Study design
This is a single-center prospective, three-arm randomized clinical trial to assess the Pilates solo and belly dance effects on the primary outcome quality of life, and secondary outcomes as physical aspects, such as cardiorespiratory fitness, lymphedema, physical activity, disabilities of the arm, range of motion, strength and flexibility and psychological aspects as depressive symptoms, body image, self-esteem, fatigue, pain, sexual function, sleep quality of women undergoing clinical treatment of breast cancer. Participants will be randomized into either a Pilates solo intervention group, belly dance intervention group or the control group. This study was conducted according to SPIRIT 2013 Checklist: Recommended items to address in a clinical trial protocol and related documents (Supplementary material).
Ethical approval
This study will be conducted in compliance with the Declaration of Helsinki (1975) and it was approved by the Research Ethics Committee in Human Beings (CEPSH) of the University of Santa Catarina Sate (UDESC) and for Ethics Committee of the Oncologic Research Center (CEPON) by the Protocol No. 2.073.549 on May 19, 2017. This trial is registered at ClinicalTrials.gov with identifier NCT03194997. Any important protocol deviations or modifications will be communicated to CEPSH and the Clinical Trials to approval, except when necessary to eliminate apparent immediate hazard(s) to human subjects. Also, the trial participants, trial registries and the journal submitted will be informed.
Participants
The study will be conducted in the city of Florianopolis – State of Santa Catarina, Brazil, the participants of the study will be women who were diagnosed with breast cancer and who will be undergoing treatment in the Oncology Research Center (CEPON) at the time of data collection. The group will receive an explanation of the stages of the study and after give the consent to participate, will sign an informed consent form and then be provided with an initial paper questionnaire for data collection.
Eligibility criteria
The inclusion criteria comprise: Women aged 18 years or older; Clinical stage 0 to III breast cancer; Be in adjuvant treatment with hormone therapy in CEPON at any time of the treatment cycle; Receive the release of the oncologist responsible for the practice of physical activity or the Physical Therapy sector of CEPON. Exclusion criteria include the diagnosis of some orthopedic or neurological limitation that prevents the practice of physical activity, as Parkinson disease, Alzheimer’s or use of a wheelchair.
Sample size
To calculate the sample size, the method of distinguishing between the means was used, being n = (α + β) 2 σ2 / d2. The values of alpha (α = 0.05) and beta (β = 0.80) were adhered to, which according to the Gauss curve table values of 1.64 and 0.84, respectively, were used. The difference between the means was obtained through the pilot study, and a variable considered for the calculation was a quality of life, in which an average of the difference between all the scales in the pre and post periods was found. This value of the expected selection was 6.15 ± 9.4. The expected variance (σ2) was 89.49. At the end of the analysis, after the inclusion of a 30% margin of sample loss, a sample of 19 patients was selected for each group.
Randomization and blinding process
The randomization of the sample will be performed by one of the researchers, who should have access to a list of patients with breast cancer (stage 0 - III) who were in adjuvant treatment with hormone therapy at CEPON in the past three years, with the intention to achieve adequate participant enrolment to reach the target sample size. From this list, a randomization will be hold in a website (http://www.randomization.com), which will predict the allocation of patients in the three groups: group A: intervention with belly dance; group B: intervention with Pilates solo; group C: control group, who will be requested to maintain their routine activities. The randomization will be stratified by age, dividing the patients between those younger and those over 60 years of age. Considering those older than 60 years of age, according to the Brazilian Statute of the Elderly, established by Law No. 10,741, dated October 1, 2003.
The data from the patients will be maintained only with the principal researcher to protect confidentiality before, during, and after the trial. Since the protocol is difficult to blind for the subjects and the instructors due no proper way to sham physical exercise, all the data analysis will be performed by an external researcher. In this way, at least the data analysis will not receive interference.
Pilates solo intervention
The women allocated to this group will participate in the Pilates solo protocol. The 16-week protocol will be implemented in 60-minute Pilates solo classes, three afternoons per week under supervision of an exercise science professional and a physiotherapist.
The Pilates protocol will be divided in three stages: (1) Warm-up and stretching: Including breathing, imprint and release, hip release, spinal rotation, cat stretch, hip rolls, scapula isolation, arm circles, head nods, elevation and depression of scapulae exercises during warm-up in all sessions.
