromal BED (EDNOS) combined, believing this to be a valid approach.
3. Results 3.1. Sample Of the 146 participants, 105 (71.9%) were women, with a mean age of 38.7 (S.D.=10.0) and a mean BMI of 49.3 kg/m2 (S.D.=7.8). No significant differences regarding age or BMI between men and women were found (Table 2). A total of 68.8% of the participants either had no degree or had 9 years of education with degree (equivalent to general-education secondary school grade 5 to 9). A total of 68% of the participants reported living in a relationship or being married, 18% reported being single at the time of the evaluation, 8% reported living apart, being divorced or being widowed (Table 3). 3.2. Education Our sample is characterized by a low educational level in comparison to the general population in Germany. In the general population, the educational level increases with younger age; especially the age cohort 60 and over (about 25% of the general population [32]) has higher rates of lower education level than the rest of the population [36]. In our sample, the mean age was 38.7 (S.D.=10.0) and no one was older than 60. The age cohort with the lowest educational status is not part of our sample, so, presumably, the data given in Table 4 underestimate the differences Table 4 Education of patients prior to bariatric surgery in Germany Education
This study General population (≥15 years) [35]
No degree 9 years 10 years At least finished high school (≥13 years)
11.6% 52.7% 16.4% 13.0%
3.5% 41.6% 20.3% 22.4%
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between our sample and the general population rather than overestimate them. 3.3. Prevalence of lifetime and current psychiatric disorders Table 5 summarizes the lifetime prevalence rates of psychiatric disorders for the total sample and divided by gender. The most common category of lifetime disorders was affective disorders (54.8%; n=80). A lifetime eating disorder (including EDNOS) was diagnosed in 50% (n=73) of the participants, with 10 participants (6.8%) reporting a history of bulimia nervosa and all 73 participants reporting a history of BED or subsyndromal BED. Women were significantly more likely than men to meet the criteria for a lifetime affective disorder (P=.001) or a lifetime eating disorder (PN.001). Of the 146 participants, 21.2% (n=31) met the criteria for a lifetime anxiety disorder and 15.1% (n=22) of the participants reported a history of substance use disorder. For these psychiatric diagnoses, no differences between women and men were found. Overall, 72.6% of the participants reported at least one lifetime psychiatric diagnosis. In women, the prevalence of at least one lifetime psychiatric disorder was 81.9%. With regard to current psychiatric disorders (Table 6), eating disorders were the most common class (37.7%; n=55), including 34 (23.3%) participants with BED and 21 (14.4%) participants with an EDNOS. A total of 31.5% (n=46) of the participants reported a current affective disorder; 22 (15.1%) participants met the criteria for a current anxiety disorder. Only two participants (1.4%) reported a current substance use disorder and five (3.4%) were diagnosed with a somatoform disorder. For most current psychiatric disorders, it was not possible to examine gender differences due to the low number of cases in each Table 5 Rates of lifetime psychiatric disorders in bariatric surgery candidates Psychiatric disorders
All subjects Women (N=146) (n=105)
Any psychiatric disorder 106 (72.6) Any affective disorder 80 (54.8) Major depressive disorder 74 (50.7) Dysthymia 12 (8.2) Mania 2 (1.4) Any anxiety disorder 31 (21.2) Social phobia 9 (6.2) Specific phobia 11 (7.5) PTSD 13 (8.9) Any substance use disorder 22 (15.1) Alcohol use disorder 16 (11.0) Any drug use disorder 9 (6.2) (without alcohol) Any somatoform disorder 5 (3.4) Somatoform pain disorder 4 (2.7) Any eating disorder 73 (50.0) EDNOS (including BED) 73 (50.0) Bulimia nervosa 10 (6.8) Values are shown as n (%).
Men (n=41)
χ2
86 (81.9) 20 (48.8) Pb.001 67 (63.8) 13 (31.7) P=.001 63 (60.0) 11 (26.8) 8 (7.6) 4 (9.8) 2 (1.9) 28 (26.7) 3 (7.3) – 9 (8.6) 10 (9.5) 1 (2.4) 13 (12.4) 16 (15.2) 6 (14.6) ns 12 (10.5) 5 (12.2) 7 (6.7) 2 (4.9) 5 (4.8) 4 (3.8) 64 (61.0) 64 (61.0) 10 (9.5)
– 9 (22.0) Pb.001 9 (22.0)
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Table 6 Rates of current psychiatric disorders in bariatric surgery candidates Men (n=41)
χ2 (1)
Psychiatric disorder
All subjects Women (N=146) (n=105)
Any psychiatric disorder Any affective disorder Major depressive disorder Dysthymia Mania Any anxiety disorder Social phobia Specific phobia PTSD Any substance use disorder Alcohol use disorder Any drug use disorder Any somatoform disorder Somatoform pain disorder Any eating disorder Binge eating disorder EDNOS Bulimia nervosa
81 (55.5) 46 (31.5) 37 (25.3) 9 (6.2)
69 (65.8) 12 (29.3) Pb.001 39 (37.1) 7 (17.1) P=.028 34 (32.4) 3 (7.3) 5 (4.8) 4 (9.8)
22 (15.1) 9 (6.2) 10 (6.8) 6 (4.1) 2 (1.4) 1 (0.7) 1 (0.7) 5 (3.4) 4 (2.7) 55 (37.7) 34 (23.3) 21 (14.4) –
20 (19.0) 2 (4.9) – 9 (8.6) 9 (8.6) 1 (2.4) 6 (5.7) 2 (1.9) – 1 (1.0) 1 (1.0) 5 (4.8) 4 (3.8) 48 (45.7) 7 (17.1) P=.001 31 (29.5) 3 (7.3) 17 (16.2) 4 (9.8) – –
Values are shown as n (%).
group. Gender differences were found for current eating disorders (P=.001), whereas for current affective disorders no differences in prevalence rates between men and women were found. Overall, 56% of our patients met the criteria for at least one current psychiatric disorder, with 66% of the women and 29% of the men meeting the criteria for at least one current psychiatric disorder. 3.4. Comorbidity with Axis I disorder in participants with an eating disorder We examined the lifetime psychiatric comorbidity in bariatric surgery candidates diagnosed with an eating disorder. Table 7 summarizes the findings for participants with or without a lifetime eating disorder diagnosis. Participants with a lifetime eating disorder diagnosis exhibited a substantially higher prevalence rate of any Axis I disorder in comparison to those without an eating disorder. Eighty-four percent of the participants with a lifetime eating disorder diagnosis reported at least one other lifetime disorder; in participants without a lifetime eating disorder diagnosis, only 45.2% exhibited another lifetime disorder. 4. Psychiatric disorders in bariatric surgery candidates: a review of the literature Recently, three studies have investigated the prevalence of psychiatric disorders among bariatric surgery candidates in the USA and Italy, using the SCID-Interview [24–26] (Table 8). In the USA, Kalarchian et al. [24] reported a lifetime prevalence rate of psychiatric disorders of 66.3% and Rosenberger et al. [25] reported a lifetime prevalence of
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Table 7 Comparison of participants with and without a lifetime eating disorder
Number of lifetime psychiatric disorder (without eating disorders)
Any psychiatric disorder Any mood disorder Any anxiety disorder Any substance use disorder Any somatoform disorder
No lifetime eating disorder (n=73), MW (S.D.)
