Caprini score risk categories: what each band means

The four Caprini score risk categories

The Caprini score risk categories come from the 2005 Caprini risk assessment model, published by Joseph Caprini in Disease-a-Month as a form that adds 1, 2, 3 or 5 points for each risk factor for venous thromboembolism (VTE) present in a surgical patient. The total falls into one of four bands: low at 0 to 1 point, moderate at 2 points, high at 3 to 4 points and highest at 5 points or more. Because the factors add up, a single 5-point item such as a hip fracture in the last month or elective major lower extremity arthroplasty puts a patient in the highest band on its own, while an older patient having long surgery for cancer reaches it by adding several 2-point items. Bahl and colleagues tested these four bands in 2010 in 8,216 surgical inpatients from the National Surgical Quality Improvement Program and found that the band was significantly associated with VTE within 30 days of surgery, with an odds ratio of 1.9.

Work out a patient's band with the Caprini score calculator, which groups every item on the 2005 form by its points.

How often VTE happened in each Caprini category

VTE rates in the Caprini categories rise with the score, but the absolute numbers depend on the population and on whether patients received prophylaxis. In Bahl's 2010 validation, VTE within 30 days of surgery occurred in 0% of the low band, 0.70% of the moderate band, 0.97% of the high band and 1.94% of the highest band, and in 1.4% of all 8,216 patients. More than half of those patients, 52.1%, were in the highest band, which shows how easily surgical inpatients reach 5 points. The study also found that pregnancy or the postpartum period (odds ratio 8.3), recent sepsis (4.0), malignancy (2.3), a history of VTE (2.1) and central venous access (1.8) were each significantly associated with VTE. Some patients in the study received prophylaxis, and the authors found a significant correlation between VTE and lack of adherence to prophylaxis guidelines, so the observed rates are lower than the risk an unprotected patient would carry.

How ACCP 2012 links Caprini categories to prophylaxis

The 2012 American College of Chest Physicians (ACCP) guideline on preventing VTE in nonorthopedic surgical patients regroups the Caprini score into four categories and attaches a general approach to each. Its recommendations call a Caprini score of 0 very low risk, with an estimated VTE risk below 0.5% without prophylaxis; 1 to 2 low risk, about 1.5%; 3 to 4 moderate risk, about 3.0%; and 5 or more high risk, about 6.0%. ACCP derived those baseline estimates from the Bahl data, adjusted for the prophylaxis patients received, and applies them to general and abdominal-pelvic surgery. For very low risk it advises early ambulation and no specific pharmacological or mechanical prophylaxis. For low risk it suggests mechanical prophylaxis, preferably intermittent pneumatic compression. For moderate risk it suggests pharmacological or mechanical prophylaxis, and for high risk it recommends pharmacological prophylaxis, with mechanical prophylaxis suggested on top, in each case when bleeding risk is not high.

For patients at moderate or high VTE risk who are at high risk of major bleeding, or in whom bleeding would be especially serious, ACCP 2012 suggests mechanical prophylaxis, preferably intermittent pneumatic compression, until the bleeding risk falls and pharmacological prophylaxis can start (Grade 2C). For all risk groups it suggests against an inferior vena cava filter for primary prevention and against surveillance compression ultrasound. Note that the ACCP bands differ from the 2005 bands: a score of 1 is low in both, but 2 is moderate in the 2005 model and low in ACCP 2012, and 3 to 4 is high in 2005 but moderate in ACCP. The guideline's own narrative text describes its two lowest groups as 0–1 and 2 points, while its recommendations and risk table use 0 and 1–2. This page gives no drug names or doses; the guideline itself sets out the options.

Why the highest Caprini category is split above 5 points

The highest Caprini category covers every score from 5 upward, yet risk keeps climbing well past 5, so later studies split it into 5–6, 7–8 and above 8. Pannucci and colleagues showed this in 2011 in 1,126 plastic and reconstructive surgery patients at five US centers, all with a Caprini score of 3 or more, operated on under general anesthesia, admitted after surgery, and given no chemoprophylaxis for 60 days. Symptomatic VTE within 60 days occurred in 0.61% at 3–4 points, 1.27% at 5–6, 2.69% at 7–8 and 11.32% above 8, about one patient in nine. Patients scoring above 8 were significantly more likely to have VTE than those at 3–4 (odds ratio 20.9), 5–6 (9.9) or 7–8 (4.6), and in the two top groups VTE was not limited to the first days after surgery. ACCP 2012 cites this study as validation of the Caprini score in plastic and reconstructive surgery.

Worked examples: placing patients in a Caprini category

Three surgical patients show how the Caprini score points add up and how the same total can fall into different categories in the 2005 model and in ACCP 2012. A 30-year-old man having minor surgery, with no other risk factors, scores 1 point for the minor surgery and nothing for his age, so his total of 1 is low risk in the 2005 model and low risk in ACCP 2012. A 35-year-old woman on oral contraceptives having a laparoscopic operation expected to last more than 45 minutes scores 2 points for the laparoscopic surgery and 1 for the oral contraceptives: a total of 3, high risk in the 2005 model but moderate risk in ACCP 2012. A 68-year-old man with a BMI of 29 having major open surgery for cancer scores 2 for his age, 2 for major surgery over 45 minutes, 2 for the malignancy and 1 for the BMI, a total of 7.

The third patient sits in the 7–8 group, where Pannucci found a 2.69% VTE rate without chemoprophylaxis after plastic surgery. Enter each patient in the Caprini score calculator to see the same totals and bands.