Clustering patients on the basis of their individual course of low back pain over a six month period

Table 2 Spline regression parameters of the final 4 clusters

	Cluster 1, n = 43, mean	Cluster 2, n = 23, mean	Cluster 3, n = 72, mean	Cluster 4, n = 27, mean
Intercept, First regression	1.45	9.44	5.76	5.07
Slope, First regression	0.06	-3.08	-1.06	-0.26
Slope, Second regression¹	-0.02	-0.03	-0.02	-0.09
Intersection between first and second regression, "knot"²	4.84	2.77	4.40	12.04

¹ The parameter used for the cluster analysis was actually the difference in slopes between the first and second regressions. To facilitate the interpretation, we show the parameter here as the slope of the second regression.
² This parameter is scaled in weeks.

ISSN: 1471-2474