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Original Articles: Nutrition

Psychometrics of the Functional Oral Intake Scale for Children With Dysphagia

Yi, You Gyoung∗,†; Shin, Hyung-Ik

Author Information
Journal of Pediatric Gastroenterology and Nutrition: November 2020 - Volume 71 - Issue 5 - p 686-691
doi: 10.1097/MPG.0000000000002861

Abstract

What Is Known/What Is New

What Is Known

  • There is a need for an objective tool for describing the eating abilities of children with dysphagia based on the food they can consume.
  • The functional oral intake scale, a 7-point observer-rating tool, has good reliability and validity in adult stroke patients.

What Is New

  • We propose a 5-point functional oral intake scale for children based on the food they can intake.
  • The scale showed adequate inter-rater reliability and validity, and could be appropriate for documenting eating abilities of children with dysphagia.

There are several factors associated with difficulty in swallowing and feeding in children, including neurological diseases, conditions that affect sucking, swallowing, and respiratory coordination, anatomical abnormalities, and genetic syndromes (1). Intervention strategies for alleviating these problems in children include environmental modifications (2), oral-motor stimulation (3), and feeding-routine modifications (4,5). Assessment scales for various feeding and swallowing aspects in children include the Dysphagia Disorder Survey (6), Schedule for Oral Motor Assessment (1), Eating and Drinking Ability Classification System (7), Children's Eating Behavior Inventory, Multidisciplinary Feeding Profile, School Functional Assessment, and Schedule for Oral Motor Assessment (8). These scales measure oromotor skills, swallowing function, eating behaviors, and caregiver assistance (8). There are, however, few scales capable of describing the consistency of the food consumable by children. The level of food consumption from ‘entire tube feeding dependency’ to ‘full oral feeding without special preparation’ could be a valid and practical indicator when describing the oral motor skills, and the kind of food children are able to eat safely and efficiently.

The functional oral intake scale (FOIS) is a 7-point observer rating clinical scale that was developed to document changes in functional oral intake of liquid and food in stroke patients (9,10). Moreover, it is widely used in adult patients with oropharyngeal dysphagia, including those with amyotrophic lateral sclerosis (11) and traumatic brain injury (12–14). It describes step by step, the level of food that can be consumed, from an entire tube feeding dependency to a total oral diet with no restriction (Table 1).

T1
TABLE 1:
The Functional Oral Intake Scale for adults, children from 1 to 7 years old, and infants

Although it has been widely used in adult populations, this original version might not be suitable for children. For example, adult FOIS Level 7 of diet, which is defined as a total oral diet (TOD) with no restrictions is not recommended in children under the age of 4 years as they should avoid eating hard, small, particulate foods, including hard candy, peanuts/nuts, seeds, whole grapes, and raw carrots (15), to reduce the risk of choking (16). Adult FOIS level 4 of diet is defined as TOD with a single consistency. In adults, feeding strategy can be set at this level for the safety and efficiency of deglutition. In children, however, single consistency foods are not preferred, as they can hinder oromotor development and could be related with oral aversion (2,17). Defining a food consistency, which is not recommended or preferred in children population as a separate FOIS level as in adults may cause confusion when clinicians decide the feeding strategy.

The FOIS for adults has been modified for infants (18) based on recommendations for complementary foods by the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition Committee on Nutrition (19). The modification was focused on food expansion from whole-bottle feeding to weaning food during infancy (Table 1). Therefore, this modified version is not suitable for children above the age of 1 year either. In the present study, we adapted the original version of the FOIS for the use in children and investigated the reliability and validity of the FOIS for children.

METHODS

We assessed children aged from 1 to 7 years, who underwent a videofluoroscopic swallowing study (VFSS) between 2011 and 2017. Children with missing records on swallowing and feeding status at the time of VFSS were excluded. All procedures were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration. Ethical approval was obtained from the Seoul National University Hospital institutional review board (No. 1812–177–1001) and the need for obtaining informed consent was waived because of this study being a retrospective review.

