Introduction Pleural infection remains common with an increasing incidence. It is associated with a high morbidity and mortality. The development of a validated clinical risk score at presentation to identify those at high risk may help formulate early management strategies.
Methods The RAPID score was constructed based on a large cohort of patients entering a multicentre UK pleural infection trial—MIST1 (n=411). Out of 32 baseline clinical characteristics recorded at trial entry, model selection was undertaken to find variables predictive of poor clinical outcome. Results were obtained by using backwards selection with a p value of 0.05. Multiple imputation was used to account for patients with missing baseline variables. The primary outcome assessed was mortality at 3 months. Total time in hospital was also assessed.
Results Age, urea, albumin, hospital acquired infection, and non-purulence were all found to be clinical predictors or poor outcome. A score was developed using these variables.
R - urea <5=0, 5–8=1, >8=2
A - age <50=0, 50–70=1, >70=2
P - purulence=0, non purulence=1
I - iatrogenic/hospital acquired infection =1 community acquired =0
D - dietary factors. Albumin >27=0 <27=1
Total RAPID score range 0–7
In order to help interpret the RAPID score, we stratified patients into low-risk, medium-risk, and high-risk groups. Patients with a RAPID score of 0–2 are considered low risk, a score of 3–4 indicates a medium risk, and a score of 5–7 indicates high risk. This scoring system was then validated using another large cohort of patients with pleural infection who had been enrolled in a UK multicentre trial –MIST2 (n=210). Abstract S61 table 1 shows the main results. Time in hospital increased with increasing RAPID score. In MIST1 patients with RAPID 0–2 had median stay 10 (7–16) days, compared to RAPID >5 who had a median stay of 18 (9–26) days. This trend was also seen in MIST2.
Conclusion The RAPID score appears to allow for risk-stratification of patients with pleural infection at presentation and could prove useful in clinical practice in guiding initial management.