Multisystem and Autonomic Complications of NMD on Long-term NIV

HRV will be analysed in time and frequency domains from short-term (5 minute) artefact free ECG recordings. Normal parameters will be determined from an age- and sex-matched exploratory reference group of healthy adults.

BRS will be analysed in time and frequency domains from short-term (5 minute) artefact free blood pressure recordings. Normal parameters will be determined from an age- and sex-matched exploratory reference group of healthy adults. This will be measured only in the patient participant group.

Composite Autonomic Symptom Scale 31 questionnaire (COMPASS 31) is a validated questionnaire for quantitative assessment of autonomic symptoms, based on the original Autonomic Symptom Profile. The 31 questions are divided into seven domains (orthostatic intolerance, vasomotor, secretomotor, gastrointestinal, bladder and pupillomotor). The raw score from each domain is multiplied by a weight index to give a total score with a maximum score of 100 (minimum score 0). Higher scores indicate greater symptom burden.

The Sydney Swallow Questionnaire (SSQ) is a validated self-reported inventory of 17 questions measuring symptomatic severity of oral-pharyngeal dysphagia using 16 visual analogue scales (VAS) and one question scored on a Likert scale (0-5) to rate swallowing difficulty and symptoms of dysphagia and aspiration in a range of situations. Each VAS measures 100mm; the raw scores from these are added to the weighted score of the additional question to make the total possible raw score 1700 when the scores are added. Higher scores indicate greater symptom burden. This will be measured only in the patient participant group.

The European Quality of Life - 5 Dimensions questionnaire (EQ-5D-5L) is a standardised instrument developed by the EuroQol Group as a measure of health-related quality of life that can be used in a wide range of health conditions and treatments. The EQ-5D-5L consists of a descriptive system comprising five dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression, each with 5 levels of severity. An EQ visual analogue scale then asks patients how they feel on the day of the visit. A unique health state is defined by sequentially combining the indicated level in each of the 5 dimensions. This will be measured only in the patient participant group.

The Patient Assessment of Constipation Symptoms questionnaire (PAC-SYM) is a symptom inventory which measures specific symptoms of constipation in adults. It consists of a 12-item measure of patient's experience of symptoms and symptom severity. The score of each question is given equal weight and domain and total scores can be calculated by summing the relevant scores and dividing by the number of non-missing items. This will be measured only in the patient participant group.

The Individualized Neuromuscular Quality of Life Questionnaire (INQoL) is a validated muscle disease specific measure use to assess health-related quality of life of adult patients with acquired or congenital neuromuscular diseases, developed from the experiences of patients with muscle disease. It consists of 45 questions within 10 sections. Four sections focus on the impact of key muscle disease symptoms; five assess at the degree and importance of impact muscle disease has on particular areas of life; one section asks about positive and negative effects of treatment. The questionnaire allows for variations in individual characteristics that influence quality of life. The scoring of the INQoL generates a profile and combining weighted scores of each domain produces a total score from 0 to 100, with higher scores indicate greater impact of disease. This will be measured only in the patient participant group.

The severe Respiratory Insufficiency quality of life tool (SRI)is a validated questionnaire assessing health-related quality of life in patients with respiratory failure on home ventilation. It consists of seven subscales covering 49 items rated on a 5-point Likert scale: respiratory complaints, physical functioning, attendant symptoms and sleep, social relationships, anxiety, psychological wellbeing and social functioning. After transformation and weighting of raw scores, a total score between 0 and 100 is calculated. Higher values indicate a better health-related quality of life. This will be measured only in the patient participant group.

The best of 3 attempts obtained through standard Spirometric assessment will be used to obtain FEV1 (L) in the patient participant group.

The best of 3 attempts obtained through standard Spirometric assessment will be used to obtain FVC (L) in the patient participant group.

The values obtained from standard Spirometric assessment will be used to determine FEV1/FVC ratio in the patient participant group.

Using a standard peak flow meter, peak cough flow will be recorded in L/min the patient participant group.

Sniff nasal inspiratory pressure (SNIP) in each nostril will be recorded in the patient participant group.

Serological brain natriuretic peptide (BNP) will be obtained through venepuncture in the patient participant group.

Serological troponin will be obtained through venepuncture in the patient participant group.

Standard blood gas tensions will be obtained from earlobe puncture in the patient participant group.

Single abdominal x-ray to evaluate number of retained radiopaque markers 5-days after oral ingestion in the patient participant group.

Inductive thematic analysis of individual interviews to provide qualitative data in the patient participant group.

Measured using calibrated scales in kilograms

Measured using calibrated scales in centimetres

Calculated using the formula BMI = weight(kg)/[height(m)]2

Nocturnal transcutaneous carbon dioxide will be measured overnight in kilopascals (kPa)

Standard transthoracic echocardiogram will be performed in the patient participant group to assess cardiac function