Functional Oral Intake Scale for Children

We adapted the original version of the FOIS by removing the item levels “TOD with no restrictions” and “TOD of a single consistency” to generate a 5-point FOIS for use in children: level 1 indicates nothing by mouth; level 2 indicates tube dependence with minimal oral attempts of food or liquids; level 3 indicates tube dependence with consistent oral intake of food or liquids; level 4 indicates total oral diet but requiring special preparations, compensations, or not expanded from whole-bottle feeding; level 5 indicates total oral diet without special preparation or compensations. Approval from the developer (Michael Crary) to modify the original version of the FOIS for use in children was obtained. Chopping food was not considered as special preparation, but grinding, and the use of commercially available thickening agents (such as xanthan gum) (20) was regarded as TOD with special preparation (FOIS level 4 for children). For children, FOIS level 4 was also assigned when food expansion to diets other than whole bottle feeding did not occur after 1 year of age, given that failure to introduce lumpy solid food by approximately 9 to 10 months of age is associated with an increased risk of feeding difficulties (19).

Inter-rater Reliability of Functional Oral Intake Scale for Children

A nutritionist interviewed each child's caregiver to record the type, amount, consistency of food and liquid intake, tube dependency, and nutrient status at the time of the VFSS. Two occupational therapists with more than 2 years of experience in swallowing therapy retrospectively reviewed the nutritionist's medical records and assigned FOIS levels. The 2 raters did not receive specific training on FOIS evaluation, as suggested by the original developer (9), and independently evaluated the FOIS level of the children while blinded to the results from other raters.

Validity

Cross-validity was determined by comparing the FOIS level to the dysphagia and aspiration severity assessed using the VFSS developed by Mann et al (21,22), which was previously used to validate the original FOIS (9). The dysphagia and aspiration severity scale was graded as normal, mild, moderate, severe, or complete. Videofluoroscopic diagnostic criteria for dysphagia employs the following ratings: normal indicates no swallowing abnormality detected; mild indicates slight delay in bolus control, initiation of swallow, or transport, resulting in some stasis of material without laryngeal penetration; moderate indicates moderate delay in bolus control, initiation of swallow, or transport, resulting in coating or stasis of materials within the oral cavity and/or pharynx, slight laryngeal penetration, or trace aspiration of thin liquid only; severe indicates substantial delay in bolus control, initiation of swallow, and transport; significant (>10% of bolus) penetration and/or aspiration of 1 or all consistencies; complete indicates no response to food stimulus; initiation of the swallow sequence is not obtained over several trials. Videofluoroscopic diagnostic criteria for aspiration employs the following ratings: normal indicates no entry of contrast material through the true vocal cords; mild indicates trace entry of contrast materials through the vocal cords; moderate indicates entry of less than 10% of the bolus through the true vocal cords; severe indicates entry of >10% of the bolus through the true vocal cords; complete indicates frank aspiration of materials through the vocal cords without an observable reaction by the patient. A physiatrist (one of the authors) obtained both ratings based on bolus control and the aspirated material amount, respectively, while blinded to the FOIS results.

Achieving Full Oral Feeding in Children With Partial Oral Feeding

To investigate the clinical relevance of separating the partial oral feeding into FOIS 2 (tube dependent with minimal oral attempts of food or liquids) and FOIS 3 (tube dependent with consistent oral intake of food or liquids), the medical records for children with partial oral feeding were further investigated to determine whether full oral feeding was accomplished within 1 year from initial FOIS evaluation.

Statistical Analysis

Weighted kappa was obtained to evaluate inter-rater reliability of the 2 evaluators using the 5-point scale FOIS for children. A 2-way random effect model was used to examine intra- and inter-rater reliability. Intraclass correlation coefficients (ICCs) >0.75 were deemed to represent good reliability, 0.50 o 0.75 represented moderate reliability, and <0.50 represented poor reliability. To assess the cross-validity of the FOIS for children, the correlations between the FOIS for children and dysphagia/aspiration severity ratings were assessed by a Spearman rho test. The chi-square test was used to determine whether the ratios of tube removal (achieving full oral feeding) within 1 year were different between children at FOIS levels 2 and 3. A P value <0.05 was considered statistically significant. Weighted kappa was calculated using SAS ver. 9.4 software (Institute Inc., Cary, NC). Other statistical analyses were performed using IBM SPSS ver. 23.0 software (IBM Corporation, New York, NY).

RESULTS

Subjects

A total of 194 children were included in the present study. The baseline characteristics and main diagnosis of the subjects are presented in Table 2 (n = 194). Brain lesion was the most frequent diagnosis (98 children), followed by myopathy/motor neuron disease in 17 children. The mean age of the 194 children was 2.49 years (range: 1.01–6.97 years).

