North Star Ambulatory Assessment (NSAA) - Quick Facts, Scoring and Assessed Skills

Sep 15, 2026

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The North Star Ambulatory Assessment (NSAA) is a validated rating scale measuring how Duchenne muscular dystrophy affects ambulatory performance. It applies only to patients who can walk independently and provides standardized methods to quantify motor function. In clinical trials, NSAA can serve as an endpoint, while longitudinal results—linked with timed functional tests and biological assessments—track disease progression. The NSAA includes 17 age-adjusted assessments and uses 0–2 activity scoring to summarize functional ability over time.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages2

Reading Time5 min

AccessFree to download

Quick Facts

Assessments Included in the NSAA

Age reordering for younger children

Scoring and Results

Highest possible score by age

NSAA Assessed Skills

North Star Ambulatory Assessment The North Star Ambulatory Assessment (NSAA) is a validated rating scale used to measure the impact of Duchenne muscular dystrophy on ambulatory performance. Duchenne is a degenerative neuromuscular disorder that causes severe progressive muscle loss and premature death. People with Duchenne experience muscle weakness in the lower limbs that spreads to the arms, neck and other areas of the body, causing decreased motor functionality.1 Quick Facts: • The NSAA is only given to patients who are ambulant, or able to walk on their own .2 • The NSAA contains universally used methods to practically and reliably measure motor function.2 In clinical trials, the NSAA can be used as an endpoint to measure a person’s functional abilities before and after receiving an investigational therapy.1 • NSAA results, viewed over time and in connection with other timed functional tests and biological assessments, provide a picture of disease progression in patients.2 Assessments Included in the NSAA The NSAA requires patients to perform 17 assessments which test the speed and functionality of their motor skills.3 For patients younger than five years old, the NSAA reorders the skills to better represent age-appropriate tasks and scoring. This demonstrates how skills are gained or lost in younger patients over time, while taking into account the average general development of motor skills that occurs in children.4 •Adjusted for age, the first eight items are in the achievable range for patients at three years old.4 • Once three and a half years old, the patient can be additionally assessed on the next five items.4 •At four years old, the patient is capable of being assessed on all tasks .4 Scoring and Results Scores of 0, 1, or 2 are given depending on activity performance, based on length of time taken to complete and whether assistance was needed.4 A higher total score represents better functional performance . Natural history studies show a precipitous decline in the NSAA score for boys with Duchenne after they peak around the age of six.1 A person's NSAA results can be compared with their previous scores to track the improvement, maintenance, or decline of their motor abilities over time.1 The highest possible score varies, as a patient’s age determines the level of development that can be assessed.1 0 Unable to perform the task.1 | AGE | HIGHEST POSSIBLE SCORE4 | | --- | --- | | 3 | At three years old the highest possible score is 16 for eight items. | | 31/2 | At three and a half years old, the highest possible score is 26 for 13 items. | | | | | 4-5 | At ages four to five, the highest possible score is 34 . | NSAA Assessed Skills 3 | SAMPLE PATIENT SCORES | | | --- | --- | | Patient A (Age 6) | Patient B (Age 5) | | Stand
| Stand barefoot for as long and still as possible without external support. | 2
| 2
| | --- | --- | --- | --- | | Walk
| Walk forward for at least 10 steps (about 8-10 feet) with a consistent heel-to-toe gait. | 2
| 2
| | Rise from chair | Begin seated with arms crossed over chest, then stand up from the chair without uncrossing arms. | 2
| 2
| | Climb step (right leg) Climb step (left leg) | Step onto a box step at least 15cm high with right (or dominant) foot.
Step onto a box step at least 15cm high with left (or non-dominant) foot, joining the other. |
1

1 |
2

2 | | Gets to sitting | Lay flat on the floor with arms by side and move to a sitting position without turning towards the floor or using both hands to get up. Using one hand is permissible to achieve the top score. | 2
| 2
| | Jump
| Stand on the floor with both feet together and jump as high as possible with minimal forward movement. | 1
| 1
| | Run
| Run as fast as possible for about 32 feet. To achieve the highest score, both feet must clear the ground when running. | 0
| 1
| | Stand on right leg | Stand

FAQs

Who is eligible to receive the NSAA?

The NSAA is given only to ambulant patients who are able to walk on their own.

How are NSAA scores determined?

Each activity is scored 0, 1, or 2 based on time to complete and whether assistance is needed. A higher total score indicates better functional performance.

How does the NSAA adapt for children under five years old?

For patients younger than five, the NSAA reorders skills to match age-appropriate tasks and scoring, reflecting how skills are gained or lost over time.

Sep 15, 2026

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