Alpha-1 antitrypsin deficiency (AATD) predisposes individuals to early onset COPD and liver cirrhosis. As with ?usual? COPD, acute pulmonary exacerbations (PEx) significantly affect mortality and morbidity in AATD-COPD. There is limited research comparing PEx in usual COPD with AATD-COPD.

Annualised PEx rates and baseline characteristics were compared between usual COPD (n=1033) and AATD-COPD (n=882) patients from two independent cohorts. The INTEGR-COPD study is a pragmatic cluster randomised controlled trial of usual COPD patients in primary care (enrolled 2017 to 2020) comparing integrated specialist respiratory care to usual care with a 1-year follow-up period. The Birmingham (UK) AATD Cohort is an observational study of patients with AATD, with and without diagnosis of COPD (recruited 1996 to 2020), with a median follow-up duration of 5 years. The association of PEx rates with disease phenotype (usual COPD vs AATD-COPD) were investigated with a mixed Poisson model adjusted for age, sex, smoking history and ppFEV1 as fixed effects, and individual and time as random effects.

AATD-COPD patients were younger (median age: 51 vs 69 years), had lower ppFEV1 (median ppFEV1: 48% vs 60%), were less likely to be current smokers (7% vs 48%), and more likely to have severe breathlessness (mMRC 4: 14% vs 3%) than usual COPD patients. Unadjusted PEx rates were higher in those with AATD-COPD than usual COPD (1.28 vs 0.94 PEx/year, p<0.001). In the adjusted analysis, there was no significant difference in AECOPD rates between usual COPD and AATD-COPD (p=0.48).

AATD-COPD patients had lower ppFEV1 and higher PEx rates than usual COPD patients despite being younger and less likely to be current smokers.