Table 2 INCIDENCE measures, variable- oriented hypotheses
Research question | Outcome | Method of analysis | Results from the model data set | |
|---|---|---|---|---|
All respondents, n = 244 | Highly compliant respondents, answering 80% (≥15/18 weeks), n = 161 | |||
3A: Incidence during the full study period for the whole sample and for subgroups | Recovery, i.e. reporting 0 or 1 pain days in 2 consecutive weeks = Event | Time to event analysis, with Kaplan Meier curves. Log rank test for differences between groups | Illustrated in Figure 2. Logrank test for effect of previous duration: p < 0.001 | Logrank testfor effect of previous duration: p = 0.002 |
3B: Incidence for the full study period in relation to the selected predictive variables | Recovery, i.e. reporting 0 or 1 pain days in 2 consecutive weeks = Event | Time to event analysis with a) Cox proportional hazard regression or b) Discrete hazard regression | Hazard ratio (HR) showing recovery, long duration reference, estimate and 95% CI: a) 1.95 (95% CI: 1.4-2.6), b) 2.03 (95% CI: 1.5-2.7). | Hazard ratio (HR) showing recovery, long duration reference, estimate and 95% CI: a) 1.95 (95% CI: 1.4-2.6), b) 2.03 (95% CI: 1.5-2.7). |
3 C: Time point for an event during the pain course | The time point of change in the course of pain = Event | Spline regressions, the event defined as the intersection of linear regression lines (the knot). | Short duration: knot at 4.5 weeks Long duration: knot at 5.9 weeks | Short duration: knot at 4.4 weeks Long duration: knot at 5.8 weeks |