Bronchiectasis overall prevalence in the Italian population referring to GPs is 163 per 100,000 population, whereas annual incidence is 16.3 per 100,000 person-years. Both prevalence and incidence increase with age, with the highest rates reported in patients aged > 75 years. Prevalence and incidence computed after the exclusion of patients with a diagnosis of either asthma or COPD is 130 per 100,000 and 11.1 person-years, respectively.
This study provides the first epidemiological report on bronchiectasis in Italy, showing that it is not a rare disease. Italian estimates seem similar to other European settings, ranked between the lower prevalence described by Ringshausen et al. in Germany (67 cases per 100,000 population) and the higher UK prevalence (566 and 485 new cases per 100,000 population in women and men, respectively) [5, 7]. Interestingly, Italian prevalence is lower if compared with the only other bronchiectasis cohort recruited in Southern Europe. In 2012 Monteagudo analyzed primary care medical reports of 5.8 million people in Catalonia and reported on a prevalence of 362 patients per 100,000 population . This inconsistency might be related to several reasons, including different data sources and algorithms for data collection; however, geographical heterogeneity might have a key role, as recently highlighted by Chandrasekaran . A better understanding of the epidemiological variability should be achieved by the analysis of international multicentric cohorts, recruited with the same methodology and using the same clinical definitions.
While Italian bronchiectasis prevalence and incidence are slightly higher in females across all age groups, different estimates were found in 2015 in people older than 75 years (prevalence 511 VS. 484 per 100,000 population and incidence 46.7 VS. 40.0 per 100,000 person-years in males and females, respectively). The increased rates in males are consistent with findings from similar studies and - as already observed - might be attributed to the high proportion of COPD patients in this age class [5, 8]. The analysis in patients without a concomitant diagnosis of COPD confirmed this hypothesis, where it was found that females were more prevalent in all age groups. Notably, in our dataset COPD is the most prevalent (23.3%) condition related to bronchiectasis. At present, though biological plausibility and epidemiological association has been reported, the definition of COPD as a cause of bronchiectasis is not widely accepted [11, 12]. A recent literature review showed conflicting bronchiectasis prevalence estimates in COPD populations, ranging from 4 to 28%, partially explained by the enrollment of different populations or different CT diagnostic criteria . While the interpretation of a simple co-existence or co-morbidity between COPD and bronchiectasis still holds a prominent position, it has been recently postulated that these medical conditions might occur as an overlap syndrome (the acronym BCOS has been proposed) with possible consequences in terms of treatment and increased mortality [14,15,16].
Annual prevalence of bronchiectasis increased from 2005 to 2015 in men and women, as well as in the overall population and in population without asthma and COPD, in agreement with previous findings [5, 6]. While some of bronchiectasis could still be post-infective, this increase in incidence among elderly people might be attributed to specific adult-onset etiologies, that are becoming more and more prevalent in aged and chronically-ill patients. However, the increasing trend might be partly explained by the wider use of chest CT scan, population ageing, as well as increased awareness of bronchiectasis among respiratory physicians.
This study has both strengths and limitations. It provides robust data on epidemiology of bronchiectasis in Italy; they are collected from GPs and provide a real-life and population-based overview. However, the use of ICD codes and the retrospective study design are likely to underestimate the real prevalence and incidence of the disease. In addition, ICD codes analysis is not related to a reliable data collection on the underlying etiology. Finally, although radiology is needed for bronchiectasis diagnosis, we could not prove if each diagnosis was supported by chest CT scan. As a consequence, diagnosis accuracy might be limited.
In addition, the study design did not allow to investigate risk factors for bronchiectasis development, but only medical conditions associated with bronchiectasis have been reported.