## 2 Materials and Methods
### Reliability and Construct Validity Analysis
#### 2.3.2 Assessment  
First, sociodemographic and clinical variables were collected: age, sex, occupation, district of residence, marital status, driving licence, playing sports, educational level, and clinical parameters: previous diseases, amputation etiology, level of amputation, time since amputation, and presence of phantom limb pain.  
Body image: The Spanish translation of the Amputee Body Image Scale (ABIS-E) self-administered questionnaire of 20 items [6] was used to assess the body image of the amputee patient from his or her own perspective. The participants were asked to indicate their responses to the questions using a scale of 1 (none of the time) to 5 (all the time). This scale produces scores from 0 to 100, where low scores indicate the relative absence of a body image concern, and higher values indicate the presence of a more severe problem. Questions 3, 12, and 16 are reverse-scored [6].  
Quality of life: EuroQol-5 Dimensions-5 Levels (EQ-5D-5L). It is a questionnaire designed to be self-administered and to assess health-related quality of life (HRQoL).  
It comprises two parts: a descriptive system of five health dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression), and a visual analogue scale (VAS) to elicit an individual's rating of their own overall current health (from 0 to 100) [22; 23]. It consists of 5 response levels: value 1 is given to the best level (no problems) and 5 to the worst (unable to/extreme problems) [24]. Data collected using EQ-5D-5L can be presented in various ways according to its structure: presenting results from the descriptive system as a health profile (a 5-digit code with no arithmetic properties), as a measure of overall self-rated health status (VAS), or as an index value. It is also possible to categorize the scores into a qualitative scale of 5 categories [25]. It has been validated in Spanish [26; 27] and used in studies with amputees [28].  
Depression and anxiety: Hospital Anxiety and Depression Scale (HADS). It is a 14-item self-administered questionnaire originally developed to indicate the presence of anxiety and depression states for non-psychiatric patients. It consists of seven items for the anxiety subscale and seven for the depression subscale. The higher score in each subscale indicates higher levels of anxiety/depression. Between 0 and 7, the result is considered normal (absence of anxiety/depression), and from 11 onwards it is positive (presence of anxiety/depression) [29]. It has been validated in Spanish [30].  
Pain: Brief Pain Inventory-Short Form (BPI-SF). It includes a diagram to record the location of the painful area on a human figure; 9 items that comprise scales for assessing the severity and interference of pain, in which pain severity is recorded using numerical scales ranging from 0 (no pain) to 10 (worst possible pain); and a set of statements about the person's life activities, general activity, mood, ability to walk, work, social relationships, and ability to have fun, measured on a scale with ten values (from no interference to complete interferes) [31; 32]. Higher scores indicate higher levels of pain [33]. It has been validated in Spanish [34].  
Functional capacity: Prosthesis Evaluation Questionnaire (PEQ). Self-administered questionnaire of 82 questions, of which 40 are individual and 42 are grouped in nine subscales that are not dependent on each other: satisfaction (3 items), pain (16 items), transfers (5 items), prosthetic care (3 items), self-efficacy (3 items), and questions about the importance of different aspects of the prosthetic experience (10 items). Originally, in 76 of the items, the response format uses a VAS, with scoring in the form of a continuous numerical variable, with a value equal to the distance in millimetres from the left end of the line, ranging from 0 to 100. The other 6 are presented in multiple-choice format. It is specific for lower limb amputees [35] and validated in Spanish [36].