Lifetime eating disorder (n=73), MW (S.D.)
T (df)
P
0.63 (0.84)
1.71 (1.55)
−5.24 (111.1)
b.001
No lifetime eating disorder (n=73), n (%)
Lifetime eating disorder (n=73), n (%)
χ2 (df)
P
24.37 (1) 19.13 (1) 12.38 (1) 8.08 (1) –
b.001 b.001 .001 .01 –
33 (45.2) 27 (37.0) 7 (9.6) 5 (6.8) 3 (4.1)
61 (83.6) 53 (72.6) 24 (23.9) 17 (23.3) 2 (2.7)
Axis I disorders of 36.8%. Mauri et al. [26] in Italy found a lifetime prevalence rate of 37.6%. The rates of current psychiatric Axis I disorders were 37.7% [24], 24.1% [25] and 20.9% [26], respectively. The direct comparison of prevalence rates between different studies can be misleading, since differences in demographic and social factors as well as differences in methodology may confound the comparison of associations between obesity and various psychiatric states. 4.1. Comparison of methodological approaches across the studies The disorders assessed in the studies were very similar — but not identical. In comparing the results, this should be kept in mind. Two of the studies did not assess EDNOS [24,26]. As EDNOS is the most common eating disorder diagnosis [37], this probably had an influence on the prevalence rates reported. Somatoform disorders were assessed in our study as well as in the study of Rosenberger et al. [25]. The other authors provided no information about somatoform disorders. The same is true for psychotic disorders; in our study, a current psychotic disorder was an exclusion criterion and lifetime diagnoses were not assessed. Rosenberger et al. [25] reported having found no psychotic disorders, and the other studies provided no information. The study of Rosenberger et al. [25] is
presumably the only one which assessed adjustment disorders. The evaluation instrument used in all three studies was the English, Italian or the German version of the SCID Interview [27]. Kalarchian et al. [24], Mauri et al. [26] and our study conducted face-to-face interviews, while Rosenberger et al. [25] did the interviews by telephone. One more difference in the evaluation process is quite important: in our study as well as in the study of Kalarchian et al. [24], the evaluation process was strictly independent from the approval process for the surgery, whereas in the studies of Rosenberger et al. [25] and Mauri et al. [26] the interviews were part of the presurgical evaluation interview. This could have had an influence on the willingness of the participants to disclose psychiatric problems. Both of the studies with an independent evaluation process (ours and Kalarchian et al. [24]) and both studies with an evaluation process linked to the approval process showed comparable results to each other but differed in their results from the other two studies, with higher prevalence rates of psychiatric disorders when interviews were conducted from the approval process for the surgery. 4.2. Comparison of sample characteristics The samples of the studies are alike in several aspects (Table 1) such as gender distribution (mainly women), mean age and mean BMI.
Table 8 Comparison across studies: rates of psychiatric disorders lifetime (current) Psychiatric diagnosis
Erlangen study (N=146)
Kalarchian et al. [24] (2007) (N=288)
Rosenberger et al. [25] (2006) (N=174)
Mauria et al. [26] (2008) (N=255)
Any psychiatric disorder Any affective disorder Any anxiety disorder Any substance use disorder Any somatoform disorder Any eating disorder
72.6% (55.5%) 54.8% (31.5%) 21.2% (15.1%) 15.1% (1.4%) 3.4% (3.4%) 50.0% (37.7%)
66.3% (37.8%) 45.5% (10.4%) 37.5% (5.9%) 32.6% (1.7%) ? 29.5% (16.3%)c
36.8% (24.1%)b 22.4% (10.9%) 15.5% (11.5%) 5.2% (0.6%) 0% 13.8% (10.3%)
38.0% (22.0%) 22.0% (6.7%) 18.0% (12.9%) 1.2% (–) ? 13.3 (7.1%)c
a b c
Prevalence rates recalculated — patients with BMI ≥35; patients with BMI 30–34.9 were excluded. Including adjustment disorder (n=2; 1.1%). Without EDNOS.
