The first iteration of the Rare Disease COA Resource focused on the assessment of daily function subdomains of gross motor function, fine motor function and self-care and communication/language. The second iteration of the Rare Disease COA Resource, launched in December 2025, focuses on pain subdomains of pain behavior and pain severity, and the sleep subdomains of sleep disturbance and sleep impact, in pediatric, non-oncologic populations. These domains and subdomains are defined below. A list of selected COAs for inclusion in the Resource follows.
Inclusion of a measure in the Rare Disease COA Resource DOES NOT mean that a COA is fit for purpose. A COA is considered fit for purpose when “the level of validation associated with a medical product development tool is sufficient to support its context of use” (Biomarkers, Endpoints and Other Tools Resource, 2016). Discuss specific COAs and situations with relevant regulators and HTAs.
Domain: Daily function
Common, everyday actions and behaviors involving functional ability that children display to show growing independence and mastery of skills.
Subdomains:
Fine motor function – Fine motor skills are involved in smaller movements that occur in the wrists, hands, fingers, feet, and toes. They involve smaller actions such as picking up objects between the thumb and finger, writing carefully, and even blinking.
Gross motor function – Gross motor (physical) skills are those which require whole body movement, and which involve the large (core stabilizing) muscles of the body to perform everyday functions, such as standing and walking, running and jumping, and sitting upright at the table. They also include eye-hand coordination skills such as ball skills (throwing, catching, kicking) as well as riding a bike or a scooter and swimming.
Self-care – Ability to perform daily skills and adaptive behaviors involved in caring for oneself with increasing independence. Tasks may include eating or drinking, dressing, bathing, toileting, disease management, and general mobility in the home, community, and school environment.
Communication/language – Includes aspects of both receptive and expressive language, oral and written language, gestures, signs of dysarthria (muscles used for speech are weak resulting in speech that is difficult to understand), apraxia of speech (loss or impairment of ability to execute coordinated movements to produce speech), and articulation (the formation of clear and distinct sounds in speech). Sensory and motor/somatic (voluntary control of body movements) issues related to communication that should be included in the assessment: dysarthria, apraxia of speech, vision, hearing, facial expression, articulation.
Domain: Pain
An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.
Subdomains:
Pain behavior: The external manifestations of experiencing pain. These actions or reactions can be verbal or nonverbal, involuntary or deliberate. Pain behaviors usually communicate to others that a person is experiencing pain. They include observable displays such as sighing or crying, and pain severity behaviors such as resting, guarding, facial expressions, and asking for help, as well as verbal reports of pain.
Pain severity: The intensity of pain experienced by individuals. Pain severity can only be known and reported by the person experiencing it.
Domain: Sleep
The natural, easily reversible periodic state of many living things that is marked by the absence of wakefulness and by the loss of consciousness of one’s surroundings, is accompanied by a typical body posture (such as lying down with the eyes closed), the occurrence of dreaming, and changes in brain activity and physiological functioning, and is usually considered essential to the restoration and recovery of vital bodily and mental functions.
Subdomains:
Sleep disturbance: Perceptions of sleep quality, sleep depth, and restoration associated with sleep; perceived difficulties and concerns with getting to sleep or staying asleep; and perceptions of the adequacy of and satisfaction with sleep.
Sleep impact: Perceptions of alertness, sleepiness, and tiredness during usual waking hours, and the perceived functional impairments during wakefulness associated with sleep problems or impaired alertness.
The table below lists tools currently included in the Resource. To apply filters, enter or select the desired input into the field at the top of each column (i.e., instrument name, abbreviation, COA type, and/or subdomain).
A list of current COAs organized by subdomain(s) may also exported in .csv format by clicking the “Export” button, below.