(2) The main stage: A brief explanation of the purpose of the class will be provided and the exercises will take place as detailed in Table2. To increase the load during the protocol, TheraBand and toning ball exercises will be added at the 10th session, in the 20th will be added the exercise in the arms and from the 24th session the exercise of the spinal rotation will be realized with weight of 1 kg. Exercises will be performed according to each patient’s ability (principle of sports training) to avoid pain (during and after exercising) and embarrassment associated with possible physical or even psychological and emotional difficulties.
(3) Relaxation: For this stage of the class, the patients will be invited to sit on the ball, spine stretch forward on the ball, self-stretching of cervical muscles on the ball (upper trapezius and scalene muscles), and active mobilization of the cervical spine. At the end of each class, a brief discussion will hold on the women’s perceptions regarding the objectives discussed in the beginning of class and whether they were achieved, and this data will be recorded by a third researcher to identify whether the participants enjoyed the class and felt that they achieved the objectives of the class.
Belly dance intervention
Women allocated to this group will participate in the belly dance protocol. The 16-week protocol will be implemented in 60-minute belly dance classes, three afternoons a week under supervision of an exercise science professional and a physiotherapist.
The classes will be divided into three stages: (1) Warm-up and stretching: The beginning of the class will include songs with up to 80 beats per minute (bpm), thus identified as slow pace. The sequence of movements for this class stage will cover large movements for specific joints, including flexion, extension, abduction, adduction and rotation, initiated by the upper body until it reaches the lower limbs, lasting 10 minutes.
(2) The main stage: A brief explanation of the purpose of the class will be provided (i.e. the theory of dance or the specific step to be developed), followed by the practical part of the technical learning. The aim of this part will be for participants to learn the movements of the belly dance technique, to stimulate motor coordination, rhythm, and body awareness, as well as to improve aspects of flexibility and range of motion (ROM) of the upper limbs. The practice of the movements will be explored using individual, pair, or group dynamics, involving movements corresponding to the rhythm of music or the rhythm stipulated for the women. The participants will have the artistic freedom to create their own pattern of movement based on the belly dance technique, while respecting their own body awareness and allowing the expression of feelings. The evolution of the belly dance technique will be applied as outlined in Table 1. For this part of the classes, medium-paced music with up to 120 bpm will be use, as well as fast-paced music with up to 150 bpm. This part of the class will have an average duration of 40 minutes.
(3) Relaxation: This stage will be developed from slow-moving practices, with music up to 80 bpm, usually the same songs used in the initial warm-up and stretching. With heart-rate normalization, this part will last 10 minutes. At the end of each class, a brief discussion will hold on the women’s perceptions regarding the objectives discussed in the beginning of class and whether they were achieved, and this data will be recorded by a third researcher to identify whether the participants enjoyed the class and felt that they achieved the objectives of the class.
Verification of the songs’ rhythm was performed by measure the beats per minute (bpm), according to the ballroom dance protocol used in the study by Braga et al (2015) [38]. The songs will be categorized in groups: slow (up to 80 bpm), medium (up to 120 bpm), and fast (up to 150 bpm). The performance score was calculated using the bpm Detector Pro application.
Safety and intensity
To control the intensity of the Pilates methods protocol and belly dance protocol assuring that all the patients experience the same intensity of the intervention and to promote the safety of the practice of physical activity in these breast cancer patients, the heart rate (HR) control will be performed in every session using a Polar pro trainer 5. HR values will be checked in four moments of the class as after the beginning of the class (1), after the warming and stretching (2), after the main stage (3) and at the end of the class (4).
The safety of the intervention will be assessed every session, according to HR and patient’s own report. If participants do experience an adverse event, this will be brought immediately to the attention of the researchers. Adverse events will be evaluated by the researchers who will make the decision to stop the study early, and researchers will take responsibility and provide all care to patients included in the study.
Control group
Women allocated in this group will be asked to continue their routine activities during the 16-week intervention period. They will be contacted every two months by telephone. It will be also offered to this group three meeting during the 16 weeks of intervention, the first meeting will focus on stretching exercise to be performed at home on a regular basis, a second meeting will be about self-esteem and the last meeting will be about prevention of lymphedema. These meetings will occur with the purpose of promoting an environment where these women could talk and share their experiences with other women with breast cancer and make sure that they also receive health educational information, as they will not receive the exercise intervention in the first phase of the study. These meetings were an exigence of the Ethics Committee of the CEPON, hospital that will take place the study in Brazil to ensure that the control group also receive possible benefits of the study. Likewise, this strategy can improve the adherence of the control group as they will feel as a group and make social binds.
