Thoracic Oncology & Chest Imaging Network
Interventional Procedures Section
The MIST-2 trial (Rahman, et al. N Engl J Med. 2011;365:518), the first randomized trial to show the benefit of intrapleural enzyme therapy (IET) with tissue plasminogen activator and deoxyribonuclease for the treatment of complicated pleural infection (cPI) is the foundational study for the use of IET. It was from this cohort that the first prospectively validated mortality prediction score for cPI was developed – the RAPID score (Rahman, et al. Chest. 2014;145[4]:848).
The RAPID score, comprised of Renal, Age, Purulence, Infection source, and Dietary factors (albumin) divides patients with cPI into three 3-month mortality groups: low (1.5%), medium (17.8%), and high (47.8%). The score was externally validated in the PILOT trial (Corcoran, et al. Eur Respir J. 2020;56[5]:2000130). Mortality outcomes were separately assessed in 1-, 3-, and 5-year follow-up by White, et al (Ann Am Thorac Soc. 2015;12[9]:1310) and found to bear out with an increased OR for mortality of 14.3 and 53.3 in the medium and high risk groups, respectively. Of note, there was a surgical referral rate of only 4% to16% in the study cohort, and the original study did not distinguish between IET use or surgery.
To look at RAPID in a purely surgical cohort, Stüben, et al (Sci Rep. 2023;13[1]:3206) applied the RAPID score to a cohort of patients with empyema all treated with initial surgical drainage. They found the RAPID score to be an accurate predictor of 90-day mortality and improved with the addition of diabetes and renal replacement therapy. Liou, et al (J Thorac Dis. 2023;15[3]:985) showed that patients with a low RAPID score who were taken to surgery early had improved length of stay and organ failure and mortality rates compared with those taken later.
Can the RAPID score differentiate between those who need IET alone, early surgery, or late surgery? Not yet, but several prospective studies are underway to help improve outcomes in this ancient disease. Until then, the RAPID score remains a useful risk-stratification tool for an increasingly broad population of patients with pleural infection.
Max Diddams, MD
Section Fellow-in-Training