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One other difference is of note. In our sample, the educational level was quite low compared to the German general population (see Table 4). This is in line with findings that a lower SES is associated with higher body weight and a higher degree of obesity. This effect is especially prominent for education as an indicator of SES and the association is particularly found in women [38] (in our sample, 71.9% of the patients were female). These effects are seen in all countries with high socioeconomic development [39]. The US samples described in the two recent articles addressing the prevalence of psychiatric disorders in patients prior to bariatric surgery [24,25] included patients with a higher educational level than found in the US general population. In the sample of Kalarchian et al. [24], 69.7% had received education beyond high school; in the sample described by Rosenberger et al. [25], 73.3% had received education beyond high school. In the general population in the USA (≥25 years), the rate of an educational level beyond high school was reported to be 53.8% [39] and in an extremely obese general-population sample (BMI ≥40) the rate of an educational level beyond high school was only 46.9% [40]. In the sample described by Mauri et al. [26], 44.9% had a high school diploma or a university degree. Considering that the figures for the highest level of education attained by adults are similar in Germany and the US but lower in Italy [41], this rate seems to be quite high. 4.3. Comparing gender issues In the general population, women are known to present with higher rates of Axis I disorders, especially anxiety and affective disorders, than men, whereas drug use disorders are more common in men. In addition to their “elevated baseline risk” for depression and anxiety disorders, the risk increases significantly in women who are obese in comparison to normal-weight controls. This effect is found in the general population only for women, not for men [19,20]. Thus women do not only ‘start’ with higher prevalence rates but also show a more pronounced comorbidity when obese. Consequently, in patients prior to bariatric surgery a difference in prevalence rates between men and women would be expected. Kalarchian et al. [24] did not report prevalence rates broken down by gender. One of four studies found no gender differences, neither for any lifetime nor current Axis I disorder [26]. In the sample of Rosenberger et al. [25], women were significantly more likely to report a current as well as a lifetime history of any anxiety disorder and were more likely to report a lifetime history of any affective disorder, especially major depressive disorder. Prevalence rates for lifetime as well as current eating disorders and current affective disorders all consistently showed a trend towards women reporting higher prevalence rates, but the outcomes did not reach statistical significance. As discussed in our sample, we found elevated rates of
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Table 9 Rates of lifetime psychiatric disorders: participants with and without a lifetime eating disorder Psychiatric diagnosis No eating disorder
Eating disorder
This study Rosenberger This study Rosenberger (n=73) et al. [25] (n=73) et al. [25] (n=150) (n=24) Any psychiatric 33 (45.2) disorder Any affective 27 (37.0) disorder Any anxiety disorder 7 (10.1) Alcohol use disorder 3 (4.3)a Drug use disorder 3 (4.3)a Any somatoform 3 (4.3) disorder
40 (26.7)
61 (83.6)
16 (66.7)
30 (20.0)
53 (72.6)
9 (37.5)
16 (10.7) 5 (3.3) 2 (1.3) 0
20 (30.8) 11 (45.8) 13 (17.8)a 2 (8.3) 6 (9.2)a 2 (8.3) 2 (2.7) 0
Italic emphasis indicates significant differences between patients with/ without an eating disorder (Pb.05). a Significant difference for “drug use disorder” (including alcohol use disorder and drug use disorder); we did not calculate χ2 if number per cell is b5.
affective disorders and eating disorders (lifetime and current) in women. 4.4. Patients with and without eating disorders Only Rosenberger at al. [25] and our study gave detailed information about other Axis I disorders in participants with a lifetime eating disorder (Table 9). Both studies found higher prevalence rates of psychiatric disorders in participants with an eating disorder diagnosis. Overall, the differences in comorbid disorders between the studies were more pronounced in the group of participants with an eating disorder than in the group of participants without an eating disorder. Whereas in our study we found a substantially higher prevalence rate of affective disorders and alcohol use disorder in the ED group, Rosenberger et al. [25] found a higher prevalence rate of anxiety disorders. 4.5. The prevalence of psychiatric disorders in the general population and in bariatric surgery candidates The prevalence rates of psychiatric disorders in our study are clearly higher than those reported in the general German and European population [42,43]. The sample of Mauri et al. [26] was characterized by a higher lifetime as well as current prevalence rate for some mood and anxiety disorders in comparison to the Italian general population, and also Kalarchian et al. [24] found higher prevalence rates in their sample in comparison to the US general population [44]. Only Rosenberger et al. [25] reported prevalence rates that were similar to those found in the National Comorbidity Survey in the US [44]. Thus there is evidence for elevated rates of Axis I disorders, especially mood and anxiety disorders in bariatric surgery candidates in comparison to the general population.
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5. Discussion In the current study, we investigated the prevalence of lifetime and current DSM-IV diagnoses in a sample of 146 morbidly obese bariatric surgery candidates. The assessment took place in a very early stage of the approval process prior to surgery and was independent of the approval process. Patients could be sure that information provided for research would not have any bearing on their candidacy for surgery. Upon interview, 73% of the patients reported a lifetime history of any Axis I psychiatric disorder and 56% met the criteria for a current Axis I disorder at the time of the evaluation. Mood disorders were the most prevalent class of lifetime disorders, and eating disorders were the most prevalent class of disorders at the time of the evaluation. Comparing our prevalence rates to the prevalence rates found in three other studies conducted in the US and in Italy, we found higher rates of Axis I disorders, lifetime as well as current, especially with regard to major depressive disorder and eating disorders. There is evidence that the studies in the US, Italy and Germany assessed different subsamples of morbidly obese patients. Whereas the bariatric surgery candidates in the US and in Italy reported a high educational level in comparison to the general population and especially in comparison to obese people in the general population, the sample in Germany reported a considerably lower educational level than that found in the general population. The basis for this finding is unclear. The health care systems differ between countries: in Germany, about 0.3% of all citizens are without a health care insurance [45]; in the US, about 16% are without health care insurance; in lower SES population this rate increases considerably [46]. It can be assumed that people without health care insurance do not qualify as bariatric surgery candidates; at least in the US this might be a confounding factor for the selection of patients not playing a role in many other countries. In the general population [33,43] as well as in obese community samples [17,19,47], a lower SES and/or fewer years of education correlate with an increased risk for psychiatric disorders, especially anxiety and mood disorders. The low SES in our study compared to the other published comorbidity studies in bariatric surgery samples might be one of the possible factors contributing to the higher prevalence rates in our study. Overall, our results are closest to the findings of Kalarchian et al. [24], who also conducted the research assessment strictly independent of the approval process for the surgery as we did. In the study of Kalarchian et al. [24], the prevalence rate of any eating disorder (which, presumably in the perception of patients, is a crucial point in the approval for surgery) is threefold higher compared to the results of the other two studies, also to that of Rosenberger et al. [25] which was also conducted in the US. The differences found in substance use disorders are
even higher; the prevalence rates for affective and anxiety disorders (which may be perceived as less essential for the approval as substance use or eating behavior) were approximately twice as high. In our study, these findings are even more pronounced and we found even higher prevalence rates than Kalarchian et al. [24], especially with regard to current diagnoses. One of the main differences in lifetime diagnoses between our results and the results of Kalarchian et al. [24] relates to the group of eating disorders (Table 8). Kalarchian et al. [24] did not assess EDNOS, which is the most common eating disorder diagnosis [37]. This may contribute to this difference but is still not a sufficient explanation for it. The studies reviewed assessed psychiatric comorbidity in bariatric surgery candidates avoiding the most criticized methodological flaws. These studies used structured clinical interviews for the assessment, applying DSM-IV criteria for the diagnosis of psychiatric disorders and included large, consecutive samples at their presentation for bariatric surgery. Thus these studies are able to give valuable information to every professional working with bariatric surgery candidates. However, none of the studies has included a control group. Consequently, differences in rating styles cannot be excluded in interpreting the differences in findings. Including a control group with well-defined rates of psychopathology from prior research might give an indication of over-/underdiagnosing of psychiatric disorders due to applying over- or underrigorous criteria. Unfortunately, there is no adequate control group of severely obese surgery candidates to check for possible influences of a bias. Additional research is needed to see whether the reported results hold true for other groups of patients in other locations or other countries. We should pay special attention to the fact that results being true for one country might require a reevaluation prior to applying them to patients in a different health care context. A subgroup of special interest in clinical practice should be patients with a history of an eating disorder. According to the evidence so far, obese patients with a comorbid BED have significantly higher rates of lifetime Axis I comorbidity compared to obese patients without a BED [48,49]. These findings seem to hold true in bariatric surgery candidates. Overall, in the last few years, a growing number of researchers have focused on patients presenting for bariatric surgery. These patients will be followed up for the next couple of years, and valuable information about the course of psychiatric comorbidity in these patients and the influence on the outcome of bariatric surgery will be assessed in detail. According to the data so far, a careful assessment of psychiatric comorbidity and of sociodemographic variables, a welldocumented proceeding as well as a characterization of subgroups such as of patients with a lifetime history of an eating disorder could be essential to obtain full comprehension of the findings.
