The AUC of CURB-65, APACHE II and SOFA was 0.78, 0.76 and 0.66 respectively for the prediction of ICU mortality (p<0. CURB 65 showed the best results (Figure)
The logistic regression model identified 4 variables associated with inpatient mortality (Table-2).
The initial assessment of severity on admission would enable physicians to triage patients to suitable level of care and help them to better communicate with family and caretakers regarding predictable outcome. The present study demonstrates effectiveness of CURB-65 and APACHE II in predicting probability of in-hospital mortality in AECOPD patients. CURB-65 is a simple bed-side scoring system based on simple variables like confusion, serum urea, respiratory rate, blood pressure and age. The system already has been successfully validated in community-acquired pneumonia (CAP) to assess severity7
and prediction of mortality. Chang et al. conducted a prospective study on patients hospitalised over a period of one year with AECOPD and found CURB-65 to be useful in stratifying patients into different management groups and also demonstrated statistically significant results for
in-hospital mortality.7 Another study conducted in the United States10 demonstrated ROC of 0.76 (95% CI: 0.75- 0.77) for CURB-65, that is consistent with our results.
Another advantage CURB-65 offers, when compared with other scores, even with APACHE, is that it utilises simple, easily available variables. Course of the disease can be confidently predicted in the first few hours of admission when comprehensive investigation results are still pending, and help in allocating the patient to the suitable site and level of care without any delay which can affect the outcome. SOFA is a simple objective scoring tool to predict morbidity and to some extent mortality based on parameters of six organ systems, namely respiratory, cardiovascular, neurological and renal systems along with coagulation and liver function 11,12
Effectiveness of SOFA is well established in medical ICU13
but its role in AECOPD has not been assessed comprehensively. Although SOFA exhibited statistically significant differences in scoresamong survivors and non survivors in the present study, its discriminatory power as predictor of in-patient mortality was shown to be much less when compared to the other two scoring systems. Recently, a study reported SOFA to be a good predictor of prognosis in elderly AECOPD patients with MODS14
in China but these results cannot
be compared to our results because MODS was part of the exclusion criteria in the present study. Patients with pneumonia, pneumothorax and other comorbidities were excluded from the study because patients with concomitant conditions respond differently to treatment and have higher mortality rates compared to patients with only AECOPD.1,15
The current study also identified two individual variables with statistical significance in predicting in-hospital mortality, namely oxygen saturation and Partial pressure of oxygen (PaO2). These results are consistent with prior studies.5,16,17
On the other hand, Age, low potential of
low mean arterial pressure (MAP), haematocrit and high blood urea nitrogen (BUN) levels5
at admission were identified to be associated with high mortality previously, but the current study did not find any significant association. A study18
in India also found no relation between these factors and mortality. Overall mortality rate in the present study was higher compared to those reported from the Western world (1.8 to 20.4%),1 but was similar to regional data of 25%.18 Wide variation in mortality rates between hospitals is not easy to explain on the grounds of adverse predictors alone, and suggest the presence of some unidentified factors. Possible explanation of high mortality in the present study is severe baseline disease supported by overall high proportion of type 2 RF in the study population and short median LOS among the non-survivors. Patients with type 2 RF who succumbed to the disease had mean CURB-65 score of 4, putting them into the 'very severe' category. Other possible reasons contributing to the high mortality could be ongoing smoking and biomass fuel exposure, non- compliance of the advised treatment and unavailability of medicines due to economic reasons and
possible late presentation to hospital. Though these factors were observed during data collection, they were not a formal part of the proforma used. Further studies are
needed to address these possibilities to improve the mortality rate. There are a few limitations of this study. Firstly, it is a retrospective analysis with a comparatively small sample size, thus serial assessment of patients' severity scores was not possible. Also, long-term mortality cannot be assessed due to the lack of follow-up record. Secondly, despite the fact that the chosen centre is one of the biggest
tertiary care centres of the country, results cannot be applied to the general population.
Compared to CURB-65 and APACHE II, SOFA scoring system did not seem to be as effective in predicting mortality. Serial assessment of severity scores in admitted patients followed by outpatient follow-up to assess long-term morbidity and mortality is required for further validation of CURB-65.
The abstract was presented at the ERS International Congress in Amsterdam on September 27, 2015, as Poster presentation.
Conflict of Interest:
Source of Funding:
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