Making a pitch for the C-reactive protein/albumin ratio

By Warren R. Heymann, MD, FAAD
Feb. 12, 2025
Vol. 7, No. 6

Studying the PhanaVision jumbotron at Citizens Bank Park on a warm Friday evening in June, I realized that when analyzing baseball data, I am “old school.” In my youth, the critical measure of a pitcher’s success was the earned run average (ERA) — I could not find that statistic easily; the WHIP (walks and hits per innings pitched) was prominent on the screen. Daniel Okrent, a writer who invented rotisserie league fantasy baseball, coined the term in 1979, initially calling it innings pitched ratio. WHIP is now one of the most commonly used statistics for evaluating a pitcher’s performance. (1) A good WHIP for a pitcher is less than 1.0. (2)

As a clinician, when concerned about an inflammatory process, I will order an erythrocyte sedimentation rate (ESR), which may be elevated in many disorders, including arthritis, vasculitis, infections, inflammatory bowel disease, and certain malignancies. An ESR may also be used to monitor an existing condition. A normal ESR is 0-20 mm per hour in women and 0-12 mm per hour in men. (3,4) The ESR will not explain the source of inflammation; I find its real value in reassuring patients that their normal ESR makes active inflammation unlikely.

The purpose of this commentary is to introduce a new measure that is increasingly appearing in the medical literature, including dermatology — the C-reactive protein/albumin ratio (CAR) (normal range C-reactive protein, CRP, 0-10 mg/L); normal albumin range 3.5-5.5 g/dl). CRP is an acute-phase protein that correlates with the degree of inflammation and that serum albumin is a negative acute-phase protein with the degree of hypoalbuminemia correlating with the intensity of the inflammatory response. (5)

Kim et al. state, “It is generally believed that the worsening of a chronic illness with an ongoing infection represents a major determinant of an adverse long-term outcome in severe sepsis and septic shock patients. Thus, rather than an analysis of each single factor on its own, CRP and albumin were combined. The combination of these markers, enabled inflammatory and nutritional factors to be merged, both of which strongly influence prognosis.” (6) Multiple studies were published demonstrating that CAR was an independent predictor of mortality in patients with severe sepsis or septic shock. An example is the study by Ranzani et al. evaluating 229 (67%) and 111 (33%) patients with severe sepsis and septic shock, respectively. During the 90 days of follow-up, 73 (22%) patients died. The CAR at admission and discharge were associated with a poor outcome and showed greater accuracy than CRP alone. (5) In a retrospective cohort study of 875 ICU patients with a 28 day mortality rate of 28%, a higher CAR was associated with increased mortality in critically ill patients. (7)

There is a burgeoning medical literature touting the utility of CAR for diverse disorders because of its simplicity and cost effectiveness. As of June 30, 2024, a PubMed search of CAR listed 11,959 references; a very partial list of diseases reporting CAR as an assessment tool included acute pancreatitis (8), Behçet’s disease (9), Fournier gangrene (10), Crohn disease (11), and colorectal cancer (12).

CAR is increasingly studied in dermatology. An elevated CAR has been demonstrated in determining the risk recurrent lower extremity cellulitis (13), and correlate with the severity of alopecia areata (14), and acne vulgaris (15). Taş-Aygar et al., in a study of 60 mycosis fungoides (MF) patients, found that the CAR was significantly higher in patients with MF than the control group, although there was no association between the CAR and disease progression. (16)

There are infinite ways in which dermatologists could utilize CAR. The following abstract by Balta and Balta (17) exemplifies how the CAR could assist dermatologists in assessing which psoriatic patients should be referred to a cardiologist.