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Psychiatric disorders in bariatric surgery candidates: a review of the literature and results of a German prebariatric surgery sample Barbara Mühlhans, Psy.D.a,⁎, Thomas Horbach, M.D.b , Martina de Zwaan, M.D.a a
Department of Psychosomatic Medicine and Psychotherapy, University Hospital of Erlangen, 91054 Erlangen, Germany b Department of Surgery, Obesity Control Center, Municipal Hospital Schwabach, 91126 Schwabach, Germany Received 21 January 2009; accepted 6 May 2009
Abstract Objective: To investigate the prevalence of Axis I psychopathology in bariatric surgery candidates and to compare our results with the findings of the few studies published thus far. Method: Structured clinical interviews (SCID) were conducted in 146 consecutive bariatric surgery candidates [71.9% women; mean age: 38.7 years (S.D.=10.0); mean BMI: 49.3 kg/m2 (S.D.=7.8)] between September 2004 and January 2007 at the University Hospital of Erlangen. Assessments were administered independently of the preoperative screening and approval process. Results: The overall prevalence of current Axis I disorders was 55.5%; 72.6% had a lifetime history of at least one Axis I disorder. Axis I psychopathology was related to gender (with women reporting higher prevalence rates) and was positively associated with a lifetime history of any eating disorder. We compared our results with the findings of the three published studies having used structured clinical interviews to assess psychiatric comorbidity in bariatric surgery candidates. The authors provide an overview of evidence so far and highlight some details in the assessment and comparisons of different samples in different countries. Conclusion: About one half of the bariatric surgery candidates in Germany presented with a current Axis I disorder. Prevalence rates reported in the literature so far are based on different premises. Details for example about the evaluation should be taken into account when interpreting the results. © 2009 Published by Elsevier Inc. Keywords: Bariatric surgery candidates; Psychiatric disorders; Psychiatric comorbidity; SCID interview; Axis I disorders
1. Introduction Obesity is an increasingly prevalent chronic condition in Europe as well as in the United States [1,2]. It is a wellestablished risk factor for a myriad of medical conditions, among them diabetes mellitus, certain forms of cancer, cardiovascular disease and degenerative joint disease, and is associated with an overall increased mortality [3–7]. Bariatric surgery is the most effective — if not the only effective treatment in patients with extreme obesity (BMI ≥40 kg/m2) [8]. Weight loss results are superior to those of conservative weight loss treatments. Two years postoperatively, patients typically lose 62% of excess body weight with gastric bypass, 48% with gastric banding, 70% with ⁎ Corresponding author. E-mail address: [email protected] (M. de Zwaan). 0163-8343/$ – see front matter © 2009 Published by Elsevier Inc. doi:10.1016/j.genhosppsych.2009.05.004
biliopancreatic diversion or duodenal switch and about 68% with gastroplasty [9]. Postoperative weight loss is associated with significant improvements in obesity-related comorbidities [10,11] and mortality rates [12]. The 1991 NIH Consensus Development Conference Panel [13] advised careful selection of candidates for bariatric surgery after evaluation by a multidisciplinary team with medical, surgical, psychiatric and nutritional expertise. The National Obesity Society in Germany in their guidelines recommended special care in making decisions regarding patients with severe depression, psychosis and severe eating disorders such as bulimia nervosa or binge eating disorder (BED). In such cases, a mental health care professional should be part of the decision-making team [14]. Whether obesity is associated with psychiatric disorders in the general population is an ongoing debate. Results are mixed, with some results indicating that obesity is related to
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increased psychopathology and some studies finding no relationship or even a negative association [15]. It became obvious that heterogeneity of associations between obesity and psychiatric states exists. Several moderators of the association between depression and obesity have been found, such as gender or socioeconomic status (SES) [16]. Onyike et al. [17] reported that increasing severity of obesity is associated with an increasing risk of depression. Friedman and Brownell [18] in their comprehensive metaanalysis described three generations of studies. The first generation merely described the association between obesity and psychosocial functioning in general — and failed to find differences between nonobese and obese persons. The second generation uses a risk factor model to identify individuals who are likely to suffer from psychosocial consequences of obesity. The third generation is going to establish causal pathways between body weight and psychosocial functioning. Today, the quality of population-based research has improved considerably. In the last few years, several studies have assessed the relationship between obesity and psychiatric disorders in large representative samples using structured clinical interviews and DSM-IV diagnostic criteria. In nearly all of these studies, obese persons show elevated rates of mood and anxiety disorders in comparison to members of the general population. This is especially true for women [19,20], and prevalence rates of mental disorders seem to increase with increasing severity of obesity [17,19]. These studies really represent the “second generation of studies” as stated by Friedman and Brownell [18], which identify risk factors such as gender and severity of obesity and linking them to psychopathology. Obese patients presenting for bariatric surgery are about 70–80 % female, some with Grade II obesity but most with Grade III obesity. So these patients present with several wellestablished risk factors linked to psychosocial impairment in obesity. The first studies assessing psychiatric comorbidity in bariatric surgery candidates were published about 30 years ago. Hopkins and Bland [21] found elevated rates of depressive disorders as well as carbohydrate craving in 73 females presenting for gastric bypass surgery. Stunkard et al. [22] described in their review assessing psychological aspects of surgical treatment of obesity two types of emotional disturbances not measured by standard tests: adverse responses to dieting and disparagement of the body image. Black et al. [23] reported in 88 gastric banding candidates an elevated rate of lifetime mood disorders, anxiety disorders, bulimia and tobacco dependence. As in population-based studies, the quality of research in the field of psychiatric comorbidity in bariatric surgery candidates has improved considerably in the last few years. Three studies assessing Axis I disorders in large consecutive bariatric surgery samples with structured interviews have been published (Table 1). The studies so far present valuable data from different countries and different methodological approaches. The
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Table 1 Comparison across studies Erlangen Kalarchian Rosenberger Mauri et al. current study et al. (2007) et al. (2006) (2008) [26] (N=146) [24] (N=288) [25] (N=174) (N=255) % Women Mean BMI (S.D.) Mean age, years (S.D.) % Married
71.9 49.3 (7.8)
83.3 52.2 (9.7)
75.3 50.2 (8.5)
79.8a N40a
38.7 (10.0)
46.6 (9.4)
42.9 (11.1)
42.1 (11.4)a
51.4
57.3
59.8
69.5a
a Mauri et al. also included patients with BMI 35–40 kg/m2. To allow a comparison to the other studies, we excluded this group and recalculated the rates of psychiatric disorders. Sample characteristics could not be recalculated, so the data given in the table is for the whole sample of Mauri et al.