T2
TABLE 2:
Characteristics of the participants

Inter-rater Reliability of Functional Oral Intake Scale for Children

The 5-point scale FOIS for children evaluated by 2 occupational therapists showed a high absolute agreement (97.4%) for the 194 children, as shown in Table 3 (weighted kappa = 0.985; ICC = 0.994; 95% confidence interval [CI] = 0.993–0.996). Disagreement between the 2 observers in terms of assigning pediatric FOIS levels 2 and 3 was noted for 1 individual (Table 3). This patient was a 13-month-old toddler, who received a total of 1000 cc/day tube feeding, 5 times a day, and consumed 50 g of complementary food twice a day. Although 1 evaluator regarded twice a day as a consistent oral intake (FOIS Level 3), the other considered this as a minimal attempt at oral intake (FOIS Level 2). Disagreement between the 2 observers in terms of assigning FOIS for children Level 4 or 5 was also noted for 4 individuals. The first child had chromosomal aberration syndrome (4 years and 7 months old) and would eat very soft and thin porridge. One evaluator assigned FOIS level 4 since she considered it a special preparation based on her age whereas the other evaluator assigned FOIS level 5. The second child was 17 months of age with a diagnosis of cricopharyngeal incoordination. She would consume commercial formula, which was considered as special preparation by 1 evaluator but not the other. The third case was a boy with 13 months of trisomy 8 mosaicism. He consumed approximately 200 cc of finely chopped weaning food along with bottle-feeding, which was evaluated as ground food (level 4) and chopped food (level 5) by the separate evaluators. The fourth child was a 23-month-old boy with an unknown diagnosis who only consumed very soft foods (eg, yogurt, cheese) and water.

T3
TABLE 3:
Interrater reliability of functional oral intake scale for children

Videofluoroscopic Swallowing Study Findings and their Correlation With Functional Oral Intake Scale

The FOIS levels for children were compared with VFSS-based dysphagia and aspiration findings (Supplemental Table 1, Supplemental Digital Content, https://links.lww.com/MPG/B891). There was an association of the FOIS levels with the dysphagia severity (P < 0.001, Spearman's correlation coefficient = 0.287). Further, a significant association was identified between the FOIS level for children and aspiration severity (P < 0.001, Spearman's correlation coefficient = 0.315).

Achieving Full Oral Feeding in Children With Partial Oral Feeding

Among 38 children who were partially dependent on tube feeding (FOIS 2 and 3 by definition), 34 children had records regarding the feeding method for 1 year after initial FOIS evaluation. There was no difference in initial age of children between FOIS level 2 and FOIS level 3 (Supplemental Table 2, Supplemental Digital Content, https://links.lww.com/MPG/B891, P = 0.341). There was no significant difference in the proportion of children with brain lesions and motor neuron disease/myopathy between the 2 groups (P = 0.493 and 0.667 by chi-square test, respectively). In 16 of the 34 children (47.1%), full oral feeding was achieved with the feeding tube being removed within 1 year. The achievement rate of full oral feeding within 1 year was higher in children with FOIS level 3 than those with FOIS level 2 (P = 0.017 by chi-square test, Fig. 1).

F1
FIGURE 1:
Percentage of achieving full oral feeding within 1 year after the initial evaluation using the functional oral intake scale for children. The number in parenthesis represents the number of children. Children with the FOIS level 3 showed a higher rate of reaching full oral feeding after 1 year (P = 0.017 by chi-square test) than those with FOIS level 2. FOIS = functional oral intake scale.

DISCUSSION

This study proposed a simple 5-point FOIS for children and demonstrated that it had adequate reliability and validity. The FOIS for children could be used to describe the severity of dysphagia and to measure or compare the effect of various interventions to alleviate the symptom. This scale might be used generically as an ordinal scale, regardless of disease group, as an oral diet only (levels 4 and 5) instead of a totally or partially tube-dependent state (levels 1, 2, 3), or consuming food orally without special preparation (level 5) instead of requiring special preparation (level 4), or a combination of oral/tube feeding (levels 2 and 3) rather than a totally tube-dependent state (level 1) could be regarded as an improved status of feeding.

Prior to the molars erupting, children use their incisors to bite off food; however, they cannot sufficiently grind food for swallowing (15). Although children ages 3 to 4 years have molars, they are easily distracted while eating and do not efficiently chew (15,23). Although the majority of children related with food-object choking or aspiration were less than 5 years of age (24), it is also reported that popcorn, peanuts, and candy caused asphyxia in children above 5 years of age (25). In line with the safety and applicability problems in pediatric population, mini-tablets sized between 2 and 5 mm have been developed especially for preschool children (26). Considering the concerns described above, we included the children ages <7 years for the testing of the FOIS-for-children in this study.

