The socio-economic cost of asthma, COPD and chronic bronchitis in Europe.

Introduction. Common chronic respiratory diseases place a huge economic burden on both society and individual but very few COI studies have been carried out in the general European population and have evaluated (i) both direct and indirect costs, (ii) the change over time in asthma costs, (iii) the relationship with the level of asthma severity and control, and (iv) the presence of comorbidities in chronic bronchitis (CB). Aims. This thesis is aimed at estimating (i) the differential costs of asthma, COPD and CB among adult subjects from the general population in Europe and (ii) the 10-year variation of asthma costs in adult asthmatics. Methods. Subjects participating in the ECRHS II (1998-2002) and III (2010-2013) were classified as patients with intermittent and persistent (“controlled/partlially controlled” or “uncontrolled”) asthma, COPD and CB. The monetary unit value of each cost component was calculated in Euro as the median of the national figures in 9 European countries and adjusted for the purchasing power parity. The cost components were estimated by multiplying for each patient the number of (i) times he/she resorted to healthcare services, (ii) doses of each drug consumed, (iii) lost working days and (iv) days with limited not work-related activities, by their proper monetary unit value. Multivariable analyses of the association among the individual total cost for each disease and a set of potential determinants were performed by using 2-level random-intercept negative binomial regression models (centre: level 2 unit). Cost variations in the individual total cost were estimated by using a 2-level random-intercept Laplace quantile regression model (centre: level 2 unit), adjusting for the effect of sex, age, ever smoking and low socio-economic status. Results. The mean annual cost per patient increased as the degree of disease control decreased, ranging from EUR 143 (95%CI: 94-204) and EUR 398 (95%CI: 345-457) for the subjects with an intermittent and a persistent controlled/partially controlled asthma, respectively, to EUR 5,050 (95%CI: 3,296-6,275) for those with a persistent uncontrolled disease. Among the persistent uncontrolled asthmatics, the 80% of the total cost was due to the INMCs. The lack of control of a persistent disease was about 27-fold higher compared to the cost of an intermittent asthma (IRR=26.80, 95% CI: 16.82-42.69) after adjusting for the effect of potential predictors. The mean annual cost per patient over a 10-year period (i) was stable in the “intermittent group” (from 166 to 157 EUR), (ii) decreased in the “improved group” (from 1,058 to 308 EUR), (iii) increased in the “worsened group” (from 2,137 to 4,023 EUR). After adjusting for a set of potential confounders, the patients with an improved or worsened asthma from the ECRHS II to the ECRHS III showed reduced [-145 (95%CI: -275;-15) EUR; p=0.029] and increased [185 (95%CI: 59;311) EUR; p=0.005] mean annual costs, respectively, compared to the patients with an intermittent disease status at both the examinations. The COPD sample was mainly represented by individuals with a mild/moderate disease (96%) and the mean annual cost per patient was 694 EUR (95%CI: 198-1,253). In patients with CB the mean annual cost (i) largely increased from 94 EUR (95%CI: 38-166) to 642 EUR (95%CI: 249-1,131) according to the presence of comorbidities and (ii) was more than 3-fold higher among patients with comorbidities compared with those with CB only (IRR=2.88, 95% CI: 1.10-7.55), after adjusting for the effect of the other potential predictors. Conclusions. The mean annual cost per patient (i) was impressive in persistent uncontrolled asthmatics and largely driven by the INMCs, (ii) significantly increased/decreased when the asthma status worsened/improved over 10 years, (iii) was not negligible even in patients with a mild/moderate form of COPD and (iv) was higher when comorbidities were present in patients with CB.