samples are similar in several aspects such as mean age, gender distribution or mean BMI. Even though there are no distinct differences in the prevalence rates of severe obesity between men and women, bariatric surgery candidates are predominantly female, a homogenous finding in all samples described so far in the academic literature. In the current study, we will review the data published thus far and present data from a German sample of bariatric surgery candidates, comparing our results with the results of the three published studies. This will be the first study to give a comprehensive overview of the findings so far, highlighting some possible health system effects, geographic differences and effects of differing approaches.
2. Methods 2.1. Patients Between September 2004 and January 2007, 240 consecutive patients considering bariatric surgery presented at the University Hospital of Erlangen. Of those patients, 146 (60.8%) gave written informed consent to participate in our study. Inclusion criteria for the present study were age ≥18 years and a BMI of ≥35 kg/m2, as well as sufficient German language skills. Assessments were typically scheduled immediately after the psychological evaluation required for an application for reimbursement of costs for the surgery by health insurance companies. Consequently, assessments were conducted at a very early stage of the process, up to 6 months prior to the surgery. Participants were assured that information provided for research would not influence their candidacy for surgery. The study was approved by the ethics committee of the medical school of the University of Erlangen-Nuremberg. All participants gave written informed consent. 2.2. Assessment The patients were scheduled for a 2- to 3-h psychological evaluation, which was independent of the evaluation required for the bariatric surgery candidacy process. We wanted to enhance patients' willingness to disclose problems that they
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Table 2 Age and BMI
Age Women Men BMI Women Men
Mean (S.D.)
T (144)
38.6 (9.8) 39.1 (10.6)
−0.31; ns
48.9 (7.8) 50.3 (8.0)
−0.96; ns
might perceive as having an influence on the approval for the surgery. Evaluation included two structured psychiatric diagnostic interviews regarding psychiatric disorders and eating behavior. The interviews were conducted by three psychologists as well as by a graduate student of psychology. All raters were trained and received ongoing supervision by the last author of this article. Current and lifetime Axis I diagnoses were assessed with the German version of the Structured Clinical Interview for DSM-IV (SCID) [27]. The SCID is considered as the “gold standard” for assessing psychiatric comorbidity and has wellestablished validity and reliability [28]. Current eating disorders were assessed in detail using the German version of the Eating Disorder Examination (EDE [29]). The EDE is a structured clinical interview for the assessment of eating patterns and eating-related psychopathology, and allows one to make DSM-IV diagnoses of all eating disorders. Therefore, the diagnostic items are also rated for duration. The EDE is used widely in the assessment of eating disorders [30]. Psychometric studies of the EDE have demonstrated good inter-rater and test–retest reliability for binge eating behaviors [31,32]. The EDE was used for the assessment of current eating disorders, since the EDE allows the assessment of current binge eating and purging behavior in a more thorough manner than the SCID. An eating disorder not otherwise specified (EDNOS) was diagnosed in patients reporting binge eating behavior and other aspects of BED but not meeting the full
Table 3 Demographic characteristics Characteristic Sex Female Male Marital status Single Relationship Married Living apart/divorced/widowed Missing Education No degree 9 years 10 years Finished high school (13 years) College/university degree (N13 years) Missing
n (%) 105 (71.9) 41 (28.1) 26 (17.8) 24 (16.4) 75 (51.4) 12 (8.2) 9 (6.2) 17 (11.6) 77 (52.7) 24 (16.4) 9 (6.2) 10 (6.8) 9 (6.2)
criteria for a BED diagnosis (“subsyndromal BED”). The extent to which the DSM-IV criteria make meaningful distinctions between full and subsyndromal eating disorders has been questioned, and it has been suggested that the diagnostic criteria should be broadened. Individuals with binge eating problems frequently do not meet the frequency criterion of two binge days per week. Other patients meet the frequency criteria but deny “marked distress.” There is evidence that subsyndromal BED subjects do not differ significantly from subjects meeting full criteria and frequently evidence the same level of distress, low self-esteem, impaired social adjustment and overconcern with shape and weight. Overall, there is no sharp demarcation between the full syndrome and the subsyndromal groups, and, consequently, some recent treatment studies have started to include subsyndromal cases [33,34]. We decided to report lifetime prevalence rates of BED and subsyndromal BED (EDNOS) combined, believing this to be a valid approach.
