Research question | Outcome | Method of analysis | Results from the model data set | ||
---|---|---|---|---|---|
All respondents, n = 244 | Respondents answering ≥ 80%, n = 161 | Respondents answering all first 8 weeks, n = 133 | |||
5: Are there subgroups of patients? | Subgroups as clusters with low within-cluster variation and high between-cluster variation | A. Visual inspection based on plots of the course of pain in a graphical presentation where predefined criteria of directions in early and late phases, a qualitative approach | A: Illustrated in Table 5 | Not applied | Not applied |
B: Regression coefficients from spline regression (1 knot) derived from each subject were used in Wards’ hierarchical cluster analysis. Optionally this analysis was followed by K-means cluster analysis. Inspection of number of clusters based on the Calinski-Harabasz criterion and the criteria by Duda & Hart | B: Not done due to lack of degrees of freedom in spline regression of some individual subjects | B: 4 clusters suggested. | Not applied | ||
C: Wards’ hierarchical cluster analysis, optionally followed by K-means cluster analysis, applied directly on the weekly number of pain days for the first 8 weeks. Cluster criteria as in B. | Cluster 2: 79 | Percentage with short duration in these clusters: | C: 6 clusters suggested. Percentage with short duration the previous year in these clusters: | ||
C: Not applied | Cluster 1: 39 | Cluster 1: 58 | |||
Cluster 2: 49 | Cluster 3: 20 | ||||
Cluster 3: 85 | Cluster 4: 33 | ||||
Cluster 4: 37 | Cluster 5: 52 | ||||
C: Not applied | Cluster 6: 50 |