Study Design
This study was a pre-post clinical trial with a 6-month intervention period. Measurements were taken at the beginning of the study (T1) and 6 months (T2) after the initial evaluation. The trial was retrospectively registered on June 07, 2018 (number: NCT03548376).
Participants
Thirty-one children with medical diagnoses of CP who attended the Equestrian Center of the Alferes Tiradentes Cavalry Regiment (CERCAT) hippotherapy program for at least 3 months participated in the study. Only children aged 4 to 12 years who had no other CP-associated diagnoses (e.g., autism) were included. Participants were stratified by CP severity (mild, moderate or severe), age (4-7 years, 8-12 years), the topography of the involved limbs (hemiplegia, diplegia or quadriplegia) and previous time of hippotherapy (3-6 months, more than 6 months).
The severity of CP was classified by the Gross Motor Function Classification System (GMFCS) [11], which consists of five ordinal categories based on the mobility and use of support devices by children with CP. Participants at GMFCS levels I and II were classified as having mild severity, participants at level III were classified as having moderate severity, and participants at levels IV and V were classified as having severe impairment. We used the translated and adapted GMFCS version [12].
The study’s procedures were explained to all children who attended the hippotherapy service and met the inclusion criteria and to their legal guardians. Written informed consent was obtained from the participants prior to data collection. Guardians provided written consent for their children and assent was secured from adolescents. This study’s protocol was approved by the Research Ethics Committee of the Universidade Federal de Minas Gerais (Certificate of Presentation for Ethical Consideration, CAAE: 42678815.3.0000.5149).
Instrumentation
Descriptive Variables
The children’s caregivers were interviewed and provided information on the therapies performed by the child, the age and educational level of the caregiver, the caregiver’s relationship with the child and the family’s socioeconomic status (SES) [13]. Other information about the child, including the topography of the affected limbs, GMFCS level, age, sex and previous time of hippotherapy, were collected from the service’s medical records.
Postural Control and Balance
The Early Clinical Assessment of Balance (ECAB) [14,15] estimates the postural stability of the child according to head and trunk controls in static activities (i.e., prone, sitting and standing) and postural control in dynamic activities (i.e., sitting to standing and standing activities). Scores assigned to the 13 ECAB items were summed, resulting in a total score of 100. The higher the score, the better the child’s postural control.
Gross Motor Function
The Gross Motor Function Measure (GMFM)-88 includes five dimensions: (A) lying and rolling, (B) sitting, (C) crawling and kneeling, (D) standing and (E) walking, running and jumping. The GMFM-88 generates a score for each dimension and a total score. Higher scores represent a greater repertoire of a child’s gross motor function [16,17,18].
Quality of Life
The Quality of Life Questionnaire for Children with Cerebral Palsy: questionnaire for primary caregivers (CPQOL-Child) [19,20] provides information regarding the wellbeing of children with CP between 4 and 12 years of age and was administered in an interview with key caregivers. This version has 66 questions organized in seven QOL domains: social wellbeing and acceptance, functioning, participation and physical health, emotional wellbeing and self-esteem, access to services, pain and disability impact and family health [19]. Scores were transformed into domain-specific percentages [19].
Intervention: Hippotherapy
The intervention was administered for 30 minutes weekly at the CERCAT and was conducted by equestrian therapists (physiotherapists or occupational therapists) qualified by the Brazilian Association of Hippotherapy.
The horses were trained for hippotherapy practice, and each patient used the same animal in all sessions. The specific hippotherapy gear included safety straps, riding blankets, stirrups and saddles with and without support straps. Use of protective helmets was mandatory in all sessions. Playful and educational toys were also used. The participants included the patient, the equestrian therapist, the horse handler (the professional who drives the horse) and, when necessary, an auxiliary helper to ensure the safety of the child.
The hippotherapy sessions were individualized. The goals set by the therapist were based on the individual demands and the motor ability level of each client. The therapeutic plans were grounded on previously published hippotherapy protocols [6,10,21,22,23,24]. The activities proposed during each session sought to stimulate the postural control of the child. Such activities could be performed in various postures (i.e., classic, inverted, lateral, dorsal decubitus, ventral decubitus and standing on the stirrups). They included demands for stability and balance (i.e., trunk rotation activities, movements in various directions and bimanual tasks), active stretches and antigravitational exercises during riding, integrated with ludic-cognitive resources (i.e., memory games and identification of colors, numbers, and letters).
For the most part, children with mild and moderate impairments rode individually and were encouraged to maintain an upright posture throughout the session. Those with more severe impairment were encouraged to maintain control and postural alignment, with the minimum of support being provided. In some cases, it was necessary to use a double riding strategy in which the therapist rode the horse along with the patient to help and stimulate the child’s postural control on the animal. Throughout the session, the horse varied its speed, cadence and direction according to the therapist’s command, using different paths (i.e., circles, zigzags, and straight lines) and crossed different types of terrain (i.e., uphill, downhill, dirt, asphalt and grass). All participants were instructed to continue with their rehabilitation routines (i.e., physical therapy, occupational therapy and others).
Procedures
All instruments were administered by a trained examiner, and the sessions were recorded with a Sony DCR-SX21® digital camcorder.
In this longitudinal study, an examiner who was not involved in the data collection (evaluations and intervention) scored the GMFM-88. This examiner watched the videos and was blinded to the child’s descriptive information and the order of the evaluation (T1 or T2). The ECAB test score was calculated by two other external examiners who watched the videos and were also blinded regarding the same information. The CPQOL-Child administration was performed by the same examiner, with no access to the child’s previous T2 score.
The examiners who performed the data collection were previously trained in the administration procedures of each outcome measure, and their consistency was assessed in relation to another experienced examiner. The consistency of the independent examiners who scored the CPQOL-Child, GMFM-88, and ECAB was assessed in evaluations of eight children with CP who were not in the sample group. The indices obtained in the test-retest and interexaminer reliabilities (intraclass correlation coefficient -ICC) ranged from 0.99 to 1.00.
Participants were recruited in September and October 2016. The trial started in November 2016 and ended in August 2017. The trial ended after the 6-month intervention period.
Data Analysis
Paired t-tests analyzed changes on postural control and balance, gross motor function and the domains of CPQOL-Child between T1 and T2. The interaction between the independent factors with three levels (severity and topography) and time (T1, T2) on each outcome was preceded by the test of equality of variances across groups. When this assumption was held, ANOVA was used to test whether the difference between times varied across groups. When the normality assumption was violated, the Kruskal-Wallis test was used to evaluate time x group interactions. A post hoc test identified effects on bivariate comparisons. The interaction between the independent factors with two levels (age and previous time of hippotherapy) and time (T1, T2) on the outcomes was also preceded by normal distribution checks in each group (Shapiro-Wilk). When normality of distributions was identified, t-tests were employed to verify whether the difference between the time points varied in the two groups. When the assumption was violated, a nonparametric alternative (Wilcoxon's test) was used. The data analysis was conducted using information from all recruited participants (n=31).