Twenty-eight studies met inclusion for the review (see Fig. 1). Information about the studies, including type of study, setting, type of ED and intervention details are given in Table 1 (Supplementary Material). The studies included varied in design: randomised controlled trials (RCT; N = 17), non-randomised (N = 3), feasibility (N = 4), qualitative (N = 2), matched control (N = 1) and case series (N = 1). Most studies originated from the United Kingdom (N = 11), followed by Australia (N = 6); United States of America (N = 3); Spain (N = 2); Canada, Belgium, Italy, Iceland, Austria (N = 1 each); and a mixed study across Australia and UK (N = 1).
Sixteen studies involved carers of patients with AN exclusively; the remainder studies recruited participants with a range of EDs. None of the studies focused exclusively on BN or Binge Eating Disorder. The majority of studies were within outpatient settings (N = 22), though a selection observed inpatients alone (N = 3), both inpatients and day patients (N = 2), and inpatients and/or those awaiting inpatient (N = 1).
Study quality is provided in Table 1 (Supplementary Material). Most were classified as high quality (N = 19) with the remaining being moderate quality. RCT studies were generally rated higher quality than those utilising a non-randomised design.
The number of recruited carers per study ranged from 6 to 268 (mean = 120); however, only sixteen studies reported the number of carer participants with others reporting number of patient participants alone. Other carer demographics (i.e. age/gender) were only reported in 7 of the 28 studies (see Supplementary Material: Table 1 for details). It is important to note, over half of the studies (N = 15) examined interventions for adolescents (< 18 years), whilst others examined both adults and adolescents (N = 6), and adults alone (N = 6). One study did not report patient age. Most carers were likely to be parents and interventions targeted more towards a younger demographic; potentially experiencing a shorter duration of illness comparatively to those older in age. 19 studies reported parents as primary caregivers and of the remaining 9 most caregivers were parents.
A range of interventions were identified, in which their content included the need for carers to take control of re-nutrition at the beginning and gradually transferring responsibility; disentangling individual psychological and family relationship factors from the ED and interactional patterns that have developed; psychoeducation around EDs themselves; skill development; behavioural management; and peer support.
Nine studies compared a style of conjoined family therapy (CFT) to either separated family therapy (SFT) [29,30,31,32,33], parental-focused therapy [34,35,36], or intensive parental coaching (IPC) . One study compared family therapy with additional IPC to family therapy alone .
Six examined the “Experienced Carers Helping Others” (ECHO) intervention [39,40,41,42,43,44], by the Maudsley group: a skill sharing and training approach using books, DVDs and at times telephone coaching. The ECHO approach is based on a cognitive interpersonal model for AN and encourages caregivers to reflect on their own response to the illness and how these behaviours could be maintaining, accommodating, and enabling the ED. The model supports caregivers with positive communication skills, education of the illness and how to demonstrate compassion, self-care, and adaptive coping strategies.
One study adapted the interpersonal model, tailoring it more specifically to CYP, designing “Supporting Carers of Children and Adolescents with Eating Disorders” (SUCCEAT) . This encompassed aspects of the cognitive interpersonal maintenance model, transtheoretical model of change and antecedent–behaviour–consequence model. Researchers compared mode of delivery (face-to-face workshop vs online equivalent); both yielded medium-to-high effect sizes, with full or partial remission observed in 72% and 87% of patients, respectively.
Seven studies reviewed “Carer Skills Workshops” [16, 17, 46,47,48,49,50]; two of which were in conjunction with family therapy [48, 50]. These workshops ranged in duration from a one three-hour session to six two-hourly sessions. Their content often included psychoeducation and some incorporated “guest speakers”—other carers whose loved one has recovered. The group workshops also enabled carers to share their caregiver experiences and thus incorporated a peer support element.
Two online only interventions were reported: “Overcoming Anorexia Online” —which combined systemic and cognitive behavioural principles, and a parental guided self-help intervention —which involved videos of expert clinicians instructing parents on the principles and application of family-based therapy, whilst emphasising parental empowerment and reframing parental criticism.
One study assessed the effectiveness of Adlerian Parental Counselling (APC) , an approach derived from psychodynamic therapy, which aimed to provide parents with cognitive and emotional tools to better understand their child’s feelings and behaviours and to respond to them in a supportive manner. Parents were also invited to participate in a counselling group.