Psoriasis vulgaris is associated with an increased risk of atherosclerosis. The C-Reactive Protein-to-Albumin Ratio (CAR) has received increasing attention as an independent prognostic factor for inflammatory diseases. The carotid intima-media thickness (cIMT) is a predictor of atherosclerosis. We assessed the correlation between CAR and cIMT in patients with psoriasis vulgaris. We enrolled 147 participants (72 with psoriasis vulgaris and 75 controls). Disease severity was assessed using the "Psoriasis Area Severity İndex (PASI)." Patient and control groups were similar with regard to gender, age, and body mass index (BMI). cIMT was measured in both the left and the right common carotid arteries. CAR values were higher in patients with psoriasis compared with controls (0.93 (0.06-4.32) vs 0.51 (0.10-2.99), p < .001). The patients with psoriasis had a significantly greater cIMT compared with control subjects. (0.53 (0.42-0.65) vs 0.50 (0.41-0.65) mm, p = .03). PASI scores were positively correlated with CAR values (r = 0.532, p < .001). A positive correlation between cIMT and CAR was found in patients with psoriasis vulgaris (r = 0.463, p < .001). CAR is an easily derived reproducible marker that could prove useful for assessing the inflammatory status of patients with psoriasis in clinical practice. CAR may also prove useful as a cardiovascular risk marker in these patients.

In conclusion, although you will not see CAR on the PhanaVision jumbotron, you will see it pitched on your computer screen as a tool to assess inflammation in various diseases.

Point to Remember: The C-reactive protein/albumin ratio (CAR) is a new measure for assessing disease severity and prognosis in inflammatory and neoplastic disorders. Dermatologists will increasingly encounter the CAR in daily practice.

Our expert’s viewpoint

Polyne Nafula, BSc
Department of clinical medicine
Jomo Kenyatta University of Agriculture and Technology
Nairobi, Kenya

The C-reactive protein/albumin ratio (CAR) has emerged as a promising, noninvasive biomarker for assessing the severity of acute pancreatitis. As one of the researchers involved in exploring its utility, I can affirm that the CAR provides clinicians with a cost-effective and efficient tool that integrates both inflammatory and nutritional status into one simple measurement. Its value lies in its ability to offer timely insights without requiring invasive procedures, thereby improving patient outcomes through earlier intervention. The continued evaluation of CAR in different clinical settings may further broaden its applicability, potentially making it a mainstay in acute care diagnostics.

1. https://www.mlb.com/glossary/standard-stats/walks-and-hits-per-inning-pitched

2. https://baseball360.com/en-us/blogs/news/what-is-whip-in-baseball

3. https://medlineplus.gov/lab-tests/erythrocyte-sedimentation-rate-esr/

4. https://www.hopkinslupus.org/lupus-tests/clinical-tests/erythrocyte-sedimentation-rate-esr/

5. Ranzani OT, Zampieri FG, Forte DN, Azevedo LC, Park M. C-reactive protein/albumin ratio predicts 90-day mortality of septic patients. PLoS One. 2013;8(3):e59321. doi: 10.1371/journal.pone.0059321. Epub 2013 Mar 12. PMID: 23555017; PMCID: PMC3595283.

6. Kim MH, Ahn JY, Song JE, Choi H, Ann HW, Kim JK, Kim JH, Jeon YD, Kim SB, Jeong SJ, Ku NS, Han SH, Song YG, Choi JY, Kim YS, Kim JM. The C-Reactive Protein/Albumin Ratio as an Independent Predictor of Mortality in Patients with Severe Sepsis or Septic Shock Treated with Early Goal-Directed Therapy. PLoS One. 2015 Jul 9;10(7):e0132109. doi: 10.1371/journal.pone.0132109. Erratum in: PLoS One. 2019 Nov 18;14(11):e0225620. doi: 10.1371/journal.pone.0225620. PMID: 26158725; PMCID: PMC4497596.

7. Park JE, Chung KS, Song JH, Kim SY, Kim EY, Jung JY, Kang YA, Park MS, Kim YS, Chang J, Leem AY. The C-Reactive Protein/Albumin Ratio as a Predictor of Mortality in Critically Ill Patients. J Clin Med. 2018 Oct 8;7(10):333. doi: 10.3390/jcm7100333. PMID: 30297655; PMCID: PMC6210319.

