Table 3.

Recommended routine monitoring and assessments in patients with MPS VI

Statement	Percentage consensus
All guidance statements are evidence Grade D (based on level 5 expert clinical opinion), unless otherwise stated
Physical examination
A physical examination should be performed during every visit to assess general health, growth, vital signs, abdominal organ size, presence of hernia, neurologic function (including gait), joint stiffness, and functions of the eyes, ears, heart and lungs	90%
Routine physical examination can also identify signs of potential respiratory problems, such as an enlarged tongue or sniffing position	90%
Radiology
While X-rays are essential to identify the natural history of disease and response to treatment, efforts should be made to minimise radiation exposure, and images should be requested only when clinically useful	85%
Hips: an anteroposterior (AP) pelvis radiograph should be performed at diagnosis and as clinically indicated (based on physical examination or reports of pain) to quantify hip dysplasia or identify early signs of hip migration [23]	88%
Lower limbs: in patients with clinical evidence of valgus deformity of the lower limbs, standing AP radiographs of lower extremities should be performed prior to guided growth surgery [24]	100%
Spine: standing or sitting plain radiography of the cervical and thoracolumbar spine to examine for spinal deformities is recommended in patients with MPS VI at diagnosis and every 2–3 years thereafter, or sooner if clinically indicated [24]  Evidence Grade: C (level 3/4 studies)	85%
Magnetic resonance imaging (MRI) of the whole spine (in neutral position) should be performed annually in children with MPS VI to assess for spinal cord injury. The frequency may be reduced for adult patients with stable imaging who do not display symptomsa	84%
Flexion/extension MRI of cervical spine may be needed to identify changes in spinal canal and spinal cord	86%
MRI of the brain is recommended at diagnosis in patients with MPS VI, and should be repeated as needed in individuals with clinical suspicion of hydrocephalus	80%
MRI of the brain and spinal cord in patients with MPS VI may require sedation or general anaesthesia depending on patient age and cooperation. General anaesthesia carries substantial risk for patients with MPS	95%
Flexion/extension computerised tomography (CT) of the craniocervical junction may be considered in individuals with MPS VI if MRI is not available or if sedation is not possible	92%
The presence of specific radiological signs may indicate the need for surgical intervention to correct skeletal deformities; however, there is insufficient evidence to support preventative surgery based on radiological findings	88%
Endurance
Choice of assessment depends on the patient’s physical and developmental ability [25]	97%
Baseline assessment is the most important and ideally two values should be obtained as a minimum. Consistent protocols should be used when performing repeat measurements to minimise variability	95%
Annual endurance testing using 6-min walk test (6MWT) is recommended, as per the American Thoracic Society guidelines [13, 25, 26]	87%
In patients with limited ambulation who are unable to perform the 6MWT, endurance should be assessed via alternative methods such as an adapted timed 25-ft walk test (T25FW)	76%
Endurance testing is also recommended prior to initiation of ERT and annually thereafter as a measure of treatment efficacy and to provide early evidence of possible neurologic or skeletal issues	87%
Growth
Assessment of growth should be performed at each clinic visit as part (ideally every 6 months) of a regular physical examination and should include: standing height (sitting height if the patient is unable to stand), length (supine position), weight, head circumference (≤3 years), Tanner pubertal stage (until maturity)	95%
Height and weight should also be measured before initiation of ERT and at every clinic visit thereafter (ideally every 6 months) to evaluate the impact of treatment	95%
Urinary glycosaminoglycan (uGAG) levels
Urinary GAG levels should be tested prior to starting galsulfase and every 6 months thereafter to determine the pharmacodynamic effects of ERT [13]  Evidence Grade: C (level 3/4 studies)	97%
Measurement of total uGAG levels may be performed using standard dye-based quantitative methods, preferably in the same laboratory and assessed against age-related reference values	93%
Where available tandem mass spectrometry may be used to assess levels of specific GAGs (such as dermatan sulphate) b [27–32]  Evidence Grade: C (level 3/4 studies)	97%
Cardiac function
Initial cardiac evaluation should be performed at the time of diagnosis and include assessment of vital signs with measurement of oxygen saturation, right arm and leg blood pressure measurements, careful auscultation, full transthoracic two-dimensional and Doppler echocardiogram, and 12-lead electrocardiogram (ECG) [33]	100%
Longer ECG monitoring (prolonged Holter/event monitoring) may be considered in older patients, especially if they have symptoms of black outs, unexpected falls or dizziness	96%
Follow-up in expert centres should be annually initially, but may be extended to every 2–3 years if there is no evidence of cardiac abnormality [34, 35]	92%
Additional cardiac assessment, including a standard ECG, should be performed prior to any surgical procedure requiring general anaesthesiac [34, 35]	92%
Neurological exam
A detailed neurological examination should be performed at every clinic visit (minimally every 6 months) and, where possible these should correlate with imaging studies of the spine to detect early spinal stenosis or instability compromising the cervical cord. For patients without clinical or radiographic concern, annual neurological examination may be sufficient [36]	87%
Standard MRI of the cervical spine should be performed to assess for presence of spinal cord compression. In the absence of significant spinal cord compression, proceed with flexion/extension MRI to confirm the presence of worsening spinal cord compression with motiond	78%
Upper limb function
Symptoms of carpal tunnel syndrome (CTS) are often atypical in patients with MPS VI, therefore recommend clinical examination, assessment of range of finger movement and strength, electrophysiology nerve conduction assessment and detailed medical history to be performed at diagnosis and annually thereafter	89%
Standardized clinical examination, assessment of active and passive range of movement and nerve conduction studies (NCS) are recommended to assess hand and upper limb function in individuals with MPS VI	89%
Respiratory function and sleep disorder
Evaluation of respiratory function by spirometry, including forced vital capacity (FVC) and maximum voluntary ventilation (MVV), should be performed to assess changes in lung volume and obstruction in children over 5 years of age	97%
Respiratory function should be assessed annually until children stop growing, and every 2–3 years thereafter, provided that respiratory symptoms remain unchanged. Additional testing should be performed if respiratory symptoms change or if intercurrent illnesses occur	91%
Normative values are not available, therefore change in absolute volume from patient’s own baseline will be the best indicator of deterioration or improvement	97%
Measurement of respiratory rate and arterial oxygen saturation before and after annual endurance testing is recommended	86%
Evaluation of gas exchange and respiratory function is also recommended before any planned air travel, to ensure safety during the flight	86%
To identify symptoms of sleep apnoea, patients should be asked to report presence of snoring and morning headaches at every clinic visite	100%
Overnight sleep study (polysomnography) is recommended at diagnosis (if possible, and no later than 2 years of age), and every 3 years thereafter or when signs and symptoms of obstructive sleep apnoea (OSA) are noted [37, 38]	94%
Ear-nose-throat (ENT)
ENT examination, including tympanometryf, should be conducted every 3–6 months during childhood and every 6–12 months thereafter	91%
ENT examination in patients with MPS VI should include visualization of the upper respiratory tract to determine diagnosis, management and assist in pre-operative planning. Endoscopic examinations should be recorded and kept, to monitor disease progression	92%
Fibreoptic examination in patients with MPS VI should be performed at diagnosis and at least annually thereafter, or as clinically indicated. For those individuals who require general anaesthesia, ENT examination should be performed during the pre-operative evaluation for other surgical procedures	83%
Upper airway CT, focused on airway anatomy preferably with reconstruction, may be useful to identify the area of the abnormality and possible cause of obstruction in patients with MPS VI with suspected obstruction or malaciag	92%
Age-adjusted audiometric assessment as a baseline objective hearing evaluation should be conducted in the first clinic visit and repeated annually to assess conductive and sensory-neural hearing loss [39]	100%
If speech problems are determined during ENT examination, an assessment by a speech pathologist should be conducted	100%
Balance tests should be conducted if the patient has a history of balance problems	95%
Ophthalmological function
Age-appropriate evaluations by an ophthalmologist is recommended every 6 months if possible, or at least annually	90%
Ophthalmic assessment may include visual acuity, refraction, slit-lamp examination of cornea, funduscopic evaluation including optic nerve, and measurement of intraocular pressure	100%
Intraocular pressure monitoring and pachymetry may be considered prior to corneal transplant	100%
Evaluation of oral health by dentist
Recommend close monitoring of dental development (at least annually) to prevent caries and attrition as is monitoring of occlusion and chewing functions	100%
The need for subacute bacterial endocarditis (SBE) prophylaxis prior to dental procedures should be assessed by a cardiologist	100%
Disease burden
Annual assessment of patient-reported outcomes is recommended for: pain severity, QoL (as assessed by reproducible and age-appropriate questionnaires [e.g. EQ-5D-5 L]), fatigue, and activities of daily living (ADL; as assessed by functional tests [6MWT/T25FW]) and age-appropriate ADL questionnaires (e.g. MPS Health Assessment Questionnaire [MPS HAQ]), and assessment of wheelchair/walking aid use	97%
These assessments may have to be adapted both for language, culture, and individual physical limitations as they have not been validated in the specific disorders	97%
Physical therapy
Regular assessments by a physical therapist (lower limb), occupational therapist (upper limb) and rehabilitation medicine specialist should be conducted to assess upper and lower limb function and provide support as needed	93%
The physical therapist could also assist in suggesting walking aids and other adaptations that may improve QoL	98%