3. Results 3.1. Sample Of the 146 participants, 105 (71.9%) were women, with a mean age of 38.7 (S.D.=10.0) and a mean BMI of 49.3 kg/m2 (S.D.=7.8). No significant differences regarding age or BMI between men and women were found (Table 2). A total of 68.8% of the participants either had no degree or had 9 years of education with degree (equivalent to general-education secondary school grade 5 to 9). A total of 68% of the participants reported living in a relationship or being married, 18% reported being single at the time of the evaluation, 8% reported living apart, being divorced or being widowed (Table 3). 3.2. Education Our sample is characterized by a low educational level in comparison to the general population in Germany. In the general population, the educational level increases with younger age; especially the age cohort 60 and over (about 25% of the general population [32]) has higher rates of lower education level than the rest of the population [36]. In our sample, the mean age was 38.7 (S.D.=10.0) and no one was older than 60. The age cohort with the lowest educational status is not part of our sample, so, presumably, the data given in Table 4 underestimate the differences Table 4 Education of patients prior to bariatric surgery in Germany Education
This study General population (≥15 years) [35]
No degree 9 years 10 years At least finished high school (≥13 years)
11.6% 52.7% 16.4% 13.0%
3.5% 41.6% 20.3% 22.4%
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between our sample and the general population rather than overestimate them. 3.3. Prevalence of lifetime and current psychiatric disorders Table 5 summarizes the lifetime prevalence rates of psychiatric disorders for the total sample and divided by gender. The most common category of lifetime disorders was affective disorders (54.8%; n=80). A lifetime eating disorder (including EDNOS) was diagnosed in 50% (n=73) of the participants, with 10 participants (6.8%) reporting a history of bulimia nervosa and all 73 participants reporting a history of BED or subsyndromal BED. Women were significantly more likely than men to meet the criteria for a lifetime affective disorder (P=.001) or a lifetime eating disorder (PN.001). Of the 146 participants, 21.2% (n=31) met the criteria for a lifetime anxiety disorder and 15.1% (n=22) of the participants reported a history of substance use disorder. For these psychiatric diagnoses, no differences between women and men were found. Overall, 72.6% of the participants reported at least one lifetime psychiatric diagnosis. In women, the prevalence of at least one lifetime psychiatric disorder was 81.9%. With regard to current psychiatric disorders (Table 6), eating disorders were the most common class (37.7%; n=55), including 34 (23.3%) participants with BED and 21 (14.4%) participants with an EDNOS. A total of 31.5% (n=46) of the participants reported a current affective disorder; 22 (15.1%) participants met the criteria for a current anxiety disorder. Only two participants (1.4%) reported a current substance use disorder and five (3.4%) were diagnosed with a somatoform disorder. For most current psychiatric disorders, it was not possible to examine gender differences due to the low number of cases in each Table 5 Rates of lifetime psychiatric disorders in bariatric surgery candidates Psychiatric disorders
All subjects Women (N=146) (n=105)
Any psychiatric disorder 106 (72.6) Any affective disorder 80 (54.8) Major depressive disorder 74 (50.7) Dysthymia 12 (8.2) Mania 2 (1.4) Any anxiety disorder 31 (21.2) Social phobia 9 (6.2) Specific phobia 11 (7.5) PTSD 13 (8.9) Any substance use disorder 22 (15.1) Alcohol use disorder 16 (11.0) Any drug use disorder 9 (6.2) (without alcohol) Any somatoform disorder 5 (3.4) Somatoform pain disorder 4 (2.7) Any eating disorder 73 (50.0) EDNOS (including BED) 73 (50.0) Bulimia nervosa 10 (6.8) Values are shown as n (%).
Men (n=41)
χ2
86 (81.9) 20 (48.8) Pb.001 67 (63.8) 13 (31.7) P=.001 63 (60.0) 11 (26.8) 8 (7.6) 4 (9.8) 2 (1.9) 28 (26.7) 3 (7.3) – 9 (8.6) 10 (9.5) 1 (2.4) 13 (12.4) 16 (15.2) 6 (14.6) ns 12 (10.5) 5 (12.2) 7 (6.7) 2 (4.9) 5 (4.8) 4 (3.8) 64 (61.0) 64 (61.0) 10 (9.5)
– 9 (22.0) Pb.001 9 (22.0)
417
Table 6 Rates of current psychiatric disorders in bariatric surgery candidates Men (n=41)
χ2 (1)
Psychiatric disorder
All subjects Women (N=146) (n=105)
Any psychiatric disorder Any affective disorder Major depressive disorder Dysthymia Mania Any anxiety disorder Social phobia Specific phobia PTSD Any substance use disorder Alcohol use disorder Any drug use disorder Any somatoform disorder Somatoform pain disorder Any eating disorder Binge eating disorder EDNOS Bulimia nervosa
81 (55.5) 46 (31.5) 37 (25.3) 9 (6.2)
69 (65.8) 12 (29.3) Pb.001 39 (37.1) 7 (17.1) P=.028 34 (32.4) 3 (7.3) 5 (4.8) 4 (9.8)
22 (15.1) 9 (6.2) 10 (6.8) 6 (4.1) 2 (1.4) 1 (0.7) 1 (0.7) 5 (3.4) 4 (2.7) 55 (37.7) 34 (23.3) 21 (14.4) –
20 (19.0) 2 (4.9) – 9 (8.6) 9 (8.6) 1 (2.4) 6 (5.7) 2 (1.9) – 1 (1.0) 1 (1.0) 5 (4.8) 4 (3.8) 48 (45.7) 7 (17.1) P=.001 31 (29.5) 3 (7.3) 17 (16.2) 4 (9.8) – –
Values are shown as n (%).
group. Gender differences were found for current eating disorders (P=.001), whereas for current affective disorders no differences in prevalence rates between men and women were found. Overall, 56% of our patients met the criteria for at least one current psychiatric disorder, with 66% of the women and 29% of the men meeting the criteria for at least one current psychiatric disorder. 3.4. Comorbidity with Axis I disorder in participants with an eating disorder We examined the lifetime psychiatric comorbidity in bariatric surgery candidates diagnosed with an eating disorder. Table 7 summarizes the findings for participants with or without a lifetime eating disorder diagnosis. Participants with a lifetime eating disorder diagnosis exhibited a substantially higher prevalence rate of any Axis I disorder in comparison to those without an eating disorder. Eighty-four percent of the participants with a lifetime eating disorder diagnosis reported at least one other lifetime disorder; in participants without a lifetime eating disorder diagnosis, only 45.2% exhibited another lifetime disorder. 4. Psychiatric disorders in bariatric surgery candidates: a review of the literature Recently, three studies have investigated the prevalence of psychiatric disorders among bariatric surgery candidates in the USA and Italy, using the SCID-Interview [24–26] (Table 8). In the USA, Kalarchian et al. [24] reported a lifetime prevalence rate of psychiatric disorders of 66.3% and Rosenberger et al. [25] reported a lifetime prevalence of
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Table 7 Comparison of participants with and without a lifetime eating disorder
Number of lifetime psychiatric disorder (without eating disorders)
Any psychiatric disorder Any mood disorder Any anxiety disorder Any substance use disorder Any somatoform disorder
No lifetime eating disorder (n=73), MW (S.D.)
Lifetime eating disorder (n=73), MW (S.D.)