Both groups, experimental (Pilates solo and belly dance) and control group, will receive, after the 16 weeks of intervention, an explanatory booklet on the benefits of practicing physical activity after the breast cancer diagnosis, as well instruction on the prevention of lymphedema. As a strategy to improve adherence of the subjects on the trials, all the patients will be invited to social meetings, groups in social medias, thematic classes according with specific dates (E.g Carnival, Easter, Halloween, Christmas), and receive a T-shirt from the Project at the first meeting. Additionally, direct contact with the subjects that miss a class will occur via SMS and phone calls. These activities are planned to make the subjects feel familiar with the trial environment. For the 2-year follow up, the intervention and control group will be invited to a physical activity program organized by the university. They will also be contacted through social media and SMS once in a month to motivate the practice of physical activity and to remind of future data collections. After the end of the study besides the publication in academic journals, the main results will be presented at the Hospital in Brazil and shared with the patients in brochure format.
Figure 1 presents the participant selection process and the execution of the steps of the protocol.
Assessment
Primary outcome measure
The main aim of the study is to evaluate the impact of 16-week Pilates solo and belly dance protocol on quality of life change (≥ 2% of the baseline scores) in breast cancer patients undergoing clinical treatment. The quality of life is the primary outcome at all time points of the study, namely baseline, post-intervention, 6-month, 12-month and 24-month after intervention. The quality of life will be the primary outcome since it involves all the physical and psychological aspects of the life of breast cancer women. Therefore, the maintenance collection will take place considering the modification in quality of life and other outcomes that the Pilates solo and belly dance intervention can promote in these women.
The primary outcome quality of life will be investigated by the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 (EORTC QLQ-C30) [39]. This instrument was created by European Organization for Research and Treatment of Cancer (EORTC) in 1986, and this is the third version. Validated to cancer population by Michels; Latorre; Maciel (2013) [40], with Cronbach alpha of 0.72 for health global scale, 0.86 for functional scale and 0.81 for symptomatic scale.
The instrument consists of 30 questions, being multidimensional and self-applied, its objective is to evaluate the quality of life in patients with cancer in the last four weeks. It presents five functional scales (physical, functional, emotional, social and cognitive), a scale on global health status, three symptom scales (fatigue, pain and nausea/vomiting) and six additional symptom items (dyspnea, appetite, constipation, diarrhea and financial difficulties). The answers are presented in the form of Likert scale following the classification: 1 – Not at all, 2 – A little, 3 – Quite a bit and 4 – Very much. The only exception applies to the global health scale. This is composed of two questions that ask the patient to rate both their health and their quality of life in the last week, in a grade of 1 to 7. In this case, 1 would be a poor quality of life and 7 a good quality of life.
The EORTC QLQ-C30 is complemented by specific cancer modules. In this study, the breast cancer module - QLQ BR-23, validated for the Portuguese language by Michels, Latorre and Maciel (2013) [40], with a Cronbach alpha of 0.78 and 0.83 will be used. The QLQ BR-23 consists of 23 questions incorporated into multi-item scales. It measures the functional scales (body image, sexual functioning, sexual enjoyment and future perspective) and symptom scales (systemic therapy side effects, arm symptoms, breast symptoms and upset by hair loss). Classifications are also in the range of 0 to 100, where values closer to 100 for the functional scale indicate better patient functionality, and values closer to 100 for the symptom scales range show higher presence of symptoms.
Other outcome measures
As secondary outcomes will be evaluated the physical and psychological variables associated with the quality of life. The physical outcomes are cardiorespiratory fitness, functional capacity, lymphedema, disabilities of the arm, range of motion, strength, flexibility and physical activity. In addition, the psychological outcomes are depressive symptoms, pain, fatigue, body image, self-esteem, sexual function and sleep quality.
