In medical terminology, LACE is an acronym that stands for a hospital readmission risk score. Each letter represents one factor: Length of stay, Acuity of admission, Comorbidities, and Emergency department visits. Hospitals use this tool to predict how likely a patient is to be readmitted or die within 30 days of discharge. The term “lace” also appears in dermatology to describe certain net-like or lace-like skin patterns, though the LACE index is by far the most common medical use.
The LACE Index Explained
The LACE index is a scoring system that combines four pieces of information about a hospital stay into a single number between 0 and 19. Higher scores mean a greater chance of being readmitted soon after going home. Here’s what each letter measures:
- L (Length of stay): How many days you spent in the hospital. A stay under one day scores 0 points, while 14 days or more scores 7 points.
- A (Acuity of admission): Whether you were admitted through the emergency department as an urgent case (3 points) or came in for a planned procedure (0 points).
- C (Comorbidities): How many other chronic health conditions you have, scored using a standardized comorbidity scale. No other conditions scores 0, while four or more scores 5 points.
- E (Emergency department visits): How many times you visited the ER in the six months before this hospital stay. No visits scores 0, while four or more visits scores 4 points.
A patient with a short planned admission and no other health issues might score 0 or 1. Someone admitted urgently after a long stay, with multiple chronic conditions and recent ER visits, could score close to the maximum of 19.
How Hospitals Use LACE Scores
Hospitals calculate LACE scores to identify patients who need extra support after discharge. A higher score signals that the care team should consider closer follow-up: scheduling an early post-discharge appointment, arranging home health visits, or making sure medication instructions are clearly understood. The goal is to prevent avoidable readmissions, which are costly for both patients and healthcare systems.
A large retrospective study found that the LACE index had an area under the curve of 0.77, a statistical measure of how well a test distinguishes between two outcomes (in this case, readmitted vs. not readmitted). A score of 1.0 would be perfect prediction, and 0.5 would be no better than flipping a coin. At 0.77, the LACE index is a reasonably strong predictor, though not perfect on its own.
If you see a LACE score on your discharge paperwork, it’s simply a flag that tells the hospital how much follow-up care to prioritize. It doesn’t diagnose anything or change your treatment plan directly.
The LACE-Plus Version
Some hospitals use an expanded version called LACE+, which adds several more variables to improve accuracy. On top of the original four factors, LACE+ incorporates patient age and sex, whether the hospital is a teaching institution, the specific diagnoses and procedures from the admission, and the number of both elective and urgent hospital admissions in the year before the current stay. This broader picture tends to sharpen the prediction, though it requires more data to calculate.
Lace-Like Patterns in Dermatology
Outside the LACE index, doctors sometimes use the word “lace” to describe the visual appearance of certain skin conditions. Two examples come up frequently.
Livedo reticularis is a condition where the skin develops a net-like pattern of reddish-blue discoloration, sometimes described as looking like lace or marble. It happens when blood vessels near the skin surface spasm or blood flow slows in a way that creates a mottled, web-shaped pattern with clear borders. In many people, livedo reticularis is harmless and triggered by cold temperatures. In others, it can signal an underlying condition affecting blood flow or clotting.
Lichen planus, a condition that causes purplish, flat-topped bumps on the skin, is another place where “lace” appears. The bumps often have fine white or gray lines across their surface called Wickham striae, first described in 1895. Inside the mouth, these lines form a lacy network most commonly seen on the inner cheeks. Dermatologists use a handheld magnifying device called a dermatoscope to confirm the characteristic white, net-like pattern of these striae, which helps distinguish lichen planus from other rashes.