msm (version 0.5.2)

psor: Psoriatic arthritis data

Description

A series of observations of grades of psoriatic arthritis, as indicated by numbers of damaged joints.

Usage

data(psor)

format

A data frame containing 806 observations, representing visits to a psoriatic arthritis (PsA) clinic from 305 patients. The rows are grouped by patient number and ordered by examination time. Each row represents an examination and contains additional covariates. rll{ ptnum (numeric) Patient identification number months (numeric) Examination time in months state (numeric) Clinical state of PsA. Patients in states 1, 2, 3 and 4 have 0, 1 to 4, 5 to 9 and 10 or more damaged joints, respectively. hieffusn (numeric) Presence of five or more effusions ollwsdrt (character) Erythrocyte sedimentation rate of less than 15 mm/h }

References

Gladman, D. D. and Farewell, V.T. (1999) Progression in psoriatic arthritis: role of time-varying clinical indicators. J. Rheumatol. 26(11):2409-13

Examples

## Four-state progression-only model with high effusion and low
## sedimentation rate as covariates on the progression rates.  High
## effusion is assumed to have the same effect on the 1-2, 2-3, and 3-4
## progression rates, while low sedimentation rate has the same effect
## on the 1-2 and 2-3 intensities, but a different effect on the 3-4. 

data(psor)
psor.q <- rbind(c(0,0.1,0,0),c(0,0,0.1,0),c(0,0,0,0.1),c(0,0,0,0))
psor.msm <- msm(state ~ months, subject=ptnum, data=psor, 
                qmatrix = psor.q, covariates = ~ollwsdrt+hieffusn,
                constraint = list(hieffusn=c(1,1,1),ollwsdrt=c(1,1,2)),
                fixedpars=FALSE, control = list(REPORT=1,trace=2), method="BFGS")
qmatrix.msm(psor.msm)
sojourn.msm(psor.msm)
hazard.msm(psor.msm)