Cardiorespiratory fitness
To assess the cardiorespiratory fitness, a submaximal incremental exercise test (85% of maximum heart rate - HRmax) will be performed using a cycle ergometer (Lode Excalibur Sport, Groningen, the Netherlands). The protocol will start with a power of 20W, and in every 3 minutes, 15W will be added, until the patient reaches 85% of his HRmax, which will be identified through the equation (207 - 0.7 * age) [41]. In the initial three minutes of the test, the patient will be asked to remain in a rest position, accommodated in the cycle ergometer, to identify the values of resting heart rate and oxygen consumption. Patients will be asked to maintain the rotation per minute (RPM) of the cycle ergometer always above 60 RPM. Expiratory gases and flow volume will be collected during the test and analyzed by calibrated metabolic system (Quark CPET Ergo, Cosmed, Rome, Italy) to provide measurements of oxygen consumption. The heart rate will be monitored by a POLAR mark frequency and will be observed within the first three minutes of the test and at the end of each minute of the three-minute test stages. Also, every three minutes, the patient will be questioned about her perception of the exercise, through the Subjective Perception Scale of Effort - Borg Scale 6-20 points [42]. This scale ranges from six to 20 points, where the sixth position would be the perception of "very easy" and 20 the "exhaustive".
The 6-minute walk test measures the distance a person can travel on a flat, rigid surface in six minutes. Its main objective is to determine the tolerance to exercise and oxygen saturation during a submaximal exercise [43]. Patients are asked to walk at their own pace as fast as possible during the six minutes, being allowed to walk slowly, stop and / or rest when necessary, and return to walking when they feel fit.
Lymphedema
The evaluation of lymphedema will be performed by calculating the arm volume, performed by measuring the circumferences of both upper limbs, at five points distributed along the arm and forearm: at 21 cm and 11.5 cm above the olecranon; to 7.5 cm, 14 cm and 24 cm below the olecranon. The circumference will be obtained, with the patient sitting, keeping the arm in abduction, flexed forearm and hand resting on the chest. These measures are used to calculate the approximate volume of the five truncated cones formed at the points of circumference measurements. The sum of these five parts gives the total limb volume [44].
Disabilities of the arm
Evaluated through the Disabilities of the Arm, Shoulder and Hand (DASH) scale developed by Hudak et al. (1996) [45] and translated and validated for Brazil by Orfale et al. (2005) [46]. This instrument was developed to assess the disability and symptoms of single or multiple upper limb disorders. It contains 30 questions, involving activities of daily living, symptoms of pain, tingling and stiffness and questions about social factors, work, sleep and self confidence. Used in other studies with patients with breast cancer [19].
Range of motion
To verify the range of motion, evaluations of flexion, abduction, and external rotation of the shoulder according to previous studies with breast cancer patients will be carried [47] using the digital goniometer (Absolute Axis 360°). The protocol used by Marques (2003) [48] to perform the range motion assessment will be performed. The shoulder flexion movement will be performed with the subject lying down, the flexion movement will be performed with the palm facing medially parallel to the sagittal plane, the fixed arm of the goniometer will be placed along the axillary line of the trunk and the movable arm placed on the lateral surface of the humerus body facing the lateral epicondyle. For abduction the individual must be seated. When performing the abduction movement, the palm of the hand will face anteriorly parallel to the frontal plane, the fixed arm of the goniometer should lie on the axillary line and posterior to the trunk and the movable arm on the posterior surface of the arm of the individual. In order to perform the external rotation, the position of the individual and the goniometer are the same, the individual will lie in the dorsal position and the shoulder will be in an abduction of 90°, with the elbow flexed at 90° and the forearm in supination. The arm of the goniometer should lie in the olecranon and the movable arm over the posterior region of the forearm directed to the third finger of the hand.
Strength of the upper limb
The muscle strength of the upper limb on both arms will be measured by the Chatillôn® portable digital dynamometer, which can measure overall appendicular muscle strength and all body segments [49]. This equipment provides the value of the peak of isometric maximum force exerted by the evaluated segment, and for this it requires a generation of fast force, that does not fatigue the muscle. The maximum force generated is registered in Newtons. The muscle groups responsible for flexion, extension, abduction, adduction, internal and external rotation of the shoulder will be evaluated. The dynamometer will be placed over the specific location and patients will be asked to perform force against the equipment for up to five seconds. Each muscle group will be evaluated three times, and the mean value of these evaluations will be used [50], with a thirty second interval between the tests, and bilaterally. In all cases, the patients will be instructed before the start and during the repetitions, on the specific position.
