A comparison of conventional and retrospective measures of change in symptoms after elective surgery

Table 1 Measuring change using the single items of the symptoms checklist

Method	Measuring change	Assessment points		Values*	Interpretation**
		Baseline	Follow-up
Conventional	Δ follow-up - baseline	"How much pain do you have?"	"How much pain do you have?"	-2 to +2	< 0 = Decrease
Retrospective A	Perceived change***		"How much pain do you have compared to the time before the intervention?"	-2 to +2	0 = No change
Retrospective B	Δ follow-up - recalled baseline		"How much pain do you have?" "How much pain did you have before the intervention?"	-2 to +2	> 0 = Increase

Notes:
* The values '-3, -2, +2, +3' were summarised to '-2' or '+2', in order to have a direct comparison between the methods
** For all types of measurements of change
*** -2 = strong worsening, -1 = mild worsening, 0 = no change, +1 = mild improvement, +2 = strong improvement

ISSN: 1477-7525