title: The BODECOST Index (BCI): a composite index for assessing the impact of COPD in real life.
abstract: BACKGROUND
  Chronic Obstructive Pulmonary Disease (COPD) is a progressive condition which is characterized by a dramatic socio-economic impact. Several indices were extensively investigated in order to asses the mortality risk in COPD, but the utilization of health care resources was never included in calculations. The aim of this study was to assess the predictive value of annual cost of care on COPD mortality at three years, and to develop a comprehensive index for easy calculation of mortality risk in real life.
  
  
  METHODS
  COPD patients were anonymously and automatically selected from the local institutional Data Base. Selection criteria were: COPD diagnosis; both genders; age ≥ 40 years; availability of at least one complete clinical record/year, including history; clinical signs; complete lung function, therapeutic strategy, health BODE index; Charlson Comorbidity Index, and outcomes, collected at the first visit, and over the following 3-years. At the first visit, the health annual cost of care was calculated in each patient for the previous 12 months, and the survival rate was also measured over the following 3 years. The hospitalization and the exacerbation rate were implemented to the BODE index and the novel index thus obtained was called BODECOST index (BCI), ranging from 0 to 10 points. The mean cost for each BCI step was calculated and then compared to the corresponding patients' survival duration. Parametrical, non parametrical tests, and linear regression were used; p < 0.05 was accepted as the lower limit of significance.
  
  
  RESULTS
  At the first visit, the selected 275 patients were well matched for all variables by gender. The overall mortality over the 3 year survey was 40.4 % (n = 111/275). When compared to that of BODE index (r = 0.22), the total annual cost of care and the number of exacerbations showed the highest regression value vs the survival time (r = 0.58 and r = 0.44, respectively). BCI score proved strictly proportional to both the cost of care and the survival time in our sample of COPD patients.
  
  
  CONCLUSIONS
  BCI takes origin from the implementation of the BODE index with the two main components of the annual cost of care, such as the number of hospitalizations and of exacerbations occurring yearly in COPD patients, and their corresponding economic impact. In other words, higher the BCI score, shorter the survival and higher the cost, these trends being strictly linked.
  
  
  CONCLUSIONS
  BCI is a novel composite index which helps in predicting the impact of COPD at 3 years in real life, both in terms of patients' survival and of COPD economic burden.
authors.affiliation: National Centre for Respiratory Pharmacoeconomics and Pharmacoepidemiology, CESFAR, Verona, Italy.
authors.forename: Roberto W
authors.initials: RW
authors.lastname: Dal Negro
authors.affiliation: Brigham and Women's Hospital and Harvard Medical School, Boston, MA USA.
authors.forename: Bartolome R
authors.initials: BR
authors.lastname: Celli
keywords: BODE index; BODECOST index; COPD; COPD impact; Cost-of-illness; Mortality prediction