Flexibility
"Sit and Reach" test, which allows assessing the flexibility of the coxofemoral joint [51]. The Sit and Reach box should be supported on a wall, and for evaluation the patient is asked to keep the knees extended, bare feet resting the Sit and Reach box, and hands overlapped on the horizontal surface of the box. It should be performed with an anterior flexion of the spine, keeping the head between the arms, without flexing the knees, revealing a pause in the moment it reaches the maximum of the dotted line. Three replicates are performed, and it is considered the best mark among the three.
Physical activity
The physical activity level will be investigated through the International Physical Activity Questionnaire (IPAQ - short version) [52]. The Brazilian validation and reproducibility were performed by Matsudo (2001) [53] and had significant Spearman correlation and high reproducibility (rho = 0.69 - 0.71: p <0.01) and validity of 0.75 observed in comparison to the instrument Computer Science & Aplications (CSA). It consists of six items that seek to verify the number of times the subject has practiced at least 10 continuous minutes of walking, moderate and vigorous physical activity, in the last week, in diverse involvements, namely, labor, domestic, leisure, recreational and sports. After completing the questionnaire, the participants can be classified into: Sedentary; Insufficiently Active; and Very Active. The IPAQ also addresses the sitting time of individuals, on weekdays and on weekends. There are two specific questions that ask: (1) How much time in total do you spend sitting on a weekday; and (2) How much time in total do you spend seated during on a weekend day; Data are presented in minutes per week and minutes per week.
Depressive symptoms
Investigated using the Beck Depression Inventory (BDI), that is a self-report questionnaire originally developed by Beck et al. (1961) [54]. It was validated in Brazil [55] and factorially validated for cancer patients, indicating a Cronbach alpha of 0.82 [56]. Contains 21 multiple-choice objective questions related to depressive symptoms, in detail: sadness, pessimism, feeling of failure, dissatisfaction, guilty feelings, punishment feelings, self-dislike, self-criticism, suicidal thoughts, crying, irritability, withdrawal from family or friends [56]. Each question provides four response options, ranging from zero to three (0-3). The sum of the scores of each question provides a total score, ranging from zero to 63, and the closer to 63, the greater the presence of depressive symptoms, indicating a higher degree of depression, and the greater the proximity to the zero greater absence of depressive symptoms.
Pain
The Visual Analogue Scale (VAS) will be used. VAS is a one-dimensional measure for assessing pain intensity. Composed of a 10 cm line, with anchors at both ends, at one end of the line is marked "no pain" and the other "worst pain imaginable". The magnitude of the pain is indicated by marking the line and a ruler is used to quantify the measurement on a scale of 0-100mm [57].
Fatigue
Investigated by the Functional Assessment of Cancer Therapy-Fatigue instrument (FACT-F). Validated in Brazil [58] showing an internal consistency of 0.91 for fatigue, and 0.92 for the total FACT-F and the total Cronbach’s alpha 0.92. It is a self-report instrument aimed at patients with cancer that includes 13 items related to the perception of fatigue. Individuals will be asked to respond to each item with a score of 0 to 4, where 0 to 4, where 0 = not at all, 1 = a little bit, 2 = somewhat, 3 = quite a bit, and 4 = very much. In the total score the possible interval is between 0 and 52, being that, a higher score indicates a level of less perceived fatigue.
Body image
Addressed by the Body Image After Breast Cancer (BIBCQ) questionnaire originally developed in Canada [59] which was translated, validated and culturally adapted in Brazil [60] with values of Cronbach’s alpha for detailed internal validity for each scale, namely, vulnerability (0.77), body stigma (0.86), concerns about the body (0.83), transparency (0.80), concerns about the arm (0.67) and limitations (0.72). This instrument aims to evaluate the body image after the diagnosis of breast cancer and can provide information related to the perceptions and attitudes regarding the side effects of breast cancer in the life of these patients. The BIBCQ is a questionnaire considered self-applicable, in which each item can be answered using the Likert scale. It consists of 44 questions divided into six scales, namely: vulnerability, body stigma, limitations, concerns about the body, transparency, and concerns about the arm. In the end, the higher the score reaches, more compromised is the patient body image.
