Package: TwoDcDAPSA 0.1.1

TwoDcDAPSA: Calculate TwoDcDAPSA: PROs-Joint Contrast (PJC) and Swollen–Tender Joints Contrast (STC) Scores and Quartiles

Provides a calculator for the two-dimensional clinical Disease Activity index for Psoriatic Arthritis (TwoDcDAPSA), a principal component-derived measure that complements the conventional clinical DAPSA score. TwoDcDAPSA captures residual variation in patient-reported outcomes (pain and patient global assessment) and joint counts (swollen and tender) after adjusting for standardized cDAPSA using natural spline coefficients derived from published models. Residuals are standardized and combined with fixed principal component loadings to yield two continuous component scores: the PROs-Joint Contrast (PJC) and the Swollen–Tender joints Contrast (STC), along with quartile-based groupings (including optional combined quartile groupings). The package applies pre-specified coefficients, residual standardization, and loadings to new datasets but does not estimate spline models or principal components itself.

Authors:Ning Meng [aut, cre], Ji Soo Kim [aut], Ana-Maria Orbai [aut], Scott L. Zeger [aut]