cliot (version 1.0.0)

leiden_arthritis_prediction: Leiden Clinical Prediction Rule for Undifferentiated Arthritis

Description

Calculates the Leiden Prediction Rule score to estimate the likelihood that a patient with recent-onset undifferentiated arthritis will progress to Rheumatoid Arthritis (RA) within one year. The score uses clinical, serological, and demographic factors to stratify risk.

Usage

leiden_arthritis_prediction(age_years, sex, distribution_small_hands_feet,
                            distribution_symmetric, morning_stiffness_severity,
                            tender_joint_count, swollen_joint_count, crp_mg_dl,
                            rf_positive, acpa_positive)

Value

A list containing:

Leiden_Score

The calculated risk score (Range 0-14).

Risk_Category

Classification (Low, Intermediate, High).

Progression_Probability_1yr

Estimated probability of progression to RA.

Arguments

age_years

Numeric. Patient age in years. (0.02 points per year).

sex

String. Patient sex ("Male" or "Female"). (Female adds 1 point).

distribution_small_hands_feet

Numeric (0 or 1). Involvement of small joints of hands or feet? (1 = Yes, +0.5 pts).

distribution_symmetric

Numeric (0 or 1). Symmetric distribution of arthritis? (1 = Yes, +0.5 pts).

morning_stiffness_severity

Numeric (0 or 1). Morning stiffness >= 1 hour? (or score on VAS >= 26mm). (1 = Yes, +1 pt).

tender_joint_count

Numeric. Number of tender joints (0-68). 1-3 joints: +0.5 pts. 4-10 joints: +1 pt. >=11 joints: +1.5 pts. Note: This logic is simplified in many calculators; original paper bins joint counts: 1-3 (+0.5), 4-10 (+1), >10 (+1.5).

swollen_joint_count

Numeric. Number of swollen joints (0-66). 1-3 joints: +0.5 pts. 4-10 joints: +1 pt. >=11 joints: +1.5 pts.

crp_mg_dl

Numeric. C-Reactive Protein level. (>= 5 mg/L or 0.5 mg/dL adds 1.5 pts. Note input unit here is mg/dL?). *Correction*: Standard input is typically mg/L or mg/dL. Common cutoff is CRP >= 5 mg/L (which is 0.5 mg/dL). Assuming standard "elevated" check.

rf_positive

Numeric (0 or 1). Rheumatoid Factor positive? (1 = Yes, +1 pt).

acpa_positive

Numeric (0 or 1). Anti-Citrullinated Protein Antibody (ACPA/Anti-CCP) positive? (1 = Yes, +2 pts).

References

van der Helm-van Mil AH, le Cessie S, van Dongen H, et al. A prediction rule for disease outcome in patients with recent-onset undifferentiated arthritis: how to guide individual treatment decisions. Arthritis Rheum. 2007;56(2):433-440. doi:10.1002/art.22380

Examples

# Example 1: High Risk
# 50yo Female (+1+1), Small joints (+0.5), Sym (+0.5), Stiffness (+1),
# 5 tender (+1), 5 swollen (+1), CRP high (+1.5), RF (+1), ACPA (+2)
# Score approx 10.5
leiden_arthritis_prediction(50, "female", 1, 1, 1, 5, 5, 10, 1, 1)

# Example 2: Low Risk
# 40yo Male, Large joint (0), Asym (0), No stiff (0), 1 tender (0.5), 1 swollen (0.5), Normal labs
# Score = 0.8 + 0 + 0 + 0 + 0 + 0.5 + 0.5 + 0 = 1.8
leiden_arthritis_prediction(40, "male", 0, 0, 0, 1, 1, 0, 0, 0)