Defining severity of disease and prognosis

In contrast with other respiratory diseases like COPD, pulmonary fibrosis and pneumonia, which have well established disease severity scores,.[69-71] assessment of disease severity is relatively new concept in bronchiectasis. A combination of clinical, radiological and microbiological features can be used to assess severity and members of EMBARC recently described a scoring system which has been validated in 1310 patients across 5 European bronchiectasis centres.  The bronchiectasis severity index was found to give excellent predictions of mortality and hospital admissions and was also predictive of exacerbations and quality of life giving a broad assessment of disease severity.[16]

CALCULATION OF FINAL SCORE:

0-4 points: 1 year outcome 0-2.8% mortality, 0-3.4% hospitalisation rate

                  4 year outcome 0-5.3% mortality, 0-9.2% hospitalisation rate

5-8 points: 1 year outcomes 0.9-4.8% mortality rate, 1-7.2% hospitalisation rate

                  4 year outcomes 4-11.3% mortality rate, 9.9-19.4% hospitalisation rate

9+ points:  1 year outcome 7.6-10.5% mortality rate, 16.7-52.6% hospitalisation rate

                  4 year outcomes 9.9-29.2% mortality rate, 41.2-80.4% hospitalisation rate

Table 3. Calculation of the bronchiectasis severity index. Abbreviations- BMI= body mass index, FEV1= forced expiratory volume in 1 second, MRC= Medical Research Council. Estimated outcomes are those observed across 5 European cohorts in the original derivation and validation study (16).

 An automated calculator for the BSI is available at www.bronchiectasisseverity.com. Identification of patients at high risk of complications may be very valuable to guide clinical decision making, such as the frequency and intensity of follow-up and the use of chronic antibiotic therapy.

Independently, a multicentre Spanish study identified similar predictors of mortality. This group derived an alternative scoring system- The FACED score (F, cut-off 50%, maximum value 2 points); age (A, cut-off 70 years, maximum value 2 points); presence of chronic colonisation by Pseudomonas aeruginosa (C, dichotomic, maximum value 1 point); radiological extension (E, number of lobes affected, cut-off two lobes, maximum value 1 point); and dyspnoea (D, cut-off grade II on the Medical Research Council scale, maximum value 1 point). The score showed excellent performance in an internal validation study to predict mortality.[72] It has so far not had independent validation or been used to predict hospital admissions or end-points other than mortality.

 In series from tertiary referral centres, mortality in bronchiectasis patients is largely attributed to `respiratory’ failure and respiratory infections.[33]  The most detailed assessment of prognosis performed to date was from the Royal Brompton Hospital cohort- Loebinger et al studied 91 patients with bronchiectasis enrolled in 1994 for a validation of the SGRQ score. Over 14 years follow-up 29.7% of patients had died, more than double the expected mortality based on UK life expectancy data. The major risk factors for mortality were P.aeruginosa colonisation, male gender, Residual volume/Total Lung capacity ratio (TLC), TLC itself and K_co. In addition, the baseline score in the activities domain of the SGRQ was also independently associated with mortality. [73] Again, in this cohort and several recent cohorts, mortality from bronchiectasis was primarily due to respiratory failure and respiratory infections.[17,20,73]

 In selected patients with bronchiectasis, lung function will deteriorate over time. Martinez-Garcia reported an average decline of FEV₁ of approximately 50ml/year.[15] In contrast, a decline of ~123ml/year was seen in patients with chronic pseudomonas aeruginosa colonisation.[15] Frequent exacerbations appear to be an important predictor of lung function decline, emphasising the importance of exacerbation prevention in management.