Chronic obstructive pulmonary disease (COPD) is a progressive lung disease, characterised by non-reversible airflow obstruction, mostly affecting middle-aged or elderly people who have smoked . It is projected that COPD will be the third leading cause of death worldwide by 2020 . Currently, treatment is mainly symptomatic and aims to slow down disease progression. The main evidence-based treatments are inhaled agents, such as bronchodilators , and pulmonary rehabilitation . Patients will have periods of no change in symptoms, and this is often considered a stable state.
As the disease progresses the lungs are unable to perform two of their basic functions: to get oxygen to the bloodstream, and to eliminate carbon dioxide. Hypoxia is the presence of low oxygen levels and long-term oxygen therapy (LTOT) is considered in selected patients . Hypercapnia describes a high carbon dioxide level, the presence of which in a stable patient is a poor prognostic sign . When the respiratory system fails like this, a patient could be considered to be in the end stage of their disease. Classically, end-stage COPD would be defined as those patients in the terminal stage of their disease, likely to die within months – a situation that is not always clear . Alternatively, it might be defined as those who have developed chronic respiratory failure and remain symptomatic on maximal therapy, with no hope of cure.
Non-invasive ventilation (NIV) is a method of providing ventilatory support via a mask, without the placement of an endotracheal tube . It is commonly used in the hospital setting as standard care for acutely unwell patients with COPD . As the technology has improved and NIV devices have become less cumbersome, an increasing number of patients have been able to use the devices outside of hospital . This includes patients with chronic respiratory failure due to kyphoscoliosis and neuromuscular disorders, for whom domiciliary NIV is an established treatment. Some centres also advocate NIV in a domiciliary setting for stable COPD patients with chronic hypercapnic respiratory failure. Physiological studies have shown improvements in lung function and carbon dioxide levels thought to be due to eliminating nocturnal hypoventilation . Some evidence suggests that it prevents episodes of recurrent acute hypercapnic respiratory failure and hospital admissions .
However based on a recent systematic review of randomised controlled trials (RCTs), evidence on the benefit of home NIV in this patient group remains inconclusive, particularly regarding long-term outcomes . Variations between the included RCTs in terms of study methods and physiological or clinical outcomes measured, together with a lack of adjustment for clinical variables (such as oxygen use or prior acute NIV use) have limited the conclusions that can be drawn. Furthermore the RCTs, for the most part, appear to have insufficiently long follow-up periods to capture outcomes relating to survival, long-term quality of life (QoL), exacerbations over the long term, adverse events or adherence rates, all of which are important in considering cost-effectiveness. Scoping searches suggest that observational studies may have included larger sample sizes, longer follow-up periods, additional outcome measures and less restrictive inclusion criteria than randomised trials and thus may have wider applicability.
Cost or cost-effectiveness evidence of non-hospital NIV in patients with stable end-stage COPD is sparse. There are no systematic reviews of the cost-effectiveness of non-hospital NIV. Some economic evaluations have been undertaken either in parallel with clinical trials or through audits of patient records [10, 12]. However, they appear not to be based on systematic review of clinical effectiveness, therefore, a robust evaluation of the literature and development of a new economic model is warranted.