Self-esteem
The Self-Esteem Scale (EAR) developed by Rosenberg (1965) [61] will be used. This scale was validated for the population with cancer [62], and in Brazil [63]. It also received a validation review [64] with Cronbach alpha of 0.90. It is a one-dimensional measure consisting of ten statements related to a set of feelings of self-esteem and self-acceptance that determine the global self-esteem. The total scale score varies from 10 to 40 points, and the following form is used as categorization: (1) satisfactory or high self-esteem, those that presented a score greater than 31 points; (2) mean self-esteem, those that resulted in their total score between 21 and 30 points; and (3) unsatisfactory or low self-esteem, those with scores lower than 20 points. It is understood in this way, that the greater the value reached by the woman on the scale the better her self-esteem.
Sexual function
Evaluated by the Female Sexual Function Index (FSFI) with cross-cultural validation [65], revealing a Cronbach alpha of 0.96. Also validated internationally for patients with breast cancer [66] with Cronbach alpha of 0.70. This questionnaire consists of 19 questions, grouped into six areas: desire, excitement, lubrication, orgasm, satisfaction and pain. The sexual function score, at the end of the analysis, can vary from two to 36 points, considering that the higher the score obtained, the better the sexual function of the woman.
Sleep quality
Evaluated by the Pittsburgh Sleep Quality Index. Validated [67] with Cronbach alpha 0.76. This instrument is composed of seven sleep-related areas: subjective quality, latency, duration, habitual efficiency, disturbances, use of sleeping medication and daytime sleepiness. Scores range from zero to 21 and correspond to overall sleep quality. In the end, scores up to five determine a good sleep quality and scores greater than five points distinguish poor sleep quality.
Descriptive and control variables
The descriptive and control variables were divided into clinical variables (cancer stage, characteristics of treatment, previous clinical treatment, characteristics of surgical intervention, mammary reconstruction, date of surgery, presence of lymphedema, physiotherapy and other diseases), sociodemographic variables (age, education, marital status, economic level and occupation) and anthropometric measures (height and body mass). The descriptive and control variables will be acquired by self report.
The variables of the study regarding the Pilates solo and belly dance protocol are present in Table 3 and in Figure 2.
Data collection
Data will be collect using an interview format with a paper questionnaire and physical tests. The principal investigator of the study, who received previously training, will conduct a 50-minute interview. The questionnaire will cover general and clinical information, quality of life and psychological variables. The physical variables will be investigated by the specific tests. All data collection will be administered before the beginning of the intervention (baseline collection) and after the conclusion of the 16-week protocol (post-intervention collection), also, 6-month, 12-month and 24-month after intervention (maintenance collection). (See Figure 1). The maintenance collection will take place considering the health behavioral change that the belly dance and Pilates solo intervention can promote in breast cancer women.
For the control group, data collection will be conduct using the same paper-based questionnaire and tests applied to the intervention group, with data on general and clinical information, quality of life, physical and psychological variables. The collection will be schedule with the participants and will take place at the same intervals as for the experimental group, before the start of the intervention (baseline collection) and after conclusion (post-intervention collection) by the same principal investigator, also, 6-month, 12-month and 24-month after intervention (maintenance collection). All the data collection of intervention and control group will occur at Santa Catarina State University.
Patients that discontinue intervention or control group that did not show for meeting, will be collect as well and analyzed as intention to treat group. During the intervention and data collection the researchers will collect spontaneously feedback from the patients to guarantee that the study will not have any adverse events. Data from all groups (experimental and control) will be held according to the Good Clinical Practice (GCP) and the Declaration of Helsinki and will be treated with confidentiality, following the current privacy policy.
Statistical Analysis
First, a spreadsheet will be created using the Excel 2016, from which the data will be transfer to SPSS version 20.0 for the analysis. Descriptive statistics (mean, standard deviation, and percentage) for the characteristics of the sample will be computed. To investigate the relationship between general and health information of the control and experimental groups, Chi-Square or Fisher's exact tests will be used. To analyze differences in the experimental and control groups in the baseline, post intervention, and in the maintenance periods, a two-way ANOVA with repeated measures and Sydak comparison tests will be conduct. Confounders variables will be considered in the analyses, as type of treatment, type of surgery, age and weight status. The analysis will occur according to the protocol and to intention to treat, meaning that all the patients will be evaluated according to the randomization process. For handle with missing data it will be used the multiple imputation method. The significance level of 5% will be two-sided.