model {
for (i in 1:N) {
Score ~ dcat(p[i,])
p[i,1] <- 1 - Q[i,1]
for (r in 2:5) {
p[i,r] <- Q[i,r-1] - Q[i,r]
}
p[i,6] <- Q[i,5]
for (r in 1:5) {
logit(Q[i,r]) <- b.apd*lAPD - c[r]
}
}
for (i in 1:5) {
dc ~ dunif(0, 20)
}
c[1] <- dc[1]
for (i in 2:5) {
c <- c[i-1] + dc
}
b.apd ~ dnorm(0, 1.0E-03)
or.apd <- exp(b.apd)
}

Data:
list(Score=c(4, 3, 1, 3, 4, 3, 2, 1, 1, 1, 1, 1, 2, 4, 4, 2, 1, 4, 1, 2, 5, 1, 4, 3, 5, 1, 1, 2, 1, 1, 3, 4, 2, 1, 1, 1, 2, 2, 4, 3, 6, 3, 1, 2, 2, 2, 1, 1, 1, 4, 6, 1, 2, 3, 4, 4, 1, 1, 4, 3, 6, 1, 6, 3, 3, 1, 1, 1, 6, 2, 1, 5, 1, 1, 4, 1, 2, 5, 1, 1, 3, 4, 2, 1, 1, 1, 2, 5, 1, 2, 2, 2, 2, 6, 1, 1, 1, 1, 1, 3, 6, 4, 3, 1, 3, 2, 1, 1, 1, 1, 1, 4, 2, 1, 4, 1, 5, 1, 4, 4, 5, 2, 1, 1, 2, 3, 4, 2, 1, 1, 2, 2, 2, 4, 3, 6, 3, 2, 2, 2, 1, 1, 1, 1, 4, 6, 1, 2, 5, 4, 1, 1, 6, 1, 6, 3, 3, 1, 1, 1, 2, 2, 1, 1, 4, 1, 2, 5, 1, 3, 2, 4, 1, 1, 2, 5, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 1, 4, 3, 6), lAPD=c(3.89182029811063, 2.07944154167984, 2.39789527279837, 3.2188758248682, 4.06044301054642, 4.4188406077966, 2.19722457733622, 2.70805020110221, -1.38629436111989, 1.09861228866811, 4.91998092582813, 6.05208916892442, 3.52636052461616, 4.97673374242057, 6.282266746896, 1.94591014905531, 1.6094379124341, 6.3578422665081, 2.99573227355399, 3.29583686600433, 0.693147180559945, -1.38629436111989, -1.38629436111989, 4.53259949315326, 6.68959926917897, -1.38629436111989, 3.52636052461616, 3.17805383034795, 2.30258509299405, 3.2188758248682, 3.04452243772342, 4.969813299576, 3.85014760171006, 3.25809653802148, 5.99645208861902, 4.35670882668959, 2.484906649788, 3.49650756146648, 5.92157841964382, 2.89037175789616, 7.55485852104068, 2.19722457733622, 2.30258509299405, 2.07944154167984, -1.38629436111989, 1.6094379124341, 3.89182029811063, 2.99573227355399, 2.19722457733622, 3.40119738166216, 3.55534806148941, 2.19722457733622, 2.70805020110221, 6.5875500148248, 2.63905732961526, 3.58351893845611, 1.94591014905531, 2.484906649788, 5.41610040220442, 3.46573590279973, 3.58351893845611, 2.94443897916644, 4.49980967033027, 2.19722457733622, 5.39362754635236, 2.56494935746154, 2.99573227355399, 2.77258872223978, -1.38629436111989, 2.484906649788, 3.89182029811063, 3.8286413964891, 2.99573227355399, 3.40119738166216, 5.48063892334199, 2.19722457733622, 5.12989871492307, 2.39789527279837, 2.70805020110221, 2.19722457733622, 3.87120101090789, 3.71357206670431, -1.38629436111989, 3.17805383034795, 2.89037175789616, 3.13549421592915, 1.09861228866811, 3.40119738166216, 2.99573227355399, 3.13549421592915, 2.83321334405622, 2.484906649788, 5.11799381241676, 4.77068462446567, 2.77258872223978, 2.56494935746154, 2.30258509299405, 2.63905732961526, 3.36729582998647, 2.70805020110221, 4.70953020131233, 3.89182029811063, 2.07944154167984, 2.39789527279837, 3.2188758248682, 2.19722457733622, 2.70805020110221, -1.38629436111989, 1.09861228866811, 4.91998092582813, 6.05208916892442, 6.282266746896, 1.94591014905531, 1.6094379124341, 6.3578422665081, 2.99573227355399, 0.693147180559945, -1.38629436111989, -1.38629436111989, 4.53259949315326, 6.68959926917897, 3.52636052461616, 3.17805383034795, 2.30258509299405, 3.2188758248682, 3.04452243772342, 4.969813299576, 3.85014760171006, 3.25809653802148, 5.99645208861902, 4.35670882668959, 2.484906649788, 3.49650756146648, 5.92157841964382, 2.89037175789616, 7.55485852104068, 2.19722457733622, 2.30258509299405, 2.07944154167984, -1.38629436111989, 1.6094379124341, 3.89182029811063, 2.99573227355399, 2.19722457733622, 3.40119738166216, 3.55534806148941, 2.19722457733622, 2.70805020110221, 4.89034912822175, 3.58351893845611, 1.94591014905531, 2.484906649788, 3.58351893845611, 2.94443897916644, 4.49980967033027, 2.19722457733622, 5.39362754635236, 2.56494935746154, 2.99573227355399, 2.77258872223978, 2.484906649788, 3.89182029811063, 2.99573227355399, 3.40119738166216, 5.48063892334199, 2.19722457733622, 5.12989871492307, 2.39789527279837, 2.19722457733622, 3.87120101090789, -1.38629436111989, 4.21950770517611, 3.17805383034795, 2.89037175789616, 1.09861228866811, 3.40119738166216, 2.99573227355399, 3.29583686600433, 3.13549421592915, 2.83321334405622, 2.484906649788, 2.77258872223978, 2.89037175789616, 2.56494935746154, 2.30258509299405, 2.63905732961526, 3.36729582998647, 1.79175946922805, 2.70805020110221, 4.70953020131233), N=190)

Inits:
list(b.apd=0, dc=c(1, 1, 1, 1, 1))

   node   mean   sd   MC error   2.5%   median   97.5%   start   sample
   b.apd   0.3749   0.08755   0.002768   0.2096   0.3723   0.5552   501   10000
   c[1]   0.7507   0.2994   0.009379   0.1869   0.7397   1.362   501   10000
   c[2]   1.716   0.3239   0.009713   1.117   1.699   2.386   501   10000
   c[3]   2.352   0.3521   0.01042   1.699   2.336   3.074   501   10000
   c[4]   3.409   0.4068   0.01104   2.65   3.396   4.252   501   10000
   c[5]   4.163   0.4639   0.01144   3.309   4.148   5.097   501   10000
   or.apd   1.46   0.1291   0.004081   1.233   1.451   1.742   501   10000