T (df)
P
0.63 (0.84)
1.71 (1.55)
−5.24 (111.1)
b.001
No lifetime eating disorder (n=73), n (%)
Lifetime eating disorder (n=73), n (%)
χ2 (df)
P
24.37 (1) 19.13 (1) 12.38 (1) 8.08 (1) –
b.001 b.001 .001 .01 –
33 (45.2) 27 (37.0) 7 (9.6) 5 (6.8) 3 (4.1)
61 (83.6) 53 (72.6) 24 (23.9) 17 (23.3) 2 (2.7)
Axis I disorders of 36.8%. Mauri et al. [26] in Italy found a lifetime prevalence rate of 37.6%. The rates of current psychiatric Axis I disorders were 37.7% [24], 24.1% [25] and 20.9% [26], respectively. The direct comparison of prevalence rates between different studies can be misleading, since differences in demographic and social factors as well as differences in methodology may confound the comparison of associations between obesity and various psychiatric states. 4.1. Comparison of methodological approaches across the studies The disorders assessed in the studies were very similar — but not identical. In comparing the results, this should be kept in mind. Two of the studies did not assess EDNOS [24,26]. As EDNOS is the most common eating disorder diagnosis [37], this probably had an influence on the prevalence rates reported. Somatoform disorders were assessed in our study as well as in the study of Rosenberger et al. [25]. The other authors provided no information about somatoform disorders. The same is true for psychotic disorders; in our study, a current psychotic disorder was an exclusion criterion and lifetime diagnoses were not assessed. Rosenberger et al. [25] reported having found no psychotic disorders, and the other studies provided no information. The study of Rosenberger et al. [25] is
presumably the only one which assessed adjustment disorders. The evaluation instrument used in all three studies was the English, Italian or the German version of the SCID Interview [27]. Kalarchian et al. [24], Mauri et al. [26] and our study conducted face-to-face interviews, while Rosenberger et al. [25] did the interviews by telephone. One more difference in the evaluation process is quite important: in our study as well as in the study of Kalarchian et al. [24], the evaluation process was strictly independent from the approval process for the surgery, whereas in the studies of Rosenberger et al. [25] and Mauri et al. [26] the interviews were part of the presurgical evaluation interview. This could have had an influence on the willingness of the participants to disclose psychiatric problems. Both of the studies with an independent evaluation process (ours and Kalarchian et al. [24]) and both studies with an evaluation process linked to the approval process showed comparable results to each other but differed in their results from the other two studies, with higher prevalence rates of psychiatric disorders when interviews were conducted from the approval process for the surgery. 4.2. Comparison of sample characteristics The samples of the studies are alike in several aspects (Table 1) such as gender distribution (mainly women), mean age and mean BMI.
Table 8 Comparison across studies: rates of psychiatric disorders lifetime (current) Psychiatric diagnosis
Erlangen study (N=146)
Kalarchian et al. [24] (2007) (N=288)
Rosenberger et al. [25] (2006) (N=174)
Mauria et al. [26] (2008) (N=255)
Any psychiatric disorder Any affective disorder Any anxiety disorder Any substance use disorder Any somatoform disorder Any eating disorder
72.6% (55.5%) 54.8% (31.5%) 21.2% (15.1%) 15.1% (1.4%) 3.4% (3.4%) 50.0% (37.7%)
66.3% (37.8%) 45.5% (10.4%) 37.5% (5.9%) 32.6% (1.7%) ? 29.5% (16.3%)c
36.8% (24.1%)b 22.4% (10.9%) 15.5% (11.5%) 5.2% (0.6%) 0% 13.8% (10.3%)
38.0% (22.0%) 22.0% (6.7%) 18.0% (12.9%) 1.2% (–) ? 13.3 (7.1%)c
a b c
Prevalence rates recalculated — patients with BMI ≥35; patients with BMI 30–34.9 were excluded. Including adjustment disorder (n=2; 1.1%). Without EDNOS.
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One other difference is of note. In our sample, the educational level was quite low compared to the German general population (see Table 4). This is in line with findings that a lower SES is associated with higher body weight and a higher degree of obesity. This effect is especially prominent for education as an indicator of SES and the association is particularly found in women [38] (in our sample, 71.9% of the patients were female). These effects are seen in all countries with high socioeconomic development [39]. The US samples described in the two recent articles addressing the prevalence of psychiatric disorders in patients prior to bariatric surgery [24,25] included patients with a higher educational level than found in the US general population. In the sample of Kalarchian et al. [24], 69.7% had received education beyond high school; in the sample described by Rosenberger et al. [25], 73.3% had received education beyond high school. In the general population in the USA (≥25 years), the rate of an educational level beyond high school was reported to be 53.8% [39] and in an extremely obese general-population sample (BMI ≥40) the rate of an educational level beyond high school was only 46.9% [40]. In the sample described by Mauri et al. [26], 44.9% had a high school diploma or a university degree. Considering that the figures for the highest level of education attained by adults are similar in Germany and the US but lower in Italy [41], this rate seems to be quite high. 4.3. Comparing gender issues In the general population, women are known to present with higher rates of Axis I disorders, especially anxiety and affective disorders, than men, whereas drug use disorders are more common in men. In addition to their “elevated baseline risk” for depression and anxiety disorders, the risk increases significantly in women who are obese in comparison to normal-weight controls. This effect is found in the general population only for women, not for men [19,20]. Thus women do not only ‘start’ with higher prevalence rates but also show a more pronounced comorbidity when obese. Consequently, in patients prior to bariatric surgery a difference in prevalence rates between men and women would be expected. Kalarchian et al. [24] did not report prevalence rates broken down by gender. One of four studies found no gender differences, neither for any lifetime nor current Axis I disorder [26]. In the sample of Rosenberger et al. [25], women were significantly more likely to report a current as well as a lifetime history of any anxiety disorder and were more likely to report a lifetime history of any affective disorder, especially major depressive disorder. Prevalence rates for lifetime as well as current eating disorders and current affective disorders all consistently showed a trend towards women reporting higher prevalence rates, but the outcomes did not reach statistical significance. As discussed in our sample, we found elevated rates of
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Table 9 Rates of lifetime psychiatric disorders: participants with and without a lifetime eating disorder Psychiatric diagnosis No eating disorder
Eating disorder
This study Rosenberger This study Rosenberger (n=73) et al. [25] (n=73) et al. [25] (n=150) (n=24) Any psychiatric 33 (45.2) disorder Any affective 27 (37.0) disorder Any anxiety disorder 7 (10.1) Alcohol use disorder 3 (4.3)a Drug use disorder 3 (4.3)a Any somatoform 3 (4.3) disorder
40 (26.7)
61 (83.6)
16 (66.7)
30 (20.0)
53 (72.6)
9 (37.5)
16 (10.7) 5 (3.3) 2 (1.3) 0
20 (30.8) 11 (45.8) 13 (17.8)a 2 (8.3) 6 (9.2)a 2 (8.3) 2 (2.7) 0
Italic emphasis indicates significant differences between patients with/ without an eating disorder (Pb.05). a Significant difference for “drug use disorder” (including alcohol use disorder and drug use disorder); we did not calculate χ2 if number per cell is b5.