8. Ghaffar S, Shahnoor S, Khan AM, Asif A, Fida M, Oduoye MO, Nafula WP. CRP Albumin Ratio: A novel noninvasive and cost-effective method for assessing the severity of acute pancreatitis. Health Sci Rep. 2024 Jan 8;7(1):e1801. doi: 10.1002/hsr2.1801. PMID: 38196567; PMCID: PMC10774490.

9. Kim M, Park YG, Park YH. C-reactive protein/albumin ratio as an indicator of disease activity in Behçet's disease and human leukocyte antigen-B27-associated uveitis. Graefes Arch Clin Exp Ophthalmol. 2021 Jul;259(7):1985-1992. doi: 10.1007/s00417-021-05207-y. Epub 2021 Apr 30. PMID: 33929591.

10. Özgül H, Uzmay Y. The role of C-reactive protein albumin ratio for predicting mortality in patients with Fournier's gangrene. Ulus Travma Acil Cerrahi Derg. 2023 Oct 27;29(11):1242-1247. doi: 10.14744/tjtes.2023.08903. PMID: 37889021; PMCID: PMC10771234.

11. Qin G, Tu J, Liu L, Luo L, Wu J, Tao L, Zhang C, Geng X, Chen X, Ai X, Shen B, Pan W. Serum Albumin and C-Reactive Protein/Albumin Ratio Are Useful Biomarkers of Crohn's Disease Activity. Med Sci Monit. 2016 Nov 16;22:4393-4400. doi: 10.12659/msm.897460. PMID: 27848931.

12. Liao CK, Yu YL, Lin YC, Hsu YJ, Chern YJ, Chiang JM, You JF. Prognostic value of the C-reactive protein to albumin ratio in colorectal cancer: an updated systematic review and meta-analysis. World J Surg Oncol. 2021 May 1;19(1):139. doi: 10.1186/s12957-021-02253-y. PMID: 33933070; PMCID: PMC8088626.

13. Yürük Atasoy P, Gürbüz E, Alkan S. Prognostic Significance of NLR, LMR, PLR, and CRP-Albumin Ratio in Lower Extremity Cellulitis: A Hospitalization and Recurrence Analysis. Int J Low Extrem Wounds. 2024 Feb 28:15347346241235873. doi: 10.1177/15347346241235873. Epub ahead of print. PMID: 38414389.

14. Kalaycı BN, Balta İ. Evaluation of the serum C-reactive protein-albumin ratio and its relationship with disease severity IN alopecia areata: A prospective case-control study. J Cosmet Dermatol. 2022 Dec;21(12):7194-7199. doi: 10.1111/jocd.15460. Epub 2022 Oct 31. PMID: 36225083.

15. Pala E, Bayraktar M. Relationships Between Disease Severity and the C-reactive Protein/Albumin Ratio and Various Hematological Parameters in Patients With Acne Vulgaris. Cureus. 2023 Aug 25;15(8):e44089. doi: 10.7759/cureus.44089. PMID: 37750127; PMCID: PMC10518065.

16. Taş-Aygar G, Ataş H, Gönül M, Kartal SP. Importance of the C-Reactive Protein to Albumin Ratio in the Diagnosis and Prognosis of Mycosis Fungoides. Dermatol Pract Concept. 2024 Apr 1;14(2):e2024097. doi: 10.5826/dpc.1402a97. PMID: 38810087; PMCID: PMC11135996.

17. Balta I, Balta S. The Relation Between C-Reactive Protein-Albumin Ratio and Carotid Intima-Media Thickness in Psoriasis. Angiology. 2022 Sep;73(8):772-780. doi: 10.1177/00033197211072599. Epub 2022 Feb 21. PMID: 35189713.

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