Data from the International Society for Heart and Lung Transplantation (ISHLT) registry show that the median survival of 45,542 adults who underwent primary lung transplantation between January 1990 and June 2013 was 5.7 years. Unadjusted survival rates were 89% at 3 months, 80% at 1 year, 65% at 3 years, 54% at 5 years, and 31% at 10 years. Lung transplant recipients who survived to 1 year after primary transplantation had a conditional median survival of 7.9 years (Yusen et al., 2015). Long-term survival rates for lung transplant recipients are much lower than those attained for kidney, liver and heart transplant recipients (Orens and Garrity, 2009; Fredericks et al., 2014).

The primary cause of mortality in the first year after transplant is infection, with graft failure due to chronic rejection or infection being the most common cause of mortality in subsequent years (Valapour et al., 2017).

Morbidities commonly associated with immunosuppressants occurred frequently in the first-year post lung transplantation for data collected between April 1994 and June 2014: hypertension (52%), renal dysfunction (23%), diabetes (23%), and hyperlipidaemia (26%). At 5 years post transplantation these morbidities increased to 81%, 53%, 40% and 58% of transplant recipients respectively (Yusen et al., 2015).

A major complication of lung transplantation is bronchiolitis obliterans syndrome (BOS), which is a manifestation of chronic allograft rejection and occurs typically in lung transplant recipients 5 years post transplantation (Orens and Garrity, 2009; Meyer et al., 2014). ISHLT data (from 1994–2014) showed that the frequency of BOS in lung transplant recipients increased from 9% at 1 year to 41% at 5 years post transplantation (Yusen et al., 2015). Clinically, patients with chronic rejection present with progressive airflow obstruction, often accompanied by dyspnoea and cough. Death from chronic rejection is either due to respiratory failure or secondary infection (Orens and Garrity, 2009; Meyer et al., 2014).

International clinical practice guidelines for the diagnosis and management of bronchiolitis obliterans syndrome have been published (Meyer et al., 2014).