There have been several studies that have applied a FOIS for adults to children. Christiaanse et al employed a FOIS for adults on children excluding a single consistency level without validation (27). Coppens et al also applied a FOIS for adults to children over 1 year old. They, however, grouped the feeding status of children into 3 categories (28) rather than following the 7 FOIS levels: tube dependency (FOIS levels 1–3), oral feeding with restriction (FOIS levels 4–6), and oral feeding without restriction (FOIS level 7).

We found that the correlation coefficient of the FOIS for children with aspiration severity was 0.315, which was comparable to the correlation coefficient of 0.30 when the FOIS was applied to the adult stroke population (9). Contrastingly, we found that the correlation coefficient of the FOIS for children with dysphagia severity was 0.287, which was significantly lower than the correlation coefficient of 0.54 when the FOIS was applied to the adult stroke population (9). In children, oral aversion, nutritional issues, and oromotor developmental issues, which are not considered in the VFSS-based dysphagia severity ratings, could affect the consumable food level of FOIS. This could explain the lower correlation of dysphagia severity with FOIS for children compared with that for adults. For example, in our study, 3 children with normal VFSS findings were given tube feeding because of nutritional issues and oral aversion.

The inter-rater reliability of the FOIS for children was high, with an absolute agreement of 97.4% (kappa = 0.985) and an ICC of 0.994 (95% CI = 0.993–0.996). These results are consistent with those of adult FOIS studies on patients with stroke (9,10). Some changes, however, were required to improve reliability and validity evaluation. In adults, FOIS levels 2 and 3, which are the parallel levels of tube and oral feeding, are described as minimal and consistent oral feeding, respectively. Increasing the oral feeding frequency in adults could be directly associated with increasing the oral intake amount. In children, however, both minimal and consistent oral feeding may be continued in parallel with tube feeding to prevent oral aversion or facilitate oromotor functional development (2,29). Therefore, it could be appropriate to include not only the oral feeding frequency but also the caloric contribution of oral feeding in the description of FOIS level 3 for children, as done in FOIS for infants (Table 1). There is a problem, however, with regard to setting the standard for the caloric contribution of oral intake. In a study on the FOIS for infants, infants who consumed >10% of the oral caloric intake in parallel with tube feeding reached full oral feeding at a higher rate than those who consumed <10%. This study, however, did not report the caloric calculation of the children's diet. For children in this study with partial oral feeding, the rate of tube removal (reaching full oral feeding) within 1 year increased as the concurrent oral diet became consistent (Fig. 1). This finding supports the feasibility of subdividing the partial oral feeding status into FOIS 2 and 3 for children.

We considered eating ability as monitored or improved if the child could not eat chopped foods and required further food modifications, including grinding. Moreover, requiring fluid thickening was considered FOIS level 4 for children. As eating chopped food is commonly observed in normal development in children, it is classified as FOIS level 5 (ie, without special preparation or compensation, unlike in adults). Despite these definitions, we observed patients with an ambiguous distinction between special preparation and general cooking process for children. Specifically, we did not define whether to consider commercially available formulas, which were provided for supplemental nutrients, as special preparations. It could be appropriate to consider supplemental nutrients as special preparation or compensations when recommended by a physician or dietician (Table 1, FOIS for children level 4).

In this study, there were 4 children who consumed only single-consistency food (ie, caloric intake by bottle-feeding alone, even after 1 year of age). These children demonstrated poor transition to weaning food because of oral aversion, and all of their VFSS findings were normal. These children were considered to be level 4 as they required monitoring and intervention for oromotor and swallowing development.

Study limitations

In this study, we could not evaluate the correlation between FOIS for children and developmental assessment as the study was designed in a retrospective nature. The Bayley Scales of Infant and Toddler Development (23) could be used in conjunction with FOIS for children in a future study. Additionally, as this was a single-center study, a selection bias may have been present. The use of a prospective and multicenter design would make it possible to decrease the chances of selection bias.

CONCLUSIONS

In the present study, we proposed the 5-point FOIS for children based on the food they can consume. The scale showed adequate reliability and validity. These findings suggest that the FOIS for children could be appropriate for documenting eating abilities of children and for evaluating the effectiveness of interventions.

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Keywords:

children; dysphagia; feeding intervention; Functional Oral Intake Scale; videofluoroscopic swallowing study

Supplemental Digital Content

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