affective disorders and eating disorders (lifetime and current) in women. 4.4. Patients with and without eating disorders Only Rosenberger at al. [25] and our study gave detailed information about other Axis I disorders in participants with a lifetime eating disorder (Table 9). Both studies found higher prevalence rates of psychiatric disorders in participants with an eating disorder diagnosis. Overall, the differences in comorbid disorders between the studies were more pronounced in the group of participants with an eating disorder than in the group of participants without an eating disorder. Whereas in our study we found a substantially higher prevalence rate of affective disorders and alcohol use disorder in the ED group, Rosenberger et al. [25] found a higher prevalence rate of anxiety disorders. 4.5. The prevalence of psychiatric disorders in the general population and in bariatric surgery candidates The prevalence rates of psychiatric disorders in our study are clearly higher than those reported in the general German and European population [42,43]. The sample of Mauri et al. [26] was characterized by a higher lifetime as well as current prevalence rate for some mood and anxiety disorders in comparison to the Italian general population, and also Kalarchian et al. [24] found higher prevalence rates in their sample in comparison to the US general population [44]. Only Rosenberger et al. [25] reported prevalence rates that were similar to those found in the National Comorbidity Survey in the US [44]. Thus there is evidence for elevated rates of Axis I disorders, especially mood and anxiety disorders in bariatric surgery candidates in comparison to the general population.
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5. Discussion In the current study, we investigated the prevalence of lifetime and current DSM-IV diagnoses in a sample of 146 morbidly obese bariatric surgery candidates. The assessment took place in a very early stage of the approval process prior to surgery and was independent of the approval process. Patients could be sure that information provided for research would not have any bearing on their candidacy for surgery. Upon interview, 73% of the patients reported a lifetime history of any Axis I psychiatric disorder and 56% met the criteria for a current Axis I disorder at the time of the evaluation. Mood disorders were the most prevalent class of lifetime disorders, and eating disorders were the most prevalent class of disorders at the time of the evaluation. Comparing our prevalence rates to the prevalence rates found in three other studies conducted in the US and in Italy, we found higher rates of Axis I disorders, lifetime as well as current, especially with regard to major depressive disorder and eating disorders. There is evidence that the studies in the US, Italy and Germany assessed different subsamples of morbidly obese patients. Whereas the bariatric surgery candidates in the US and in Italy reported a high educational level in comparison to the general population and especially in comparison to obese people in the general population, the sample in Germany reported a considerably lower educational level than that found in the general population. The basis for this finding is unclear. The health care systems differ between countries: in Germany, about 0.3% of all citizens are without a health care insurance [45]; in the US, about 16% are without health care insurance; in lower SES population this rate increases considerably [46]. It can be assumed that people without health care insurance do not qualify as bariatric surgery candidates; at least in the US this might be a confounding factor for the selection of patients not playing a role in many other countries. In the general population [33,43] as well as in obese community samples [17,19,47], a lower SES and/or fewer years of education correlate with an increased risk for psychiatric disorders, especially anxiety and mood disorders. The low SES in our study compared to the other published comorbidity studies in bariatric surgery samples might be one of the possible factors contributing to the higher prevalence rates in our study. Overall, our results are closest to the findings of Kalarchian et al. [24], who also conducted the research assessment strictly independent of the approval process for the surgery as we did. In the study of Kalarchian et al. [24], the prevalence rate of any eating disorder (which, presumably in the perception of patients, is a crucial point in the approval for surgery) is threefold higher compared to the results of the other two studies, also to that of Rosenberger et al. [25] which was also conducted in the US. The differences found in substance use disorders are
even higher; the prevalence rates for affective and anxiety disorders (which may be perceived as less essential for the approval as substance use or eating behavior) were approximately twice as high. In our study, these findings are even more pronounced and we found even higher prevalence rates than Kalarchian et al. [24], especially with regard to current diagnoses. One of the main differences in lifetime diagnoses between our results and the results of Kalarchian et al. [24] relates to the group of eating disorders (Table 8). Kalarchian et al. [24] did not assess EDNOS, which is the most common eating disorder diagnosis [37]. This may contribute to this difference but is still not a sufficient explanation for it. The studies reviewed assessed psychiatric comorbidity in bariatric surgery candidates avoiding the most criticized methodological flaws. These studies used structured clinical interviews for the assessment, applying DSM-IV criteria for the diagnosis of psychiatric disorders and included large, consecutive samples at their presentation for bariatric surgery. Thus these studies are able to give valuable information to every professional working with bariatric surgery candidates. However, none of the studies has included a control group. Consequently, differences in rating styles cannot be excluded in interpreting the differences in findings. Including a control group with well-defined rates of psychopathology from prior research might give an indication of over-/underdiagnosing of psychiatric disorders due to applying over- or underrigorous criteria. Unfortunately, there is no adequate control group of severely obese surgery candidates to check for possible influences of a bias. Additional research is needed to see whether the reported results hold true for other groups of patients in other locations or other countries. We should pay special attention to the fact that results being true for one country might require a reevaluation prior to applying them to patients in a different health care context. A subgroup of special interest in clinical practice should be patients with a history of an eating disorder. According to the evidence so far, obese patients with a comorbid BED have significantly higher rates of lifetime Axis I comorbidity compared to obese patients without a BED [48,49]. These findings seem to hold true in bariatric surgery candidates. Overall, in the last few years, a growing number of researchers have focused on patients presenting for bariatric surgery. These patients will be followed up for the next couple of years, and valuable information about the course of psychiatric comorbidity in these patients and the influence on the outcome of bariatric surgery will be assessed in detail. According to the data so far, a careful assessment of psychiatric comorbidity and of sociodemographic variables, a welldocumented proceeding as well as a characterization of subgroups such as of patients with a lifetime history of an eating disorder could be essential to obtain full comprehension of the findings.
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