You are moonlighting in your busy local community emergency department one afternoon when you encounter Mrs. P, a 67-year-old patient who was sent in from her nursing home with concern for pneumonia. She reports three days of a productive cough, fever to 38.4 °C, and mild shortness of breath with exertion. She denies chest pain, vomiting, or diarrhea. She has a history of end-stage renal disease, for which she has been on hemodialysis three days a week for the last five years. In addition, she has a history of hypertension and non-insulin dependent diabetes. Her last hospital admission was for leg cellulitis after minor trauma, but that was over a year ago.
The patient’s vital signs on arrival are as follows:
BP 145/95 HR 102 Temp 38.1 O2 sat 91% on room air RR 21
She is nontoxic appearing, mildly tachypneic, and oriented X 4. She is mildly
tachycardic with no murmurs, rubs, or gallops. Lung auscultation reveals rhonchi
in the right lower lung fields. Lab work reveals a WBC of 16K, a lactate of 1.6,
normal electrolytes, and normal cardiac enzymes. CXR reveals a dense
consolidation in the right lower lobe consistent with pneumonia.
You diagnose the patient with pneumonia, order ceftriaxone and azithromycin,
and admit her to the hospital given her medical history and new oxygen
requirement. When you speak to the hospitalist, she suggests you broaden your
antibiotic coverage to include MRSA and anti-pseudomonal coverage, as the
patient qualifies for healthcare associated pneumonia (HCAP) given her nursing
home status and dialysis dependence. You order vancomycin, azithromycin, and
cefepime, but wonder if this is overkill. You remember hearing that the Infectious
Disease Society of America (IDSA) had scrapped HCAP as a clinical diagnosis
and recall hearing about something called the Drug Resistance in Pneumonia
(DRIP) score, and wonder if this could be used to tailor your antibiotic selection
more appropriately. At the end of your shift, you go online and begin your
Population: Adults patients presenting to the ED with community-onset pneumonia
Intervention: Use of the DRIP score to risk stratify patients
Comparison: HCAP criteria or clinical gestalt
Outcome: Diagnostic accuracy for presence of drug-resistant organisms (specifically MRSA and Pseudomonas aeruginosa); impact on drug prescribing habits, mortality, readmission, need for retreatment of pneumonia.
PubMED was searched using the terms DRIP score OR “drug resistance in pneumonia score” with a limit to the previous 5 years (https://tinyurl.com/y32ve7fd). This resulted in 198 citations, from which the four most relevant articles were chosen.
Article 1: Webb BJ, Dascomb K, Stenehjem E, et al. Derivation and Multicenter Validation of the Drug Resistance in Pneumonia Clinical Prediction Score. Antimicrob Agents Chemother. 2016 Apr 22;60(5):2652-63
Article 2: Webb BJ, Sorensen J, Mecham I, Buckel W. Ooi L. Jephson A, Dean NC. antibiotic Use and Outcomes After Implementation of the drug Resistance in Pneumonia Score in Ed Patients With Community-Onset Pneumonia. Chest. 2019 May 8. pii:S0012-3692(19)31012-8.
Article 4: Farkas A, Sassine J, Mathew JP, Stavropoulos c, Stern R, Mckinley G. Outcomes associated with the use of a revised risk assessment strategy to predict antibiotic resistance in community-onset pneumonia: a stewardship perspective J Antimicrob Chemother. 2018 Sep 1;73(9):2555-2588.
Since the introduction of the concept of healthcare associated pneumonia
(HCAP), clinicians have wrestled with the use of broad-spectrum antibiotics to
treat potentially drug-resistant organisms in patients with community-onset
pneumonia with exposure to the healthcare system. After previously embracing
HCAP terminology and criteria, the Infectious Disease Societies of America
(IDSA) has recently eliminated this diagnosis given its poor sensitivity and
specify for drug-resistant organisms. Still, patients with exposure to the
healthcare system are known to be at risk for drug-resistant pathogens (DRPs),
particularly methicillin-resistant Staph aureus (MRSA) and Pseudomonas
aeruginosa, and a system to identify patients with these organisms would be
In an attempt to fill the void, Webb et al attempted in 2016 to derive and validate
a clinical decision rule to identify patients at high risk of said DRPs. The resulting
Drug Resistance in Pneumonia (DRIP) score is composed of major criteria that
confer 2 points each and minor criteria that confer 1 point reach. If the resulting
score was 4 or greater, the score was considered positive. This rule performed
moderately well in both the derivation cohort (LR+ of 8.44 and LR- of 0.26) and
the validation cohort (LR+ of 4.26 and LR- of 0.23), and outperformed the HCAP
criteria in both groups.
These same authors (Webb 2019) then attempted to evaluate the clinical impact
of this score by replacing their HCAP-based electronic support tool with one that
was DRIP-score based. This before-and-after study comprised 2169 total
patients and found a significant reduction in the use of broad-spectrum antibiotics
following implementation of the DRIP-score based tool (absolute reduction 7.2%,
95% CI 3.1% to 11.2%) with no difference in mortality, length of stay, or cost.
Interestingly, one-third of patients in the DRIP group received broad-spectrum
antibiotics despite a 2.8% rate of DRPs, suggesting there is much room for
improvement and further reduction in unnecessary antibiotic administration.
Further attempts to evaluate the efficacy of the DRIP score have provided mixed
results. Farkas et al found that days of MRSA and anti-pseudomonas coverage
was reduced following introduction of the DRIP score, but this effect was poorly
quantified. Additionally, the method by which the DRIP score was disseminated
and utilized was not described, making it impossible to reproduce these results.
In a letter to the editor, Babbel et al describe the theoretical effect of the DRIP
score and HCAP criteria at the Salt Lake City VA Medical Center. Based purely
on clinician gestalt, they report an overall 16% use of “broad-spectrum
antibiotics,” though this was defined only by the use of anti-pseudomonas
antibiotics and did not consider coverage for MRSA. Use of the DRIP score
would have resulted in a 49% increase in use of anti-pseudomonas antibiotics
while use of the HCAP criteria would have resulted a nearly 300% increase.
While the DRIP score certainly seems to outperform HCAP criteria in terms of reducing the need fro broad-spectrum antibiotics in community-onset pneumonia, its utility remains somewhat controversial. When compared to gestalt alone, it seems to have the potential to increase antibiotic usage, although this data was limited to a single letter to the editor with very little methodological information provided. This concept is somewhat supported by the low overall incidence of DRPs in other studies, suggesting that there is significant room to further reduce the use of broad-spectrum antibotics in patients admitted to the hospital with pneumonia. Further research is needed to validate this novel clinical decision rules in disparate patient populations, and perhaps further refine the rule to increase its specificity and further decrease unnecessary antibiotic administration.