Post-consensus comments by the SC to be taken into consideration

^aMagnetic resonance imaging (MRI) can also be used to assess for spinal cord compression. The frequency may be reduced for older patients with stable imaging who do not display symptoms

^bTandem mass spectrometry may also be used to assess disease specific oligosaccharides [32]

^cEchocardiogram (ECHO) should also be performed prior to any surgical procedure requiring general anaesthesia

^dThis topic was discussed in detail with the neurosurgical and orthopaedic colleagues in the SC group. It was their expert clinical opinion that flexion/extension MRI is not dangerous to perform within the hands of an experienced team. It is important that the range of motion (ROM), flexion and extension of the patient is evaluated while they are awake immediately before anaesthesia. The ROM during anaesthesia should not exceed the ROM as noted in the awake state, and should only be carried out after it is confirmed that there is no spinal cord compression. See Table 9 for guidance statements on spinal surgeries including spinal cord decompression

^eSigns and symptoms for sleep apnoea (a type of sleep disordered breathing (SDB)) can be divided into nocturnal and daytime symptoms. Nocturnal symptoms include loud snoring, observed episodes of breathing cessation during sleep, abrupt awakenings accompanied by gasping or choking, and awakening with a dry mouth or sore throat. Daytime symptoms include excessive daytime sleepiness, morning headaches, difficulty concentrating during the day, personality and mood changes including depression or irritability, and high blood pressure. To identify presence of SDB, patients should be asked to report snoring and other signs and symptoms of SDB at every clinic visit

^fTympanometry is used to measure the volume of the ear canal/tympanic membrane movement and indirectly assess for fluid accumulation and opening of pressure equalising tubes

^gUpper airway CT may also be useful to identify the area of the abnormality and possible cause of obstruction in patients with MPS VI