Abstract

The aim of the present study was to evaluate, among older persons, the association between respiratory impairment and hospitalisation for chronic obstructive pulmonary disease (COPD), based on spirometric Z-scores, i.e. the LMS (lambda, mu, sigma) method, and a competing risk approach. Using data on 3,563 white participants aged 65-80 yrs (from the Cardiovascular Health Study) we evaluated the association of LMS-defined respiratory impairment with the incident of COPD hospitalisation and the competing outcome of death without COPD hospitalisation, over a 5-yr period. Respiratory impairment included airflow limitation (mild, moderate or severe) and restrictive pattern. Over a 5-yr period, 276 (7.7%) participants had a COPD hospitalisation incident, whereas 296 (8.3%) died without COPD hospitalisation. The risk of COPD hospitalisation was elevated more than two-fold in LMS-defined mild and moderate airflow limitation and restrictive pattern (adjusted HR (95% CI): 2.25 (1.25-4.05), 2.54 (1.53- 4.22) and 2.65 (1.82-3.86), respectively), and more than eight-fold in LMS-defined severe airflow limitation (adjusted HR (95% CI) 8.33 (6.24-11.12)). Conversely, only LMS-defined restrictive-pattern was associated with the competing outcome of death without COPD hospitalisation (adjusted HR (95% CI) 1.68 (1.22-2.32)). In older white persons, LMS-defined respiratory impairment is strongly associated with an increased risk of COPD hospitalisation. These results support the LMS method as a basis for defining respiratory impairment in older persons.