Finally, one study measured the effect of Acceptance-based Separated Family Treatment , which aimed to prepare parents with acceptance-based strategies to target negative reinforcement for symptom expression and increase behavioural flexibility.
Carer interventions in outpatient settings
Twenty-two of the examined studies were conducted within outpatient settings. Content of these interventions included: SFT (carer only), in some cases compared with CFT (patient and carer; N = 9); Skills-based/psycho-education (N = 6); ECHO with and without telephone coaching (N = 3); APC (N = 1); SUCCEAT (N = 1); ‘Overcoming Anorexia Online’ (N = 1); and, acceptance-based treatment (N = 1).
SFT was found to be at least as effective, and in some cases more effective, than CFT. Eisler [30, 31] found SFT more effective than CFT for those with high levels of maternal criticism, which was maintained at five-year follow-up. Large effect sizes were also reported for weight gain (z = 1.2), BMI (z = 1.2), Nutrition (z = 1.8), Mental State (z = 1.0), Depression (z = 0.9), and ED behaviour and cognitions [EDI (z = 1.0); EAT (z = 1.3)]. These studies were classified as high quality. Furthermore, two studies found higher levels of ED remission at the end of SFT treatment compared to CFT [34, 36]; however, the differences between the two treatments did not persist into the 6- or 12-month follow-up.
Three studies examined the addition of carer sessions to family therapy [37, 38, 48]. Ganci et al.  tested a one-off, 3-h group workshop in the early stages of family therapy treatment. Whilst there was no difference in length of treatment or ED psychopathology, BMI at week 4 had greater increases compared to treatment as usual (TAU), though this difference was not maintained at week 12 or end of treatment. Lock and colleagues  held 3 parenting coaching sessions in addition to TAU; there were no differences between the groups. Rhodes et al.  found an additional 20 parent sessions led to a small improvement in weight restoration compared to TAU, but this was a small sample (N = 20 families).
There was mixed evidence for the effectiveness of the ECHO intervention. Keshen et al.  found no statistically significant differences in symptomology severity between ECHO (without telephone coaching) and TAU, whilst Hodsoll et al.  found the ECHO group showed improved BMI and fewer inpatient admissions. These differences may be understood when considering Keshen et al.  included patients with BN; ECHO’s content is tailored more towards AN symptomology. Furthermore, with reference to telephone guidance Hodsoll et al.  reported that the ECHO treatment group with telephone guidance had no positive impact on BMI outcomes and rather in the ECHO treatment group without telephone guidance BMI was higher at both 6 and 12 months, with small-to-medium effect size.
Salerno and colleagues  also compared ECHO (with and without telephone coaching) to TAU. The results suggest that in both ECHO groups parents were able to regulate emotions better post-intervention, thus preventing mirroring and maladaptive caregiver responses and reducing illness maintenance and patient distress. Furthermore, patients with improved distress were more likely to report a better outcome after 12 months (BMI) in the ECHO condition. Their findings continue to suggest no increased positive impact from the addition of telephone coaching .
Two RCT studies compared skills training and psychoeducation workshops for carers [47, 49]. Skills training was found to be more effective at reducing patient psychological distress than the psycho-educational programme: (effect size ŋ = 0.73), anxiety (ŋ = 0.38) and depression (ŋ = 0.32) from baseline to 3-month follow up . Opposingly, the second study suggested that both workshops were similarly efficacious in reducing patient psychological distress and ED psychopathology .
Carer interventions in inpatient and day patient settings
Interventions within inpatient and day patient settings were also evaluated (N = 6). Multi-family group, without the patient, was suggested to be similarly effective in reducing ED symptoms than multi-family group with the patient . Another found a 3-day “family workshop” with two families was as effective as 18 h of 1–1 individual family sessions . Furthermore, a high-quality, qualitative study within an inpatient setting found that a skills training workshop for carers had positive impacts on patient outcomes .
Two studies reporting on one large RCT (N = 238); [39, 43] found positive impacts of ECHO on patient outcomes, including ED psychopathology, distress and quality of life; all persisting 24 months post-intervention. These studies were classified as high quality. Supporting this, qualitative research within inpatient and day patient populations also suggests that the ECHO treatment enhances patient wellbeing .